Posted on by Fraser Cain

Stars Can Survive Being Engulfed

Image credit: Chandra
The V471 Tauri system comprises a white dwarf star (the primary) in a close orbit – one thirtieth of the distance between Mercury and the Sun – with a normal Sun-like star (the secondary). The white dwarf star was once a star several times as massive as the Sun. Chandra data on this system provide the best evidence yet that a star can be engulfed by its companion star and survive.

The illustration shows X-ray spectra made by Chandra’s Low Energy Transmission Grating Spectrometer of two individual stars and V471 Tauri: a red giant star (Beta Ceti, top panel), V471 Tauri, and a Sun-like star (Epsilon Eridani). The peak in the spectrum due to carbon ions is much smaller in the giant star than in the Sun-like star, whereas the carbon peak in V471 is intermediate between the two. These differences provide important clues to the different evolutionary histories of the stars.

Nuclear fusion reactions in the core of such a star convert carbon into nitrogen over a period of about a billion years. When the fuel in the core of the star is exhausted, the core collapses, triggering more energetic nuclear reactions that cause the star to expand and transform into a red giant before eventually collapsing to become a white dwarf.

The carbon-poor material in the core of the red giant is mixed with outer part of the star, so its atmosphere will have a deficit of carbon, as compared with Sun-like stars, as shown in the figure. If a red giant is part of binary system of closely orbiting stars, the evolution of the secondary star can be dramatically affected.

Theoretical calculations indicate that the red giant can completely envelop its companion star. During this common envelope phase, friction causes the companion star to spiral inward rapidly where it will either be destroyed by the red giant, or it will survive when much of the envelope is spun away.

If the companion star manages to survive, it will bear the marks of its ordeal in the form of contamination by carbon-poor material that it accreted while it was inside the red giant envelope. The X-ray spectrum of V471 Tauri in the middle panel shows just this effect – the carbon peak is intermediate between that of a Sun-like star and an isolated red giant star. The data indicate that about 10 percent of the star’s mass has been accreted from the red giant.

In the future the companion star can return the favor. It will expand and dump material back onto the white dwarf. If enough material is dumped on the white dwarf, it could cause the white dwarf to explode as a supernova.

Original Source: Chandra News Release

Posted on by Fraser Cain

NASA is Getting More Opinions on Hubble

After receiving complaints, NASA Administrator Sean O’Keefe has said he’s looking for a second opinion on what to do about the Hubble Space Telescope. NASA had recently announced that it would cancel the next servicing mission for the aging telescope, which will likely fail by 2007. O’Keefe is looking to retired Admiral Harold Gehman, who chaired the independent Columbia Accident Investigation Board. Gehman has yet to say if he’ll take up the task of investigating the case for Hubble.

Posted on by Fraser Cain

Spirit is On the Mend

Image credit: NASA/JPL
NASA’s Spirit rover on Mars has resumed taking pictures as engineers continue work on restoring its health. Meanwhile, Spirit’s twin, Opportunity, extended its rear wheels backward to driving position last night as part of preparations to roll off its lander, possibly as early as overnight Saturday-to-Sunday.

Spirit shot and transmitted a picture yesterday to show the position of its robotic arm. “The arm is exactly where we expected,” said Jennifer Trosper, mission manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. It is still extended in the same position as when the rover developed communication and computer problems on Jan. 22. A mineral-identifying instrument called a Moessbauer spectrometer, at the tip of the arm, is positioned at a rock nicknamed Adirondack.

Engineers have been carefully nursing Spirit back toward full operations for the past week. They are sending commands today for the rover to begin making new scientific observations again, starting with panoramic camera images of nearby rocks. Today’s commands also tell the rover to send data stored by two instruments since they took readings on Adirondack last week — the Moessbauer spectrometer and the alpha particle X-ray spectrometer, which identifies the chemical elements in a target.

“We know we still have some engineering work to do, but we think we understand the problem well enough to do science in parallel with that work,” Trosper said. Several attempts to get a full trace of data related to the rover’s problem have only partially succeeded. The engineers might choose to reformat the rover’s flash memory in the next few days.

A health check of Spirit’s camera mast is on the agenda for today. Another health check, of an actuator motor for a periscope mirror of the miniature thermal emission spectrometer, is planned for Friday.

