A meteor, or shooting star, is usually the size of a pebble, or even a grain of sand, burning up in the atmosphere.

On Monday night, an asteroid that may be the size of a car will likely burn up in the atmosphere over northeastern Africa, according to the Harvard-Smithsonian Center for Astrophysics.

But the planet is not in peril. The asteroid, spotted by an Arizona observatory only Monday afternoon, will burn up in the upper atmosphere at about 10:46 p.m. ET (2:46 a.m. GMT).

It will not pose a threat to aircraft or people on the ground, but it may put on a show.

Called an asteroid while in space, astronomers refer to it as a meteor once it interacts with the atmosphere and begins to heat and glow. While the meteor will burn up over Egypt and the Sudan, traveling from the southwest to the northeast, it could be visible from much of southern Europe, northeastern Africa, and the Middle East, according to Christine Pulliam of the Harvard center.

She said the meteor could appear, cloud-cover permitting, as bright as a full moon, and may produce a loud boom or popping noise. Italy's University of Pisa calculated the odds are between 99.8 percent and 100 percent that the object, traveling at 28,800 mph, will encounter the Earth's atmosphere.

"We want to stress that this object is not a threat," said Dr. Timothy Spahr, director of the International Astronomical Union's Minor Planet Center. "We're excited since this is the first time we have issued a prediction that an object will enter Earth's atmosphere."

"We're eager for observations from astronomers near the asteroid's approach path," said Gareth Williams of the Minor Planet Center. "We really hope that someone will manage to photograph it."

The Minor Planet Center, at the Harvard-Smithsonian Center for Astrophysics, is a worldwide clearinghouse for asteroid and comet observations. It collects and disseminates observations and calculates orbits.

Peter Dykstra

If the notion of dark energy sounds improbable, get ready for an even more outlandish suggestion.

Earth may be trapped in an abnormal bubble of space-time that is particularly void of matter. Scientists say this condition could account for the apparent acceleration of the universe's expansion, for which dark energy currently is the leading explanation.

Dark energy is the name given to the hypothetical force that could be drawing all the stuff in the universe outward at an ever-increasing rate. Current thinking is that 74 percent of the universe could be made up of this exotic dark energy, with another 21 percent being dark matter, and normal matter comprising the remaining 5 percent.

Until now, there has been no good way to choose between dark energy or the void explanation, but a new study outlines a potential test of the bubble scenario.

If we were in an unusually sparse area of the universe, then things could look farther away than they really are and there would be no need to rely on dark energy as an explanation for certain astronomical observations.

"If we lived in a very large under-density, then the space-time itself wouldn't be accelerating," said researcher Timothy Clifton of Oxford University in England. "It would just be that the observations, if interpreted in the usual way, would look like they were."

Scientists first detected the acceleration by noting that distant supernovae seemed to be moving away from us faster than they should be. One type of supernova (called Type Ia) is a useful distance indicator, because the explosions always have the same intrinsic brightness. Since light gets dimmer the farther it travels, that means that when the supernovae appear faint to us, they are far away, and when they appear bright, they are closer in.

But if we happened to be in a portion of the universe with less matter in it than normal, then the space-time around us would be different than it is outside, because matter warps space-time. Light travelling from supernovae outside our bubble would appear dimmer, because the light would diverge more than we would expect once it got inside our void.

One problem with the void idea, though, is that it negates a principle that has reined in astronomy for more than 450 years: namely, that our place in the universe isn't special. When Nicholas Copernicus argued that it made much more sense for the Earth to be revolving around the sun than vice versa, it revolutionized science. Since then, most theories have to pass the Copernican test. If they require our planet to be unique, or our position to be exalted, the ideas often seem unlikely.

"This idea that we live in a void would really be a statement that we live in a special place," Clifton told SPACE.com. "The regular cosmological model is based on the idea that where we live is a typical place in the universe. This would be a contradiction to the Copernican principle."

Clifton, along with Oxford researchers Pedro G. Ferreira and Kate Land, say that in coming years we may be able to distinguish between dark energy and the void. They point to the upcoming Joint Dark Energy Mission, planned by NASA and the U.S. Department of Energy to launch in 2014 or 2015. The satellite aims to measure the expansion of the universe precisely by observing about 2,300 supernovae.

