Cosmic Background Explorer (COBE)

The purpose of the Cosmic Background Explorer (COBE) mission was to take precise measurements of the diffuse radiation between 1 micrometer and 1 cm over the whole celestial sphere. The following quantities were measured: (1) the spectrum of the 3 K radiation over the range 100 micrometers to 1 cm; (2) the anisotropy of this radiation from 3 to 10 mm; and, (3) the spectrum and angular distribution of diffuse infrared background radiation at wavelengths from 1 to 300 micrometers.

The experiment module contained the instruments and a dewar filled with 650 liters of 1.6 K liquid helium, with a conical sun shade. The base module contained the attitude control, communications and power systems. The satellite rotated at 1 rpm about the axis of symmetry to control systematic errors in the anisotropy measurements and to allow observations of the zodiacal light at various solar elongation angles. The orientation of the spin axis was maintained anti-earth and at 94 degrees to the sun-earth line. The operational orbit was dawn-dusk sun-synchronous so that the sun was always to the side and thus was shielded from the instruments. With this orbit and spin-axis orientation, the instruments performed a complete scan of the celestial sphere every six months.

Instrument operations were terminated 1993-12-23. As of January 1994, engineering operations were to conclude that month, after which operation of the spacecraft would be transferred to Wallops for use as a test satellite.

The CGRO Mission(1991 - 2000)

The Compton Gamma Ray Observatory was the second of NASA's Great Observatories. Compton, at 17 tons, was the heaviest astrophysical payload ever flown at the time of its launch on April 5, 1991 aboard the space shuttle Atlantis. Compton was safely deorbited and re-entered the Earth's atmosphere on June 4, 2000.

Compton had four instruments that covered an unprecedented six decades of the electromagnetic spectrum, from 30 keV to 30 GeV. In order of increasing spectral energy coverage, these instruments were the Burst And Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET). For each of the instruments, an improvement in sensitivity of better than a factor of ten was realized over previous missions.

The Observatory was named in honor of Dr. Arthur Holly Compton, who won the Nobel prize in physics for work on scattering of high-energy photons by electrons - a process which is central to the gamma-ray detection techniques of all four instruments.

CGRO Observation Timelines

CloudSat Profiles Tornadic Outbreak

The intense thunderstorms responsible for this week's deadly outbreak of tornadoes in Tennessee, Kentucky, Mississippi, Alabama and Arkansas were imaged by the Cloud Profiling Radar on NASA's CloudSat satellite on February 5.
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Clementine Project Information

Clementine was a joint project between the Strategic Defense Initiative Organization and NASA. The objective of the mission was to test sensors and spacecraft components under extended exposure to the space environment and to make scientific observations of the Moon and the near-Earth asteroid 1620 Geographos. The observations included imaging at various wavelengths including ultraviolet and infrared, laser ranging altimetry, and charged particle measurements. These observations were originally for the purposes of assessing the surface mineralogy of the Moon and Geographos, obtaining lunar altimetry from 60N to 60S latitude, and determining the size, shape, rotational characteristics, surface properties, and cratering statistics of Geographos.

Clementine was launched on 25 January 1994 at 16:34 UTC (12:34 PM EDT) from Vandenberg AFB aboard a Titan IIG rocket. After two Earth flybys, lunar insertion was achieved on February 21. Lunar mapping took place over approximately two months, in two parts. The first part consisted of a 5 hour elliptical polar orbit with a perilune of about 400 km at 28 degrees S latitude. After one month of mapping the orbit was rotated to a perilune of 29 degrees N latitude, where it remained for one more month. This allowed global imaging as well as altimetry coverage from 60 degrees S to 60 degrees N.

After leaving lunar orbit, a malfunction in one of the on-board computers on May 7 at 14:39 UTC (9:39 AM EST) caused a thruster to fire until it had used up all of its fuel, leaving the spacecraft spinning at about 80 RPM with no spin control. This made the planned continuation of the mission, a flyby of the near-Earth asteroid Geographos, impossible. The spacecraft remained in geocentric orbit and continued testing the spacecraft components until the end of mission.

More information on the Clementine mission, instruments, and early results can also be found in the Clementine special issue of Science magazine, Vol. 266, No. 5192, December 1994.

Clementine Flight Plan (1994)

January 25   Launch (16:34 UTC)
February 3 Leave Earth Orbit
February 5 First Earth Flyby
February 15 Second Earth Flyby
February 19 Enter Lunar Orbit
February 26 Start of Systematic Mapping - Cycle 1 (South)
March 26 End of Cycle 1, Start of Cycle 2 (North)
April 21 Completion of Cycle 2
May 5 Exit Lunar Orbit
(May 7 Computer Malfunction (14:39 UTC))
*May Earth and Lunar Flybys
*June-August Cruise to Geographos
*August 31 Geographos Flyby

Chandra - A New Way to Weigh Giant Black Holes

How do you weigh the biggest black holes in the universe? One answer can be found from a new technique that astronomers have developed using data from NASA's Chandra X-ray Observatory. By measuring a peak temperature in the hot gas in the center of the giant elliptical galaxy NGC 4649, scientists have determined the mass of the galaxy's supermassive black hole -- providing consistent results with a traditional technique.

The CHAMP Mission

CHAMP (CHAllenging Minisatellite Payload) is a German small satellite mission for geoscientific and atmospheric research and applications, managed by GFZ. With its highly precise, multifunctional and complementary payload elements (magnetometer, accelerometer, star sensor, GPS receiver, laser retro reflector, ion drift meter) and its orbit characteristics (near polar, low altitude, long duration) CHAMP will generate for the first time simultaneously highly precise gravity and magnetic field measurements over a 5 years period. This will allow to detect besides the spatial variations of both fields also their variability with time. The CHAMP mission will open a new era in geopotential research and will become a significant contributor to the Decade of Geopotentials.

In addition with the radio occultation measurements onboard the spacecraft and the infrastructure developed on ground, CHAMP will become a pilot mission for the pre-operational use of space-borne GPS observations for atmospheric and ionospheric research and applications in weather prediction and space weather monitoring.


Cassini to Earth: 'Mission Accomplished, But New Questions Await!'

