Mars Rover Opportunity Gets Green Light To Enter Crater

NEWS RELEASE: 2004-142

NASA has decided the potential science value gained by sending Opportunity into a martian impact crater likely outweighs the risk of the intrepid explorer not being able to get back out.

Opportunity has been examining the rim of the stadium-sized "Endurance Crater" since late May. The rover team used observations of the depression to evaluate potential science benefits of entering the crater and the traversability of its inner slopes.

The soonest Opportunity could enter Endurance is early next week. It will drive to the top of a prospective entry-and-exit route on the southern edge of the crater and make a final check of the slope. If the route is no steeper than what recent testing runs at NASA's Jet Propulsion Laboratory, Pasadena, Calif., suggest a rover can climb, controllers plan to radio Opportunity the command to go into the crater.

"This is a crucial and careful decision for the Mars Exploration Rovers' extended mission," said Dr. Edward Weiler, NASA's associate administrator for space science. "Layered rock exposures inside Endurance Crater may add significantly to the story of a watery past environment that Opportunity has already begun telling us. The analysis just completed by the rover team shows likelihood that Opportunity will be able to drive to a diagnostic rock exposure, examine it, and then drive out of the crater. However, there's no guarantee of getting out again, so we also considered what science opportunities outside the crater would be forfeited if the rover spends its remaining operational life inside the crater."

Opportunity and its twin, Spirit, successfully completed their primary three-month missions on Mars in April.

At a rock outcrop in a small impact feature nicknamed, "Eagle Crater," where Opportunity first landed, the rover found small-scale rock textures and evaporite mineral compositions testifying that a body of salty water covered the site long ago.

The wet environment may have been a suitable habitat for life, if it ever existed on Mars. However, only the uppermost layer of the region's layered crust was exposed at Eagle Crater, not deeper layers that could reveal what the environment was like earlier.

The rock layer seen at Eagle Crater appears at Endurance Crater, too. At Endurance, though, it lies above exposures of thicker, older layers, which are the main scientific temptation for sending Opportunity inside the crater.

"Answering the question of what came before the evaporites is the most significant scientific issue we can address with Opportunity at this time," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the science instruments on both rovers. "We've read the last chapter, the record of the final gasps of an evaporating body of water. What came before? It could have been a deep-water environment. It could have been sand dunes. It could have been a volcano. Whatever we learn about that earlier period will help us interpret the upper layer's evidence for a wet environment and understand how the environment changed."

Richard Cook, project manager at JPL for the rovers, said that reaching one exposure of the older rock layers inside Endurance requires driving only about 5 to 7 meters (16 to 23 feet) into the 130-meter-diameter (140-yard-diameter) crater. The rover is on the rim at that site, which had been dubbed "Karatepe."

"We'll take an incremental approach, edging our way down to the target," Cook said. The plan is to use the tools on Opportunity's robotic arm to analyze the exposed layers for several days, then drive in reverse back up the slope and exit the crater. The slope between the rim and the layered outcrop at Karatepe is about 25 degrees.

"We have done testing that says we can do 25 degrees, provided the wheels are on a rock surface and not loose sand," Cook said. Engineers and scientists on the rover team built a test surface mimicking the rocks and sand seen in Opportunity's images of Endurance Crater. The surface was tilted to 25 degrees, and a test rover climbed it. If portions of the route to the outcrop turn out to be between 25 and 30 degrees, the team plans to proceed slowly and use Opportunity to assess the amount of traction the rover is getting.

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.

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Cassini-Huygens Will Unlock Saturn's Secrets

NEWS RELEASE: 2004-141

Jet Propulsion Laboratory, Pasadena, CA -- The international Cassini-Huygens mission is poised to begin an extensive tour of Saturn, its majestic rings and 31 known moons. After a nearly seven-year journey, Cassini is scheduled to enter orbit around Saturn at 7:30 p.m. PDT (10:30 p.m. EDT) June 30, 2004.

"The Saturn system represents an unsurpassed laboratory, where we can look for answers to many fundamental questions about the physics, chemistry and evolution of the planets and the conditions that give rise to life," said Dr. Ed Weiler, associate administrator for space science at NASA Headquarters, Washington, D.C.

Launched Oct. 15, 1997, on a journey covering 3.5 billion kilometers (2.2 billion miles), Cassini is the most highly instrumented and scientifically capable planetary spacecraft ever flown. It has 12 instruments on the Cassini orbiter and six more on the Huygens probe. The mission represents the best technical efforts of 260 scientists from the United States and 17 European nations. The cost of the Cassini mission is approximately $3 billion.

The Cassini-Huygens mission is a four-year study of Saturn. The 18 highly sophisticated science instruments will study Saturn's rings, icy satellites, magnetosphere and Titan, the planet's largest moon.

