lundi 20 octobre 2014

All Three NASA Mars Orbiters Healthy After Comet Flyby












NASA - 2001 Odyssey Mission patch / NASA - Mars Reconnaissance Orbiter (MRO) patch / NASA - MAVEN Mission patch.

Oct. 20, 2014.


Image above: This artist's concept shows NASA's Mars orbiters lining up behind the Red Planet for their "duck and cover" maneuver to shield them from comet dust from the close flyby of comet Siding Spring (C/2013 A1) on Oct. 19, 2014.  Image Credit: NASA.

All three NASA orbiters around Mars confirmed their healthy status Sunday after each took shelter behind Mars during a period of risk from dust released by a passing comet.

Mars Odyssey, Mars Reconnaissance Orbiter and the Mars Atmosphere and Volatile Evolution (MAVEN) orbiter all are part of a campaign to study comet C/2013 A1 Siding Spring and possible effects on the Martian atmosphere from gases and dust released by the comet. The comet sped past Mars today much closer than any other know comet flyby of a planet.

 Comet Siding Spring (C/2013 A1)

Image above: Comet Siding Spring (C/2013 A1) is racing toward Mars for a close encounter on October 19, 2014. Image Credit: NASA.

Additional information about the precautions and observations by each of the three orbiters:

NASA's Mars Odyssey Orbiter Watches Comet Fly Near

Mars Odyssey Mission Status Report:

The longest-lived robot ever sent to Mars came through its latest challenge in good health, reporting home on schedule after sheltering behind Mars from possible comet dust.

NASA's Mars Odyssey was out of communications with Earth, as planned, while conducting observations of comet C/2013 A1 Siding Spring on Sunday, Oct. 19, as the comet flew near Mars. The comet sped within about 88,000 miles (139,500 kilometers) of Mars, equivalent to about one-third of the distance between Earth and Earth's moon. Odyssey had performed a maneuver on Aug. 5 to adjust the timing of its orbit so that it would be shielded by Mars itself during the minutes, around 1 p.m. PDT (4 p.m. EDT) today, when computer modeling projected a slight risk from high-velocity dust particles in the comet's tail.


Image above: Artist's concept of NASA's Mars Odyssey spacecraft. Image credit: NASA/JPL-Caltech.

"The telemetry received from Odyssey this afternoon confirms not only that the spacecraft is in fine health but also that it conducted the planned observations of comet Siding Spring within hours of the comet's closest approach to Mars," said Odyssey Mission Manager Chris Potts of NASA's Jet Propulsion Laboratory, Pasadena, Calif., speaking from mission operations center at Lockheed Martin Space Systems, Denver.

Comet Siding Spring observations were made by the orbiter's Thermal Emission Imaging System (THEMIS). Resulting images are expected in coming days after the data is downlinked to Earth and processed. THEMIS is also scheduled to record a combined image of the comet and a portion of Mars later this week. In addition, the Odyssey mission is using the spacecraft's Neutron Spectrometer and High Energy Neutron detector to assess possible effects on Mars' atmosphere of dust and gas from the comet.

Three NASA Mars orbiters, two Mars rovers and other assets on Earth and in space are studying comet Siding Spring. This comet is making its first visit this close to the sun from the outer solar system's Oort Cloud, so the concerted campaign of observations may yield fresh clues to our solar system's earliest days more than 4 billion years ago.

Following the comet flyby, operations teams have also confirmed the good health of NASA's Mars Reconnaissance Orbiter and of NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter.

Mars Odyssey has worked at the Red Planet longer than any other Mars mission in history. NASA launched the spacecraft on April 7, 2001, and Odyssey arrived at Mars Oct. 24, 2001. Besides conducting its own scientific observations, the mission provides a communication relay for robots on the Martian surface.

Odyssey is managed by JPL for NASA's Science Mission Directorate in Washington. Lockheed Martin Space Systems built the spacecraft. JPL and Lockheed Martin collaborate on operating the spacecraft. The California Institute of Technology in Pasadena manages JPL for NASA.

Arizona State University, Tempe, designed and operates THEMIS, which takes images in a range of visible light and infrared wavelengths. Odyssey's Neutron Spectrometer, provided by the U.S. Department of Energy's Los Alamos National Laboratories in New Mexico, and High Energy Neutron Detector, provided by the Russia's Space Research Institute, are parts of the mission's Gamma Ray Spectrometer suite, managed by the University of Arizona, Tucson.

For more about the Mars Odyssey mission, visit: http://mars.jpl.nasa.gov/odyssey

NASA's Mars Reconnaissance Orbiter Studies Comet Flyby

Mars Reconnaissance Orbiter Mission Status Report:

NASA's Mars Reconnaissance Orbiter, which has sent home more data about Mars than all other missions combined, is also now providing data about a comet that buzzed The Red Planet today (Oct. 19).

The orbiter continues operating in good health after sheltering behind Mars during the half hour when high-velocity dust particles from comet C/2013 A1 Siding Spring had the most chance of reaching the paths of Mars orbiters. It maintained radio communications with Earth throughout the comet's closest approach, at 11:27 a.m. PDT (2:27 p.m. EDT), and the peak dust-risk period centered about 100 minutes later.


Image above: Artist's concept of the Mars Reconnaissance Orbiter spacecraft. Image credit: NASA/JPL-Caltech.

"The spacecraft performed flawlessly throughout the comet flyby," said Mars Reconnaissance Orbiter Project Manager Dan Johnston of NASA's Jet Propulsion Laboratory, Pasadena, California. "It maneuvered for the planned observations of the comet and emerged unscathed."

