Mars Odyssey Alters Orbit to Study Warmer Ground

Jun 22, 2009
Pastel colors swirl across Mars, revealing differences in the composition and nature of the surface in this false-color infrared image taken on May 22, 2009,by the Thermal Emission Imaging System (THEMIS) camera on NASA's Mars Odyssey orbiter.

(PhysOrg.com) -- NASA's long-lived Mars Odyssey spacecraft has completed an eight-month adjustment of its orbit, positioning itself to look down at the day side of the planet in mid-afternoon instead of late afternoon.

This change gains sensitivity for infrared mapping of Martian minerals by the orbiter's Thermal Emission Imaging System camera. Orbit design for Odyssey's first seven years of observing used a compromise between what worked best for the infrared mapping and for another onboard instrument.

"The orbiter is now overhead at about 3:45 in the afternoon instead of 5 p.m., so the ground is warmer and there is more thermal energy for the camera's infrared sensors to detect," said Jeffrey Plaut of NASA's Jet Propulsion Laboratory, Pasadena, Calif., project scientist for Mars Odyssey.

Some important mineral discoveries by Odyssey stem from mapping done during six months early in the mission when the orbit geometry provided mid-afternoon overpasses. One key example: finding salt deposits apparently left behind when large bodies of water evaporated.

"The new orbit means we can now get the type of high-quality data for the rest of Mars that we got for 10 or 20 percent of the planet during those early six months," said Philip Christensen of Arizona State University, Tempe, principal investigator for the Thermal Emission Imaging System.

Here's the trade-off: The orbital shift to mid-afternoon will stop the use of one of three instruments in Odyssey's Gamma Ray Spectrometer suite. The new orientation will soon result in overheating a critical component of the suite's gamma ray detector. The suite's neutron spectrometer and high-energy neutron detector are expected to keep operating. The Gamma Ray Spectrometer provided a dramatic 2002 discovery of water-ice near the Martian surface in large areas. The gamma ray detector has also mapped global distribution of many elements, such as iron, silicon and potassium.

Last year, before the start of a third two-year extension of the Odyssey mission, a panel of planetary scientists assembled by NASA recommended the orbit adjustment to maximize science benefits from the spacecraft in coming years.

Odyssey's orbit is synchronized with the sun. Picture Mars rotating beneath the polar-orbiting spacecraft with the sun off to one side. The orbiter passes from near the north pole to near the south pole over the day-lit side of Mars. At each point on the Mars surface that turns beneath Odyssey, the solar time of day when the southbound spacecraft passes over is the same. During the five years prior to October 2008, that local solar time was about 5 p.m. whenever Odyssey was overhead. (Likewise, the local time was about 5 a.m. under the track of the spacecraft during the south-to-north leg of each orbit, on the night side of Mars.)

On Sept. 30, 2008, Odyssey fired thrusters for six minutes, putting the orbiter into a "drift" pattern of gradually changing the time-of-day of its overpasses during the next several months. On June 9, Odyssey's operations team at JPL and at Denver-based Lockheed Martin Space Systems commanded the spacecraft to fire the thrusters again. This five-and-a-half-minute burn ended the drift pattern and locked the spacecraft into the mid-afternoon overpass time.

"The maneuver went exactly as planned," said JPL's Gaylon McSmith, Odyssey mission manager.

In another operational change motivated by science benefits, Odyssey has begun in recent weeks making observations other then straight downward-looking. This more-flexible targeting allows imaging of some latitudes near the poles that are never directly underneath the orbiter, and allows faster filling-in of gaps not covered by previous imaging.

"We are using the spacecraft in a new way," McSmith said.

In addition to extending its own scientific investigations, the Odyssey mission continues to serve as the radio relay for almost all data from NASA's Mars Exploration Rovers, Spirit and Opportunity. Odyssey's new orbital geometry helps prepare the mission to be a relay asset for NASA's Mars Science Laboratory mission, scheduled to put the rover Curiosity on Mars in 2012.

Provided by JPL/NASA (news : web)

Explore further: SDO captures images of two mid-level flares

add to favorites email to friend print save as pdf

Related Stories

Mars Odyssey Shifting Orbit for Extended Mission

Oct 10, 2008

(PhysOrg.com) -- The longest-serving of six spacecraft now studying Mars is up to new tricks for a third two-year extension of its mission to examine the most Earthlike of known foreign planets.

Mars Odyssey Works Overtime After Successful Mission

Aug 26, 2004

NASA's Mars Odyssey orbiter begins working overtime today after completing a prime mission that discovered vast supplies of frozen water, ran a safety check for future astronauts, and mapped surface textures and minerals ...

Mars Orbiter's Computer Reboots Successfully

Mar 12, 2009

(PhysOrg.com) -- NASA's Mars Odyssey orbiter properly followed commands today to shut down and restart, a strategy by its engineers to clear any memory flaws accumulated in more than five years since Odyssey's ...

Recommended for you

SDO captures images of two mid-level flares

Dec 19, 2014

The sun emitted a mid-level flare on Dec. 18, 2014, at 4:58 p.m. EST. NASA's Solar Dynamics Observatory, which watches the sun constantly, captured an image of the event. Solar flares are powerful bursts ...

Why is Venus so horrible?

Dec 19, 2014

Venus sucks. Seriously, it's the worst. The global temperature is as hot as an oven, the atmospheric pressure is 90 times Earth, and it rains sulfuric acid. Every part of the surface of Venus would kill you ...

Image: Christmas wrapping the Sentinel-3A antenna

Dec 19, 2014

The moment a team of technicians, gowned like hospital surgeons, wraps the Sentinel-3A radar altimeter in multilayer insulation to protect it from the temperature extremes found in Earth orbit.

Video: Flying over Becquerel

Dec 19, 2014

This latest release from the camera on ESA's Mars Express is a simulated flight over the Becquerel crater, showing large-scale deposits of sedimentary material.

Spinning up a dust devil on Mars

Dec 19, 2014

Spinning up a dust devil in the thin air of Mars requires a stronger updraft than is needed to create a similar vortex on Earth, according to research at The University of Alabama in Huntsville (UAH).

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.