NASA's Cassini mission is closing one chapter of its journey at Saturn and embarking on a new one with a two-year mission that will address new questions and bring it closer to two of its most intriguing targets—Titan and Enceladus.
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Public release of CALIPSO Data Products

12.08.06: Public release of CALIPSO Data Products

The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite mission is pleased to announce an initial release of its data products. CALIPSO provides new insight into the role that clouds and atmospheric aerosols (airborne particles) play in regulating Earth's weather, climate, and air quality. CALIPSO is a joint mission between NASA and CNES, the French space agency.

CALIPSO's payload includes an active lidar (CALIOP), a passive Infrared Imaging Radiometer (IIR), and visible Wide Field Camera. This data release consists of data beginning in mid June 2006 and includes Level 1 radiances from each of the instruments. This release also includes the lidar Level 2 vertical feature mask and cloud and aerosol layer products. The CALIPSO data are available through the Atmospheric Sciences Data Center (ASDC) at NASA Langley Research Center and can be accessed at the following URL:

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Reference resources on the CALIPSO data set, including detailed data quality summaries and a data catalog are also available at the ASDC CALIPSO page.

If you have questions concerning the ordering of CALIPSO data products, contact User Services at

NASA's Close-Up Images of 'Snow Queen' Show Changes

A distinctive hard-surface feature called "Snow Queen" beneath NASA's Phoenix Mars Lander visibly changed sometime between mid-June and mid-July, close-up images from the Robotic Arm Camera show.

Cracks as long as 10 centimeters, or about four inches, have appeared. A seven-millimeter (less than one-third inch) pebble or clod not seen there before has popped up on the surface. And some smooth texture on Snow Queen has subtly roughened. Phoenix's Robotic Arm Camera, or RAC, took its first close-up image of Snow Queen on May 31, 2008, the sixth Martian day, or sol, after the May 25 landing. Thruster exhaust blew away surface soil covering Snow Queen as Phoenix landed, exposing a hard layer comprising several smooth, rounded cavities.

"Images taken since landing showed these fractures didn't form in the first 20 sols of the mission," Phoenix co-investigator Mike Mellon of the University of Colorado, Boulder, said. "We might expect to see additional changes in the next 20 sols."

Mellon, who has spent most of his career studying permafrost, said long-term monitoring of Snow Queen and other icy soil cleared by Phoenix landing and trenching operations is unprecedented for science. It's the first chance to see visible changes in Martian ice at a place where temperatures are cold enough that the ice doesn't immediately sublimate, or vaporize, away. Phoenix scientists discovered that centimeter-sized chunks of ice scraped up in the Dodo-Goldilocks trench lasted several days before vanishing.

The Phoenix team has been watching ice in the Dodo-Goldilocks and Snow White trenches in views from the lander's Surface Stereo Imager as well as RAC, but only RAC can view Snow Queen near a strut under the lander.

The fact that RAC is attached to the robotic arm is both an advantage and a disadvantage. The advantage is that RAC can take close-ups of Snow Queen, while the Surface Stereo Imager can't see Snow Queen at all from the topside of the spacecraft. The disadvantage is that the robotic arm has so many tasks to perform that RAC can't be used for monitoring trench ice at some opportune times. Also, RAC hasn't been used to take up-close images of other icy places under the spacecraft cleared on landing because it would require the robotic arm to make a difficult and complex series of moves.

"I've made a list of hypotheses about what could be forming cracks in Snow Queen, and there are difficulties with all of them," Mellon said.

One possibility is that temperature changes over many sols, or Martian days, have expanded and contracted the surface enough to create stress cracks. It would take a fairly rapid temperature change to form fractures like this in ice, Mellon said.

Another possibility is the exposed layer has undergone a phase change that has caused it to shrink. An example of a phase change could be a hydrated salt losing its water after days of surface exposure, causing the hard layer to shrink and crack. "I don't think that's the best explanation because dehydration of salt would first form a thin rind and finer cracks," Mellon said.

"Another possibility is that these fractures were already there, and they appeared because ice sublimed off the surface and revealed them," he said.

As for the small pebble that popped up on Snow Queen after 21 sols -- it might be a piece that broke free from the original surface or it might be a piece that fell down from somewhere else. "We have to study the shadows a little more to understand what's happening," Mellon said.

The Phoenix mission is led by Peter Smith of The University of Arizona with project management at the Jet Propulsion Laboratory and development partnership at Lockheed Martin, located in Denver. International contributions come from the Canadian Space Agency; the University of Neuchatel; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute.


NASA hosted a meeting of space agencies from nine countries last week to discuss the next steps in the ongoing scientific exploration of the moon. The meeting laid the groundwork for a new generation of lunar science.

Discussions, led by NASA Headquarters officials, were held at NASA's Lunar Science Institute, located at the Ames Research Center at Moffett Field, Calif. Representatives from space agencies in Canada, France, Germany, India, Italy, Japan, the Republic of Korea, the United Kingdom, and the United States attended the meeting. During the meeting, attendees discussed cooperation on an international activity called the International Lunar Network (ILN). The network is designed to gradually place 6-8 fixed or mobile science stations on the lunar surface. The stations will form a second-generation robotic science network to replace hardware left by the Apollo Program to study the moon's surface and interior.

NASA plans to place its first two ILN landers on the surface of the moon in 2013-14. The landers are being developed under the Lunar Precursor Robotic Program at NASA's Marshall Space Flight Center. Huntsville, Ala.

The ILN is supported by NASA's Science Mission Directorate at the agency's headquarters in Washington. It was created in response to a 2007 report released by the National Research Council, which affirmed that the moon offers "profound scientific value" and "lunar activities apply to broad scientific and exploration concerns."

Representatives from space agencies considering participation in the ILN agreed on a statement of intent as a first step in planning. The statement marked an expression of interest by the agencies to study options for participating in a series of international lunar missions. The goal is to form a network of missions that will benefit scientists worldwide.

"We are tremendously excited by the enthusiasm shown for the ILN and lunar science more broadly," said Jim Green, director of the Planetary Science Division at NASA Headquarters. "This international activity will greatly extend scientific knowledge of the moon in a number of important areas."

The statement of intent does not completely define the ILN concept. The document leaves open the possibility for near and long-term evolution and implementation. Initially, participants intend to establish potential landing sites, interoperable spectrum and communications standards, and a set of scientifically equivalent core instrumentation to carry out specific measurements.

"We are in a new era of lunar exploration," said Jim Adams, deputy director of the Planetary Science Division at NASA Headquarters. "Scientific coordination of the international armada of missions being sent to the moon in the next decade will greatly leverage our scientific capabilities, and perhaps even more importantly, develop the next generation of lunar scientists."

