NASA says it is narrowing a short list of things its scientists can to extricate its stuck Mars Spirit rover.
The space agency said it is exploring a couple of remaining options, such as driving backwards and using Spirit's robotic arm to sculpt the ground directly in front of the left-front wheel, the only working wheel the arm can reach. The amount of energy that Spirit has each day however is declining as autumn days shorten on southern Mars, NASA stated.
NASA said it is currently analyzing results of a Jan. 13th attempt to move the spacecraft that involved a very slow rotation of the wheels. Earlier drives in the past two weeks using wheel wiggles and slow wheel rotation produced only negligible progress toward extricating Spirit, NASA stated.
If NASA cannot move Spirit, one remaining option would be to spin the wheels on the north side of Spirit, letting it dig in deeper in the Martian sand but improving the tilt of the rover’s solar panels toward the Sun. Spirit's tilt, nearly five degrees toward the south, is unfavorable because the winter sun crosses low in the northern sky, NASA stated.
Unless the tilt can be improved or luck with winds affects the gradual buildup of dust on the solar panels, the amount of sunshine available will continue to decline until May 2010. During May, or perhaps earlier, Spirit may not have enough power to remain in operation, NASA stated.
NASA said it was investigating the type of research a stationary Spirit could do in the future. For example, it could study the interior of Mars, monitor the weather and continue looking at the deposits uncovered by its wheels, a task it has already been performing.
Mobility is still the first priority, NASA stated. Spirit's right-front wheel, which had stopped operating in March 2006, showed signs of life late last year by spinning slightly during one of the attempts to move the rover. The wheel however stopped later in another test and has not worked since.
In related news, NASA's Mars Odyssey orbiter will next week make a number of passes over the presumed dead Phoenix Mars Lander on the surface of the planet and listen for what the space agency called possible, though improbable, radio transmissions.
Odyssey will pass over the Phoenix landing site about 10 times this month and two longer listening tries in February and March trying to determine if the craft survived Martian winter and try to lock onto a signal and gain information about the lander's status.
Should the lander show signs of life, it should follow instructions programmed on its computer. If systems still operate, once its solar panels generate enough electricity to establish a positive energy balance, the lander would periodically try to communicate with any available Mars relay orbiters in an attempt to reestablish contact with Earth. During each try, the lander would alternately use each of its two radios and each of its two antennas, NASA stated.
NASA Jet Propulsion Laboratory, which is monitoring the craft, said the Phoenix site is seeing about the same amount of sunshine as when the lander was last heard from, on Nov. 2, 2008, with the Sun above the horizon about 17 hours each day.
The Phoenix Mars Lander went silent last November, after successfully completing its mission and returning unprecedented primary science phase and returning science data to Earth, NASA stated.