Halfway around Mars from Spirit, Opportunity’s lander platform successfully tilted itself forward by pulling airbag material under the rear portion of the lander then flexing its rear petal downward. “What this did is drive our front edge lower,” said JPL’s Matt Wallace, mission manager. “The tips of the egress aid (a reinforced fabric ramp) are now in the soil. That makes egress look perfect. It’s going to be an easy ride.” The rover also retracted a lift mechanism underneath the rover, to get it out of the way for the egress, or drive-off.

During Opportunity’s sol 6, the martian day that started today at 10:26 a.m. PST, the rover will be commanded to lower the middle pair of its six wheels and to release its robotic arm from the latch that has held it since before launch.

Yesterday, Opportunity used its minature thermal emission spectrometer on a portion of the landing neighborhood that includes a rock outcrop. The instrument identifies the composition of rocks and soils from a distance. Opportunity did not return the data from those observations before going to sleep for the martian night, but may later today.

The rovers’ main task in coming weeks and months is to explore their landing sites for evidence in the rocks and soil about whether the sites’ past environments were ever watery and possibly suitable for sustaining life.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA’s Office of Space Science, Washington, D.C. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu.

Original Source: NASA/JPL News Release

Posted on by Mark Mortimer

Book Review: Beyond: Visions of the Interplanetary Probes

People usually associate squads of bespectacled engineers and scientists as being the sole guardians of space. Beyond: Visions of the Interplanetary Probes by Michael Benson is the type of book that rationalizes and moreover encourages the inclusion of other specialists, especially those in the arts. Containing 295 photographs chosen both for their artistic, awe inspiring impact as well as their voluminous scientific content, the reader will want to quickly put aside numerical calculations about orbital mechanics and let their eyes float across the vistas of other planets. It is easy to imagine that only a thin visor of a helmet separates them from the visions in the book. Michael Benson’s collection of breathtakingly clear images gives credit to the machines that took the pictures and the will of all the bespectacled and clear sighted individuals who worked so hard to get the machines to their complete their mission.

This book is all about its photographs. These come as both true colour and black and white. They range from compact portraits to large expanses. In keeping true to the sources, collages of contiguous single frames give fantastic perspectives including a 110cm x 26cm full colour image of a dust cloud as it storms across a broad swathe of the Martian surface. Each image is silhouetted against a matte black background that enhances the reader’s feeling of ‘being there’. My personal favourites are views of satellites with their host planet behind them and the satellite’s shadow etched on the host’s surface. The details evident in black and white shots of crater rims softened by dunes are better than most tour guides of earthly locales. These photographs are like beauty contest entrants each vying to allure the judge to vote for them.

The photographs are grouped into chapters or collections for each planet, except Pluto, for which no clear images exist. Chapters are introduced with a brief passage discussing the imaging history, the relevant probes and some of the provocative visual features. Often a planet’s chapter includes its satellites though there is a separate chapter for Earth’s moon as well as a chapter for asteroids within the Asteroid Belt. Either adjoining or nearby each photograph is a caption identifying the probe that acquired the image, the date this occurred and a description. As a bonus, there are black and white block drawings of the probes themselves. Leading this beauty contest is a provocative essay where Arthur C. Clarke muses about future explorers. After showing off all the contestants, Benson delivers a short essay on the selection process and the image processing. The book concludes in an afterward by Lawrence Weschler where he contemplates the relative importance of humankind in the context of so much other-world beauty.

I liked the black background and paper type of the book though black, as is its nature, shows up printing artifacts (not many) and fingerprints (becoming more frequent). In addition, sometimes description on the captions do not identify the significance of a picture. Perhaps this may be because there are no features to remark on and only the emotive force caused a picture to be selected.

The clarity of the photographs is so great that I can easily forget myself and try to touch the textures and shapes to gain a tactile sense. It seems I need more than one sense to fully absorb the grandiose scale of the subjects themselves and the specialised effort that made them come into being. I have been perhaps a little bit too guilty of self importance, but after viewing this book my self estimation of where I stand in the scale of things has changed, for the better.

Learn more about the book from Amazon.com

Review by Mark Mortimer

Posted on by Fraser Cain

O’Keefe Grilled About Space Initiative

NASA Administrator Sean O’Keefe faced some tough questions from US senators on Wednesday as they attempted to learn how the agency would actually pay for the ambitious plan presented by President Bush a few weeks ago. Senator Bill Nelson was concerned that Bush didn’t mention the space initiative in his State of the Union announcement just six days later, “if we don’t put the full weight of the president behind it, I’m afraid it’s going to fizzle.”