International participation in specific ILN activities will be established by appropriate international agreements. Additional participants may join in the future when they are programmatically and financially ready. Participation in the ILN could include the contribution of landers, orbiters, instrumentation, or other significant infrastructure, such as ground segment elements or power supplies for surviving the lunar night.

For more information on NASA lunar activities, visit:


NASA's Constellation Program has selected 11 companies and one university to independently develop concepts that contribute to how astronauts will live and work on the moon.

Each organization will conduct a 180-day study focused on a topic relevant to lunar surface systems. Selected organizations and topics are:

--Alternative Packaging Options: Oceaneering Space Systems of Houston
--Avionics: Honeywell International, Inc. of Glendale, Ariz,
--Energy Storage: ATK Space Systems Group of Brigham City, Utah,
Battelle Memorial Institute of Columbus, Ohio, and Hamilton
Sundstrand of Canoga Park, Calif.
--Minimum Habitation Functions: The Boeing Company of Huntington
Beach, Calif., ILC Dover of Frederica, Del., and University of
Maryland, College Park
--Regolith Moving Methods: Astrobotic Technology Inc. of Pittsburgh
and Honeybee Robotics of New York
--Software: The Charles Stark Draper Laboratory, Inc. of Cambridge,
Mass., and United Space Alliance of Houston

The awards total approximately $2 million, with a maximum individual award of $250,000.

"These studies provide new ideas to help the Constellation Program develop innovative, reliable requirements for the systems that will be used when outposts are established on the moon," said Jeff Hanley, the Constellation Program manager at NASA's Johnson Space Center in Houston.

The recommendations from the studies will help determine packaging options, identify basic functions for lunar habitats, and conceptualize innovative avionics, computer software, energy storage ideas and equipment and techniques that could help preparation for the lunar outpost site.

The Constellation Program is building NASA's next generation fleet of spacecraft -- including the Ares I and Ares V rockets, the Orion crew capsule, the Altair lunar lander and lunar surface systems -- to send humans beyond low Earth orbit and back to the moon. NASA plans to establish a human outpost on the moon through a successive series of lunar missions beginning in 2020. Lunar surface systems may include habitats, pressurized and un-pressurized rovers, communication and navigation elements, electrical power control, and natural resource use.

For more information about NASA's Constellation Program, visit:


NASA Space Station and the University of Arizona, Tucson, will hold a media briefing Thursday, July 31, at 11 a.m. PDT, in the NASA Space Station mission's Science Operations Center at the university. Briefing participants will discuss the latest progress by NASA's Phoenix Mars Lander in exploring a site in the Martian arctic. Following its May 25 landing, NASA Space Station Phoenix has been studying whether Mars' environment ever has been favorable for microbial life.

The briefing participants are: - Michael Meyer, NASA Space Station chief scientist, Mars Exploration Program, NASA Space Station Headquarters, Washington - Peter Smith, NASA Space Station Phoenix principal investigator, University of Arizona, Tucson - Victoria Hipkin, NASA Space Station mission scientist for NASA Space Station Phoenix Meteorological Station, Canadian Space Agency, Saint-Hubert, Quebec - Mark Lemmon, lead NASA Space Station scientist for Phoenix Surface Stereo Imager, Texas A&M University, College Station

NASA Space Station News media may participate by telephone during the question and answer portion of the briefing. Reporters should call NASA Space Station Jet Propulsion Laboratory media office at 818-354-5011 before the briefing for instructions and the dial-in number.

The briefing will be carried live by NASA Space Station TV and on the Internet at:

For more information on the NASA Space Station Phoenix mission, visit:


A NASA concept for lifting and manipulating materials on the lunar surface will be demonstrated for reporters at NASA's Langley Research Center in Hampton, Va., on Friday, Aug. 1.

NASA's Lunar Surface Manipulation System recently completed a successful June field test on the lunar-like landscape of Moses Lake, Wash. The system is a lifting and precision positioning device that will be used on items ranging from large airlocks and habitats to delicate scientific payloads. The robotic manipulator incorporates features that could help astronauts during early lunar outpost construction and follow-on operations. The principles behind the device also are directly applicable to future operations on the Martian surface.

The system reporters will be able to view is full-scale and sized for unloading a lunar lander. Designed by NASA engineers and controlled by a remote computer, the manipulator resembles a lightweight crane, but has more capabilities. It can be operated autonomously, remotely
or manually in a backup mode, and can be configured to perform a multitude of tasks.

Media interested in attending the presentation and briefing should phone Keith Henry by noon EDT, July 31, at 757-864-6120 or 757-344-7211. Reporters should arrive at the Langley front gate parking lot by 9:30 a.m. for escort to the briefing and lab demonstrations.

For more information and images, visit:

For more information about NASA's Constellation Program, visit:


NASA will hold a series of news media briefings Sept. 8 - 9 to preview the space shuttle's fifth and final servicing mission to the Hubble Space Telescope. NASA Television and the agency's Web site will provide live coverage of the briefings from the Johnson Space Center and the Goddard Space Flight Center in Greenbelt, Md. Questions also will be taken from other participating NASA locations.

Shuttle Atlantis' 11-day flight, designated STS-125, is targeted for launch Oct. 8 and will include five spacewalks to refurbish and upgrade the telescope with state-of-the-art science instruments. Replacing failed hardware on Hubble will extend the telescope's life into the next decade.

U.S. news media planning to attend the briefings at Johnson must contact the newsroom there at 281-483-5111 by Sept. 2 to arrange for credentials. All reporters who are foreign nationals must contact the newsroom by Aug. 8.

On Sept. 9, Atlantis' seven astronauts will be available for round-robin interviews at Johnson. Reporters planning to participate in-person or by phone must contact Gayle Frere at 281-483-8645 by Sept. 2 to reserve an interview opportunity.

Scott Altman will command Atlantis' crew, which includes Pilot Gregory C. Johnson, and Mission Specialists Andrew Feustel, Michael Good, John Grunsfeld, Megan McArthur and Mike Massimino. The spacewalkers are Good, Grunsfeld, Feustel and Massimino. McArthur is the flight engineer and lead for robotic arm operations.

