Astronomical News

sunspot8

Junior Acolyte
Joined
Apr 3, 2004
Messages
61
Likes
0
Points
22
#31
Elffriend said:
I know I am hoping that Huygens will provide us with some spectacular information, but I fear in reality that the whole mission will fail beacuse someone didn't write the correct programme to send the info back, or some piece of equipment on the damn thing will fail.
As long as the first parachute deploys we should get lots of data, remember, it's an atmospheric probe really, if it survives hitting the surface, anything that happens thereafter is a bonus.
 

pintquaff

Devoted Cultist
Joined
Oct 9, 2003
Messages
243
Likes
6
Points
49
#33
rynner said:
Yee Har!

Finally found thecomet (Machholz) - pretty high, just a fuzzy blob in the bins. Couldn't see a tail though.
Luky you, saturn was high and bright in the sky, the rings looking quite spectacular i saw that in me scope but just could'nt find the comet. Oh well i dont really now what im doing when using me scope i just point and wiggle it a bit. :lol:
 

Mal_Adjusted

Justified & Ancient
Joined
Aug 6, 2003
Messages
2,262
Likes
25
Points
69
#34
The space hatchery where a star is born

Greets

The Scotsman
Fri 14 Jan 2005

The space hatchery where a star is born

JAMES REYNOLDS
SCIENCE CORRESPONDENT

ASTRONOMERS have discovered a hatchery for massive stars inside a dark cloud of cosmic dust.

Using a telescope that functions in a similar way to ultrasound, striking images of the vibrant, glowing "stella incubator cloud" called the Trifid Nebula were picked up.

NASA’s Spitzer Space Telescope - employing infrared radiation to home in on hot spots in the universe - found the so-called stella embryos which are invisible to optical telescopes because they are hidden deep in the cloud.

The new view gives astronomers a rare glimpse of the earliest stages of massive star formation - a time when developing stars are about to burst into existence.

Dr Jeonghee Rho, of the California Institute of Technology, who is the principle investigator of the observations, said: "Massive stars develop in very dark regions so quickly that it is hard to catch them forming.

"With Spitzer, it’s like having an ultrasound for stars. We see into dust cocoons and visualise how many embryos are in each of them."

Previous images of the Trifid Nebula, 5,400 light years away in the constellation Sagittarius, revealed four cores of dust.

Such cores are "incubators" where stars are born, but until now astronomers believed the cores inside Trifid were inactive.

When Spitzer set its sensors on the area, it found they had already begun to develop warm stella embryos.

Dr William Reach, of the Spitzer Science Centre, said: "By measuring the infra-red brightness, we can not only see the individual embryos, but determine their growth rate."

The Trifid Nebula is unique in that it is dominated by one, massive central star 300,000 years old. Radiation and winds emanating from the star have sculpted the Trifid cloud into its cavernous shape. These winds have also acted like shock waves to compress gas and dust into dark cores, whose gravity causes more material to fall inward until embryonic stars are formed. In time, the growing embryos will accumulate enough mass to ignite and explode out of their cores, the astronomers said.

Because the Trifid Nebula is home to just one massive star, it provides researchers with a rare chance to study an isolated family unit. All of the new-found stella embryos are descended from the nebula’s main star.

Dr Rho said: "Looking at the image, you know exactly where the embryos came from. We use their colours to determine how old they are. It’s like studying the family tree for a generation of stars."

The telescope discovered 30 embryonic stars in the Trifid Nebula’s four cores and dark clouds. Multiple embryos were discovered inside two massive cores, while a sole embryo was detected in each of the other two.

This is one of the first times that clusters of embryos have been observed in single cores at this early stage of stella development.
http://thescotsman.scotsman.com/index.cfm?id=46982005

mal
 

Timble2

Imaginary Person
Joined
Feb 9, 2003
Messages
5,762
Likes
1,266
Points
234
Location
In a Liminal Zone
#35
There may be yet more stuff out at the edge of the solar system (and why it won't be a invisible death star).

Solar system planetoids could be really far out
16:43 20 January 2005
NewScientist.com news service
Maggie McKee


Large planetoids may have formed hundreds of times farther from the Sun than previously thought, new calculations reveal. The work suggests a vast population of undetected icy bodies - like the recently discovered Sedna - may skirt the fringes of the solar system.

All of the objects in the solar system are thought to have condensed from a disc of dust and gas, starting about 4.5 billion years ago. But the process was far from orderly.

Observations of comets suggest some objects that formed in the disc - probably around the orbit of Saturn - were flung outwards within 100 million years. These scattered bodies are currently believed to make up a shell called the Oort Cloud that surrounds the solar system like a bubble.

The astronomers who discovered the large object Sedna in November 2003 think it may be one of these scattered objects. The planetoid is nearly the size of Pluto and about three times as far away.

But now, Alan Stern, director of space studies at the Southwest Research Institute in Boulder, Colorado, US, says Sedna may have formed at its current distance - or perhaps even farther out.

Cut-off point
This suggestion is based on computer simulations that assume the solar system's original gas and dust disc extended beyond the Kuiper Belt, a ring of icy objects beyond Neptune. This belt, first discovered in 1992, seems to cut off abruptly at 50 astronomical units (1 AU being the distance between the Sun and Earth). The cut-off delineates an apparent "edge" to the main portion of the solar system.

But when Stern tested models in which the disc extends out to 500 AU, those containing relatively high densities of material produced planetoids like Sedna in just 100 million years.

"The implication is that our solar system's planet-forming disc was really large," Stern says. "The outer edge of the Kuiper Belt may actually be the inner edge of a gap in the disc." Such a gap may have been carved out early in the solar system's history by a passing star or a Mars-sized planet being ejected into space.

Compact disc
He adds that dusty discs have been seen around other stars and tend to be big, with diameters of up to 3000 AU. "It's rare to find a compact disc like the Kuiper Belt," he told New Scientist. "Instead of trying to explain why ours is different, I thought: what if it isn't?"

Stern says Sedna was probably born in a circular orbit, possibly as far away as 500 AU. But he agrees with other astronomers who say that a passing star or unseen planet must have knocked it into its current, elongated trajectory, which stretches from about 75 to 900 AU.

The simulations suggest many hundreds of objects like Sedna may have formed at those distances. Stern admits that finding the extremely faint objects will be incredibly hard, but says his theory would be bolstered if deep surveys turned up far-distant objects in circular orbits.

But Renu Malhotra, an astronomer at the University of Arizona in Tucson, US, has some reservations about the work. She says dust thins out toward the outer edges of a disc, so building distant objects as big as Sedna within the age of the solar system "is pretty hard even in very large discs".

And quick timing is crucial. If a passing star did cause Sedna's extreme orbit, that suggests the planetoid must have formed in solar system's first 100 million years - the time it took to assemble the Oort Cloud. If the star passed by after that time, it would have disturbed and dissipated the cloud.

She also questions Stern's suggestion that other planetoids would lie in circular orbits. Any passing star that disturbed Sedna's orbit would probably also affect its siblings, she told New Scientist. But she says the discovery of the Kuiper Belt's edge at 50 AU in recent years has puzzled theorists and says Stern's paper "suggests we should keep our minds open to the possibility that what we're seeing is indeed a gap".

Journal reference: Astronomical Journal (vol 129, p 526)
New Scientist
 

Mal_Adjusted

Justified & Ancient
Joined
Aug 6, 2003
Messages
2,262
Likes
25
Points
69
#36
U.S. to Cut Funds to Fix Hubble Telescope-Source

Greets

U.S. to Cut Funds to Fix Hubble Telescope-Source
Sun Jan 23, 2005 11:28 AM ET

By Caren Bohan and Deborah Zabarenko

WASHINGTON (Reuters) - The Bush administration plans to propose cuts in funds to fix the aging Hubble Space Telescope, a U.S. official said on Saturday, as the head of the telescope project said he hoped Congress would approve money for repairs.

