Complex sentence: At the base, the astronauts are informed by NASA official Kelloway (Hal Holbrook) that a faulty life-support system would have killed the astronauts during the flight, and they must help counterfeit the television footage during the flight to and from Mars.
Split into simpler sentences: At the base, the astronauts are informed by NASA official Kelloway (Hal Holbrook) that a faulty life-support system would have killed the astronauts during the flight. He tells them that they must help counterfeit the television footage during the flight to and from Mars.