Following the critical period of dust flux, the orbiter is communicating at 1.5 megabits per second with NASA's Deep Space Network. It remained on Side A of its two redundant computers, and all subsystems are working as expected.

Downlink of data has begun from today's comet observations by three instruments on Mars Reconnaissance Orbiter. The full downlink may take days. These instruments -- the High Resolution Imaging Science Experiment (HiRISE), the Compact Imaging Spectrometer for Mars (CRISM), and the Context Camera (CTX) -- also observed the comet for days before the flyby and will continue to make observations of it in the next few days. The orbiter's other three instruments are being used to study possible effects of gas and dust in the comet's tail interacting with the atmosphere of Mars. These are the Mars Climate Sounder (MCS), the Mars Color Imager (MARCI) and the Mars Shallow Radar (SHARAD).

Three NASA Mars orbiters, two Mars rovers and other assets on Earth and in space are studying comet Siding Spring. This comet is making its first visit this close to the sun from the outer solar system's Oort Cloud, so the concerted campaign of observations may yield fresh clues to our solar system's earliest days more than 4 billion years ago.

Following the comet flyby, operators of NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter are assessing the status of that orbiter and operators for NASA's Mars Odyssey are anticipating resumption of communications.

The Mars Reconnaissance Orbiter mission met all its science goals for the two-year primary science phase ending in 2008. The spacecraft's overtime work since then has added to the science returns. The mission has provided more than 240 trillion bits of data about Mars, a volume equivalent to three-and-a-half months of nonstop, high-definition video. The data it acquired during the comet's closest approach to Mars are now being transmitted to Earth, but it will take many hours before downlink is complete and processing can start.

Objectives of the observing program are to attempt to image the comet nucleus, to study its surrounding coma of dust and gas, and to search for signatures of that material interacting with the Mars atmosphere. Observations of the comet will continue for another day or so, as the comet and Mars separate, with the comet reaching its closest approach to the sun in about a week, on Oct. 25.

JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the spacecraft and supports its operations. Lead organizations for the orbiters' six science instruments are University of Arizona, Tucson, for HiRISE; Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, for CRISM; Malin Space Science Systems, San Diego, for CTX and MARCI; Sapienza University of Rome, Italy, for SHARAD; and JPL for MCS.

For more about the Mars Reconnaissance Orbiter mission, visit: http://mars.jpl.nasa.gov/mro/

NASA's MAVEN Studies Passing Comet and Its Effects

MAVEN Mission Status Report:

NASA's newest orbiter at Mars, MAVEN, took precautions to avoid harm from a dust-spewing comet that flew near Mars today and is studying the flyby's effects on the Red Planet's atmosphere.

The MAVEN spacecraft -- full name Mars Atmosphere and Volatile Evolution -- reported back to Earth in good health after about three hours of precautions against a possible collision with high-velocity dust particles released by comet C/2013 A1 Siding Spring.


Image above: Artist's concept of the MAVEN Mars orbiter spacecraft. Image credit: NASA/JPL-Caltech.

"We're glad the spacecraft came through, we're excited to complete our observations of how the comet affects Mars, and we're eager to get to our primary science phase," said MAVEN Principal Investigator Bruce Jakosky of the University of Colorado, Boulder.

MAVEN began orbiting Mars on Sept. 21. The opportunity to study this rare near-miss of a planet by a comet comes during the project's commissioning phase. A few weeks of instrument calibration and orbit fine-tuning remain before the start of the primary science phase. The mission will study the upper atmosphere of Mars and its interaction with the solar wind.

Comet Siding Spring hurtled past Mars today at about 125,000 mph (56 kilometers per second), coming within about 87,000 miles (139,500 kilometers) of the planet. That is equivalent to about one-third of the distance between Earth and Earth's moon. The closest approach by the comet's nucleus came at about 11:27 a.m. PDT (2:27 p.m. EDT). The period when dust from the comet was most likely to reach Mars and the orbits of spacecraft around Mars peaked about 100 minutes later.

From about 10:45 a.m. to 2 p.m. PDT (1:45 p.m. to 5:00 p.m. EDT) MAVEN kept in a defensive posture to reduce its profile relative to the direction from which the comet's high-velocity dust particles would come. In that "hunkered down" orientation, its main antenna was not facing the right way for transmitting to Earth, so communications were maintained at low data rate via a secondary antenna. Also, the mission performed a maneuver on Oct. 2 that set its orbit timing so that the spacecraft was behind Mars, relative to the possible dust flow, from about 12:53 p.m. to 1:23 p.m. PDT (3:53 p.m. to 4:23 p.m. EDT).

Downlink of data has begun from MAVEN observations of the comet and Mars' atmosphere. Some observations are designed to provide information about the composition of the gases and dust being released by the comet. Others are investigating possible interaction between material from the comet and the atmosphere of Mars.

Three NASA Mars orbiters, two Mars rovers and other assets on Earth and in space are studying comet Siding Spring. This comet is making its first visit this close to the sun from the outer solar system's Oort Cloud, so the concerted campaign of observations may yield fresh clues to our solar system's earliest days more than 4 billion years ago.

MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. The University of California at Berkeley's Space Sciences Laboratory also provided four science instruments for the mission. NASA's Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, as well as the Electra telecommunications relay hardware and operations.

For more about MAVEN, visit: http://www.nasa.gov/maven

For more information about comet Siding Spring and the investigations of its Mars flyby, visit: http://mars.jpl.nasa.gov/comets/sidingspring/

Images (mentioned), Text, Credits: NASA / Dwayne Brown / JPL / Guy Webster / Goddard Space Flight Center / Nancy Jones / Bill Steigerwald.

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