Posted on by Fraser Cain

An Advocate for Gusev Crater

Image credit: Seth Shostak
Dr. Nathalie Cabrol spoke with me about her experiences as a scientist working with the Spirit team. This is a personal story, a snapshot taken in the midst of the swirl of events as Spirit prepares to rove the surface of Mars. She’s been at JPL since the Spirit rover landed. When asked if it’s been hard to sleep, Nathalie replied, “If this is a dream, don’t wake me up! I’ve been waiting for 15 years to see this place we’ve been dreaming about. It’s as beautiful as I expected! I’m excited and eager to step off the lander and explore Gusev Crater.”

For more than a decade, Dr. Nathalie Cabrol has been going to Mars every morning as she pursued her dreams of exploring Gusev Crater. She’s a planetary geologist with the SETI Institute and NASA Ames Research Center. In a unique scientific partnership with her husband, Dr. Edmond Grin, Cabrol studied and successfully proposed, and promoted Gusev Crater as a landing site for the martian rovers. Gusev may hold an ancient lakebed; Spirit is seeking evidence of water on Mars.

Cabrol’s dreams came true when Spirit successfully landed in Gusev Crater on January 3, 8:35 PM PST. Cabrol described the landing with excitement: “These first few days are baby steps in our giant leap toward understanding the environment of Mars. The rover landing went perfectly. We had only one tense moment after the 4th bounce when we lost contact, but we regained contact after a few minutes, and all was well. Actually, Spirit landed 32 times as it bounced across Gusev before coming to rest in the vast plain encompassed by the crater. It was a fantastic achievement! The engineers are doing the checkout now. For them, it’s business as usual, and all seems to be going well.”

After coming to a stop, the lander paused; its great balloons deflated. The rover came to life, unfolded, and phoned home. Like any good tourist, it sent a postcard home. It’s the first view of a new place, a new terrain on Mars.

Cabrol said that she felt “at home” when she saw the first views of Gusev Crater. Here on Earth, she considers herself to be a “desert rat”. She does field research in some of the most inhospitable locations on the planet such as the Atacama Desert and Lincancabur volcano in South America, extreme environments that offer Earth-analogs for Mars. Viewing Gusev through the eyes of Spirit, Nathalie sees “landscapes we know on Earth. Mars is really an Earth-like planet. But, it’s a new place on Mars. Gusev is very different from the Viking and Pathfinder landing sites. At Gusev we see lots of smaller rocks. There are fewer boulders than we saw at the other landing sites. We’re in new terrain with Spirit.”

How does she feel about where Spirit finally landed? “We landed in the sweet spot. Gusev is known to be dusty, but we landed where most of the dust has been removed in places by winds and dust devils. Some rock looks clean enough, and this will make our scientific work much easier. We’ll spend less energy cleaning and scraping the surfaces of rocks we wish to study because there appears to be little dust on them,” said Cabrol. And there are lots of rocks to study; everywhere around the lander the plain is strewn with rocks.

She’s interested in understanding the population of stones: the distribution of their shapes and sizes, the morphology and composition of the rocks, and how they were transported to their present locations. As the new, hi-resolution panoramas stream in over the next few days, she’s eagerly looking forward to seeing both the visible and infrared images as these will begin to reveal the mineralogy of the rocks.

There are other great targets for Spirit: as they retracted, the airbags scraped the surface and revealed differently colored soil that is intriguing in both its color and apparent stickiness. It’s a puzzle that requires closer inspection. There’s a nearby depression that could be an impact crater, Sleepy Hollow that offers the opportunity to get a close-up look as subsurface materials. Cabrol explained, “With the 3-D glasses, Sleepy Hollow was a blast! It just jumped out and looked a lot like as an impact crater with a solid rim armored with rock. It’s spectacular! That depression makes our lives as geologists easier. It’s like an excavated surface–so we can see what’s below.”

Why Gusev? The scientific motive for the Mars Exploration Rovers is to seek evidence of water and life, extant or extinct, on Mars. Gusev may be an ancient lakebed, and Spirit’s onboard scientific instrument package provides the virtual tools to Earth-bound geologists to look for evidence of sediments and water in the past. Where to look? There’s a team of about 50 scientists assembled at JPL. “Ideas and hypotheses are flying about the room as we actually see Gusev Crater. We are discussing and debating the best targets for Spirit as the images come back to us on Earth. It is so exciting!” said Cabrol.

