[meteorite-list] NASA Moves Longest-Serving Mars Spacecraft for New Observations (Mars Odyssey)

[Ron Baalke]

February 12, 2014

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown at nasa.gov 

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov 
     
RELEASE 14-051
     
NASA Moves Longest-Serving Mars Spacecraft for New Observations

NASA's Mars Odyssey spacecraft has tweaked its orbit to help scientists make  
the first systematic observations of how morning fogs, clouds and surface  
frost develop in different seasons on the Red Planet.

The maneuver took place Tuesday. Odyssey team engineers at NASA's Jet  
Propulsion Laboratory (JPL) in Pasadena, Calif., and Lockheed Martin Space  
Systems of Denver, designed the gentle move to accelerate Odyssey's drift  
toward a morning-daylight orbit. The desired change will occur gradually  
until the intended orbit geometry is reached in November 2015 and another  
maneuver halts the drift.

The change will enable observation of changing ground temperatures after  
sunrise and after sunset in thousands of places on Mars. Those observations  
could yield insight about the composition of the ground and about  
temperature-driven processes, such as warm-season flows observed on some  
slopes, and geysers fed by spring thawing of carbon-dioxide ice near Mars'  
poles.

"We're teaching an old spacecraft new tricks," said Odyssey Project Scientist  
Jeffrey Plaut of JPL. "Odyssey will be in position to see Mars in a more  
different light from ever before."

Neither Odyssey, nor any other NASA Mars orbiter since the 1970s, has flown  
an orbital pattern with a view of the ground in morning daylight. Earlier  
NASA orbiters and the European Space Agency's Mars Express orbiter have  
provided some tantalizing views of morning mists on Mars, but have  
concentrated on afternoon observation times when views of the surface are  
less hazy.

Odyssey was launched in 2001 and began its science mission 12 years ago this  
month. It is the longest-working spacecraft ever sent to Mars.

Odyssey completed Tuesday's maneuver at 12:03 p.m. PST (3:03 p.m. EST). It  
used four thrusters, each providing about 5 pounds (22 newtons) of force for  
a 29-second burn.

"This veteran spacecraft performed exactly as planned," said Odyssey Project  
Manager David Lehman of JPL.

Odyssey flies in an orbit nearly over the poles and synchronized with the  
sun. For most of its first six years at Mars, the orbit was set at about 5  
o'clock, local solar time. At every spot Odyssey flew over as it made its  
dozen daily passes from the north pole region to the south pole region, the  
local solar time was about 5 p.m. Beneath the south-to-north leg of the  
orbit, the time was about 5 a.m. That orbit provided an advantage for the  
orbiter's Gamma Ray Spectrometer to have its cooling equipment pointed away  
from the sun. The spectrometer checked for evidence of water near the Martian  
surface. It made important discoveries of how widely water ice -- detected as  
hydrogen-- and other elements are distributed on Mars.

Later, Odyssey worked for three years in a 4 o'clock orbit. That provided an  
advantage for mineral mapping by the orbiter's Thermal Emission Imaging  
System (THEMIS). Mid-afternoon warmth made minerals' infrared signatures  
easier to identify. This timing, however, added stress to Odyssey's power  
system. It put more of each orbit into the planet's shadow, where solar  
panels are unproductive. After providing radio-relay support for the 2012  
landing of NASA's Curiosity Mars rover, a maneuver set Odyssey on a slow  
drift to later times of day to help preserve the spacecraft's aging battery.

THEMIS Principal Investigator Philip Christensen of Arizona State University  
in Tempe, proposed letting the time of the orbit shift past 6 o'clock and  
then making daylight observations on the south-to-north half of the orbit, at  
about 6:45 a.m., rather than the north-to-south half. The science team and  
NASA agreed, and the Odyssey project planned this week's maneuver to get to  
the desired orbit sooner.

"We don't know exactly what we're going to find when we get to an orbit where  
we see the morning just after sunrise," Christensen said. "We can look for  
seasonal differences. Are fogs more common in winter or spring? We will look  
systematically. We will observe clouds in visible light and check the  
temperature of the ground in infrared."

After the next orbit-adjustment maneuver, to lock into the 6:45 a.m. local  
time in November 2015, Odyssey will have about enough propellant left for  
nine to 10 years of operation at estimated annual consumption rates. In  
addition to conducting its own observations, Odyssey serves as an important  
communications relay for spacecraft on Mars' surface.

JPL manages Odyssey for NASA's Science Mission Directorate in Washington.  
Lockheed Martin Space Systems built the spacecraft and collaborates with JPL  
in mission operations.

For more about the Mars Odyssey mission, visit:

http://mars.jpl.nasa.gov/odyssey 

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