For the critical Saturn orbit insertion maneuver, the spacecraft will fire its main engine for 96 minutes. The maneuver will reduce Cassini's speed and allow it to be captured into orbit as a satellite of Saturn. Cassini will pass through a gap between two of Saturn's rings, called the F and G rings. Cassini will swing close to the planet and begin the first of 76 orbits around the Saturn system. During Cassini's four-year mission, it will execute 52 close encounters with seven of Saturn's 31 known moons.

There are risks involved with orbit insertion, but mission planners have prepared for them. There is a backup engine in case the main engine fails. The region of passage through the ring plane was searched for hazards with the best Earth- and space-based telescopes.

Particles too small to be seen from Earth could be fatal to the spacecraft, so Cassini will be turned to use its high-gain antenna as a shield against small objects.

Saturn is the sixth planet from the sun. It is the second largest planet in our solar system, after Jupiter. The planet and its ring system serve as a miniature model for the disc of gas and dust surrounding the early Sun that formed the planets. Detailed knowledge of the dynamics of interactions among Saturn's elaborate rings and numerous moons will provide valuable data for understanding how each of the solar system's planets evolved.

The study of Titan, Saturn's largest moon, is one of the major goals of the mission. Titan may preserve, in deep-freeze, many of the chemical compounds that preceded life on Earth. Cassini will execute 45 flybys of Titan, coming as close as approximately 950 kilometers (590 miles) above the surface. This will permit high-resolution mapping of the moon's surface with an imaging radar instrument, which can see through the opaque haze of Titan's upper atmosphere.

"Titan is like a time machine taking us to the past to see what Earth might have been like," said Dr. Dennis Matson, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The hazy moon may hold clues to how the primitive Earth evolved into a life-bearing planet."

On Dec. 25, 2004 (Dec. 24 in U.S. time zones) Cassini will release the wok-shaped Huygens probe on its journey toward Titan. Huygens will be the first probe to descend to the surface of a moon of another planet. It will also make the most distant descent by a robotic probe ever attempted on another object in the solar system. On Jan. 14, 2005, after a 20-day ballistic freefall, Huygens will enter Titan's atmosphere. It will deploy parachutes and begin 2.5 hours of intensive scientific observations. The Huygens probe will transmit data to the Cassini spacecraft, which will relay the information back to Earth.

JPL designed, developed and assembled the Cassini orbiter. The European Space Agency managed the development of Huygens and is in charge of operations of the probe from its control center in Darmstadt, Germany. The Italian Space Agency provided the high-gain antenna, much of the radio system and elements of several of Cassini's science instruments. JPL manages the overall program for NASA's Office of Space Science, Washington, D.C.

For information about the Cassini-Huygens mission to Saturn and Titan on the Internet, visit: http://www.nasa.gov/cassini or http://www.esa.int/Cassini-Huygens.

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Spitzer Leads NASA's Great Observatories to Uncover Black Holes, Other Hidden Objects in the Distant Universe

Release Number: STScI-2004-19

Astronomers unveiled the deepest images from NASA's new Spitzer Space Telescope today, and announced the detection of distant objects — including several supermassive black holes — that are nearly invisible in even the deepest images from telescopes operating at other wavelengths.

Dr. Mark Dickinson, of the National Optical Astronomy Observatory, Tucson, Ariz., and principal investigator for the new observations, said, "With these ultra-deep Spitzer images, we are easily seeing objects throughout time and space, out to redshifts of 6 or more, where the most distant known galaxies lie. Moreover, we see some objects that are completely invisible, but whose existence was hinted at by previous observations from the Chandra and Hubble Observatories."

Seven of the objects detected by Spitzer may be part of the long-sought population of "missing" supermassive black holes that powered the bright cores of the earliest active galaxies. The discovery completes a full accounting of all the X-ray sources seen in one of the deepest surveys of the universe ever taken.

This detective story required the combined power of NASA's three orbiting Great Observatories — the Hubble Space Telescope, Chandra X-ray Observatory, and Spitzer Space Telescope. Each observatory works with different wavelengths of electromagnetic radiation, from high-energy X-rays with Chandra, through visible light with Hubble, and into the infrared with Spitzer. Together, these telescopes yield far more information than any single instrument.

All three telescopes peered out to distances of up to 13 billion light-years toward a small patch of the southern sky containing more than 10,000 galaxies, in a coordinated project called the Great Observatories Origins Deep Survey (GOODS). Chandra images detected more than 200 hundred X-ray sources believed to be supermassive black holes in the centers of young galaxies. The X-rays are produced by extremely hot interstellar gases falling into the black holes.