Beyond the immediate terrain, there are hills and mesas. Until the stereoscopic panoramas arrive at Earth in the next few days, it is difficult to determine the distance to these features. So, it is not known whether Spirit can travel to these hills and, perhaps, come to the shore of an ancient lake. Mission success is defined as at least 90 sols (Mars days) of exploration and science, but how long can Spirit continue to rove? “As long as the rover and the scientists remain healthy, we’ll keep exploring. It’s so challenging to get to Mars, and land successfully that we have to go on as long as possible.”

Today, Cabrol is making her first virtual steps on the Martian surface. In the future, she dreams of going to Mars. When asked about the Saturday night landing, she said, “There’s only one thing that didn’t land on Mars, and that’s me!” For now, she’s there virtually and she just finds Gusev Crater “beautiful. It’s simply beautiful.”

Original Source: Astrobiology Magazine

Posted on by Fraser Cain

Researchers Create a New Plasma Thruster

Image credit: ANU
The dream of manned missions to Mars and beyond could become a reality thanks to plasma technology developed at ANU.

Research results to be published in the journal Applied Physics Letters this week show that the ANU Helicon Double Layer Thruster (HDLT) can be powered by hydrogen ? an otherwise unusable waste product in manned spacecraft.

The HDLT uses solar electricity from the sun to create a magnetic field through which hydrogen is passed to make a beam of plasma, which powers a ship through space.

While the plasma thruster has a fraction of the power of the rockets that launch the space shuttle, it uses far less fuel and gets more thrust as a ratio of the fuel it burns, making it ideal for interplanetary missions.

“The Americans say they want to send men to Mars ? this is the technology to take them there,” said the HDLT’s inventor Dr Christine Charles.

“This thruster gives Australia a fantastic opportunity to be part of the international space race.”

The ANU team led by Professor Rod Boswell has been in close collaboration with NASA, helping US scientists fix glitches with their own plasma thruster, the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) invented by veteran shuttle astronaut Franklin Chang-Diaz, who visited ANU last year.

While the technology of plasma thrusters is not new, its popularity has only taken off in recent years, with it being used to help satellites maintain their positions in orbit. However, the NASA VASIMR concept and more recently the ANU HDLT are very recent inventions which may open the door to deep space exploration.

The ANU thruster has the edge on rival technologies as it is simpler and has been proven to work with hydrogen. Importantly, it also does not emit positively charged ions that could potentially cause a disaster by interfering with a spacecraft’s communications systems.

“The HDLT is a beautiful piece of physics because it is so simple. It doesn’t need any moving parts,” Dr Charles added.

Original Source: ANU News Release

Posted on by Fraser Cain

Opportunity Begins Standing Up

Image credit: NASA/JPL
NASA’s Opportunity rover has untucked its front wheels and latched its suspension system in place, key steps in preparing to drive off its lander and onto martian soil.

Overnight tonight, mission controllers at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., plan to try tilting the lander platform down in the front by pressing the rear petal downward to raise the back.

“What we want to do is lower the front edge by about 5 degrees,” said JPL’s Dr. Rick Welch, activity lead for preparing the rover for roll-off. Plans call for driving off straight ahead, possibly as early as overnight Sunday-Monday, if all goes well.

Meanwhile, halfway around Mars, Opportunity’s twin, Spirit, continues on the mend from a computer memory problem that struck it a week ago. “Right now we’re working to get complete control of the vehicle, and we’re still not quite there,” said JPL’s Jennifer Trosper, mission manager. “If we’re on the right track, we hope to be back doing some science by early next week. If we’re not on the right track, it could take longer than that.”

Opportunity’s infrared sensing instrument, the miniature thermal emission spectrometer, passed a health check last night. Scientists plan to begin using it tonight. The instrument detects the composition of rocks and soils from a distance. That information will help scientists decide what targets to approach after Opportunity drives off the lander.

Scientists and rover engineers are already discussing which specific rocks within an outcropping near the lander will make the best targets, said Dr. Jim Bell of Cornell University, Ithaca, N.Y., lead scientist for the panoramic cameras on Opportunity and Spirit. Details of the outcrop can be seen in a new a color-picture mosaic Bell presented, the first portion of a full-circle panorama that has been taken and partially transmitted.

Other new images show how Opportunity’s airbags left detailed impressions in the fine-textured soil as the spacecraft was rolling to a stop in the small crater where it now sits. “These marks are telling us about the physical properties of the material,” Bell said.