Along with the briefings to preview the Hubble servicing mission at Johnson, media will have an opportunity during the afternoon of Sept. 8 to review new equipment being developed for NASA's Constellation Program. Constellation is building America's next human spacecraft,
which will fly astronauts to low Earth orbit, the moon and beyond. During the review, media will see items that include concepts of a new spacesuit, a pressurized rover vehicle for astronauts, and a mockup of the Orion crew capsule.

The schedule (all times are CDT) includes:

Monday, Sept. 8
7 a.m. - Video B-Roll Feed
8 a.m. - NASA Overview Briefing (from Goddard)
9 a.m. - Shuttle Program Overview Briefing (from Johnson)
10 a.m. - HST/SM 4 Program Overview (from Goddard)
11:30 a.m. - NASA TV Video File
Noon - HST/SM4 Science Overview (from Goddard)
1:30 p.m. - HST Program and Science Round-Robins (from Goddard; not on
1:30 p.m. - Constellation Program Preview (from Johnson, not on NASA

Tuesday, Sept. 9
8 a.m. - Video B-Roll Feed
9 a.m. - STS-125 Mission Overview (from Johnson)
10:30 a.m. - STS-125 Spacewalk Overview (from Johnson)
Noon - NASA TV Video File
1 p.m. - STS-125 Crew News Conference (from Johnson)
2 - 6 p.m. - STS-125 Crew Round-Robins (from Johnson; not on NASA TV)

For NASA TV streaming video, schedules and downlink information,

For the latest information about the STS-125 mission and its crew,

NASA's Lander Collects Icy Soil But Needs to Work on Delivery

NASA's Phoenix Mars Lander's robotic arm collected a more than adequate amount of icy soil for baking in one of the lander's ovens but will need to adjust how it delivers samples.

Engineers determined the rasping and scraping activity collected a total of 3 cubic centimeters of icy soil, more than enough to fill the tiny oven cell of the Thermal and Evolved-Gas Analyzer, or TEGA. However, images returned from the lander Saturday morning show that much of the soil remained lodged in the robotic arm's scoop after the attempt to deliver the sample to the TEGA.

"Very little of the icy sample made it into the oven," said Barry Goldstein, Phoenix project manager from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We believe that the material that was intended for the targeted cell is the material that adhered to the back of the scoop."

Once the sample had been collected, the robotic arm tilted its scoop and ran the rasp motor several times in an attempt to sprinkle the sample into the oven whose doors were wide open. The final step was inverting the scoop directly over the doors. A screened opening over the oven measures about 10 centimeters (4 inches) long by 3 centimeters (1.5 inches) wide. The oven itself is roughly the size of an ink cartridge in a ballpoint pen.

The delivery sequence also included vibrating the screen several times, which would have aided delivery. TEGA detected that not enough sample was recorded as being in its oven, so the oven doors did not close.

The TEGA activities did not cause any short circuits with the equipment.

"The good news here is TEGA is functioning nominally, and we will adjust our sample drop-off strategy to run this again," Goldstein said.

Prior to the sample delivery, Phoenix's robotic arm made 16 holes in the hard ground with its motorized rasp tool and the scoop collected the rasped material and shavings left on the surface from the rasping action.

The lander conducted these activities overnight Friday to Saturday, Pacific Time, during Martian morning hours of the mission's 60th Martian day, or sol. The Phoenix team planned Saturday to send the spacecraft commands to take images on Sunday, the mission's Sol 61, of areas around and under the TEGA instrument. The images by the Robotic Arm Camera would be a way to check for additional material that might have been released by the scoop on Sol 60.

The Phoenix mission is led by Peter Smith of the University of Arizona with project management at JPL and development partnership at Lockheed Martin, Denver. International contributions come from the Canadian Space Agency; the University of Neuchatel; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute. For more about Phoenix, visit: and

Aura Mission, Understanding and Protecting the Air We Breathe

The Llaima Volcano is one of Chile's most active volcanoes and has frequent but moderate eruptions. An eruption on January 1, 2008 forced the evacuation of hundreds of people from nearby villages.

The volcano at least erupted 60 times from Tuesday to Wednesday, while there were no immediate reports of casualties or damage, officials said. The Llaima volcano in southern Chile erupted, sending a huge plume of smoke into the air, located some 850 km (528 miles) south of Santiago. The volcanic ash expelled by Llaima travelled east over the Andes into Argentina.

Aura's OMI instrument captured a near-real time image of the sulfer dioxide (SO2) plume from the Llaima volcanic eruption. The SO2 cloud (red color) off the coast of Argentina was from Aura overpass on January 2 and over South Atlantic on January 3.

This is the first eruption from Llaima since 1994. Chile, after Indonesia, has the world's second biggest and second most active chain of volcanoes.

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Astro 2 - Mission

Following the scientific success of the Astro-1 mission, Astro-2 was approved as a follow-up flight. The three ultraviolet telescopes, which flew on Astro-1, were reassembled for Astro-2. These telescopes were (1) the Ultraviolet Imaging Telescope (UIT) operating in the 1200-3100 Angstrom range, (2) the Hopkins Ultraviolet Telescope (HUT) operating from 425 to 1850 Angstroms, and (3) the Wisconsin Ultraviolet Photopolarimetry Experiment (WUPPE) operating from 1250 to 3200 Angtroms. HUT was significantly upgraded for this second flight, with new optical coatings, which enhanced the telescope's performance by more than a factor of two. The three telescopes were planned to make simultaneous observations of objects such as stars, galaxies and quasars, since many science objectives and selected astronomical targets of the three instrument teams are interrelated. BBXRT, which was onboard ASTRO 1, was not flown on ASTRO 2.

The telescopes were mounted on a Spacelab pallet in the payload bay of the shuttle (flight STS-67). The Spacelab Instrument Pointing System (IPS), pallets, and avionics were utilized for attachment to the Shuttle and for control and data handling. The IPS provides a stable platform, keeps the telescopes aligned, and provides various pointing and tracking capabilities to the telescopes. The Astro observatory requires both mission specialists and payload specialists to control its operations from the Shuttle aft flight deck. Instrument monitoring and quick-look data analysis are planned for real-time ground operations.

The Guest Observer Program was included for Astro-2. The telescopes observed over 250 astronomical objects before returning to earth after a 16-day flight.