Hubble's Advanced Camera for surveys revealed optical galaxies around almost all the X-ray black holes. However, there remained seven mysterious X-ray sources for which there was no optical galaxy. Dr. Anton Koekemoer of the Space Telescope Science Institute, Baltimore, Md., who discovered these sources, presented three intriguing possibilities for their origin. "The galaxies around these black holes may be completely hidden by thick clouds of dust absorbing all their light, or may contain very old, red stars. Or some of them could be the most distant black holes ever observed — perhaps as far as 13 billion light-years." In this case all their optical light would be shifted to very long infrared wavelengths by the expansion of the universe.

The Spitzer images were anxiously awaited to resolve this puzzle. Because Spitzer observes at infrared wavelengths up to 100 times longer than those probed by Hubble, Spitzer might be able to see the otherwise invisible objects. Indeed, the very first Spitzer images of these objects, obtained earlier this year, immediately revealed the telltale infrared glow from the host galaxies around all the missing X-ray black holes. "The Spitzer images are fantastic," said Koekemoer, who led the effort to compare and identify the missing X-ray black holes in the Spitzer images. "For the first time ever, we have identified 100 percent of the galaxies around X-ray black holes."

Three of Koekemoer's galaxies are extremely red, or bright in the infrared. The Spitzer data, together with new images at shorter infrared wavelengths from the Very Large Telescope at the European Southern Observatory, indicate that the galaxies around these black holes could be heavily obscured by dust, perhaps more distant than other known dust-obscured galaxies. Some of the other objects, however, have quite different colors, and are even more intriguing. "Their colors may be consistent with objects more distant than any now known," said Dickinson, who cautioned that additional Spitzer observations later this year will provide more color information to confirm what kind of objects these might be.

Old Galaxies Shine in Infrared: In another study using the same Spitzer data, Haojing Yan of the Spitzer Science Center at the California Institute of Technology, Pasadena, Calif., studied 17 unusual galaxies in the area of the Hubble Ultra Deep Field. This small patch of sky within the GOODS area was recently the target for the deepest optical images ever taken with Hubble's Advanced Camera, and was also studied with Hubble's Near Infrared Camera and Multi-Object Spectrometer. The Ultra Deep Field optical images, released in March 2004, reach more than five times fainter than the GOODS Hubble data. But even with that phenomenal sensitivity, two of the 17 Spitzer-selected objects remain completely invisible in optical light, while the others are only faintly detected. Yan finds that these galaxies get steadily brighter at longer wavelengths, and seem to be more distant cousins of the so-called "Extremely Red Objects," known from previous deep surveys. Most are distant galaxies that are red because they are either old or dusty. These new Spitzer-identified objects, however, appear to lie at higher redshifts, out to nearly a redshift of 3, when the universe was only two billion years old.

"These objects could be the remnants of the first stars — the very first galaxies formed in the earliest stages of the universe," said Yan. Most galaxies that we see today formed their stars gradually over a long period of time. But these 17 objects seem to be "old before their time," perhaps almost as old as the universe itself at that early epoch. "If we indeed are seeing the direct, 'pure' descendants of the first stars, this would make a thrilling story," said Yan. Further Spitzer observations at longer wavelengths, planned for later this year, should help decide whether these objects are red because they are old, or because they are young and actively forming stars, but enveloped in dust.

Black Holes in Hiding: Using Hubble and Chandra data, Dr. Meg Urry, a GOODS astronomer at Yale University, New Haven, Conn., and her team suggest that most accreting black holes are hidden from view at visible wavelengths, even in the early universe. Few such hidden black holes had previously been found at such large distances, despite theoretical arguments for their existence. They were missed because their visible radiation is so dim they look like faint, ordinary galaxies. "With the great sensitivity of the new Spitzer infrared cameras, and with the superb spatial resolution of Chandra, finding all of the black holes that are powered by infalling gas is now possible."

Urry's team is using data from the three space observatories to take a census of the supermassive black holes that formed two to five billion years after the big bang. Most of these active galactic nuclei are hidden by dust, which absorbs visible and some X-ray light but emits strongly at infrared wavelengths. "The Spitzer GOODS observations verify that large numbers — perhaps three-quarters — of the obscured active galactic nuclei were indeed present in the early universe. The longer-wavelength Spitzer data still to come will reveal even more shrouded AGNs," said Urry, "including some, missed by X-ray observations, which look like ultraluminous infrared galaxies."

The Spitzer Space Telescope is a mission managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spitzer science operations are conducted at the California Institute of Technology. The Space Telescope Science Institute (STScI), Baltimore, Md. is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA). NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA's Office of Space Science, Washington. Northrop Grumman of Redondo Beach, Calif., formerly TRW, Inc., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

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Scientists Measure Sun's Smallest Visible Magnetic Fields

Denver, CO., June 1, 2004 -- Solar physicists from Lockheed Martin [NYSE: LMT], and The Institute of Theoretical Astrophysics of the University of Oslo have analyzed the highest resolution images ever taken near the solar disk center and found surprising new small-scale magnetic field structures. Their results, which were reported yesterday at the American Astronomical Society's meeting in Denver, address long-standing issues on the formation and decay of sunspots and the forecasting of magnetic activity such as solar flares and coronal mass ejections. Such activity influences the upper atmosphere and magnetosphere of Earth and can damage satellites in orbit.

