Mars dust is a big problem for technology; it’s very fine, abrasive and sticks to everything. Airborne dust has been blamed for accelerating Phoenix’s death, and the hardy Mars Exploration Rover Spirit looks like it has finally met its match. The critical issue here is a build-up of the red powder over the surface of the energy-collecting solar panels our robotic explorers depend on to power their experiments and movement over the Martian terrain. If solar cells cannot receive light, electricity cannot be generated, hastening the end of of Phoenix, and possibly one of the rover twins…
It’s sad, but it was inevitable. Phoenix is slowly turning into a block of ice. Far from being downhearted, the NASA team responsible for Phoenix are very happy with what they’ve achieved. “At this time we’re pretty convinced the vehicle is no longer available for us to use, and we’re declaring the end of the mission,” said Barry Goldstein, Phoenix project manager, during a press conference yesterday (Nov. 10th). “We’ve been surprised by this vehicle before, and we’re still listening. We’ll try to hail Phoenix, but no one has the expectation we’ll hear from it again. We’re completely proud of what we’ve accomplished. We’ve achieved all of the science goals and then some.”
On October 31st, Phoenix re-awoke from its power-saving “Lazarus” mode to send a message to Earth via Mars Odyssey as the satellite passed overhead. Although the lander was brought back from the dead in time for Halloween, mission controllers knew it was the beginning of the end for Phoenix. It is believed a dust storm may have blocked the already meagre winter sunlight from providing power to the vehicle, switching it into a fail-safe low power mode to conserve electricity stored in its batteries. At least the Lazarus mode brought Phoenix another ten days of communication with NASA.
There is, however, a tiny chance NASA might be able to touch base with Phoenix next Mars spring (Oct. 2009), but it will be a long-shot. “By the mid October time frame, there would be enough sunlight hitting the solar arrays to create power,” said Peter Smith, Phoenix Principal Investigator. “But its highly unlikely the vehicle will come back. It will be encased in CO2 ice, in temperatures under -150 C. The solar arrays will likely crack and fall off the vehicle,… the electronics will become brittle and break, so the wiring boards won’t work. But this vehicle has behaved so superlatively, we’ll look again in October.”
So, dust contributed to Phoenix’s demise, what about the rovers Spirit and Opportunity? Looking at the year-old self portrait of Spirit (above), it is hard to see the wheeled robot, its red camouflage is causing it to blend in nicely with the regolith. This is great if you’re trying to hide, but not so great if you’re trying to collect sunlight to survive.
On its 1,725th sol (Mars day, equating to November 9th here on Earth), Spirit generated record low power output from its solar panels – only 89 watt hours, a level much lower than the rover requires to operate throughout the day. This problem has been put down to a Mars robot’s old foe: a dust storm. The build-up of dust on the nearly five-year old Mars explorer’s panels could cause a low power fault in Spirit’s electronics, possibly killing the rover currently located in Gusev Crater. NASA is obviously very concerned about this turn of events and will be keeping a close eye on Spirit’s power situation.
It would really suck if we lost two Mars surface missions in such a short space of time. Let’s hope MER Opportunity continues to operate at full-power…