The 14-year-old orbiting observatory has produced path-breaking science and created a popular appetite for its spectacular images of the cosmos. It is due for a servicing mission to replace its batteries and the gyroscopes that keep it steady, and to upgrade some of its equipment.

The repair mission has been on hold since the Feb. 1, 2003, disintegration of shuttle Columbia. Debate in the astronautical community has raged over whether to send robots or astronauts to fix the telescope, or whether to fix it at all.

Reports on the Web site www.Space.com and in The Washington Post said the Bush administration plans to scrap any Hubble repair mission and eliminate those funds from the proposed budget for fiscal 2006. A U.S. official confirmed those reports.

Bush will release his fiscal 2006 budget proposal on Feb. 7.

Speaking on condition of anonymity, the U.S. official told Reuters the estimated cost of a robotic repair was $2 billion and one feasibility study gave it an 80 percent chance of failure.

"Hubble is in year 14 of a planned 15-year mission," the official said. "Trying to send a robotic mission to extend that time period would be a $2 billion gamble with taxpayer dollars where the odds are 80-20 that it would fail."

The official also noted that a National Academy of Sciences panel concluded a shuttle repair mission would have a greater chance of success, but said outgoing NASA Administrator Sean O'Keefe has ruled this out as too risky for astronauts.

RISK FOR ASTRONAUTS?

Steve Beckwith, head of the Space Telescope Science Institute that manages Hubble, said he was surprised by the reports, and questioned the relative risk of sending astronauts to the orbiting telescope.

Beckwith said the National Academy of Sciences report found an astronaut mission to fix Hubble would be no riskier than a shuttle mission to the International Space Station.

"I understand that they plan to fly between 25 and 30 flights to complete the space station ... so I would hope that if NASA plans to continue flying the space shuttle, that one of those flights can go and service Hubble, because that will have a very high probability of mission success," Beckwith said.

He discounted the unnamed U.S. official's assessment that the telescope is nearing the end of its useful life.

"Hubble could easily live well beyond 20 years, and furthermore, the National Academy committee stated that the future discoveries from Hubble over the next five years are every bit as bright as the discoveries we've seen in the past," Beckwith said.

"I'm hoping that our lawmakers will see the value of Hubble and make it a priority in NASA's budget," he said.

Sen. Barbara Mikulski, a Maryland Democrat who has championed Hubble and other NASA space science projects, said in a statement on Friday: "It is essential that we have a safe and reliable servicing mission to Hubble ... I led the fight to add $300 million to NASA's budget last year for a Hubble servicing mission, and I plan to lead the fight again this year."

NASA's O'Keefe announced plans to ax the Hubble repair mission a year ago, just days after President Bush unveiled a plan to send humans back to the Moon and eventually to Mars. Public outcry and congressional pressure prompted a reconsideration.
http://www.reuters.com/newsArticle.jhtml?type=scienceNews&storyID=7402010

mal
 

Mal_Adjusted

Justified & Ancient
Joined
Aug 6, 2003
Messages
2,262
Likes
25
Points
69
#37
Blazing speed: The fastest stuff in the universe

Greets

Blazing speed: The fastest stuff in the universe

By Robert Roy Britt
SPACE.comexternal link
Tuesday, January 18, 2005 Posted: 11:05 AM EST (1605 GMT)



(SPACE.com) -- If you're light, it's fairly easy to travel at your own speed -- that is to say 186,282 miles per second or 299,800 kilometers per second.

But if you are matter, then it's another matter altogether.

Nothing we know of zips along more quickly than light. Einstein, nearly 100 years ago, said it's not possible. For us, the speed limit makes strange sense: Go faster than light, and you could return before you've left, become your own grandpa, or other perform other leaps of cosmic logic.

Fast forward a century. Astronomers are now measuring stuff -- material, matter, things -- that moves at so close to the speed of light you might think it'd make Einstein a bit nervous. His theory of relativity appears not to be endangered by the blazing speeds, though.

Among thee speed demons of the universe are Jupiter-sized blobs of hot gas embedded in streams of material ejected from hyperactive galaxies known as blazars. Last week at a meeting here of the American Astronomical Society, scientists announced they had measured blobs in blazar jets screaming through space at 99.9 percent of light-speed.

"This tells us that the physical processes at the cores of these galaxies ... are extremely energetic and are capable of propelling matter very close to the absolute cosmic speed limit," said Glenn Piner of Whittier College in Whittier, California.

Ponder the power of the fast moving superheated gas, known as plasma:

"To accelerate a bowling ball to the speed newly measured in these blazars would require all the energy produced in the world for an entire week," Piner said. "And the blobs of plasma in these jets are at least as massive as a large planet."

The blazar jets are running around the universe in some fast company. Slightly faster, in fact.

In another study presented at the meeting, ultra high-energy cosmic rays thought to originate in a collision of galaxy clusters are slamming into Earth's atmosphere at more than 99.9 percent of the speed of light. Measurements put the number at 99.9 followed by 19 more nines -- about as close to light-speed as you can get without splitting hairs.

The particles are not light, but actual matter. They are tiny, thought to be mostly protons, but the energy that motivates them is similarly fantastic, and the mechanisms may be intertwined.

Scientists still don't know the exact mechanisms involved in accelerating matter to such high speeds, however. In the case of a blazars, it appears a black hole is involved. Anchoring an active galaxy, a supermassive black hole draws gas inward. Some is swallowed, yet some is simply accelerated and then ejected in high-speed jets along the galaxy's axis of rotation. Intense, twisted magnetic fields may play a role.

Some ultra high-energy cosmic rays might originate in blazar jets, Piner told SPACE.com. But other phenomena may serve as particle accelerators in space, such as merging galaxies or colliding black holes.

Piner and his colleagues observed three blazars, known from previous observations to be super speedy, using the National Science Foundation's Very Long Baseline Array radio observatory.

The results confirm the previous work and pin down the speeds with greater accuracy. The phenomenal pace of the plasma blobs looks to have reached a limit.

"All the results from blazar jet observations are in agreement with Einstein's Theory of Special Relativity," Piner said. "The jets are accelerated right up to the edge of the speed-of-light barrier but not beyond, even though these are some of the most efficient accelerators in the universe."
http://www.cnn.com/2005/TECH/space/01/18/universe.speed/index.html

mal
 

Mal_Adjusted

Justified & Ancient
Joined
Aug 6, 2003
Messages
2,262
Likes
25
Points
69
#38
Asteroid named after ‘Hitchhiker’ humorist

Greets

Asteroid named
after ‘Hitchhiker’ humorist
Late British sci-fi author
honored after cosmic campaign
Douglas Adams, was the author of "The Hitchhiker's Guide to the Galaxy," a cult science-fiction comedy. He died suddenly after a heart attack in 2001 at the age of 49.
By Alan Boyle
Science editor
MSNBC
Updated: 8:55 p.m. ET Jan. 25, 2005

The week he died, science-fiction humorist Douglas Adams was honored with an asteroid named after one of the characters from his classic "Hitchhiker's Guide to the Galaxy." Now, almost four years later, Adams has his own name in the heavens as well — thanks to a campaign in which MSNBC.com played a part.

advertisement
Asteroid Douglasadams was among the 71 newly named celestial objects announced Tuesday by the International Astronomical Union's Minor Planet Center in Cambridge, Mass. Other honorees range from Ball Aerospace and the city of Las Vegas to the sometimes-overlooked co-discoverer of the DNA double helix, Rosalind Franklin.

