Image of a spacecraft approaching Mars


    To ensure a successful entry, descent, and landing, engineers begin intensive preparations during the approach phase, about 60 days before the spacecraft enters the Martian atmosphere. The preparations last until the spacecraft enters the Martian atmosphere.

    The activities that engineers typically focus on during the approach phase include:

    • the final trajectory correction maneuvers, which are used to make final adjustments to the spacecraft's incoming trajectory at Mars
    • attitude pointing updates, as necessary, for communications and power
    • frequent "Delta DOR" measurements that monitor the spacecraft's position and ensure accurate delivery
    • start of the entry, descent, and landing software, which automatically executes commands during landing
    • entry, descent, and landing parameter updates
    • spacecraft activities leading up to the final turn to the entry attitude and separation from the cruise stage
    • the loading of surface sequences and communication windows needed for the first several sols (a "sol" is a Martian day)

    During the approach phase, the amount of tracking requested from the Deep Space Network is substantially increased to allow engineers to determine more accurate trajectory solutions in the final weeks before arrival at Mars. This tracking supports the safe delivery of the InSight lander to the surface of Mars. The Deep Space Network's 34-meter and 70-meter antennas provide tracking coverage of the spacecraft during the approach phase.