The scientists suggest that by looking at a large number of supernovae in a certain region of the universe, they should be able to tell whether the objects are really accelerating away, or if their light is merely being distorted in a void.

The new study will be detailed in an upcoming issue of the journal Physical Review Letters.

• Top 10 Strangest Things in Space
• Nearby Evidence for Dark Energy
• Images: Hubble's New Views

Clara Moskowitz 

A problem that struck the Hubble Space Telescope on Saturday will delay the final space shuttle mission to service it, moving the launching from next month to next year, NASA officials said Monday.

A crew of seven astronauts was scheduled to blast off in the shuttle Atlantis on Oct. 14 for an 11-day visit to the telescope, which for 18 years has been beaming cosmic postcards to Earth from its orbital vantage point above the atmosphere.

During five spacewalks, the astronauts were set to install two new instruments and repair the telescope’s best camera and a spectrograph, both of which had electrical failures. They were also scheduled to replace the telescope’s batteries and gyroscopes, among other things.

But on Saturday, a channel on a control system known as the Hubble Control Unit/Science Data Formatter — which helps relay data to the ground — failed, causing the telescope to go into a “safe mode” and cease observations. Hubble’s managers expect that activating a backup channel will restore the telescope to service later this week.

But that will leave the telescope with no backup if the new channel stops working, so NASA would like to have the astronauts replace the failed control unit with a spare from the Goddard Space Flight Center.

In a telephone news conference with reporters on Monday evening, Preston Burch of Goddard, Hubble’s program manager, said the control unit hangs, attached by 10 bolts, on the inside door of a bay that the astronauts can access easily. With luck, it could be exchanged during a two-hour spacewalk, he said. “We think it’s a relatively straightforward activity.”

It is too soon to tell, the mission managers said, whether replacing the control unit will bump another activity from the servicing schedule. The mission’s five spacewalks are tightly packed with activities, but the lead astronaut, John M. Grunsfeld, has been able in training to complete the camera repair in one spacewalk instead of the scheduled two.

“This may be a doable thing, that we can have our cake and eat it too,” Mr. Burch said.

Understanding what went wrong, testing the spare unit, integrating its installation into the mission schedule and training the crew to install it will take several weeks or more, Mr. Burch said.

The Hubble mission cannot be launched until another shuttle, the Discovery, which is scheduled for a Feb. 12 trip to the space station, is ready to serve as the backup rescue shuttle. As a result, the flight will not take place before February 2009.

DENNIS OVERBYE

Mars Craft Detects Falling Snow

Soil Tests Also Hint at Past Presence of Liquid Groundwater

Icy snow falls from high in Mars's atmosphere and may even reach the planet's surface, scientists working with NASA's Phoenix lander reported yesterday.

Laser instruments aboard the lander detected the snow in clouds about 2 1/2 miles above the surface and followed the precipitation as it fell more than a mile. But because of limitations with the technology, it was unclear whether any of the powdery stuff made it all the way to the surface.

"Nothing like this view has ever been seen on Mars," said Jim Whiteway of York University in Toronto, lead scientist for the Canadian-supplied Meteorological Station on Phoenix. "We'll be looking for signs that the snow may even reach the ground."

In addition to finding snow, the Phoenix team reported discovering material in the Martian soil that had once been dissolved in water -- clays and calcium carbonate (limestone) that could have formed only in the presence of liquid water. Although the lander's instruments earlier found water ice below Mars's polar surface and had photographed surface fog and clouds, it has found nothing like liquid water on the surface.

The presence of nutrients and other material that once dissolved in water, however, plus the continuing presence of water as snow, vapor and ice, is leading researchers to conclude that Mars's polar regions might have supported life in the past -- when the region was much warmer. Because Mars wobbles on its axis far more than Earth does -- in some very long-term cycles, the poles face the sun -- the northern region where Phoenix landed has, in the past, been warm.

"Is this a habitable zone on Mars? I think we are approaching this hypothesis," said principal investigator Peter Smith of the University of Arizona.

In addition, Michael Hecht of NASA's Jet Propulsion Laboratory said that further analysis of the Martian dust by the lander's onboard laboratory has determined that it is as alkaline as ocean water, with a pH of 8.3. He said this finding also suggests that life could have existed on Mars.

Whiteway said the snow, along with frost and fog, began to appear about a month ago, as temperatures cooled on Mars. "This is now occurring every night," he said.

