Odyssey shifting to a "morning" orbit Options

[Doug M.]

Long, informative press release from the Odyssey team today: http://mars.jpl.nasa.gov/odyssey/news/what...amp;NewsID=1602

Key points: Odyssey has just yesterday made an orbital maneuver, which will cause its orbit to gradually evolve over the next 20 months. It's moving from an "evening" to a "morning" sun-synchronous orbit. The change is slow, and will be completed in November 2015. I thought this part of the article particularly interesting:

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."

So, assuming the maneuver is successful, we could be looking at a whole new set of observations from Odyssey! Pretty amazing for a spacecraft that's already been in orbit for over twelve years.

One additional throwaway line caught my eye: right now they think they have enough propellant for 9 or 10 years. That's at the high end of earlier published estimates; presumably they've been able to refine their numbers. Very encouraging.


Doug M.