But Adams' asteroid should hold special appeal for fans of science fiction and pop culture: His "Hitchhiker" saga, which traces the adventures of a motley interplanetary crew after Earth is destroyed to make way for a hyperspace bypass, started out as a BBC radio comedy. Eventually, the tale inspired a five-novel "trilogy" as well as a TV series, and a long-simmering movie version is due for release in May.

Asteroid tributes
When Adams died of a heart attack in 2001, at the age of 49, tributes came in from around the world — but one of the biggest tributes was actually announced just days before his death: the naming of an asteroid after Arthur Dent, the Earthling at the center of the "Hitchhiker" story.

Through the years, about 12,000 asteroids have been given proper names by the IAU's Committee on Small Body Nomenclature — including fictional characters as well as mythological names (Ceres and Quaoar) and real-life personages (Lincoln and Elvis). The names are traditionally proposed by a particular asteroid's discoverer. For example, the "Arthurdent" asteroid was so named at the suggestion of the man who actually found it, German astronomer Felix Hormuth.

But there's a backlog of not-yet-named asteroids, and so the discoverers occasionally take requests. That's where MSNBC.com enters into the story of Asteroid Douglasadams.

What's in a name?
In August 2003, we reported on the naming of seven asteroids after Columbia's fallen astronauts, and solicited readers' suggestions for future asteroid names. One reader, Sean Ferris, put Adams' name forward — and we took it a step further by seeing if there was an asteroid particularly fitting for the honor.

One prospect stood out: an asteroid given the provisional designation 2001 DA42, discovered by the Lincoln Near Earth Asteroid Research project, or LINEAR. It's a relatively unremarkable space rock, orbiting 224 million miles (358 million kilometers) from the sun in the main asteroid belt, between Mars and Jupiter. But its name held triple significance.

Not only did it memorialize the year of Adams' death (2001) and his initials (DA), but it also referenced the number 42 — which is absurdly meaningful in the "Hitchhiker" saga as the "answer to the Ultimate Question." (The problem was, no one ever knew precisely what the Ultimate Question was.)

We proposed the name to Brian Marsden, the Minor Planet Center's director and the secretary for the naming committee — and Marsden was tickled by the idea. "This was sort of made for him, wasn't it?" he recalled Tuesday.

Long process

It took almost a year and a half for the proposal to make its way through the relevant committees at LINEAR and the IAU — but Marsden finally issued the citations for Douglasadams and the 70 other named asteroids on Tuesday in Minor Planet Circular 53469.

Looking back, Marsden said the asteroid-naming process isn't always as fun as you might think. "It ought to be," he said. "But at times it can be very frustrating."


Some names had to be rejected this time around because they took the form of unpronounceable acronyms, running afoul of the IAU's rules. Another rule is that asteroids shouldn't be named after controversial historical figures such as Stalin or Hitler. That sparked a debate over a proposal to name an asteroid (1998 OU7) after the Prussian military strategist Carl von Clausewitz, Marsden said.

In the end, Asteroid Clausewitz was victorious. "It was decided he wasn't in the same class as Hitler," Marsden said.

Among the other notables on Tuesday's list:


* Rosfranklin (1997 PE6): Chemist Rosalind Franklin's work was instrumental in identifying the molecular structure of DNA, but she died without receiving due credit for her contribution.

* Ballaero (1925 BA): Recognizes Ball Aerospace and Technology Corp., which has contributed to the development of the Hubble and Spitzer space telescopes, the Deep Impact probe and other spacecraft.

* NEAT (2001 SS272): Named after the Near Earth Asteroid Tracking program. Other asteroids honor the Rome Planetarium in Italy and Kharkiv National University in Kiev.

* Wollstonecraft (2004 DA): Honors 18th-century feminist Mary Wollstonecraft. Other asteroids recognize theologians Roger Bacon and Thomas Woolston, and the recently appointed U.S. poet laureate, Ted Kooser.

* Las Vegas (2001 LV6): A celestial tribute to the Nevada city in honor of its centennial this year. Among other places newly honored by asteroid names are Sewanee in Tennessee, Bora-Bora and the Lithuanian city of Kaunas.
http://www.msnbc.msn.com/id/6867061/

mal
 

Rubyait

Justified & Ancient
Joined
Sep 10, 2004
Messages
1,185
Likes
6
Points
54
#39
Ok we'ver had magnetic beams but now.....


Solar super-sail could reach Mars in a month


A LICK of paint could help a spacecraft powered by a solar sail get from Earth to Mars in just one month, seven times faster than the craft that took the rovers Spirit and Opportunity to the Red Planet.

Gregory Benford of the University of California, Irvine, and his brother James, who runs aerospace research firm Microwave Sciences in Lafayette, California, envisage beaming microwave energy up from Earth to boil off volatile molecules from a specially formulated paint applied to the sail. The recoil of the molecules as they streamed off the sail would give it a significant kick that would help the craft on its way. "It's a different way of thinking about propulsion," Gregory Benford says. "We leave the engine on the ground."
Solar sails are in essence nothing more than giant mirrors. Photons of light from the sun bounce off the surface, giving the sail a gentle push. It was while developing a solar sail five years ago that the brothers stumbled upon their idea for enhancing the effect.
The pair were testing a very thin carbon-mesh sail by firing microwaves at it. To their surprise, the sail experienced a force several times stronger than they expected. They eventually worked out that the heat from the microwave beam was causing carbon monoxide gas to escape from the sail's surface, and that the recoil from the emerging gas molecules was giving the sail an extra push.

In a forthcoming issue of the journal Acta Astronautica, the Benfords explain how a sail covered with a paint designed to emit gas when it is heated might propel a spacecraft to Mars in just a month. A rocket would take the craft to low-Earth orbit, 300 kilometres up. After the craft unfurls a solar sail 100 metres across, a transmitter on Earth would fire microwaves at it to heat it up. The Benfords calculate a one-hour burst of microwaves could accelerate the craft to 60 kilometres per second, faster than any interplanetary spacecraft to date.

The feat would require a 60-megawatt microwave beam with a similar diameter to the sail. It would also have to be capable of tracking the craft as it accelerated away. But this power level could not be delivered by any existing microwave transmission system. The deep-space communications network that NASA uses to communicate with Mars rovers and the Cassini probe now orbiting Saturn can only manage half a megawatt. The Benfords say the power could be ramped up in future and hope to persuade NASA to consider doing this as part of a future upgrade to the network.

A further challenge is how to formulate the evaporating paint. The ideal material would lock up large amounts of a light gas like hydrogen and only release it at very high temperature, when the high speed of the gas molecules would maximise the recoil. Ideally all the paint would boil away, leaving a micrometre-thin sail to continue the voyage to Mars.

"It's pretty cool," says Geoffrey Landis, a physicist at NASA's Glenn Research Center in Cleveland, Ohio. "There are obviously some details to be worked out here, but in a fundamental way the idea makes sense."


http://www.newscientist.com/channel/spa ... 524846.500
 

rynner2

Great Old One
Joined
Aug 7, 2001
Messages
55,246
Likes
8,961
Points
284
#40
sjoh9 said:
A further challenge is how to formulate the evaporating paint. The ideal material would lock up large amounts of a light gas like hydrogen and only release it at very high temperature, when the high speed of the gas molecules would maximise the recoil. Ideally all the paint would boil away, leaving a micrometre-thin sail to continue the voyage to Mars.
http://www.newscientist.com/channel/spa ... 524846.500
Hmm... Presumably it would still have to carry chemical rockets to get in to Mars orbit (or whatever).

A normal minimum energy transfer orbit requires the probe to accelerate to keep up with Mars, but a fast transfer orbit, like this 'sail' idea involves, might involve having to decelerate. Either way, you'd need fuel, unless you send another microwave transmitter to Mars first!
 