In an interview after the teleconference, Whiteway likened the snow to "diamond dust" that falls in the Arctic and Antarctica.

"What this is telling us is that water does rise from the ground to the atmosphere and then precipitates down," he said. "So there is a hydrological cycle on Mars, and now other experts will study the data and try to determine what it all means."

Although the Phoenix instruments could not determine whether the snow hit the ground, Whiteway said there are some indications that it does. Images of the thin but distinct Martian clouds can be seen on the NASA Web site at http://www.nasa.gov/phoenix.

With daylight quickly diminishing as the Martian winter starts, the Phoenix is not expected to continue operating for many more weeks. The spacecraft has a "Lazarus" feature that could return it to operation when the sun returns, but the brutally cold temperatures during the winter are expected to freeze and crack parts essential to its operation.

Smith said that in the remaining weeks, the scientists plan to turn on a microphone that was designed to record the lander's descent in May. It did not work then, but Smith said, "We are going to try to turn on this microphone and try to listen to Mars for the first time."

Phoenix was scheduled to operate for 90 Martian days, known as sols, but the lander's robotic arm has been digging up soil and ice for more than 120 sols and delivering it to chemistry labs inside the lander. Smith said many of the mission's primary goals have been accomplished, although difficulties transferring the scooped-up material into the lander have interfered with some experiments.

In particular, researchers are eager to know whether the isotopic makeup of the water in the air is the same as the water in the soil, but they have not been able to load the proper material to find out. They have searched in vain for organic (although not necessarily biological) material in the soil.

Scientists have theorized that snow falls on Mars, but they had never before seen it in real time. Future research on the data collected by Phoenix will try to determine where the snow came from -- whether it originated in the ice-covered polar regions or evaporated from the broader Martian surface, or even from the large collections of ice below the surface.

The Phoenix team was surprised in the summer by the presence of the chemical perchlorate in the Martian soil. Used in many industrial capacities and in rocketry, the potentially toxic chemical is also found in the driest deserts on Earth. Smith said its presence on Mars suggests again that there was once liquid groundwater and raises the possibility that life has existed in the planet's seemingly hostile environment.

Because perchlorate changes the freezing point of water dramatically, it could keep water in a liquid state at temperatures of 76 degrees below zero.

"This could form brines for microbes, which could then use the perchlorate as a chemical energy source," he said.

Marc Kaufman

A tiny, six-legged critter that can suspend all biological activity in extreme environments survived a journey to space that would have instantly killed any human and most other life forms.

In the first test of its kind, researchers exposed the hardy segmented creatures, called "water bears," to the open and harsh vacuum of space, with all its deadly radiation, on a spacecraft in low-Earth orbit. Many of them survived.

The water bears, known formally as tardigrades, have an ability similar to brine shrimp (also known as Sea Monkeys), which are familiar to many children for their ability to come to life after being sent to homes by mail-order. Tardigrades are speck-sized things, less than 1.5 millimeters long. They live on wet lichens and mosses, but when their environment dries out, they just wait for a return of water. They also resist heat, cold and radiation.

The radiation resistance was most surprising to scientists.

The tardigrades were aboard the FOTON-M3 spacecraft launched by the European Space Agency (ESA) in September 2007 and were exposed to open space conditions, the scientists reported today. They were examined upon return to Earth.

Most survived exposure to the vacuum and cosmic rays, and some even survived the exposure to the deadly levels of solar UV radiation, which are more than 1,000 times higher than on the surface of the Earth.

The survivors "could reproduce fine after their space trip," according to a statement released today by Cell Press, the journal that published results of the test.

How the post-flight tardigrades could do it "remains a mystery," the researchers write.

UV rays consist of high-energy light particles that cause severe damage to living tissue, as is evident when you get a sunburn. But more so, they can also damage cells' genetic material, causing skin cancer, for example. The radiation, in wide-open space, also is thought to be sterilizing.

The work was led by K. Ingemar Jonsson of Kristianstad University in Sweden.

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The European Space Agency obtained on Saturday the first images of an asteroid 360 million km (224 million miles) from earth, part of a space mission which scientists hope will help them understand the origins of the planets.

The images were transmitted to the control team in Darmstadt, Germany, by Europe's Rosetta spacecraft which completed its flyby of the Steins asteroid, in the asteroid belt between the orbits of Mars and Jupiter, late on Friday.