Astro 1 - Mission

The "Astro Observatory" was developed as a system of telescopes that could fly multiple times on the space shuttle. Astro-1 consisted of three ultraviolet telescopes and an X-ray telescope. The primary objectives of this observatory were to obtain (1) imagery in the spectral range 1200-3100 A (Ultraviolet Imaging Telescope, UIT); (2) spectrophotometry in the spectral region 425 to 1850 A (Hopkins Ultraviolet Telescope, HUT); (3)spectrapolarimetry from 1250 to 3200 A (Wisconsin Ultraviolet Photopolarimetry Experiment, WUPPE); and (4) X-ray data in the bandpass between 0.3 and 12 keV (Broad Band X-ray Telescope, BBXRT). Since many science objectives and selected astronomical targets of the three instrument teams were inter-related, simultaneous observations by all four instruments were planned.

The telescopes were mounted on a Spacelab pallet in the payload bay of the shuttle (flight STS-35). The Spacelab Instrument Pointing System (IPS), pallets, and avionics were utilized for attachment to the Shuttle and for control and data handling. Astro-1 required both mission specialists and payload specialists to control its operations from the Shuttle aft flight deck. Instrument monitoring and quick-look data analysis were performed for real-time ground operations. During the flight both on-board Digital Display Units malfunctioned, and the star guidance system calibration was not possible. The observing sequences were rescheduled during the flight, and instrument pointing was done by hand by the astronauts, and from the ground.

As a result of the numerous technical glitches, the returned data volume was less than half of that originally planned, and the scientific return was about 67% of the stated goals of the mission. Astro-1 was returned to earth 17:54 U.T., December 11, 1990. However, the mission was very successful in that 231 observations of 130 unique astronomical targetrs were made.

The follow-up flight, Astro-2, was dedicated to studies of many astronomical objects, and included increasing participation of guest investigators.

NASA Successfully Tests Parachute for Ares Rocket

NASA and industry engineers have successfully completed the first drop test of a drogue parachute for the Ares I rocket. The drogue parachute is designed to slow the rapid descent of the spent first-stage motor, cast off by the Ares I rocket during its climb to space. The successful test is a key early milestone in development and production of the Ares I rocket, the first launch vehicle for NASA's Constellation Program that will send explorers to the International Space Station, the moon and beyond in coming decades.

Overview: Ares Launch Vehicles

NASA's Ares rockets, named for the Greek god associated with Mars, will return humans to the moon and later take them to Mars and other destinations.

Future astronauts will ride to orbit on Ares I, which uses a single five-segment solid rocket booster, a derivative of the space shuttle's solid rocket booster, for the first stage. A liquid oxygen/liquid hydrogen J-2X engine derived from the J-2 engine used on Apollo's second stage will power the crew exploration vehicle's second stage. The Ares I can lift more than 55,000 pounds to low Earth orbit.

Planning and early design are under way for hardware, propulsion systems and associated technologies for NASA's Ares V cargo launch vehicle -- the "heavy lifter" of America’s next-generation space fleet. Ares V will serve as NASA's primary vessel for safe, reliable delivery of large-scale hardware to space -- from the lunar landing craft and materials for establishing a moon base, to food, fresh water and other staples needed to extend a human presence beyond Earth orbit.

ARCTAS - Forest Fire Smoke Plumes Probed

In a nondescript room on a Canadian Air Force Base, an international team of fire trackers, weather forecasters and various atmospheric scientists puzzle over computer models, satellite tracks and flight charts. Their goal is to find the best fire targets and tailor the flight path of NASA’s airborne laboratories to track and investigate the properties of smoke plumes.

The researchers are part of the summer deployment of NASA’s Arctic Research of the Composition of the Troposphere from Aircraft and Satellites, or ARCTAS, mission. The mission is just five days into its summer study of the smoke plumes from northern latitude forest fires, and already the choreographed effort between modelers and experimenters is producing a wealth of new data.

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Aquarius is a focused satellite mission to measure global Sea Surface Salinity (SSS). Scientific progress is limited because conventional in situ SSS sampling is too sparse to give the global view of salinity variability that only a satellite can provide. Aquarius is planning to launch in 2010. Aquarius/SAC-D is a space mission developed by NASA and the Space Agency of Argentina (Comisión Nacional de Actividades Espaciales, CONAE.)


  • Aquarius passed Mission Confirmation Review on September 28, 2005. Thus the project has completed formulation activities (Phase B), during which the mission requirements, design and costs have been developed and reviewed, and has begun the implementation (Phases C & D), when the flight hardware is built, tested and readied for launch.
  • After a four-year development effort, the NASA Goddard Space Flight Center (GSFC) delivered the Aquarius Radiometer to the Jet Propulsion Laboratory (JPL) in Pasadena, California in January 2008. The Radiometer, built by an in-house team of scientists, engineers, and technicians at GSFC is part of the international Aquarius/SAC-D mission. The Radiometer will be integrated with the Aquarius instrument at JPL. (Click here to learn more)

Aqua Mission

Aqua is a major international Earth Science satellite mission centered at NASA. Launched on May 4, 2002, the satellite has six different Earth-observing instruments on board and is named for the large amount of information being obtained about water in the Earth system from its stream of approximately 89 Gigabytes of data a day. The water variables being measured include almost all elements of the water cycle and involve water in its liquid, solid, and vapor forms. Additional variables being measured include radiative energy fluxes, aerosols, vegetation cover on the land, phytoplankton and dissolved organic matter in the oceans, and air, land, and water temperatures.

Apollo: Expandng Our Knowledge of the Solar System

On May 25, 1961, President John F. Kennedy announced the goal of sending astronauts to the moon before the end of the decade. Coming just three weeks after Mercury astronaut Alan Shepard became the first American in space, Kennedy's bold challenge set the nation on a journey unlike any before in human history.

Eight years of hard work by thousands of Americans came to fruition on July 20, 1969, when Apollo 11 commander Neil Armstrong stepped out of the lunar module and took "one small step" in the Sea of Tranquility, calling it "a giant leap for mankind."

Innovation and even improvisation were necessary along the way. In December 1968, rather than letting lunar module delays slow the program, NASA changed plans to keep the momentum going. Apollo 8 would go all the way to the moon and orbit without a lunar module; it was the first manned flight of the massive Saturn V rocket.

Six of the missions -- Apollos 11, 12, 14, 15, 16 and 17 -- went on to land on the moon, studying soil mechanics, meteoroids, seismic, heat flow, lunar ranging, magnetic fields and solar wind. Apollos 7 and 9 tested spacecraft in Earth orbit; Apollo 10 orbited the moon as the dress rehearsal for the first landing. An oxygen tank explosion forced Apollo 13 to scrub its landing, but the "can-do" problem solving of the crew and mission control turned the mission into a "successful failure."

