After three consecutive flight failures plus an on-land test explosion, there was a lot riding on the 10th suborbital test flight (IFT-10) of the Starship/Super Heavy. Success was needed for both SpaceX and for NASA’s Artemis lunar programme – and it was achieved.
A scorched Starship on its IFT-10 mission makes its controlled powered approach to a splashdown in the Indian Ocean. Courtesy: Elon Musk/X
The launch occurred from the Starbase launch site at Boca Chica beach in West Texas at 2330 GMT on 26 August. All except one of 33 Raptor first-stage engines burned successfully, but the launch was not affected by the single engine shutdown. A hot-staging was accomplished with the ignition of six vacuum-optimised Raptor engines on the second-stage. The Super Heavy first-stage Booster 16 made a controlled flip after separation and a performed a boost back burn. At T+ 6 minutes 45 seconds it completed a powered splashdown, including a planned early landing engine shutdown during approach (a middle ring engine was fired in its place), in the Gulf of Mexico. As expected, the stage was destroyed during its splashdown landing. As a landing and approach test, it was not intended for reuse. However, previous tests have managed to recover boosters back on the pad using the famous chopstick arms of the launch tower.
The Starship upper stage flew on its trajectory at a velocity only just short of orbital. At about T+18 minutes 27 seconds, the Starship second stage/spacecraft deployed eight dummy Starlink satellites, helping to validate the deployment mechanism. A reignition test of one of the six Raptor engines was also conducted and then it successfully re-entered. Using its aerodynamic flaps to guide the vehicle’s direction and attitude, Starship made a controlled approach. At T+ 1 hour 6 minutes 30 seconds into the flight, the Starship Ship 37 spacecraft made a powered splashdown involving a short final hover in the Indian Ocean.
Starship Ship 37 (on IFT-10) hovers for its splashdown landing. Courtesy: SpaceX
A total success – at a cost of payload mass
While the launch demonstrated the potential for reusability of both the booster and the upper stage, it did so at a price: payload mass. Recently published information by SpaceX shows payload mass to be much lower than the originally envisaged 100 metric tons to low Earth orbit for a fully reusable version. The V2 version can apparently only carry 35 metric tons. The reason is that structure and thermal protection systems have, over the course of the test programme, had to be beefed up and made heavier to make re-entry survival viable. As it was, this flight still suffered some flap damage and thermal damage to the aft skirt of the stage, even if this was not fatal to the mission. SpaceX wants a larger payload. A stretched V3 version will be able carry the originally advertised 100 metric tons, and a projected V4 version may reach 200 metric tons.
SpaceX needs to press on with its flights to prove its cryogenic propellant storage and transfer technology, both of which are needed for the Artemis HLS. It is already under fire for the delays to the programme which threatens to hold up the entire Artemis human lunar landing mission, allowing China to return humans to the Moon first. Some have criticised the decision to use Starship HLS given the many refuelling operations required for each landing attempt.
While worries persist over the viability of a Starship-derived HLS, nevertheless, Elon Musk and SpaceX were universally congratulated for the execution of this flight.
Expected versions of the Starship/Super Heavy combination. Courtesy: SpaceX