Steins was the first target for Rosetta in its more than eleven year mission to explore the nucleus of a far away comet.

Through the study of minor bodies, such as asteroids, Rosetta is opening up a new window onto the early history of the solar system, said the ESA in a statement.

"Steins looks like a diamond in the sky," said Uwe Keller, Principal Investigator for the Osiris imaging system from the Max Planck Institute for solar system research in Lindau, Germany.

"Steins might be small, but we're making big science here," said David Southwood, ESA's Director of Science and Robotic Exploration. "The better we learn to know the different kinds of asteroids, the better we will understand our origins in the past."

He added that with enhanced knowledge, scientists hoped to mitigate the chances of asteroids becoming a threat to earth.

The ESA said the images showed several small craters on the asteroid and two huge ones, one of which is 2 km in diameter, indicating the asteroid must be very old.

Rosetta's instruments have so far focused on the asteroid's orbital motion, rotation, shape and density.

From the images, scientists will try to understand why the asteroid is unusually bright. Steins is a small asteroid of irregular shape with a diameter of only 4.6 km.

It belongs to a type of asteroid which probably came from larger asteroids destroyed in the early history of the solar system. They are believed to be composed mainly of silicate minerals with little or no iron content.

Rosetta was launched in March 2004. Since then, it has travelled about 3.7 thousand million km.

The highlight of the mission will be in late 2014 when it releases a landing vessel in the first attempt at a controlled landing on Comet 67P/Churyumov-Gerasimenko.

Madeline Chambers, Diana Abdallah

NASA's Phoenix Mars Lander has taken its first-ever picture of a single particle of rusty Martian dust with one of its microscopes.

The speck of dust was shown at a higher magnification than anything outside of Earth has been imaged before. The rounded particle measured only about one micrometer, or one millionth of a meter, across.

"Taking this image required the highest resolution microscope operated off Earth and a specially designed substrate to hold the Martian dust," said Tom Pike, a Phoenix science team member from Imperial College London. "We always knew it was going to be technically very challenging to image particles this small."

The device that imaged the dust speck is called an atomic force microscope, which maps the shape of particles in three dimensions by scanning them with a sharp tip at the end of a spring.

The atomic force microscope can detail the shapes of particles as small as about 100 nanometers, about one one-thousandth the width of a human hair.  That is about 100 times greater magnification than seen with Phoenix's optical microscope, which made its first images of Martian dirt about two months ago. Until now, those images held the record for the most highly magnified images to come from another planet.

And this won't be the last dust particle that Phoenix will image. "After this first success, we're now working on building up a portrait gallery of the dust on Mars," Pike said.

Dust is a ubiquitous substance on Mars, coating the surface and giving it its rusty red hue. Airborne dust particles also color the Martian sky pink and feed storms that regularly envelope the planet.

The ultra-fine dust is the medium that actively links gases in the Martian atmosphere to processes in Martian soil, so it is critically important to understanding Mars' environment, the researchers said.

The $420-million Phoenix mission is analyzing the dust and subsurface ice layers of Mars' arctic regions to look for signs of potential past habitability.

The particle seen in the atomic force microscope image was part of a sample scooped by the robotic arm from the "Snow White" trench and delivered to Phoenix's microscope station in early July.

• Video: Digging on Mars
• Special Report — Phoenix Mars Lander: Digging for Secrets of the Martian Arctic
• New Images: Phoenix on Mars!

Andrea Thompson

A Dutch primary school teacher and amateur astronomer has discovered what some are calling a "cosmic ghost," a strange, gaseous object with a hole in the middle that may represent a new class of astronomical object.

The teacher, Hanny van Arkel, discovered the object while volunteering in the Galaxy Zoo project, which enlists the help of members of the public to classify galaxies online.

"At first, we had no idea what it was. It could have been in our solar system, or at the edge of the universe," Yale University astrophysicist Kevin Schawinski, a member and co-founder of the Galaxy Zoo team, said in a statement.

The find, nicknamed "Hanny's Voorwerp" (Dutch for object), soon had scientists training their telescopes on the object.

"What we saw was really a mystery," Schawinski said. "The Voorwerp didn't contain any stars."

Made entirely of very hot gas, the eerie green object is illuminated by remnant light from the nearby galaxy IC 2497.

