Human Rated Starship
Next big hurdle for Moon and Mars missions is to human rate Starship
Starship development is going from strength to strength, following the sixth successful flight test. It is an enormously powerful launch vehicle, designed to carry up to a thousand people to Low Earth Orbit (LEO), or a hundred to the moon and Mars. However, achieving a human rating for Starship will be far from easy, Falcon 9 flew 84 times before it launched crew to the ISS on the Demo-2 mission. Fortunately SpaceX has begun to address all the issues associated with human rating, in many cases taking a quite unusual approach…
Proving Starship
SpaceX want to perform 100 launches of Starship before they begin crew operations, to prove it is completely reliable. They plan 25 launches from Starbase in 2025, and 400 over the next 4 years, hence the first crew flight might occur in less than 2 years. While this flight rate sounds aggressive, their ability to reuse both stages of Starship should considerably speed the process. Having both stages return should also improve reliability, because close inspection will show which components are likely to fail, allowing them to be redesigned and replaced to prevent this occurring. Until recently most launch vehicles were expendable, so NASA only require 12 successful flights to begin the human rating process. SpaceX could achieve this total relatively quickly with Starship, possibly using a single vehicle, if they manage to catch both stages.
Launch Abort
While launch failures are comparatively rare, Space Shuttle Challenger demonstrated why a viable launch abort system is vital for crew safety. Mindful of this, SpaceX has begun to practise hot staging with Starship, i.e. igniting the ship’s engines to separate it from the booster. If the booster loses thrust, they could use hot staging to save the ship, allowing it to make an emergency landing in the ocean. If the booster fails early in the flight, the ship could even return to the launch site to be caught by one of the launch towers; Starbase features two such towers for redundancy.
Crew missions will use Starship 3, which has 9 Raptor engines on the upper stage, consisting of 3 sea level and 6 vacuum optimized versions of this engine. Normal vacuum engines suffer from flow separation if ignited at sea level, which effectively shakes them to pieces, but Raptor Vacs don’t suffer from this problem and are routinely tested at sea level.
“Raptor has a very high chamber pressure, which in turn allows for a large expansion ratio nozzle [used on Raptor Vac] without flow separation at sea level.” ~ Elon Musk/X
When combined, Starship’s 9 Raptor engines should produce 2,700 tons of thrust, enough power to separate the ship at any altitude, even if the booster fails on the launch pad during the fueling process. Raptor engines need to be chilled with Liquid Oxygen (LOX) before ignition to prevent thermal shock, as they consume vast quantities of cryogenic propellant. Hence LOX can be flowed through the ship’s engines prior to launch, ensuring fast startup is possible from the beginning of the fueling process through to stage separation.
Life Support
SpaceX is already developing an Environment Control and Life Support System (ECLSS) for the Human Landing System (HLS) version of Starship, built for NASA’s Artemis Program. This ECLSS should support 4 crew members for 2 months on the lunar surface, hence ideal for most crew flights across cislunar space. SpaceX want to send crew flights to Mars in 2028, lasting at least 26 months, which suggests further ECLSS development should follow, to achieve this far more ambitious goal.
Stage Recovery
Needless to say NASA will require many successful catches of Starship before they approve this novel procedure for crew missions. Currently the only crew launch scheduled for Starship is the Polaris 3 mission, the third flight in the Polaris Program, a private initiative financed by the entrepreneur Jared Isaacman. All being well, this crew test flight should occur in 2026-27, to ensure Starship is human rated before Mars landings commence in 2028.
NASA Ramrod
Jared Isaacman was recently nominated to become the new NASA Administrator, which should be confirmed by the senate in early 2025. He focuses on positive action to produce meaningful results, so we can expect NASA to increase its use of commercial providers.
“With the support of President Trump, I can promise you this: We will never again lose our ability to journey to the stars and never settle for second place. We will inspire children, yours and mine, to look up and dream of what is possible. Americans will walk on the Moon and Mars and in doing so, we will make life better here on Earth.” ~ Jared Isaacman/X
Currently NASA has one crew transport vehicle, i.e. SpaceX’s Falcon 9 and Crew Dragon, because Boeing’s Starliner needs years of corrective work before it becomes operational. No doubt Jared intends to replace these NASA capsules with more capable spacecraft like Crew Starship, in order to advance the space frontier. Hence he will prioritize the human rating process for Starship, perhaps donating some astronauts for the Polaris 3 mission, which he had planned to command personally.
Parallel Mars
Before the election, SpaceX planned to perform its own Mar missions, because NASA prioritized moon landings over Mars. But if Jared Isaacman, a sworn exponent of commercial space, becomes NASA administrator...expect many changes of policy.
Currently Starship costs ~$100m per flight, and this will reduce by 90% when SpaceX reuse both stages. The Space Launch System (SLS) used by NASA for the Artemis program costs $4.1bn to launch, likely to rise to $5bn for the upgraded SLS 1B version. Given Starship’s starkly lower cost, NASA can afford to pursue Mars as a side project in parallel with Artemis moon landings. This should be technically possible because both Starship HLS and Mars Starships will utilize the same launch facilities and orbital refueling depots, currently being built by SpaceX.
Big Picture
President Trump expects to see big advances in space before his term ends in 2028. Unfortunately NASA has delayed the first moon landing mission to 2027, which comes dangerously close to his deadline. Hence NASA will likely use the crew version of Starship as a backup to SLS, producing a more competitive approach to moon landings.
Expanding Space Force operations is another Trump priority, so developing a Crew Starship for NASA is a necessary precursor, before Space Force begin to operate the vehicle. Given Starship’s advanced capabilities, expect many NASA programs to be radically amended. For example, SpaceX plan to land multiple Starships on Mars in 2026, one of which could be adapted into a Mars Sample Return (MSR) mission. This would allow samples to be returned in 2030, 4 years earlier than NASA planned for MSR, and reducing cost from the previously projected $10bn.
In Conclusion
Major roadblocks to human rating Starship have been addressed by SpaceX, and NASA’s new administrator will likely accelerate the process. This should allow a smooth transition to Starship, guaranteeing space access at unprecedented scale.
From a political perspective, it would be unwise of congress to oppose this transition and risk President Trump’s ire, who’s a firm believer in change. Unshackled from the past, almost anything seems possible.
Succinctly: welcome to the second space age!