Rubyait

Justified & Ancient
Joined
Sep 10, 2004
Messages
1,185
Likes
6
Points
54
#41
rynner said:
sjoh9 said:
A further challenge is how to formulate the evaporating paint. The ideal material would lock up large amounts of a light gas like hydrogen and only release it at very high temperature, when the high speed of the gas molecules would maximise the recoil. Ideally all the paint would boil away, leaving a micrometre-thin sail to continue the voyage to Mars.
http://www.newscientist.com/channel/spa ... 524846.500
Hmm... Presumably it would still have to carry chemical rockets to get in to Mars orbit (or whatever).

A normal minimum energy transfer orbit requires the probe to accelerate to keep up with Mars, but a fast transfer orbit, like this 'sail' idea involves, might involve having to decelerate. Either way, you'd need fuel, unless you send another microwave transmitter to Mars first!

"It's pretty cool," says Geoffrey Landis, a physicist at NASA's Glenn Research Center in Cleveland, Ohio. "There are obviously some details to be worked out here, but in a fundamental way the idea makes sense."

Yup like stopping! Well i guess it would have to carry extra fuel to slow down, stop and alter direction.It could be another flyby....oh here comes Mars.....and there it goes!
 

Anome

Bibliomancer
Joined
May 23, 2002
Messages
5,490
Likes
480
Points
164
Location
Left, and to the Back
#42
You slow down with gravitational capture, and maybe aerobraking.

By the way, interesting to see Greg Benford involved. And the similarities between this and the solar sail used in Rocheworld by Robert L. Forward.
 

rynner2

Great Old One
Joined
Aug 7, 2001
Messages
55,246
Likes
8,961
Points
284
#43
anome said:
You slow down with gravitational capture, and maybe aerobraking.
Pure gravitational capture is a very difficult trick to pull off. In the case of satellites that are thought to be captured asteroids (like those of Mars), most astronomers think a third body must have been involved.

And aerobraking in Mars thin atmosphere can be problematical, especially if you're coming in fast.
 

Mal_Adjusted

Justified & Ancient
Joined
Aug 6, 2003
Messages
2,262
Likes
25
Points
69
#44
Scientists Find Missing Matter

Greets

Scientists Find Missing Matter

By Amit Asaravala

02:00 AM Feb. 03, 2005 PT

For years, astrophysicists have been boggled by the fact that the grand sum of all the known "normal" matter in the universe -- that which makes up the stars, the Earth and even our own bodies -- only amounts to half of what should exist based on computer simulations.

Given that multiple simulations have continually yielded the same result, they theorized that the rest of the normal matter, known as baryons, must be hiding somewhere in the space between galaxies. However, they haven't had much evidence to support the theory until now.

Astrophysicists used the Chandra X-ray Observatory to detect traces of 'normal' matter known as baryons floating between galaxies. The intergalactic baryons are too hot and too diffuse to be detected by optical telescopes.

A new study conducted with the help of the Earth-orbiting Chandra X-ray Observatory has revealed the existence of baryons in at least two giant, intergalactic clouds of super-hot gas 150 million and 380 million light-years from our planet.

The study, which appears in the Feb. 3 issue of the journal Nature, shows how certain wavelengths of X-rays emitted from a distant galaxy in the constellation Ursa Major are being absorbed by the two clouds. The absorption pattern, as detected by Chandra, is consistent with interference caused by carbon, neon, nitrogen and oxygen ions -- in other words, baryons.

When the study's authors extended the number of baryons in the two clouds to account for the volume of all the intergalactic clouds in the universe, the resulting figure equaled that of the missing matter from their computer simulations.

"Assuming that what we see is a standard portion of the universe, we extrapolated the data and derived the volume density (of baryons in all the clouds) -- and it's consistent with 50 percent," said astronomer Fabrizio Nicastro, of the Harvard-Smithsonian Center for Astrophysics and lead author of the study.

The findings extend the reach of a similar study published by Nicastro and his colleagues in 2003. In that research, the scientists discovered baryons between galaxies in the Local Group, a selection of 30 galaxies near to, and including, our own Milky Way. But astrophysicists weren't sure at the time if the data would apply to intergalactic spaces outside the Local Group, so they kept searching.

Even with the new evidence, they plan to keep looking, said Nicastro. That's because intergalactic baryons not only fill a gap in scientists' understanding of the universe, but they may also lead to a better understanding of "dark matter," a mysterious and unseen form of matter that has so far only been detected by the gravitational pull it exerts on other bodies in the universe.

"If we are right, each single one of these filaments is connected to a cloud of dark matter," said Nicastro. "If there wasn't dark matter there, or something with strong gravity that pulled on the matter in these filaments, we wouldn't have galaxies or filaments." Rather, the baryons would be pulled into galaxies and the galaxies into each other.

Whereas baryons account for 4 percent of the total matter and energy in the universe, dark matter is thought to make up 23 percent. The remaining 73 percent of the so-called matter-energy budget consists of what scientists call "dark energy." This energy acts like an anti-gravitational force that, in theory, is causing the universe to expand rather than contract.

Nicastro and his team used the Chandra X-ray Observatory to search for traces of the baryons because X-ray light from space does not reach Earth-based telescopes. They are too hot and too diffuse in the intergalactic clouds to be detected by optical telescopes.

Chandra was released from the space shuttle Columbia in 1999.

NASA is currently developing a series of four satellites known as Constellation-X that would enhance astronomers' ability to study baryons, dark matter and dark energy. It is expected to launch no sooner than 2015.

End of story
http://www.wired.com/news/space/0,2697,66487,00.html

mal
 

sunsplash1

Justified & Ancient
Joined
Jan 9, 2004
Messages
1,316
Likes
8
Points
54
#45
anome said:
You slow down with gravitational capture, and maybe aerobraking.

By the way, interesting to see Greg Benford involved. And the similarities between this and the solar sail used in Rocheworld by Robert L. Forward.
Noticed the similiarity meself...
Aerobraking... might be a bit 'messy'
 

Rubyait

Justified & Ancient
Joined
Sep 10, 2004
Messages
1,185
Likes
6
Points
54
#46
Mars Express 'divining rod' to deploy



A "divining rod" to search for underground water on Mars will be deployed on Europe's Mars Express spacecraft early this spring, after a year of delays. The new deployment date for the radar antenna - to be announced within days - is likely to fall in April 2005.

Mars Advanced Radar for Subsurface and Ionosphere Sounding - or MARSIS - consists of wires strung inside three long fibreglass tubes. These will seek water - which might provide oases for life - as deep as several kilometres below the Martian surface.

The tubes, currently folded and stored onboard Mars Express, were originally scheduled for deployment in April 2004. But mission managers postponed the date when computer simulations showed that a similar antenna planned for launch later in 2005 could swing back and damage the spacecraft upon deployment. So the MARSIS team spent several months last autumn running vacuum-chamber tests of the antenna material and modelling the deployment on computers.

The research now reveals that there is indeed a "high likelihood" that one of the three tubes "will whip back and strike the spacecraft", says MARSIS manager William Johnson of NASA's Jet Propulsion Laboratory in Pasadena, California, US. "But the antenna is quite light and flexible - about the diameter and strength of a toilet paper tube," he adds. "So the impact would most likely not cause any damage."

Centre of gravity
More worrisome than a direct hit is the small chance that a tube could get caught on the spacecraft or tangled up with itself. In that case, MARSIS would not work and could leave the spacecraft with a new and unanticipated centre of gravity, forcing mission managers to tweak how they control the probe. "There is some risk attached to this," Johnson told New Scientist.

