Flight 9 Progress

SpaceX plan to accelerate Starship

Flight 9 launch, credit SpaceX

On Tuesday May 27, SpaceX successfully performed the ninth test flight of Starship. Test programs progress by degrees so let’s itemize the many improvements they managed to achieve: -

1. Raptor 2 engines are now highly reliable. All engines ignited on both stages for the ascent phase then successfully reigniting for Super Heavy’s boost-back and landing burn. Rigorous engine tests at SpaceX’s McGregor site revealed the injector head worked loose from the thrust chamber after the first firing of each engine. This caused propellant to leak from this high pressure joint on Flight 8 which led to an “energetic engine failure.” Hence the fault was easily fixed by simply tightening the bolts that secured the joint together.

2. Starship completed its ascent to space, and reached the desired trajectory. This proves the resonant frequency problem that ruptured fuel lines on Flight 7 has now been overcome.

3. This was Booster 14’s second flight, proving Super Heavy boosters can be reused. SpaceX now has reusable boosters for two different types of rockets, a feat yet to be emulated by any other launch provider.

4. SpaceX like to test to failure, something they certainly managed to achieve with the veteran Booster 14. During descent it had a high angle of attack, to deliberately stress the vehicle, yet still managed to reignite its engines for the simulated landing burn over the gulf. The stage was subsequently lost but SpaceX now know how far they can push the booster and possible areas for improvement.

“No significant loss of heat shield tiles during ascent.” ~ Elon Musk/X

5. On previous flights Starship visibly shed a number of heat shield tiles, rendering the vehicle unsuitable for reuse due to the heat stress from reentry. SpaceX has continually refined the formula and fitment of these Tufroc tiles, and they now provide sufficient protection to reuse Starship on future missions.

Overall this was only the third flight of Starship Version 2, which is effectively a new vehicle design with new engines. Starship Version 1 managed to soft land in the ocean after 4 flights suggesting Version 2 should soon do likewise.

Future Objectives

Starship achieved all the milestones necessary for a normal launch vehicle, i.e. it reached orbital velocity with the payload intact. Of course SpaceX asks far more of this vehicle to fulfill their far reaching goals, so there’s plenty more to achieve: -

“Leaks caused loss of main tank pressure during the coast and re-entry phase. Lot of good data to review.” ~ Elon Musk/X

1. Starship was exposed to considerable stress and shaking during ascent, which caused leaks from the main propellant tanks. These tanks are normally maintained at 6 bar (i.e. ~6 times air pressure at sea level), so even relatively small ruptures can result in considerable loss of tank pressure. No doubt SpaceX will reinforce any affected areas and upgrade their pressure test procedures.

2. Unfortunately the escaping jets of tank pressurant made Starship tumble, causing it to reenter at the wrong angle and subsequently breakup. This exposed the vehicle to far more stress than normal, no doubt showing up any weaknesses in its subsystems e.g. heat tiles, avionics, communications etc. While they didn’t intend to test these systems to destruction, likely they will implement further improvements to account for extreme cases in the future.

3. The payload bay door didn’t fully open, aborting any deployment of the satellites. Fortunately these were dummy satellites used to test the “Pez dispenser system,” designed to deploy the latest generation of Starlink satellites. While the tumbling stage must have experienced some unusual stresses, the payload bay door should operate under severe conditions, so SpaceX will no doubt revisit the design.

Way Forward

“Launch cadence for next 3 flights will be faster, at approximately 1 every 3 to 4 weeks.” ~ Elon Musk/X

Following this latest Starship test, SpaceX intend to accelerate the development schedule. Elon Musk isn’t known for his patience and the next Mars launch window opens November 2026…

Currently SpaceX has three more Version 2 Starships in production plus one Version 3 beginning to take shape. However, they want to recover one V2 Starship before they progress to V3, because they need to reuse this ultimate version of Starship to achieve the 2026 deadline. Fortunately SpaceX has 2 launch mounts at Starbase Texas, which provides redundancy in case a returning Starship causes serious damage to the catch arms or launch tower. Alternately they could land Starship on Johnston Atoll, a remote Air Force facility in the South West Pacific. The Air Force Research Laboratory (AFRL) want to land Starship there as part of their Rocket Cargo Program. Hence performing the first landing test at Johnston would reduce risk for SpaceX and potentially unlock millions in revenue from AFRL.

After a successful landing at either Starbase or Johnston we can expect any remaining V2 Starships to be scrapped, so they can proceed directly to V3 and accelerate the development program. Reportedly V3 Starships have docking hardware so we could see the first orbital refueling test by the end of this year or early next.

Shortcut to Moon and Mars

Presently SpaceX intend to use a propellant depot in Low Earth Orbit (LEO) to refuel Starships sent to the moon and Mars. However, to meet an accelerated timeline they will likely dispense with the propellant depot and refuel the first outbound Starships in LEO using multiple tankers. If Starship is pointed at the sun that should minimize propellant boil-off allowing tankers to transfer sufficient propellant for a successful landing mission. Starship requires 3.8km/s delta-v to reach Mars and 5.7km/s for the moon when refueled in LEO but V3 Starship has a maximum delta-v of ~9km/s with minimum payload. Thus these early proving missions will require only 4 tanker flights for Mars and 6 for the moon, assuming fast reuse of tankers and 3 launch mounts (2 at Starbase and 1 at Cape Canaveral) which should be possible by the end of 2026.

In Conclusion

Building rockets is hard, particularly colossal launch vehicles like Starship. Version 3 should be 142m in height because there’s no small solutions to making life multiplanetary.

“In recent weeks, Musk has dialed back his focus on politics and said he wants to devote the majority of his time to SpaceX and his other companies” ~ Eric Berger/Ars Technica

Love or hate him, Elon Musk is arguably the best troubleshooter on the planet, considering the success of his companies. Now he’s spending more time on SpaceX we should expect more positive results, paving the way to the moon and Mars.

Chris Prophet