"We think that in the recent past the galaxy IC 2497 hosted an enormously bright quasar," Schawinski said.

He said light from the past still illuminates the ghostly object, even though the quasar shut down some 100,000 years ago and the galaxy's black hole went quiet.

"It's this light echo that has been frozen in time for us to observe," said Chris Lintott, a co-organizer of Galaxy Zoo at Oxford University in the United Kingdom, said in a statement.

Researchers will soon use the Hubble Space Telescope to get a closer look.

"It's amazing to think that this object has been sitting in the archives for decades and that amateur volunteers can help by spotting things like this online," van Arkel said in a statement.

Van Arkel is one of more than 150,000 amateur astronomers who have assisted in classifying more than 1 million galaxies over the past year as part of the Galaxy Zoo project.

The next stage of Galaxy Zoo will ask volunteers to search for more unusual astronomical objects. >>>>

Traces of a rocket fuel ingredient found in the Martian soil would not necessarily hinder potential life, mission scientists said Tuesday.

NASA's Phoenix spacecraft earlier this summer detected the chemical perchlorate, a highly oxidizing salt, in soil samples dug up from near the Martian surface. On Earth, it can be found naturally in the arid Atacama Desert in Chile where some extreme organisms use it as a source of energy.

"We know that microbes can exist quite happily in oxidizing conditions," said Phoenix scientist Richard Quinn of the NASA Ames Research Center. "The story possibly could turn out to be the same for Mars. We don't know yet."

The surprising find comes after scientists previously reported that the soil near Mars' north pole was Earth-like where plants such as asparagus, green beans and turnips could thrive. The presence of perchlorate, if confirmed, would appear to make the soil more exotic than previously believed.

But scientists insisted that has no bearing on the red planet's habitability.

"In itself, it is neither good nor bad for life," chief scientist Peter Smith of the University of Arizona in Tucson said of the chemical.

Some researchers who have no role in the $420 million mission were less enthusiastic.

"Perchlorate is not a particularly nice thing to find in the soil," said astrobiologist Kenneth Nealson of the University of Southern California. "No one hunting for life would be happy to see it in any sort of abundance."

Although some microbes on Earth thrive on perchlorate, "it is not a molecule of choice for most life," Nealson said.

Phoenix landed in the Martian arctic plains on May 25 to study whether the region could support life, past or present. It confirmed the presence of ice at the landing site, but it has yet to uncover organic, or carbon-based, building blocks of life.

The spacecraft detected perchlorate in two soil samples taken from different shallow trenches in June and July using its onboard chemistry lab. Scientists are working to confirm the signal because another Phoenix instrument, also capable of sniffing out the chemical, failed to turn up any evidence in a test last week.

It's unknown whether the detected perchlorate occurs naturally on Mars. NASA is investigating whether the contaminant could have hitchhiked aboard Phoenix during launch preparations. It's unlikely the chemical leaked from the spacecraft's thrusters since they carried hydrazine fuel. Engineers said there's a remote possibility that Phoenix may have been contaminated by the rocket that launched it.

Perchlorate is used in solid rocket fuel, fireworks, pyrotechnics and other explosives. In the United States, perchlorate contamination has been found in the waterways of at least 25 states, according to the federal Environmental Protection Agency. The toxin can interfere with thyroid function and poses developmental health risks, particularly to fetuses.

While oxidizers can be harmful to living things, perchlorate is relatively stable in soil and would not react with organics unless triggered, said geochemist David Parker of the University of California, Riverside.

The last time NASA searched for organics was during the twin Viking missions in the 1970s. The spacecraft turned up empty. Some scientists theorized that an oxidant, perhaps peroxide, in the Martian soil may be responsible for breaking down carbon compounds if they had existed.

ALICIA CHANG

Earthlings might be scrambling to find liquid hydrocarbons buried in our planet, but Saturn's moon Titan has plenty to spare.

Scientists say that a dark, smooth surface feature spotted on the moon last year is definitely a lake filled primarily with liquid ethane, a simple hydrocarbon.

"This is the first observation that really pins down that Titan has a surface lake filled with liquid," said the paper's lead author, University of Arizona professor Robert Brown.

The new observations affirm that Titan is one of the likeliest places to look for life in our solar system. Some astrobiologists have speculated that life could develop in the moon's hydrocarbon lakes, although it would have to be substantially different from known life on Earth, which requires liquid water.