Some scientists believe that dark colored granules covering most of the crater’s surface were pressed down into an underlying layer of powdery, lighter red material when the airbags hit. Others hold to a theory that the dark granules are agglomerations that crumble into the finer, lighter material when disturbed. After roll-off, soil near the lander will be the rover’s first target for close-up examination with a microscope and two tools for detecting the composition of the target. The soil at Opportunity’s landing site appears to have different properties than the soil at Spirit’s landing site, Bell said.

Opportunity has already validated predictions about the landing site made on the basis of images and measurements taken by spacecraft orbiting Mars, said JPL’s Dr. Matt Golombek, a member of the rover science team and co-chair of a steering committee that evaluated potential landing sites for the rovers. The predictions included that the region of Meridiani Planum where Opportunity landed would be safe for landing, would be safe for rover driving, would have very few rocks and would look unlike any place previously seen on Mars.

“This bodes well for our ability to use remote sensing data in the future for picking landing sites,” Golombek said.

Engineers have been able to confirm a diagnosis that an unplanned drawdown of battery power each night on Opportunity is due to a heater on the rover’s robotic arm. A switch designed to overrule the heater’s thermostatic control has not been working. “In the near term, it’s not providing any operational constraints,” Welch said.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA’s Office of Space Science, Washington, D.C. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University at http://athena.cornell.edu.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Scientific Equipment Headed to the Station

Image credit: ESA
Preparing for the arrival of the first European Automated Transfer Vehicle. Europe’s scientific utilisation of the International Space Station (ISS) took an important step forward with the launch of an unmanned Russian Progress cargo spacecraft today at 12:58 Central European Time (16:58 local time) from the Baikonur Cosmodrome in Kazakhstan.

The Progress supply vehicle will take two days to reach the International Space Station, carrying experiment hardware for the Delta mission to be carried out by ESA’s Dutch astronaut Andr? Kuipers in April, Matroshka, a European experiment facility for measuring radiation levels to which astronauts are exposed in space, and hardware to allow the European Automated Transfer Vehicle (ATV) to dock with the Station.

Launched by a Soyuz rocket on mission 13P, the Progress spacecraft with the serial number M1-11 is due to dock with the International Space Station on 31 January at 14:19 Central European Time. The Progress-type spacecraft are currently serving as supply vehicles for the International Space Station and are also uploading European hardware and equipment in advance of European missions to be carried out on the International Space Station.

Among other cargo, Progress is transporting scientific equipment which will be used during the upcoming Delta mission (Dutch Expedition for Life science, Technology and Atmospheric research). Andr? Kuipers, who on 19 April flies out to the ISS on a 10-day mission, will be employing this equipment to carry out a programme of scientific and educational activities. The Delta experiments on board Progress are:

* ARGES: This experiment will study high-intensity discharge (HID) lamps, which are used in all kinds of outdoor illuminations, making use of the absence of gravity to get new insights into how these lamps work and help develop more efficient lamps in future.
* HEAT: This experiment will be testing heat transfer properties in a section of a heat pipe with the aim of developing more efficient heat distribution systems for satellites and space vehicles in future.
* PROMISS-3: The experiment aims to analyse the growth of protein crystals in weightlessness, which cannot be observed to the same extent and with the same homogeneity on the ground.
* SUIT: The aims of this technology demonstration are to improve the orientation capabilities of astronauts and reduce space sickness. The experiment involves the astronaut wearing a special vest containing vibrating elements to assist his awareness of his position.
* ETD: This is a human physiology experiment which uses an eye-tracking device to determine eye movements in weightlessness and compare how they differ from eye movements on Earth and hence determine the effect the body?s balance system has on eye movements. This has an important bearing on balance disorders on the ground as well as in space.
* SAMPLE: This is a study into the composition and physiology of microbe species at different points around the ISS and also from the astronauts. The experiment will take samples from the chosen locations and further analyse how the different microbes found adapt to weightlessness.
* MOT: The aim of MOT is to calibrate accelerometers to be used to measure acceleration in three directions. Once calibrated the accelerometers will be incorporated into radio sensitive abdominal implants in mice for measuring acceleration, heart rate and body temperature.

Specialised containers called “biokits” are also part of the Progress cargo. They will be used to return the samples from the biological experiments taking place on the Delta mission.

Also on board Progress is a Russian spectrum analyser, not part of the Delta mission, to perform a dedicated in-orbit checkout on the European Global Transmission Services (GTS) experiment on the ISS. It will analyse the quality of the radio frequency cables of the GTS experiment, which might be the cause of the weaker than expected transmission signals received on the ground so far.

