According to a report by one of its engineers, contact was lost with the two MarCo cubesats just prior to InSight’s landing on Mars, and was recovered just in time.
The team spent all day looking at the fault tree to fix the issue, Klesh recalled. “At 6:05 a.m. [California time] the next morning, MarCO-B shows up just on time,” apparently recovering automatically from an attitude-control issue, Klesh said. He proudly told mission managers at 6:30 a.m. that both cubesats were ready to go.
But then, “45 minutes later,” he said, “MarCO-A disappeared.”
At that point, it was too late to make any changes. JPL had already sent its last commands to InSight and MarCO through NASA’s Deep Space Network (DSN) of telescopes that communicate with spacecraft far out in the solar system. So the engineers could only watch and wait. “We didn’t know what was going to happen [during landing] in a few hours’ time,” Klesh said.
Luckily for the team, MarCO-A (and its twin) both popped into communications at 12:14 p.m. and succeeded in relaying data from the InSight touchdown, sending back valuable information about the dangerous entry, descent and landing phase to NASA engineers to plan for future missions.
They have traced the issue of MarCo-A’s disappearance to being blinded by the light from Mars, thus confusing its star tracker. That both spacecraft auto-recovered when contact with Earth was lost however is I think a fine testament to their design.