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SPACE & SCIENCE NEWS: February 2001
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Life on Mars: skeptics remain unconvinced Feb 28, 2001
Case for biology on Mars grows Feb 27, 2001
Evidence for Martian life conclusive, say researchers Feb 26, 2001
Impact caused mass extinction in 250 million BC Feb 22, 2001
NEAR-Shoemaker mission continues Feb 22, 2001
Galaxy teeming with Earths argues astrophysicist Feb 19, 2001
A lake like Vostok on Mars? Feb 18, 2001
Uncertain communications: NEAR, Huygens, Pioneer 10 Feb 14, 2001
As NEAR as you can get Feb 13, 2001
NEAR poised to make history Feb 11, 2001
Life on Europa? Scientists meet to discuss Feb 9, 2001
The Day the Earth Moved Feb 6, 2001
2020 vision for SETI Feb 4, 2001
NEAR: The End Feb 1, 2001


Life on Mars: skeptics remain unconvinced
(Feb. 28, 2001)


Despite the flurry of announcements over the past couple of days (see news items below) that three meteorites from Mars carry biogenic signatures of Martian life, some researchers continue to argue that the magnetite and carbonate traces within these rocks could well have an inorganic origin. For more on the reaction of the skeptics, go here.

Mars
Case for biology on Mars grows
(Feb. 27, 2001)


NASA is insisting today that new results from investigations of two other Martian meteoritesNakhla and Shergotty – in addition to ALH 84001 provide proof beyond reasonable doubt that life once existed on Mars. A paper by a large group of researchers that includes members of the original Mars "fossils" discovery team in 1996 puts forward four primary reasons why the traces found in these meteorites are biogenic. If indeed they are due to Martian bacteria this would indicate there has been life on Mars throughout the period 3.9 billion to about 170 million years ago. For more on this, go here.

For more on the new research on the biogenicity of the magnetite crystals in ALH 84001 (see yesterday's news item immediately below), go here.

For yet more coverage, go to Spaceflight Now, space.com and BBC news.

ALH 84001
Evidence for Martian life conclusive, say researchers
(Feb. 26, 2001)


A NASA-backed international team of researchers publishes evidence in the February 27 issue of the Proceedings of the National Academy of Sciences that microscopic crystals of magnetite in the ALH 84001 Martian meteorite were almost certainly produced by living organisms. Imre Friedmann, Jacek Wierzchos, Carmen Ascaso and Michael Winklhofer have shown that the tiny hexagonal columns of magnetite were laid down in exactly the same way as their bacteria-produced equivalent on Earth.

For more, go here (BBC) and here (spaceref.com).

fullerene with trapped atom
Impact caused mass extinction 250 million years ago
(Feb. 22, 2001)


Extraterrestrial helium trapped inside cage-like molecules of carbon known as fullerenes have revealed that a devastating mass extinction at the boundary between the Permian and Triassic periods was caused by an asteroid or comet collision. This evidence of an impact-related extinction earlier than that which put paid to the dinosaurs is presented in the journal Science by a team led by University of Washington's Luann Becker. The site of the impact remains unknown. The signature fullerenes were extracted from rocks in Japan, China and Hungary.

For more, go here.

NEAR on the surface of Eros
NEAR mission continues
(Feb. 22, 2001)


The NEAR-Shoemaker probe, now lying on the surface of the asteroid Eros, is sending back data collected by its gamma-ray spectrometer. These measurements will reveal the elemental composition in the spacecraft's immediate vicinity. Scientists are delighted with the quality of the data and additional time is being made available on NASA's Deep Space Network to communicate with the spacecraft.