But officials at the European Space Agency (ESA), which manages Mars Express, have apparently decided it is worth the risk and will soon announce a deployment date - anticipated for April 2005. They had earlier resolved to wait until at least March 2005 for deployment, when the spacecraft will spend less time swinging through the planet's shadow during each orbit. Such an "eclipse" requires Mars Express to rely on its battery power, which has the potential to fail.

The MARSIS experiment's own requirements also affect its deployment. The radar rods must be close to the planet to function - limiting its use to just 28 minutes in each 6-hour elliptical orbit. And it works best over the night side of Mars. That half-hour operational window is maximised in April, May and June, when the spacecraft's close passes occur over the planet's darkened northern latitudes.

Priority data
The three sections of the antenna - two of which are a remarkable 20 metres long, while the third measures 7 m - will each be deployed separately over the course of about two weeks. MARSIS team members will then have a further two weeks to organise their experiment in a "commissioning" phase, taking priority over the spacecraft's other six instruments in sending data back to Earth.

But the experiment's success is anything but certain. MARSIS works by sending out pulses of radio waves and analysing the time delay and strength of the waves that return. The theory is that some of the longer wavelength waves may penetrate Mars's porous rocky soil and bounce back when they encounter a transition between two materials with different electrical properties, such as an underground pool of water.

Similar radar experiments have been done on Earth, but over ice, where "usually you sort of know what to expect", says Johnson. That is not the case with Mars. "We don't even know if we're going to get an echo from the subsurface," he says. Johnson adds that any signal the team does get will be difficult to interpret, as waves that bounce back from the surface at large angles can mimic those that come from underground.

"It may be a dud. There may be nothing there," Johnson says. "But MARSIS has fantastic potential. It may tell us more than any other combination of instruments we've ever sent to Mars."

http://www.newscientist.com/article.ns?id=dn6974
 

floyd23a1

Devoted Cultist
Joined
Jul 24, 2002
Messages
102
Likes
2
Points
49
#47
I'm rather upset about this :x Surely Hubble's got many more years service left.

Nasa plans to bring down Hubble

The Hubble Space Telescope and a mission to explore Jupiter's moons look to be the biggest casualties in Nasa's 2006 budget plans outlined on Monday. Under the proposals, a mission to service Hubble would be scrapped and the telescope left to die in orbit.

Nasa's total budget would rise 2.4% over 2005 to about $16.5bn, but only $93m would be spent on Hubble.

About $75m of that will be aimed at bringing the observatory down to Earth safely, officials have announced.

The US space agency (Nasa) has fared better than many government agencies in President George Bush's 2006 budget request. But the White House is not seeking as much money for the space agency as had previously been planned - and that is bad news for Hubble.

"Hubble is a spacecraft that is dying," Nasa comptroller Steve Isakowitz said at a briefing in advance of the budget's release.

"We have decided that the risks associated with the Hubble servicing at this time don't merit going forward."

This will infuriate Hubble supporters who believe the telescope still has good years of science observation ahead of it - provided it is serviced.

They will hope Congress, which has to approve the budget, will insist on money being found to save the orbiting observatory.

"There is a long history of Congress putting into the Nasa budget what Nasa or the executive branch don't like and have taken out," said Rodger Thompson, a University of Arizona astronomer and principal investigator of the Near-Infrared Camera and Multi-Object Spectrometer (Nicmos), which astronauts placed on Hubble in 1997.

"The Gravity Probe-B was cancelled many times and each time was put back in the budget by Congress.

"There is going to be a large debate about this and there is a significant chance that funding for Hubble will be returned to the budget," he told the BBC News website.

The multi-billion dollar Jupiter Icy Moons Orbiter (Jimo) mission was to have been launched in about 2015 as a demonstration for the Project Prometheus nuclear power and propulsion initiative.

It would have gone into orbit around the giant planet and its moons, possibly putting landers on their surfaces in much the same way as Cassini has done with Huygens on Titan.
Source

Cheers

Floyd
 

Mal_Adjusted

Justified & Ancient
Joined
Aug 6, 2003
Messages
2,262
Likes
25
Points
69
#48
Greets

Bubble bursts for pioneer Hubble

Tim Radford, science editor
Tuesday February 8, 2005
The Guardian

It watched the broken pieces of a comet crash, one after another, into the clouds of Jupiter. It peered at a dark patch of sky no bigger than a grain of sand at arm's length for 150 orbits and spotted so many galaxies that cosmologists had to double their estimates of the size of the universe.

It confirmed the existence of black holes and caught stars in the act of formation. Its astonishing images have become the stuff of poster art and gallery displays.

But the Hubble space telescope, which orbits the planet 360 miles above the clouds and atmosphere, could soon plunge to Earth and perish in a fireball over the Pacific Ocean.

Nasa chiefs last night confirmed that their budget rise for 2006 would not be enough to cover the cost of a repair mission to the 14-year-old instrument. The US space agency will have $16.5bn (£8.9bn) to spend, but only $75m to spend on Hubble. This is just about enough for a robot spacecraft that could rendezvous with the world's most famous telescope and nudge it back into the deadly embrace of the planet's gravitational field.

The decision is likely to infuriate astronomers: last year the US National Academy of Sciences urged a final visit by a team of astronauts to Hubble, to replace parts likely to wear out in a year or two.

Hubble was launched in a blaze of glory that turned to tragicomedy: when the telescope returned its first snaps of the heavens, researchers discovered faulty curvature in its 2.4 metre mirror.

In 1993, astronauts went aloft and fitted the equivalent of spectacles, and suddenly Hubble revealed its astonishing capacity: it could resolve galaxies 13bn light years away, at the edge of space and time.

But techniques in Earth-based astronomy advanced, and British astronomers now use a telescope in Hawaii twice as powerful as Hubble.

Nasa began looking for ways to save money. "We have been as eager as the Congress to try to save the Hubble, but at the end of the day what we're trying to save is the science related to Hubble," said Nasa's controller, Steve Isakowitz.
http://www.guardian.co.uk/life/science/story/0,12996,1408049,00.html

mal
 

Mal_Adjusted

Justified & Ancient
Joined
Aug 6, 2003
Messages
2,262
Likes
25
Points
69
#49
Star Wants Out of Milky Way

Greets

Star Wants Out of Milky Way

By Amit Asaravala

02:00 AM Feb. 09, 2005 PT

A star three times bigger than the sun has been seen fleeing our galaxy at over 1.5 million mph, according to astronomers at the Harvard-Smithsonian Center for Astrophysics.

The gravitational pull of a black hole thought to exist there is likely responsible for the extreme velocity of the star, swinging it around the center of the Milky Way. A companion star may once have traveled with the speeding star and contributed to its velocity before being trapped by the black hole.

Planets are thought to be formed from disks of dust and gas, like the one shown orbiting a brown dwarf star in this artist's rendering. Astronomers have announced the discovery of such a disk around the smallest brown dwarf yet to be found.Astronomers have discovered a star traveling over 1.5 million mph -- fast enough to escape the gravitational pull of the Milky Way galaxy. This image from the Sloan Digital Sky Survey shows an area of the sky one-fiftieth the size of the full moon (the arrow marks the star).


The first-of-its-kind finding not only confirms an earlier theory about the existence of such speeding stars, but also reinforces the notion that the Milky Way spins around a black hole, said Warren Brown, a postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics and a member of the team that discovered the star.

"It's a hypothesis on our part, but there's no other good way of explaining a star moving this fast," said Brown. "The only way to get velocity that high on a star is you have to interact with something more extreme, like a black hole."

The star is currently 180,000 light years from Earth. Based on its trajectory, the astronomers believe it will exit the Milky Way and scream through miles of empty space until it burns out.

"The space between galaxies is extremely empty," said Brown. "It will have a nice view of the Milky Way for a while. At some point, the night sky from that star would look like a couple big galaxies. But everything else would be pure black."
http://www.wired.com/news/space/0,2697,66542,00.html

mal
 

Mighty_Emperor

Beloved of Ra
Joined
Aug 18, 2002
Messages
19,431
Likes
113
Points
129
#50
Another report on this:

Outcast star quits the Milky Way

Wednesday, February 9, 2005 Posted: 0629 GMT (1429 HKT)



WASHINGTON (Reuters) -- A star is zooming out of the Milky Way, the first seen escaping the galaxy, astronomers have reported.

The so-called "outcast star" is heading for the emptiness of intergalactic space after being ejected from the heart of the Milky Way following a close encounter with a black hole, said Warren Brown, an astronomer at the Harvard-Smithsonian Center for Astrophysics.

It is going so fast -- over 1.5 million mph (2.4 million km/h) -- that astronomers believe it was lobbed out of the galaxy by the tremendous force of a black hole thought to sit at the Milky Way's center.

That speed is about twice the velocity needed to escape the galaxy's grip, Brown said by telephone.

"We have never before seen a star moving fast enough to completely escape the confines of our galaxy," he said.

"We're tempted to call it the outcast star because it was forcefully tossed from its home."

The star used to be part of a binary pair, waltzing with its companion star close to the rim of the black hole.

In this case, "close" is a relative term; the actual distance was probably about 50 times the 93 million mile (150 million km) distance between Earth and the sun.

As the two stars twirled around each other, they were pulled faster and faster toward the edge of the black hole, one of those monster drains in space whose gravity is so strong that nothing, not even light, can escape once it is consumed.

While the companion star was captured by the black hole, the outcast continued on its whirling path around its edge.

Objects go faster the closer they get to black holes and this star was probably moving at extraordinary speed, perhaps as high as 20 million mph (32 million km/h).

That very speed, coupled with the speed of its twirling, sent the star zooming toward the edge of the Milky Way and beyond.

At this point, the outcast is about 180,000 light-years from Earth, in an outer region of the galaxy known as the halo.

A light-year is about 6 trillion miles (10 trillion km), the distance light travels in a year.


-----------------
Copyright 2005 Reuters.
Source
 
A

Anonymous

Guest
#51
LIFE ON MARS!!!!

http://www.space.com/scienceastronomy/mars_life_050216.html


Exclusive: NASA Researchers Claim Evidence of Present Life on Mars
By Brian Berger
Space News Staff Writer
posted: 16 February 2005
02:09 pm ET


WASHINGTON -- A pair of NASA scientists told a group of space officials at a private meeting here Sunday that they have found strong evidence that life may exist today on Mars, hidden away in caves and sustained by pockets of water.



The scientists, Carol Stoker and Larry Lemke of NASA’s Ames Research Center in Silicon Valley, told the group that they have submitted their findings to the journal Nature for publication in May, and their paper currently is being peer reviewed.



What Stoker and Lemke have found, according to several attendees of the private meeting, is not direct proof of life on Mars, but methane signatures and other signs of possible biological activity remarkably similar to those recently discovered in caves here on Earth.



Stoker and other researchers have long theorized that the Martian subsurface could harbor biological organisms that have developed unusual strategies for existing in extreme environments. That suspicion led Stoker and a team of U.S. and Spanish researchers in 2003 to southwestern Spain to search for subsurface life near the Rio Tinto river—so-called because of its reddish tint—the product of iron being dissolved in its highly acidic water.



Stoker did not respond to messages left Tuesday on her voice mail at Ames.



Stoker told SPACE.com in 2003, weeks before leading the expedition to southwestern Spain, that by studying the very acidic Rio Tinto, she and other scientists hoped to characterize the potential for a “chemical bioreactor” in the subsurface – an underground microbial ecosystem of sorts that might well control the chemistry of the surface environment.



Making such a discovery at Rio Tinto, Stoker said in 2003, would mean uncovering a new, previously uncharacterized metabolic strategy for living in the subsurface. “For that reason, the search for life in the Rio Tinto is a good analog for searching for life on Mars,” she said.



Stoker told her private audience Sunday evening that by comparing discoveries made at Rio Tinto with data collected by ground-based telescopes and orbiting spacecraft, including the European Space Agency’s Mars Express, she and Lemke have made a very a strong case that life exists below Mars’ surface.



The two scientists, according to sources at the Sunday meeting, based their case in part on Mars’ fluctuating methane signatures that could be a sign of an active underground biosphere and nearby surface concentrations of the sulfate jarosite, a mineral salt found on Earth in hot springs and other acidic bodies of water like Rio Tinto that have been found to harbor life despite their inhospitable environments.



One of NASA’s Mars Exploration Rovers, Opportunity, bolstered the case for water on Mars when it discovered jarosite and other mineral salts on a rocky outcropping in Merdiani Planum, the intrepid rover’s landing site chosen because scientists believe the area was once covered by salty sea.



Stoker and Lemke’s research could lead the search for Martian biology underground, where standing water would help account for the curious methane signatures the two have been analyzing.



“They are desperate to find out what could be producing the methane,” one attendee told Space News. “Their answer is drill, drill, drill.”



NASA has no firm plans for sending a drill-equipped lander to Mars, but the agency is planning to launch a powerful new rover in 2009 that could help shed additional light on Stoker and Lemke’s intriguing findings. Dubbed the Mars Science Laboratory, the nuclear-powered rover will range farther than any of its predecessors and will be carrying an advanced mass spectrometer to sniff out methane with greater sensitivity than any instrument flown to date.



In 1996 a team of NASA and Stanford University researchers created a stir when they published findings that meteorites recovered from the Allen Hills region of Antarctica contained evidence of possible past life on Mars. Those findings remain controversial, with many researchers unconvinced that those meteorites held even possible evidence that very primitive microbial life had once existed on Mars.
 

Rubyait

Justified & Ancient
Joined
Sep 10, 2004
Messages
1,185
Likes
6
Points
54
#52
Meshed theories could explain planet formation


Astronomers meshed a 50-year-old idea with a planet formation model from the 1990s to create a new model of how planets are created in the gaseous discs surrounding young stars.

"Maybe reality is just a little complicated and both things are happening at the same time," suggests astronomer Richard Durisen at Indiana University, Bloomington, US.

In the 1990s, the dominant model of how planets form was "core accretion". In this model, solid objects bump into one another and stick together in an early solar system. If an object grows to about 10 times the Earth's mass, it can become big enough to attract surrounding gas, possibly leading to the birth of a gaseous giant planet.

But that process may be too slow to be a realistic explanation of how gas giants form, Durisen says. And it probably would not work for the formation of the "super Jupiter" planets spotted around other stars. "It's hard enough just to make Jupiter in a reasonable amount of time," Durisen told New Scientist. Super Jupiters are estimated to be several times the mass of Jupiter.

Torn apart
Another possible explanation for planetary formation - the "gravitational-instability model" - was first proposed over half a century ago. In this, a spinning cloud of gas, dust and ice around a star collapses into a disc and forms spiral arms. Those arms then break into clumps that grow until planets form. "It's like a little seed that keeps growing on the disc," says Scott Kenyon, an astronomer at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, US.

But this method comes with its own problems. When computer models create these clumps, they are often torn apart by the violent, spinning system.

Now Durisen and his colleagues suggest that even if the gravitational instabilities in an infant solar system do not lead to permanent clumps, the instabilities may speed up core accretion.

In their hybrid computer simulation, dense gas rings form at the border of stable and unstable areas of the spinning disc. The gas is hot inside the border but cold outside, and the cold gas is drawn inward until it hits the wall of hot gas.

Once enough gas builds up in the ring, it draws in solid material through its own gravity. Eventually, the core accretion model could kick in, and material in the ring could begin to coalesce into a planet. And each solar system could have more than one ring, according to the model, so more planets would be a possibility.

The study will be published in the February issue of the Icarus.


http://www.newscientist.com/article.ns?id=dn7022
 

MrSnowman

Abominable Snowman
Joined
Aug 5, 2002
Messages
874
Likes
10
Points
49
#53
Kaboom!

http://news.bbc.co.uk/1/hi/sci/tech/4278005.stm

"Huge 'star-quake' rocks Milky Way

Astronomers say they have been stunned by the amount of energy released in a star explosion on the far side of our galaxy, 50,000 light-years away.

The flash of radiation on 27 December was so powerful that it bounced off the Moon and lit up the Earth's atmosphere.

The blast occurred on the surface of an exotic kind of star - a super-magnetic neutron star called SGR 1806-20.

If the explosion had been within just 10 light-years, Earth could have suffered a mass extinction, it is said.

"This is a once-in-a-lifetime event"
Dr Rob Fender, Southampton University

"We figure that it's probably the biggest explosion observed by humans within our galaxy since Johannes Kepler saw his supernova in 1604," Dr Rob Fender, of Southampton University, UK, told the BBC News website.

One calculation has the giant flare on SGR 1806-20 unleashing about 10,000 trillion trillion trillion watts.

"This is a once-in-a-lifetime event. We have observed an object only 20km across, on the other side of our galaxy, releasing more energy in a 10th of a second than the Sun emits in 100,000 years," said Dr Fender.

Fast turn

The event overwhelmed detectors on space-borne telescopes, such as the recently launched Swift observatory.

This facility was put above the Earth to detect and analyse gamma-ray bursts - very intense but fleeting flashes of radiation.

The giant flare it and other instruments caught in December has left scientists scrabbling for superlatives.

Swift moved quickly to track down the source of the gamma-rays
Twenty institutes from around the world have joined the investigation and two teams are to report their findings in a forthcoming issue of the journal Nature.

The light detected from the giant flare was far brighter in gamma-rays than visible light or X-rays.

Research teams say the event can be traced to the magnetar SGR 1806-20.

This remarkable super-dense object is a neutron star - it is composed entirely of neutrons and is the remnant collapsed core of a once giant star.

Now, though, this remnant is just 20km across and spins so fast it completes one revolution every 7.5 seconds.

"It has this super-strong magnetic field and this produces some kind of structure which has undergone a rearrangement - it's an event that is sometimes characterised as a 'star-quake', a neutron star equivalent of an earthquake," explained Dr Fender.

"It's the only possible way we can think of releasing so much energy."

Continued glow

SGR 1806-20 is sited in the southern constellation Sagittarius. Its distance puts it beyond the centre of the Milky Way and a safe distance from Earth.

"Had this happened within 10 light-years of us, it would have severely damaged our atmosphere and would possibly have triggered a mass extinction," said Dr Bryan Gaensler, of the Harvard-Smithsonian Center for Astrophysics, who is the lead author on one of the forthcoming Nature papers.

"Fortunately there are no magnetars anywhere near us."

The initial burst of high-energy radiation subsided quickly but there continues to be an afterglow at longer radio wavelengths.

This radio emission persists as the shockwave from the explosion moves out through space, ploughing through nearby gas and exciting matter to extraordinary energies.

"We may go on observing this radio source for much of this year," Dr Fender said.

This work is being done at several centres around the globe, including at the UK's Multi-Element Radio-Linked Interferometer Network (Merlin) and the Joint Institute for VLBI (Very Long Baseline for Interferometry) in Europe - both large networks of linked radio telescopes. "
 
A

Anonymous

Guest
#54
Magnetars are disturbingly unusual;
the magnetic field is so strong that it stretches the neutrons and the thin crust of non-degenerate atoms so much that they are a hundred times as long as they are wide.
 

intaglio

Justified & Ancient
Joined
Oct 14, 2001
Messages
1,592
Likes
20
Points
69
#55
That magnetar is more than a little wierd. As I understand it, the fact that is did not slow down after the emission of so much energy puts the hypothoses on how they "work" into doubt
 
Joined
Aug 19, 2003
Messages
48,667
Likes
20,616
Points
284
Location
Eblana
#56
'Pack ice' suggests frozen sea on Mars

'Pack ice' suggests frozen sea on Mars
11:48 21 February 2005
NewScientist.com news service
Kelly Young
A frozen sea, surviving as blocks of pack ice, may lie just beneath the surface of Mars, suggest observations from Europe's Mars Express spacecraft. The sea is just 5° north of the Martian equator and would be the first discovery of a large body of water beyond the planet's polar ice caps.

Images from the High Resolution Stereo Camera on Mars Express show raft-like ground structures - dubbed "plates" - that look similar to ice formations near Earth's poles, according to an international team of scientists.

But the site of the plates, near the equator, means that sunlight should have melted any ice there. So the team suggests that a layer of volcanic ash, perhaps a few centimetres thick, may protect the structures.

"I think it's fairly plausible," says Michael Carr, an expert on Martian water at the US Geological Survey in Menlo Park, California, who was part of the team. He says scientists had previously suspected there was a past water source north of the Elysium plates. "We know where the water came from," Carr told New Scientist. "You can trace the valleys carved by water down to this area."

He says the evidence is "compelling" for past flooding near the plates. "Maybe the ice is still there in the ground, protected by a volcanic cover, as they suggest," he says.

There is abundant evidence for the past presence of water on Mars but today it appears relatively dry, with water ice confined to the planet's polar caps. Remote observations of hydrogen atoms by NASA's Odyssey spacecraft in 2002 hinted that ice might be locked in the top metre of soil at lower latitudes. But the evidence was inconclusive as the signal could have come from minerals exposed to water in the past.

45 metres deep
The team of researchers, led by John Murray at the Open University, UK, estimates the submerged ice sea is about 800 by 900 kilometres in size and averages 45 metres deep. Images of the pack-ice-like plates can be seen in this PDF document, which was not embargoed when New Scientist first viewed it on 15 February.

The paper is for a presentation to be made at the Lunar and Planetary Science Conference in Texas on March 18. A talk with the same title is scheduled to be given by Murray at the 1st Mars Express Science Conference in Noordwijk, the Netherlands, today.

The team arrived at the depth estimate by studying craters in the plates. They say the craters appear too shallow for their diameters - suggesting ice is filling them up. Moreover, the surface appears unusually level - as if ice were beneath it. This evidence suggests the plates are not just imprints left by ice that has now completely vanished. Crater counts indicate the age of the plates is about 5 million years.

In their paper, the researchers trace a possible history for the underground ice. It begins with huge masses of ice floating in water on Mars. The ice was later covered with volcanic ash, preventing it from sublimating away into the thin atmosphere. Then, the ice broke up and drifted before the remaining liquid water froze. All of the ice not protected by ash sublimated away, leaving the pack ice plates behind.

"If the reported hypothesis is true, then this would be a prime candidate landing site to search for possible extant life on Mars," says Brian Hynek, a research scientist at the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder, US.

Lava flow
One problem with this proposed frozen sea is that there is very little water vapour in the Martian atmosphere today. Carr says that if there had been relatively recent sublimation, as the scientists propose, some traces of water should remain in the atmosphere.

Also, similar plate formations have been seen on Mars before but attributed to solidified lava. But Murray's team says a lava flow does not fit their observations. These plates are up to two times larger than known lava plates on Earth, and they leave behind smooth, straight lanes when they ram into craters and islands. These observations "imply an extremely mobile fluid, with similar characteristics to water," the researchers write.

