Sleipnir Probes

“All three Sleipnir probes use identical tumbler-landed supply casings,” Bruce replied. “They all contain transponders that the rover navigation system will identify, allowing Mark to drive his modified rover to each site.

“Each probe will deliver just under one metric ton to Mars- one-tenth the payload of a typical presupply flight. Five hundred kilograms of that will be payload. Four hundred kilograms of that will be food, providing a total of three hundred days of rations for four astronauts at full rations.

“The remaining hundred kilos will include a replacement radio system on both Sleipnir 1 and 3, a replacement flight suit and shatter-proof helmet for Watney on Sleipnir 2, replacement spare Hab canvas and resin on all three ships, plus whatever we can cram in the remaining space and weight.

“And finally, we’re configuring the onboard radio for all three probes so they can take the place of Hermes as radio relays for Pathfinder. It’ll only do any good for the last four months or so of the flight, but it’s better than nothing. After launch we’re planning software adjustments which will let us turn the three probes into a flying radio array that can error-check incoming transmissions and so increase bandwidth from Mars. Unfortunately the time lag between ships won’t let us do that in reverse.”

Sleipnir 2 launched without incident, achieving first Earth orbit and then Mars insertion trajectory with perfect precision. Almost one hundred sols’s worth of food, plus spare hab canvas and other spare parts, were on course for a Sol 585 landing somewhere to the south of the Ares III Hab.