Low-cost missions to Mars must overcome a series of mission design hurdles, which represent the challenges of multiple steps from departing Earth to arriving at or on Mars. The nature of these hurdles depends on factors such as whether the spacecraft will be manifested as a rideshare, piggyback, or dedicated launch. There are three key methods for Earth departure: 1) a dedicated launch, where the launch vehicle upper stage performs the trans-Mars injection burn, 2) co-manifesting with a Mars-bound primary, where the primary provides a “free” ride directly to Earth escape or all the way to Mars, and 3) rideshare to high Earth orbits such as GTO, which are becoming more ubiquitous and affordable. The spacecraft would then be responsible for its own propulsion to Mars.
Traditional launch vehicle costs anchor the high prices of Mars transportation. However, there are multiple small, low-cost launch vehicles in development with over 1000 kg capability to LEO. Interplanetary cruise can range from 6 months to 2 years or more depending on trajectory and propulsion. Basic needs include nominal power, telecom, and navigation. Ballistic transfers require small trajectory correction maneuvers, whereas solar electric propulsion (SEP) needs sufficient power for near-continuous thrust.
A spacecraft must decelerate to be captured in Mars’s gravity and enter orbit. Mars orbit insertion (MOI) can be done propulsively or can be assisted by the planetary atmosphere. Direct insertion is the most straightforward but requires significant propellant. Aerobraking reduces the ΔV by ~50% but adds many months of operations. SEP-powered spacecraft gradually approach and spiral in over many months, eliminating critical events and making many intermediate orbits accessible, including equatorial.