Galaxy teeming with Earths argues Canadian astrophysicist
(Feb. 19, 2001)


Speaking at the the annual meeting of the American Association for the Advancement of Science in San Francisco, Norman Murray, from the Canadian Institute for Theoretical Astrophysics, said that of the 470+ Sun-like stars in a recent study he conducted over half showed evidence of having consumed rocky, iron-rich material. This being the case, he argued, it was likely these stars still had material in orbit about them, possibly in the form of terrestrial-type planets. Given that the direct detection of Earth-sized planets will require more sensitive observation techniques and next-generation telescopes that those presently available, statistical methods such as Murray's are the only indicators to hand. "There is evidence that there is terrestrial-type material orbiting most of the stars in the solar neighborhood," Murray told the meeting. "So, the implication, if this result holds up, is that there are Earth-like bodies in orbit around most of the stars in our galaxy." Murray's study took in more than 450 middle-aged stars like our Sun and about 20 that were entering senility. All were within about 325 light-years of Earth. The analysis indicated most had high iron content in their photospheres. Based on what we knew about the way our Solar System behaved, Murray claimed most of this iron would have come from asteroids being thrown into the stars by the gravitational slingshot effect of orbiting planets. "Something like 50 percent or higher of these stars have accreted more than an Earth-mass of terrestrial material. In our Solar System, we believe the Sun has accreted about two-and-a-half Earth-masses of rocky material. Now, the implication here is that there must be something going on around those stars in order to accrete that amount of material, and we know from our own Solar System that this accretion process is not 100% efficient. Therefore, it's likely these stars still have material in orbit around them in the form of terrestrial-type bodies. There are planets there."

Visit Norman Murray's homepage.

North pole of Mars
A lake like Vostok on Mars?
(Feb. 18, 2001)


Lake Vostok – a huge body of fresh water lying under some 4 kilometers of Antarctic ice – has often been cited as a terrestrial analogue of what it might be like under Europa's icy crust. But now a team of scientists has suggested that Lake Vostok might more closely resemble the situation on Mars. JPL's Natalia Duxbury and her colleagues have proposed that Vostok didn't form by geothermal heating after all. Instead their models imply that the Antarctic lake was originally an open body of water that froze over between 5 and 30 million years ago. If this is the case, any life found inside the lake would be older than the Antarctic ice sheet.

And this is where the similarity with the Red Planet comes in. The Martian north pole, shown in the MGS image here, is known to be covered with ice. However, Mars's axial tilt has changed dramatically over the planet's lifetime and the current polar regions were once much warmer. So it's quite possible that sometime in Mars's past, the poles, like Duxbury's model of Vostok, were once open bodies of water that subsequently froze over. Assuming life was present while Vostok was an exposed lake, and assuming life is eventually found in the lake today, it seems possible that if life existed in an ancient Martian polar lake, it may still be there too. ESA's Mars Express, scheduled for launch in 2003, will examine the Martian poles from orbit for buried liquid water. Details of this JPL study can be found in the January 25th issue Journal of Geophysical Research.

For more on the latest plans to explore Lake Vostok - or delays to them - go here (Scientific American, March 2001 issue).

NEAR on the surface of Eros
Uncertain communications: NEAR, Huygens, Pioneer 10
(Feb. 14, 2001)


Mission managers have announced that the NEAR mission on the surface of Eros will be extended for at least 10 days. By a great stroke of luck, the probes forward low gain antenna is pointed more or less optimally for communicating with Earth – even though the data rate, at 10 bits/sec is very low. NEAR's imager has been turned on in preparation for transmitting more pictures. Also, the craft's gamma ray spectrometer will be used to carry out a precise analysis of the asteroid's surface composition. One intriguing option being considered is to relaunch NEAR so that it could take more close-up shots from a hovering position; however, this is thought unlikely.

Meanwhile, ESA and NASA engineers are working to formulate a strategy to overcome a threat to the Cassini/Huygens mission, due to arrive at Saturn in 2004. The problem became apparent last fall when tests carried out at ESA revealed that Cassini's receiver might not be able to receive the full range of frequencies being transmitted by Huygens as the latter makes its way down through the atmosphere of Titan. Doppler shifting of the transmissions, as the spacecraft move apart, will take some of the signals from Huygens effectively out of Cassini's earshot. Members of the Huygens Recovery Task Force, however, are now optimistic of circumventing the glitch. For more, go here (ESA science).

Finally, after concerns that we may have heard the last from Pioneer 10, 11.5 billion light-years distant, mission controllers were delighted to discover the probe had sent back a signal with data in it.

NEAR landing site
As NEAR as you can get
(Feb. 13, 2001)


The asteroid orbiter NEAR has become the lander NEAR. After a five year mission and a year in orbit around Eros, the desk-sized craft touched down yesterday (Feb. 12, 2001) on the surface of the asteroid at the location shown by the arrow in this image. And, remarkably, it continues to send back a beacon signal. For more, go here (BBC news). For the closest view of Eros sent back, moments before NEAR landed, showing detail as small as a few centimeters across, go here (NEAR site at Johns Hopkins).

NEAR approaching the surface of Eros
NEAR poised to make history
(Feb. 11, 2001)


The NEAR probe will attempt a reasonably soft landing on the surface of the asteroid Eros on Monday (Feb. 12). From a 35 km high orbit, the little craft will descend over a four-hour period starting at 1631 GMT, using its thrusters to decelerate. Pictures will be sent back and relayed live over the Internet throughout this time. There is the possibility that NEAR will exhaust its fuel supply on the way down. But if all goes well the craft will make contact with the asteroid traveling at a mere 5 km (3 miles) per hour. The target landing site is the edge of a protruding region of Eros known as Himeros, near the boundary of two different types of terrain. This will bring to four the number of extraterrestrial objects that spacecraft have landed on (the others being the Moon, Mars and Venus).

For more, go to the NEAR website.

Europa
Life on Europa? Scientists meet to discuss
(Feb. 9, 2001)


A focus group of researchers met at NASA Ames lat week (Feb. 1-2) to assess the biological potential of Jupiter's enigmatic moon Europa. Mounting evidence for a salt-water ocean has encouraged astrobiologists to speculate that this might be an ideal home for halophiles, like those found in some extreme environments on Earth.

Earth
The Day the Earth Moved
(Feb. 6, 2001)


Over the next billion years or so the Sun will increase in brightness until the Earth becomes uncomfortably hot for life. One way around this problem would be for humans, or their descendants, to colonize some other world. A more dramatic solution, however, has been proposed by Don Korycansky of the University of California, Gregory Laughlin of NASA, and Fred Adams of the University of Michigan. They suggest using the gravitational sling-shot effect of a large asteroid to swing the Earth into a new orbit further from the Sun. All that is required, they say, is for an asteroid about 100 km across to fly past the Earth and transfer some of its orbital energy to our planet. The asteroid would then move out to encounter Jupiter where it would acquire more energy that it could impart to the Earth on a subsequent encounter. Humans would have many thousands of years to select the appropriate asteroid and develop the necessary technology to deflect the giant rock our way. To enlarge the Earth's orbit at a rate that compensates for the increasing brightness of the Sun would require an asteroid encounter every 6,000 years, the researchers explain.

For more, visit Korycansky's website.

Allen Telescope Array
2020 vision for SETI
(Feb. 4, 2001)


Finding signs of extraterrestrial intelligence (ETI) makes hunting needles in haystacks seem trivial. Where to look? And, perhaps more importantly, how to look? Assuming there are other technological civilizations out there, what search methods offer the best chances of uncovering them? To address these questions, the SETI Institute assembled an international team of scientists and engineers to come up with SETI 2020 – a report on how the hunt for ETI should be pursued over the coming two decades. To be published shortly, it will recommend three key approaches: (1) a greater emphasis on the search for signals at optical and infrared wavelengths; (2) an all-sky, all-the-time radio search of the type under development at Ohio State; and (3) implementation of the Allen Telescope Array (shown here in the artist's impression).

For more, go here.

Eros
NEAR: The End
(Feb. 1, 2001)


The NEAR-Shoemaker probe, currently orbiting the asteroid Eros at an altitude of 35 km (22 miles) will attempt a historic first touchdown on the surface of a minor planetary body on Monday, 12 February. On the landing day, NEAR will fire its thrusters six times during a four-hour descent to slow down to one-to-three meters per second. The object is to touch down gently at the edge of a saddle-shaped feature called Himeros, but mission controllers have no idea if the spacecraft will survive the attempt. "The unknown nature of the surface makes it hard to predict what will happen to the spacecraft," said mission director Robert Farquh, "especially since it wasn't designed to land." However, the touchdown is a bonus, since the craft has already achieved its objectives. The hope is that if NEAR lands reasonably unscathed and upright, it could continue sending back signals and serve as a beacon.

For more, visit the NEAR homepage.

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