"These new images and magnetic field measurements show that the Sun can still surprise us when we look at things 100 km (62 mile) in size," said Dr. Tom Berger, principal investigator on the study, and solar physicist at the Lockheed Martin Solar and Astrophysics Lab (LMSAL) at the company's Advanced Technology Center in Palo Alto, Calif. "Using the Swedish one-meter Solar Telescope (SST) on the island of La Palma, Spain, we have discovered new ways in which the smallest 'elements' of the Sun's magnetic field arrange themselves in the turbulent flowfields of the Sun's surface.

The Sun undergoes an 11-year cycle in which its magnetic flux, as seen most prominently in the form of dark sunspots, peaks and wanes. Sunspots demarcate highly magnetic 'active regions' in the solar atmosphere that unleash flares and coronal mass ejections. When coronal mass ejections are directed toward Earth they can damage satellites in orbit, expose high flying airplanes to radiation, and even adversely effect power stations on the ground. Scientists still do not understand how active regions are formed, why they vary with a roughly 11-year period, or how and when flares and mass ejections occur.

In addition to the large and obvious sunspots, active regions contain a myriad of smaller magnetic structures surrounding the sunspots. These smaller structures are much more dynamic than sunspots, constantly emerging, moving, and rearranging due to their interactions with the convective flowfield. This constant motion in the small-scale 'plage' fields around sunspots builds up magnetic 'tension' in the larger scale magnetic fields, like a spring winding tighter and tighter. The magnetic 'spring' eventually snaps causing 'magnetic reconnection' and subsequent flares and/or mass ejections.

Scientists are uncertain of the origin of the small-scale magnetic structures on the Sun. Some of the structure clearly originates from sunspots as they decay away over their lifetime. But small-scale structure is found all over the Sun, often far from sunspots in regions of 'quiet Sun.' Sunspots are believed to be formed by a 'global-scale dynamo' system located about 30% of the way down to the Sun's center, at the bottom of the 'convection zone.' However recent observational and theoretical evidence suggests that most of the small-scale magnetic flux in the quiet Sun may be generated by a 'local dynamo' mechanism seated in the upper convection zone and photosphere. Determining where and how magnetic fields are generated on the Sun, and by inference on other stars as well, is a key goal of astrophysics.

The images used in this study (that can be accessed at the URL below) reveal small-scale magnetic fields in the area of a decaying active region. By studying the structure and motion of these small-scale fields, scientists hope to be able to differentiate between magnetic structures generated from sunspot decay and those perhaps generated by a local dynamo process.

When these images were first seen, Dr. Berger and the team were surprised to find a variety of magnetic formations that had not previously been seen on the Sun. Earlier studies, based on images from smaller telescopes, had led scientists to believe that small-scale magnetic structure always took the form of small discrete 'flux tubes,' or individual blobs of magnetic field. However the new images show surprising 'ribbon' and 'flower' structures that indicate much more complex interactions of the small-scale magnetic field with the granule flowfield.

In addition to the images, the new data includes the highest resolution magnetogram, or direct measurement of the density of magnetic fields on the Sun, ever taken. By combining the images and the magnetogram, Dr. Berger and the team are measuring the magnetic content of these new structures for the first time. Further studies of magnetic flux in quiet Sun regions will be used to compare with the images shown here in an effort to understand the origin and fate of small-scale magnetic flux on the Sun.

Preliminary analyses of the data are in a paper submitted for peer-review to the journal Astronomy & Astrophysics .The authors are Dr. Tom Berger and Dr. Alan Title of Lockheed Martin Solar and Astrophysics Lab; Dr. Luc Rouppe van der Voort, Dr. Mats Carlsson, Dr. Viggo Hansteen, Astrid Fossum, and Elin Marthinussen of The Institute for Theoretical Astrophysics, University of Oslo; and Dr. Göran Scharmer and Dr. Mats Löfdahl of The Institute for Solar Physics of the Royal Swedish Academy of Sciences, Stockholm. Future studies will examine movies of these small-scale structures to determine their dynamical interactions with granules.

Headquartered in Bethesda, Md., Lockheed Martin employs about 130,000 people worldwide and is principally engaged in the research, design, development, manufacture and integration of advanced technology systems, products and services. The corporation reported 2003 sales of $31.8 billion.

Contact:
Buddy Nelson, (510) 797-0349; e-mail, buddynelson@mac.com

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