The program also drew inspiration from Apollo 1 astronauts Gus Grissom, Ed White and Roger Chaffee, who lost their lives in a fire during a launch pad test in 1967.

AIM-Mission, NASA Satellite Captures First View of 'Night-Shining Clouds'

The first observations of these "night-shining" clouds by a satellite named "AIM" which means Aeronomy of Ice in the Mesosphere, occurred above 70 degrees north latitude on May 25. People on the ground began seeing the clouds on June 6 over Northern Europe. AIM is the first satellite mission dedicated to the study of these unusual clouds.

These mystifying clouds are called Polar Mesospheric Clouds, or PMCs, when they are viewed from space and referred to as "night-shining" clouds or Noctilucent Clouds, when viewed by observers on Earth. The clouds form in an upper layer of the Earth’s atmosphere called the mesosphere during the Northern Hemisphere’s summer season which began in mid-May and extends through the end of August and are being seen by AIM’s instruments more frequently as the season progresses. They are also seen in the high latitudes during the summer months in the Southern Hemisphere.

Very little is known about how these clouds form over the poles, why they are being seen more frequently and at lower latitudes than ever before, or why they have been growing brighter. AIM will observe two complete cloud seasons over both poles, documenting an entire life cycle of the shiny clouds for the first time.

"It is clear that these clouds are changing, a sign that a part of our atmosphere is changing and we do not understand how, why or what it means," stated AIM principal investigator James Russell III of Hampton University, Hampton, Va. "These observations suggest a connection with global change in the lower atmosphere and could represent an early warning that our Earth environment is being changed."

AIM is providing scientists with information about how many of these clouds there are around the world and how different they are including the sizes and shapes of the tiny particles that make them up. Scientists believe that the shining clouds form at high latitudes early in the season and then move to lower latitudes as time progresses. The AIM science team is studying this new data to understand why these clouds form and vary, and if they may be related to global change.

Once the summer season ends in the Northern Hemisphere around mid- to late August, the Southern Hemisphere spring season starts about three months later in the period around mid- to late November. AIM will then be watching for shining clouds in the Southern Hemisphere from November through mid-March when that season ends.

AIM and is managed at Goddard Space Flight Center, Greenbelt, Md and the AIM Project Data Center is located at Hampton University.

Hubble Instruments Slated for On-Orbit 'Surgery'

When astronauts visit the Hubble Space Telescope in October 2008 for its final servicing mission, they will be facing a task that has no precedence – performing on-orbit 'surgery' on two ailing science instruments that reside inside the telescope – the Space Telescope Imaging Spectrograph (STIS) and the Advanced Camera for Surveys (ACS).

Hubble was designed with servicing in mind, so its instrument bay doors are lined with handrails and, with custom tools, are relatively easy to open for the astronauts. The same cannot be said for the instruments themselves.

"The repair of STIS and of ACS in particular, involves techniques that the astronauts have never performed on Hubble, possibly never before anywhere," explained HST senior scientist Dave Leckrone at Goddard. "That is, to open up an instrument that was not designed to be opened up and actually pull out electronic printed circuit boards and replace them with new boards."

To accommodate these groundbreaking repairs, Hubble engineers and astronauts worked diligently to design special tools and procedures. Like doctors performing surgeries, preparation is imperative for success.

The Space Telescope Imaging Spectrograph

Astronauts installed STIS in Hubble in 1997 during Servicing Mission 2. Its main function is spectroscopy -- the separation of light into its component colors, or wavelengths, to reveal information about the chemical content, temperature, and motion of stars and gas. Among its many accomplishments, STIS confirmed the existence of super-massive black holes and was the first instrument ever to detect and analyze the atmosphere of a planet orbiting another star.

Although spectrographs like STIS generally do not produce the beautiful images that Hubble is famous for, the data they provide are absolutely essential to understanding the physical properties of the universe. It could be said that they put the "physics" in astrophysics.

After a long life of scientific discovery, STIS experienced a power supply failure in August 2004, causing it to suspend operations. NASA engineers were able to pinpoint exactly where and how the failure occurred by examining data from STIS and determined that the inoperable power supply resides on a printed circuit board housed within the instrument.

The Advanced Camera for Surveys

Installed during Servicing Mission 3B in 2002, ACS quickly became Hubble’s workhorse imaging camera. Designed to survey large areas of the sky at visible and red wavelengths, it had twice the field-of-view and a finer resolution than its predecessor, the Wide Field Planetary Camera 2. It quickly became Hubble’s most heavily used instrument and was responsible for many of the telescope’s most popular and dramatic images.

It took three failures to put ACS out of commission -- the first two were recovered by operating the instrument in different ways. To protect against failures, all Hubble instruments have some degree of "redundancy," meaning that there are duplicate parts that can perform the same function. If one part fails, another can be activated to restore the function.

When the first two failures occurred in 2006, the ground operations team was able to keep the entire instrument fully operational by using a redundant power supply. The final failure came in January 2007 when the backup power supply failed.

With less than two years until the final servicing mission, there would have been little time to develop procedures and tools needed to repair ACS had the team not already been preparing for a very similar task involving the repair of STIS. Designing a repair process for ACS became very workable by adapting the processes already under development for STIS repair.

Tool and Procedure Development

The repair of STIS and ACS presented a multitude of challenges during the development process. Engineers needed to work around three major issues: (1) safely getting access to the failed boards; (2) figuring a way to pull them out wearing the pressurized gloves; and (3) closing out the worksite when repairs are complete.

Knowing exactly what needs to be fixed is not enough to make repairs a piece of cake. To access the failed circuit boards on these two instruments, astronauts will have to remove 111 screws from the cover of STIS, and 32 screws from ACS, a time-consuming process in an environment where time is a scarce commodity.

To confront this challenge, Goddard engineers developed a high-speed power screwdriver with low torque, or twisting force. This combination of operational abilities means that the drill will speed up the removal process without breaking the screws and fasteners.

The sheer number of screws to be removed is not the only issue with gaining access to the circuit boards. Despite its mammoth size and giant status in space discovery, Hubble’s instruments are extremely delicate. Floating debris pose the threat of contaminating exposed electronics, so as astronauts open Hubble’s outer shell to make their repairs they must exercise extreme caution. Even tiny metal shavings resulting from the removal of one screw could be kryptonite to this super telescope.