Another experiment on board Progress in addition to the Delta mission is the Matroshka experimental facility, which will be placed on the outside of the Russian Zvezda module. It will measure radiation levels experienced by astronauts in space. The facility has a human shape, consisting of a head and torso. It is made of natural bone and a synthetic material similar to human tissue. Sensors measuring radiation will be placed at various key external and internal positions on the model such as the areas of the stomach, lungs, kidney, colon and eyes. The facility will remain outside the ISS for a year. Matroshka is an ESA payload under the project leadership of DLR, the German Aerospace Centre in Cologne.

This flight is also carrying elements of the rendezvous and docking system of the Automated Transfer Vehicle (ATV), the European unmanned ISS supply spacecraft, similar in function – but not in size – to the Russian Progress. It will carry up to three times the cargo of the Progress vehicles, i.e. up to 7500kg.

The ATV-related equipment flown to the ISS consists of the following items:

* the videometer target assembly,
* laser retroreflectors,
* a container for old laser retroreflectors,
* two communication antennas,
* several cables.

This equipment from Russia and from ESA is required for the rendezvous between the first ATV, called Jules Verne, and the ISS early next year. The videometer, which will be located on the ATV spacecraft, will enable rendezvous operations in orbit to be carried out with a degree of precision never yet attained. This instrument will analyse the laser light emitted by the ATV and reflected back to it by the retroreflectors. These retroreflectors make up part of the videometer target assembly, serving as targets on the docking side of the service module. Two sets of different patterns of retroreflectors will enable the ATV ? from a distance of 300m onwards – to know its distance from and angular orientation to the ISS precisely.

The two antennas are needed for voice and data communications between the Russian Zvezda Module and the ATV. This sophisticated antenna system made in Russia will require six more, to be flown out later by other Progress ships.

All these ATV-related elements will be installed on the rear side of the Zvezda module during extravehicular activities scheduled for this July. Some old ATV retroreflectors, installed on Zvezda before its launch in 1998, will be brought back to Earth for material analysis.

The remaining experiment equipment for the Delta mission will be launched to the ISS together with Andr? Kuipers in the manned Soyuz TMA-4. This is scheduled for launch from Baikonur as mission 8S on 19 April. Kuipers is currently training for the mission at Star City near Moscow.

Original Source: ESA News Release

Posted on by Fraser Cain

Opportunity Landing Site Named for Challenger Crew

NASA announced plans to name the landing site of the Mars Opportunity rover in honor of the Space Shuttle Challenger’s final crew. The area in the vast flatland called Meridiani Planum, where Opportunity landed this weekend, will be called the Challenger Memorial Station.

The seven-member crew of Space Shuttle Challenger was lost when the orbiter suffered an in-flight breakup during launch Jan. 28, 1986, 18 years ago today.

NASA selected Meridiani Planum because of extensive deposits of a mineral called crystalline hematite, which usually forms in the presence of liquid water. Scientists had hoped for a specific landing site where they could examine both the surface layer that’s rich in hematite and an underlying geological feature of light-colored layered rock. The small crater in which Opportunity alighted appears to have exposures of both, with soil that could be the hematite unit and an exposed outcropping of the lighter rock layer.

Challenger’s 10th flight was to have been a six-day mission dedicated to research and education, as well as the deployment of the TDRS-B communications satellite.

Challenger’s commander was Francis R. Scobee and the mission pilot was Michael J. Smith. Mission specialists included Judith A. Resnik, Ellison S. Onizuka and Ronald E. McNair. The mission also carried two payload specialists, Gregory B. Jarvis and Sharon Christa McAuliffe, who was the agency’s first teacher in space.

Opportunity successfully landed on Mars Jan. 25. It will spend the next three months exploring the region surrounding what is now known as Challenger Memorial Station to determine if Mars was ever watery and suitable to sustain life.

Opportunity?s twin, Spirit, is trailblazing a similar path on the other side of the planet, in a Connecticut-sized feature called Gusev Crater.

A composite image depicting the location of the Challenger Memorial Station can be found on the Web at:

http://www.jpl.nasa.gov/mer2004/rover-images/jan-28-2004/captions/image-1.html

NASA’s Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology, Pasadena, manages the Mars Exploration Rover project for NASA’s Office of Space Science in Washington.

Additional information about the project is available from NASA, JPL and Cornell University, Ithaca, N.Y., on the Internet at: http://www.nasa.gov/