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Planetary News: Mars Global Surveyor (2006)Mars Global Surveyor Update: Mars Reconnaissance Orbiter Fails to Spot Missing SpacecraftBy Emily LakdawallaNovember 21, 2006
As was reported here last week, NASA's Mars Global Surveyor spacecraft has been missing in action since November 5, three days after the spacecraft first reported a problem with one of its solar panels. In a press conference held today at the Jet Propulsion Laboratory, mission managers reported that their effort to locate Mars Global Surveyor using several cameras on Mars Reconnaissance Orbiter has not been successful. "Our preliminary analysis has not so far yielded any definitive sighting," stated JPL Mars Program Manager Fuk Li. With this failure to sight the spacecraft, but more importantly with Mars Global Surveyor's continued silence, hope is now ebbing for its recovery, Li continued. "In the past two weeks we have sent up 800 command files. None have been successful. While we have not exhausted everything we could do, we believe that the prospect of recovery of MGS is not looking very good at all. However, MGS has been a good friend; it has had an illustrious career. We are holding out hope, but we are prepared in our hearts that we may never hear from the spacecraft again." Still, the recovery efforts aren't over. Li reported that they are still continuously using a 34-meter antenna at the Deep Space Network stations to send commands to and listen for signals from the missing spacecraft. Further analysis could also yield a possible sighting of the spacecraft within the Mars Reconnaissance Orbiter images. The imaging efforts from Mars Reconnaissance Orbiter included 750 observations from the wide-angle star camera and one image each from two science cameras, the Context Imager (or CTX) and HiRISE, said project manager Jim Erickson. "All of them showed stars. And there are other features that you have to determine what they really are -- whether they are a low magnitude star, a cosmic ray hit, or a data error. These are very, very large images, in the case of CTX and HiRISE. So it's a lot of work to sort through the data points and determine exactly what they are. We're still doing analysis on all the images we've taken. We'd like to finish the analysis before we make definitive statements like 'it's not there.'" Opportunity Is Up NextThe next effort to locate Mars Global Surveyor will employ the Mars Exploration Rover Opportunity and orbiting Mars Odyssey to relay signals, Li said. "Today and tomorrow, we are going to ask a transmitter on MGS to talk to Opportunity, and ask Opportunity to listen to MGS. It will relay anything it could hear, through Odyssey, back to Earth. We should be getting data from that experiment sometime later in the afternoon today, as well as later in the afternoon tomorrow." The UHF antenna on Mars Global Surveyor that was used for communicating with spacecraft on the surface can be commanded independently of the spacecraft's other communications systems. Mars Exploration Rover Project Manager John Callas explained that the effort involves an attempt at a routine data relay using Mars Global Surveyor, an activity that Opportunity performed regularly during its nominal mission. "Opportunity has been sequenced to conduct two relay passes with MGS. MGS has been one of the orbital assets that the rovers can use for data return. We've asked Opportunity to conduct a relay pass both today and tomorrow. And we programmed the rover to return the status of that relay pass back through Mars Odyssey, which has been our normal return path. What we hope Opportunity will tell us is whether it saw a UHF signal from MGS, and whether its own receiver was in lock. Those are the two pieces of information that will tell us if there is a UHF signal coming from MGS." Of course, part of the problem facing Mars Global Surveyor mission managers at this point is uncertainty in the position of the spacecraft, which increases with every hour that the spacecraft is out of contact with Earth. But provided that Mars Global Surveyor's relay antenna has heard the command from Earth to conduct the relay attempt, Opportunity should be able to find the signal in the sky, as Callas explains. "The relay passes are typically about 12 minutes long, so they pretty much cover horizon to horizon. Even if the position of MGS is unknown by several minutes, which would be a very large uncertainty, it would be within the relay pass that we scheduled for the rovers. And the UHF signals are designed to go through antennas which have a broad antenna pattern. So if MGS is anywhere in the sky and its UHF system is on, then Opportunity should receive it." Stay tuned to planetary.org for further updates on the search for Mars Global Surveyor. |
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