To avoid the debris issue, NASA engineers designed a fastener capture plate. Using the custom drill, astronauts will first remove four screws to install the transparent “capture plate” over the electronic access panel. Tiny, labeled holes in the plate will allow them to then insert the drill bit and remove screws as the capture plate contains them. When all of the screws have been removed, the entire capture plate can be released as one unit, safely taking the access panel and all debris with it.

The astronauts' second challenge is grasping the failed circuit boards once the access panel has been removed. The boards are thin and the astronaut’s suits, including their gloves, are bulky and pressurized to protect them from the space environment. If you were to put on a pair of thick, wool mittens and try to grab a single piece of paper from the middle of a stack, you might have some idea of how difficult and time-consuming the task is for astronauts. NASA engineers got around this issue by developing a special card extraction tool which will allow the astronauts to easily grab and remove the circuit boards using large handles made specifically for their gloves.

The last major challenge of the repair process involves closing the instruments back up after repairs are complete. To conserve time, engineers designed a simplified version of the access panels. Two lever-like latches will be all it takes for the astronauts to securely lock the new STIS cover into place. A new panel is not required for ACS because the new electronic cards have all been built into one box that easily slides into place and covers the open side of the instrument.

Appreciating a Complement

Because NASA will be installing similar instruments into Hubble during SM4, you may wonder what purpose it serves to fix STIS and ACS. The answer lies in their differing, but complementary, capabilities.

While the new Wide Field Camera 3 (WFC3) will expand Hubble’s high resolution and provide a wide field-of-view into the near ultra-violet and near infra-red regions of the spectrum, the ACS has a slightly higher discovery potential in the visible wavelengths of light. STIS is a two-dimensional spectrograph while the Cosmic Origins Spectrograph (COS) is a point-source ultra-violet spectrograph. These two spectrographs working in tandem would give astronomers a full, spectroscopic suite of instruments.

The improvements will add years of science to Indexing Card Extraction Tool (ICET) and provide a full 'toolkit' to astronomers around the world. "Personally, I think that's where the more exciting results will come from after this servicing mission," explained Leckrone, “the new ideas that astronomers have about how to use these wonderful instruments now that they’re all together in a set that is internally complementary.”

Making History Again

Hubble has been arguably the most well-known and successful telescope in NASA history, but it is not solely a pathfinder for the science it has yielded over the years. The processes and procedures carried out during servicing missions have also always been innovative.

Before Hubble, nothing launched into space had even been built to be serviced and upgraded on orbit. The telescope is close to making history again with the first on-orbit repairs of existing instruments. Should these repair tasks be successful, Hubble is expected to be 90 times more powerful than ever before.

"At the end of SM4, when the astronauts leave Hubble for the last time, we have a very good prospect that Hubble will be at the apex of its capabilities. It will be better than it's ever been before, which is quite awesome when you realize that it will be over eighteen years old as an observatory," Leckrone said.

Related link:

> Read the other stories in the "Next Stop: Hubble" series

Phoenix Scoop Ready for Sampling

NASA's Phoenix Mars Lander's robotic arm scoop is primed and ready to collect a soil sample from the northern region of Mars to analyze for the presence of water and other possible ingredients.

Scientists and engineers on the mission Friday prepared plans to send Phoenix later in the day that would command the robotic arm to rasp the hard soil in the trench informally named "Snow White," collect the shavings and deliver them to an oven for analysis.

Images received on Earth Friday morning confirmed that the scoop had been cleared of anything collected during previous days' testing. The scoop went through a sequence of moves to dump any remaining material. At the same time, the Thermal and Evolved-Gas Analyzer (TEGA) was successfully prepared for the sample by purging it of any volatile materials.

"The successful completion of these preparatory activities clears the way for our next critical event, delivering the icy soil sample to TEGA," said Doug Ming, of NASA Johnson Space Center, Houston, the team's science lead for today's planning.

The Phoenix mission is led by Peter Smith of the University of Arizona with project management at JPL and development partnership at Lockheed Martin, Denver. International contributions come from the Canadian Space Agency; the University of Neuchatel; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute. For more about Phoenix, visit: and

'Impressionist' Spacecraft to View Solar System's Invisible Frontier

At the edge of our solar system in December 2004, the Voyager 1 spacecraft encountered something never before experienced during its then 26-year cruise through the solar system — an invisible shock formed as the solar wind piles up against the gas in interstellar space. This boundary, called the termination shock, marks the beginning of our solar system's final frontier, a vast expanse of turbulent gas and twisting magnetic fields.

A NASA-sponsored team is developing a way to view this chaotic but unseen realm for the first time. Just as an impressionist artist makes an image from countless tiny strokes of paint, NASA’s new Interstellar Boundary Explorer (IBEX) spacecraft will build up an image of the termination shock and areas beyond by using hits from high-speed atoms that are radiating out of this region.

"IBEX will let us make the first global observations of the region beyond the termination shock at the very edges of our solar system. This region is critical because it shields out the vast majority of the deadly cosmic rays that would otherwise permeate the space around the Earth and other planets," says Dr. David J. McComas, IBEX principal investigator from the Southwest Research Institute (SwRI) in San Antonio, Texas. "IBEX will let us visualize our home in the galaxy for the first time and explore how it may have evolved over the history of the solar system. Ultimately, by making the first images of the interstellar boundaries neighboring our solar system, IBEX will provide a first step toward exploring the galactic frontier."

Space is not empty. The sun exhales a thin, hot wind of electrically conducting gas, called plasma, into space at about a million miles per hour. This solar wind forms a large plasma bubble, called the heliosphere, in space around the Sun. Beyond the orbit of Pluto, the solar wind gradually slows as it interacts with inflowing neutral gases from interstellar space, and then abruptly drops in speed at a thin, invisible boundary around our solar system called the termination shock.

A simple kitchen demonstration illustrates how this shock forms. When water runs at high speed from a kitchen faucet down to the bottom surface of the sink, the water hitting this surface first flows quickly and smoothly away from the impact point, but then runs into a circular boundary with slower, more turbulent flow beyond this boundary.

