On July 12, the 11 year old Mars orbiter Odyssey experienced a glitch that first prompted entry into safe mode and now seems to have affected one of the spacecraft’s reaction wheel. Usually, the problem would have minimal impact on the orbiter’s performance. However, Odyssey is supposed to serve as relay for the Mars Science Laboratory Curiosity. Without the Odyssey in place, the communication lag between Curiosity’s August 5th landing and when NASA receives word from the spacecraft could more than double.
Curiosity will be landing in Gale Crater, the walls of which prevent direct communication between the rover and Earth. Three satellites were scheduled to watch Curiosity’s descent – the infamous “seven minutes of terror” detailed in a recent NASA video, referring to the seven minutes of lag time between Mars and Earth communications. With a relay satellite in the appropriate position, NASA would receive transmissions from Curiosity seven minutes after they are sent. However, of the three satellites, Odyssey is the only one with relay capability. The other two, Mars Reconnaisance Orbiter and ESA’s Mars Express, can only record the transmission and forward it along during its next scheduled data dump. This would result in a gap of hours from the time Curiosity lands and the time Earth finds out what happened.
The damage to Odyssey does not put the aging satellite completely out of commission. The spacecraft is still orbiting and will still pass over Gale Crater. But because the incapacitated reaction wheel impairs the orbiter’s navigation, Odyssey won’t be in position until several minutes after Curiosity has already made touchdown. It could be as much as 17 minutes before anyone knows whether Curiosity’s intricate landing system successfully put the 900 kg rover down in one piece.
NASA officials are emphasizing that the issue with Odyssey will have no actual impact on the Mars Science Laboratory’s landing, which is completely automated. Still, for the nailbiting engineers and scientists waiting for word, it may feel a whole lot longer than seven minutes.
Below, discover the “Seven Minutes of Terror”: