Image Credits: Darrell Etherington
Have you ever dreamed of going to the Moon, Mars, or beyond? SpaceX’s Starship rocket could be the vehicle to get you there – after a few kinks are ironed out, of course.
On 3 March 2020, the Starship SN10 (Serial No. 10) spacecraft launched from SpaceX’s Boca Chica, South Texas site for a high-altitude test flight. Previous tests, the SN8 and SN9, successfully flew but did not stick the landing. “Third time’s a charm, as the saying goes,” said John Insprucker, SpaceX’s principal integration engineer. And, despite blowing up 8 minutes later, that proved true as SN10 was the first rocket to successfully land after such a test.
Elon Musk’s SpaceX Starship rocket will eventually be combined with their Super Heavy rocket to create the fully reusable Starship. It will be capable of transporting both crew and cargo, totalling more than 100 metric tons, to Earth orbit, the Moon, and Mars. One key challenge, if the rocket is to be totally reusable, is the landing. Normal spacecrafts land using the aerodynamic drag in the atmosphere in order to slow down and employ parachutes to control the landing. However, the engines burn up due to the heat caused during the deceleration phase and crash into the sea. Starship hopes to avoid that and become the first fully reusable launch system.
Musk’s latest SN prototypes have a first stage booster used to shoot the rocket into orbit. It then separates and lands safely to be reused in the next mission. It is ejected only two minutes after launch and so it never reaches a high altitude, making the landing relatively easy. SpaceX pioneered this technology with the Falcon rocket. The most difficult part is landing the Starship rocket itself. The famous Space Shuttle rockets did this by using wings as part of the heat shield and to glide it onto a runway. This is crucial as in order for cargo and the rocket itself to survive, 99% of the energy must be dissipated. Due to the lack of atmosphere (and runways) on the Moon and Mars, Starship uses a landing flip manoeuvre. It free falls using the atmosphere to slow it down so that as it approaches the ground, it is travelling slow enough to achieve a flip-and-landing burn. This enables it to softly touchdown on the landing pad. It is essentially a carefully-controlled belly-flop where the rocket flips on its side during free fall but proceeds to land vertically. Just as a skydiver uses their two arms and two legs to control their fall, Starship has four flaps that actively control the whole manoeuvre.
This landing manoeuvre worked for all of eight minutes, as Starship stood proudly on the landing pad before following the safe fate as its predecessors – in a colossal fireball. SpaceX called it a “rapid, unscheduled disassembly”, the term they commonly use for explosions. Before landing, fire on one side of the rocket was seen and continued lightly burning after touchdown. Additionally, the rocket was leaning to one side once stationary. Although SpaceX has not officially commented, expert observers at the test flight have suspected a methane leak combined with a rough landing, and New York Times science reporter Kenneth Chang has suggested a leak in the propellant tank.
SN8 landing failed due to low pressure in the fuel header tank resulting in the rocket not slowing enough before touchdown. However, the ascent phase was a success and it was Starship’s first high-altitude test. SN9 did also not slow down enough for landing, failed to get fully vertical in time, and one of its raptor engines failed to ignite. Inspruker said, “again, we’ve just got to work on that landing a little bit”. And the primary objective, which was to “demonstrate control of the vehicle in the subsonic re-entry” was also a positive. This most recent test marks great progress from the prior prototypes and is in keeping with their “test, fly, fail, fix, repeat” testing philosophy.
Despite it blowing up, the test run was a huge success. It successfully landed, which other prototypes haven’t done before. Before the flight, Elon Musk predicted a 60% chance of success. Later, on his Twitter, Musk commented “Starship 10 landed in one piece! RIP SN10, honourable discharge.” Honourable indeed. Keep your eyes peeled for SN11, which is likely to launch in the next couple of months if it follows the current trend in flight schedules.