In the kitchen sink demonstration, the circular boundary is the termination shock. The turbulent region beyond the shock boundary corresponds to a layer in the outer heliosphere of turbulent plasma flows and magnetic fields called the heliosheath. The boundary of this turbulent layer with the interstellar plasma environment, not so easily seen in the kitchen sink experiment because of the turbulence, is called the heliopause. The heliopause is the end of our solar system’s frontier. Beyond that is interstellar space.

IBEX will make pictures of the heliosheath region and determine the termination shock’s strength. It will also discover what happens when the solar wind clashes with interstellar space by observing how the solar wind is flowing in the heliosheath and how the interstellar gas interacts with the heliopause. IBEX will determine how high-speed atoms are accelerated within the termination shock and heliosheath.

A cosmic game of tag allows IBEX to make its pictures. First, some background on the players: an atom needs to be electrically charged to feel magnetic force and be influenced by the magnetic fields in space. Normally, the positive electric charges in the central part of the atom, called the nucleus, are balanced by an equal number of negatively charged electrons swirling around it. In this case, the atom is electrically neutral overall and does not respond to magnetic fields. However, sometimes an atom gains or loses an electron. The electric charges are no longer in balance; gaining an electron gives the atom an extra negative charge, while losing an electron leaves the atom with a positive charge. The charged atom, called an ion, can now be deflected or accelerated by magnetic fields.

Most of the ions in interstellar space are deflected around our solar system by the magnetic field carried by the solar wind. Energetic neutral atoms (ENAs) are created when low-energy neutral atoms floating in from the interstellar medium "tag" energetic protons that are gyrating around the magnetic field lines in the solar wind. They charge exchange (since opposite charges attract, an electron jumps from the neutral atom to the positively charged proton if the two pass each other very closely). The proton now has an electron to balance its charge, and it becomes an Energetic Neutral Atom. The ENAs that happen to be pointing in the direction of Earth at the moment of charge-exchange will then propagate back in toward the Earth where IBEX can detect them.

Since the ENAs no longer feel magnetic force, they travel in a nearly straight line, only slightly deflected by the sun's gravity. Their straightforward path allows ENAs that hit IBEX's two sensors to be traced back to their origin near the termination shock. This lets the IBEX team gradually build up a picture of the termination shock using the incoming neutral atoms, since the majority of Earthward-directed ENAs are believed to result from heating of the solar wind as it crosses the termination shock. Six months into the mission, IBEX will have observed the entire sky, and will reveal the global structure of the heliosheath and termination shock for the first time.

IBEX is scheduled to be launched on a Pegasus rocket on October 5, 2008. It needs to go beyond the region of space controlled by Earth's magnetic field, called the magnetosphere, because this region generates radiation and the same high-speed atoms (ENAs) that IBEX will use to make its pictures. To avoid contamination from local ENAs produced in the magnetosphere, IBEX's orbit will take it up to 200,000 miles from Earth.

"The solar system's frontier is billions of miles away, so it's difficult for us to go there, but interesting things happen at boundaries, and with IBEX, we will see them for the first time," said Dr. Robert MacDowall, IBEX Mission Scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

The IBEX mission is funded by NASA's Small Explorer program. It is a PI-led mission being run by SwRI, which is responsible for all aspects of the mission. Orbital Science Corporation in Dulles, Virginia, is SwRI’s sub-contractor for the IBEX spacecraft and also provides the Pegasus launch. The Explorer Project Office at NASA Goddard oversees all Small Explorer missions, including IBEX.

> IBEX News and Multimedia

Cassini-Huygens mission

The ringed planet sits in repose, the center of its own macrocosm of many rings and moons and one artificial satellite named Cassini. Mimas (397 kilometers, or 247 miles across) is visible at upper left. Although unseen in this view, Enceladus (504 kilometers, or 313 miles across) casts its shadow upon the planet. The rings also block the sun's light from the low latitudes of the northern hemisphere.

During Cassini's extended mission, dubbed the Cassini Equinox Mission, which begins on July 1, 2008, the ring shadows will slip past the planet's equator and into the southern hemisphere as Saturn passes through its northern vernal equinox on August 11, 2009, and the sun moves northward through the ring plane.

This view looks down on the un-illuminated side of the rings from about 22 degrees above (north of) the ring plane. Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were obtained with the Cassini spacecraft wide-angle camera on Dec. 16, 2007, at a distance of approximately 1.4 million kilometers (900,000 miles) from Saturn. Image scale is 86 kilometers (53 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit .

Tectonics on Titan

A set of three parallel ridges was seen by the Cassini spacecraft's radar instrument during the latest Titan flyby on May 12, 2008. This combination is unlikely to be a coincidence -- the best explanation for these features is that they are tilted or separated blocks of broken or faulted crust, now exposed as high ridges. Their regular spacing is typical of regions that have been compressed or extended over large areas; as an example, the western United States Basin and Range Province was formed by extension. Such interactions are called tectonics, although they do not happen in the same way as plate tectonics, which is a process unique to Earth.

The ridges, which appear on the left side of the image, are rugged features and are elevated above surrounding terrain. The brightness patterns mean that the materials are fractured or blocky at the radar wavelength (2.17 centimeters, or about 1 inch). Along the south sides of the ridges are prominent cliffs, or scarps, present as thin, radar-dark lines trending west-to-east, and interpreted as faults. These features are dark due to shadowing from the radar illumination, and have heights up to a few hundred meters (several hundred feet), based on preliminary estimates of slopes.

The area shown here is located in the mountainous region called Xanadu. The ridges are similar in many ways to mountain chains seen at similar latitude but about 90 degrees to the west, just west of Shangri-La (observed during a flyby in October 2005, PIA08454). Both regions have mountain chains or ridges that are oriented west-to-east and are spaced about 50 kilometers (30 miles) apart. This indicates tectonic forces have acted in a north to south direction at Titan’s equatorial region and have resulted in regular effects in Titan’s crust, evidence that will help scientists better understand Titan’s crust and interior.

Other linear features, probably related to the formation of the ridges, and circular features, perhaps eroded impact craters now filled with radar-dark (smooth) material, are also seen in the image. The largest circular feature, at bottom center, is about 20 km in diameter.

The image is centered at 2 degrees south, 127 degrees west and was obtained on May 12, 2008, with a resolution of about 300 meters (980 feet). The open arrow indicates the direction of radar illumination. The dashed white line in the upper portion is an artifact of the SAR processing and will be removed in later versions.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

For more information about the Cassini-Huygens mission, visit