Mixed in solution with the ethane, the lake is also believed to contain nitrogen, methane, and a variety of other simple hydrocarbons.

The Cassini-Huygens probe determined the chemical composition of the liquid by the way it reflected light, a technique known as spectrometry that has provided most of our knowledge about other planets' atmospheric compositions.

"It was hard for us to accept the fact that the feature was so black when we first saw it," Brown said. "More than 99.9 percent of the light that reaches the lake never gets out again. For it to be that dark, the surface has to be extremely quiescent, mirror smooth. No naturally produced solid could be that smooth."

Further, the scientists saw the specific absorption signature of ethane, which absorbs light at exactly 2-micron wavelengths.

These kinds of measurements are made more difficult by the hydrocarbon haze that engulfs the moon, making it hard to actually see the Titanic ground. Cassini scientists have to take advantage of narrow observation windows. One of these occurred in December 2007, which allowed them to catch this view of the lake, Ontario Lacus. At 7,800 square miles, it's slightly larger than the Earthbound Lake Ontario

Ethane is the byproduct of a solar-energy-induced reaction that transforms atmospheric methane, aka natural gas. Scientists believe ultrafine particles of ethane fall from the atmosphere to the surface and fill the lake.

Here on earth, ethane is used to create ethylene, which is used as an all-purpose chemical precursor and is the world's most-produced organic compound.

Brown and his team will publish their results in the July 31 issue of the journal Nature.

 Alexis Madrigal

http://blog.wired.com/wiredscience/2008/07/lake-of-petrole.html

F-15 crashes in Nevada during training, killing 1

An Air Force official says the crash of an F-15 jet in the Nevada desert during a training exercise has left one pilot dead and the other injured.

Air Force spokesman Andrew Dumboski says the two-seater plane went down at about 11:30 a.m. Wednesday on the Nevada Test and Training Range outside of Goldfield, Nev.

The names of the pilots were not immediately released. Dumboski says the injured pilot is in stable condition and is under observation at Mike O'Callaghan Federal Hospital.

The pilots were assigned to the 65th Aggressor Squadron at Nellis Air Force Base near Las Vegas.

Goldfield is about 180 miles north of the base. >>>>

NASA scientists said on Thursday they had definitive proof that water exists on Mars after further tests on ice found on the planet in June by the Phoenix Mars Lander.

"We have water," said William Boynton, lead scientist for the Thermal and Evolved-Gas Analyzer instrument on Phoenix.

"We've seen evidence for this water ice before in observations by the Mars Odyssey orbiter and in disappearing chunks observed by Phoenix last month, but this is the first time Martian water has been touched and tasted," he said, referring to the craft's instruments.

NASA on Thursday also extended the mission of the Phoenix Mars Lander by five weeks, saying its work was moving beyond the search for water to exploring whether the red planet was ever capable of sustaining life.

"We are extending the mission through September 30," Michael Meyer, chief scientist for NASA's Mars exploration program, told a televised news conference.

The extension will add about $2 million to the $420 million cost of landing Phoenix on May 25 for what was a scheduled three-month mission, Meyer said.

Phoenix is the latest NASA bid to discover whether water -- a crucial ingredient for life -- ever flowed on Mars and whether life, even in the form of mere microbes, exists or ever existed there.

Phoenix touched down in May on an ice sheet and samples of the ice were seen melting away in photographs taken by the lander's instruments in June.

Boynton said that water was positively identified after the lander's robotic arm delivered a soil sample on Wednesday to an instrument that identifies vapors produced by heating.

Mission scientists said the extension would give time for more analysis of Martian samples. They plan to dig two additional trenches -- dubbed "cupboard" and "neverland" -- using the robotic arm on the Phoenix craft.

"We hope to be able to answer the question of whether this was a habitable zone on Mars. It will be for future missions to find if anyone is home on this environment," Phoenix principal investigator Peter Smith told the news conference.

Mission scientists said in June that Martian soil was more alkaline than expected and had traces of magnesium, sodium, potassium and other elements. They described the findings as a "huge step forward."

Meyer said the scientific proof of the existence of water meant that Phoenix could "move from looking for water to seeing whether there were habitats for life.

"We are moving towards understanding whether there were or could be places on Mars that are habitable," Meyer said.

Jill Serjeant