Carr says there are other regions on Mars with similar plate formations, meaning this might not be the only subterranean water. But ultimately, it may be difficult to prove whether the frozen sea still exists today.

The MARSIS radar, which will soon be deployed on Mars Express, should be able to detect underground liquid water but may have trouble differentiating between ice and rocky soil. And the ice is not visible directly. "To preserve it, you've got to bury it," Carr says. "But if you bury it, you can't detect it."

http://www.newscientist.com/article.ns?id=dn7039

Related Articles
Mars special: Celebrating a year of exploration
15 January 2005
Why oceans on Mars have proved so elusive
25 September 2004
Mars Express 'divining rod' mission delayed
08 October 2004
Weblinks
Mars Express, European Space Agency
Lunar and Planetary Science Conference
1st Mars Express Science Conference
John B Murray, The Open University
 
Joined
Aug 19, 2003
Messages
48,667
Likes
20,616
Points
284
Location
Eblana
#57
Space Observations Suggest Frozen Sea Under Mars' Surface

Space Observations Suggest Frozen Sea Under Mars' Surface

Did a series of volcanic eruptions cover an ancient sea on Mars, that to this day lies dormant as a frozen ocean?
Paris (AFP) Feb 21, 2005
A frozen sea surviving as blocks of pack ice may lie just beneath the surface of Mars, the New Scientist magazine said Monday citing observations from Europe's Mars Express spacecraft.
Images from the high resolution stereo camera on Mars Express showed of structures called plates that look similar to ice formations near Earth's poles.

These plates could indicate the first discovery of a large body of water beyond Mars' polar ice caps, the review said.

The team of researchers, led by John Murray of Britain's Open University, estimated the possible submerged ice sea at about 800 by 900 kilometresby 560 miles) in size and 45 metres (150 feet) deep on average.

The researchers said the evidence suggested that the plates, estimated to be about 5 million years old, were not just imprints left by ice that has now completely vanished.

While the site of the plates near Mars' equator means that sunlight should have melted any ice there, the team suggested that a layer of volcanic ash, perhaps a few centimetres thick, may protect the structures.

"I think it's fairly plausible," said Michael Carr, an expert on Martian water at the US Geological Survey in Menlo Park, California, who was not part of the team.

"Maybe the ice is still there in the ground, protected by a volcanic cover as they suggest," Carr said.

There is abundant evidence for the past presence of water on Mars but today the planet appears relatively dry, with ice confined to the planet's polar caps.

The discovery wwas to be presented Friday at the first Mars Express science conference in Noordwijk, the Netherlands.

In their paper the researchers traced a possible history for Mars' underground ice, saying it began with huge masses of ice floating in water that were later covered with volcanic ash, leaving the pack ice plates behind.

"If the reported hypothesis is true, then this would be a prime candidate landing site to search for possible extant life on Mars," said Brian Hynek, a research scientist at the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder in the United States.

All rights reserved. © 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.

Related Links
MarsDaily
Search MarsDaily
Subscribe To MarsDaily Express

http://www.marsdaily.com/news/mars-wate ... e-05a.html
 

Heckler

The unspeakable mass
Joined
Jul 16, 2004
Messages
5,290
Likes
2,153
Points
219
#58
Are pulsars gravity-wave generators?

Are pulsars gravity-wave generators?
By Lucy Sherriff
Published Tuesday 22nd February 2005 17:32 GMT
Scientists at the European Space Agency (ESA) say that a newly discovered star could provide a test for the existence of gravitational waves.

The object, a pulsar, was discovered by the INTEGRAL spacecraft, and is one of the fastest spinning stars ever seen, rotating nearly 600 times every second. Most millisecond pulsars hover around the 300 revolutions per second mark, and the fastest spinning pulsar ever detected clocked in at 641 rps.

But even this is far short of the theoretical maximum of around 3,000 revolutions per second. Any faster that this and the object would tear itself apart. "Nature is applying some kind of brake, but we don't know what that is," MIT's Deepto Chakrabarty told New Scientist

Theoretically, a spinning body's speed should be limited by gravitational waves, the researchers say, which would carry energy away in the form of ripples in spacetime. Rapidly rotating, uneven objects are predicted to generate these waves, with faster spinning bodies creating more waves than slower ones.

The pulsar was discovered by a research team at the University of Southampton, and the findings are published in Astronomy & Astrophysics. As more super-fast millisecond pulsars are discovered, researchers will be able to tell if gravitational waves really are at work.

Chakrabarty explains that if there is a bunching of pulsars at and around the 600rps mark, this would suggest that gravitational waves are indeed involved. But if the upper speed limit tails off more gradually, then other factors are more likely responsible.

But researchers will have to wait for the upgrades to the Laser Interferometer Gravitational Wave Observatory (LIGO), to be complete before they can say for sure. These will be finished in 2008, and will be sensitive enough to detect any gravitational waves emanating from a pulsar.
Source: http://www.theregister.co.uk/2005/02/22/pulsar_spinner/
 

tzb57r

Devoted Cultist
Joined
May 15, 2002
Messages
137
Likes
2
Points
49
#59

Astronomers find star-less galaxy


Astronomers say they have discovered an object that appears to be an invisible galaxy made almost entirely of dark matter.

The team, led by Cardiff University, claimed it is the first to be detected.

A dark galaxy is an area in the Universe containing a large amount of mass that rotates like a galaxy, but contains no stars.

It was found 50 million light years away using radio telescopes in Cheshire and Puerto Rico.

The unknown material that is thought to hold these dark galaxies together is known as 'dark matter', but scientists still know very little about what that is.

The five-year research has involved studying the distribution of hydrogen atoms throughout the Universe, estimated by looking at the rotation of galaxies and the speed at which their components moved.

Hydrogen gas releases radiation that can be detected at radio wavelengths.

In the Virgo cluster of galaxies, they found a mass of hydrogen atoms a hundred million times the mass of the Sun.


The Universe has all sorts of secrets still to reveal to us, but this shows that we are beginning to understand how to look at it in the right way
Dr Jon Davies

The mysterious galaxy has been called VIRGOHI21.

Similar objects that have previously been discovered have since turned out to contain stars or be remnants of two galaxies colliding.

However, the scientists from the UK, France, Italy and Australia found no visible trace of any stars, and no galaxies nearby that would suggest a collision.

Dr Robert Minchin, of Cardiff University, said: "From its speed, we realised that VIRGOHI21 was a thousand times more massive than could be accounted for by the observed hydrogen atoms alone.

"If it were an ordinary galaxy, then it should be quite bright and would be visible with a good amateur telescope."

The astronomers say it is hard to study the universe's dark, hidden objects because of the Earth's proximity to the Sun.

They liken it to looking out at the darkest night from a well-lit room - it is easy to make out street lights but not trees, hedges and mountains.

Astronomers say it marks an important breakthrough because, according to cosmological models, dark matter is five times more abundant than the ordinary (baryonic) matter that makes up everything we can see and touch.

Another of the Cardiff team, Dr Jon Davies, added: "The Universe has all sorts of secrets still to reveal to us, but this shows that we are beginning to understand how to look at it in the right way. It's a really exciting discovery."
Source: http://news.bbc.co.uk/1/hi/wales/south_east/4288633.stm
 

tzb57r

Devoted Cultist
Joined
May 15, 2002
Messages
137
Likes
2
Points
49
#60
Sorry about replying to my own post, but I forgot to add this :oops:

Why don't we see any on-going mergers between invisible and visible galaxies. If they are so common (5 times more dark than normal matter) surely we should be seeing gravitationally driven mergers actually happening out there. We already see a fair number of mergers underway between two visible galaxies, but why not a severely distorted visible galaxy that is merging with an invisible dark matter galaxy :?:
 
Top