Mars Global Surveyor is the oldest of five NASA robotic devices, which is designed to find out signs that Mars once had water;and it had been taking detailed pictures of the red planet for a decade. Unfortunately, it stopped working on November 2 after itdeveloped a motor problem.After two days of silence, ground control teams received a signal that the device had put itself into an emergency standby mode.There was no information about what had gone wrong. Since then, the mission team at NASA's laboratory in California has tried tocontact the device. This week, NASA engineers are preparing for what may be their last chance to recover the spacecraft.NASA plans to use a newly arrived device to take a picture of the Surveyor to see how the failed craft is oriented to the sun forpower and to Earth for communications. It is reported that the picture will be taken on Friday when the satellites are about 93 milesapart. The new high-powered camera should be able to image details of the Surveyor as small as about 10 centimeters. There is agood chance of recovering it.Flight controllers also plan to try to get the Surveyor to contact one or both of NASA's roving（漫游）geology stations, Spiritand Opportunity, which are located on opposite sides o. Mars'equator（赤道）.The rovers would not be able to transmit thespacecraft'5 science data, but engineers at least would get an idea of its general position. The linkup also could show if the Surveyorstill has power. If the device has been unable to charge its batteries due to a positioning problem or failed component, it could runout of power with no hope of recovering. But if it has power, the device is quite capable of autonomous control even if it doesn'thear from Earth. The Surveyor has far surpassed its design lifetime, but scientists still have more targets for the probe's camera andscience instruments.
The decisive factor for the recovery of the Surveyor is _.