Starship has extraordinary capabilities even before reuse

Orbital Starship is next level

Mechazilla arms lift Super Heavy booster onto Orbital Launch Mount ~ credit SpaceX

SpaceX have heralded Starship as humanities best hope for cheap space access (estimated at $1.5m per launch) chiefly because both stages are reusable. At present they plan to catch returning stages with ‘Mechazilla’ arms fitted to the launch tower, a novel and no doubt challenging procedure. Realistically it may take several years to successfully recover the Super Heavy booster, possibly longer for the Starship upper stage, which must endure some pretty arduous conditions during reentry never attempted at this scale. However, even lacking partial reuse Starship has enormous potential; for example if used simply as a disposable vehicle it could launch 250-300 tons to orbit, more than twice as much as its closest rival the Space Launch System (SLS).

The saga of Falcon 9 development might provide some insight into what we might reasonably expect with Starship. Falcon 9 was designed to be reusable from the outset, yet it took 5 years before SpaceX managed to recover the boost stage and another 2 years before it was reflown. However, they achieved a huge amount with Falcon 9 even without reuse, such as ISS cargo deliveries, launching the Iridium Next constellation and a plethora of civil and commercial satellites. Of course Starship is an order of magnitude more capable so expectations are far greater for what can be achieved, with or without reusability…

Orbital Refueling

SpaceX want to place a propellant storage depot in Low Earth Orbit (LEO) to refuel outward bound Starships. In order to carry the maximum payload (~200 tons), a Version 2 Starship will normally expend all its propellant to reach LEO then refuel at a propellant depot, allowing it to send that payload far beyond Earth orbit. As Robert H Heinlein once said: “When you reach orbit you are half-way to anywhere.”

The propellant depot used for this refueling process will likely resemble Starship, except with larger propellant tanks to increase its refueling capability. No doubt SpaceX plan to reuse this propellant depot in orbit, hence it won’t need to survive reentry or be caught by Mechazilla to operate normally. After each refueling operation, SpaceX plan to replenish the propellant depot using Tanker vehicles, a simplified version of Starship sans payload section to decrease its dry mass. Hence if Starship is partially or fully expended, each Tanker flight could carry at least 250 tons of propellant to orbit. In real terms, that means it should take only 4 Tanker flights to refuel a lunar Starship (which requires ~ 983 tons of propellant), or 3 Tanker flights to refuel a Mars Starship (which requires ~ 660 tons of propellant due to an assist from atmospheric braking). Admittedly these Tanker vehicles would need to be disposed of after each flight but considering their simplicity and relatively low cost (a Raptor engine costs <$1m to produce) this should allow orbital refueling to occur fairly regularly as SpaceX aim to produce one Starship per day.

Artemis Program

Once orbital refueling is available this should allow NASA to commence moon landings with their Artemis program. They intend to use Starship as a Human Landing System (HLS) to send astronauts and cargo to the lunar surface every 2 years and fortunately they don’t require the first couple of HLS landers to be reused. While fully reusable Tankers would be a godsend for refueling purposes, technically they could still perform the initial moon landings using a partially or fully expended launch vehicle.

Mars Landings

SpaceX have long sought to colonize Mars, hence reaching orbit with Starship could be seen as the starter pistol for this process. Once the orbital depot is operational, SpaceX could use its down time between Artemis missions to launch Starship vehicles to Mars. These would be unmanned missions to test Entry, Descent and Landing (EDL) techniques through the tenuous Martian atmosphere, something SpaceX need to master before they send people. Technically this effort could occur in parallel with early Artemis landings, considering Starship’s prodigious production rate and Elon Musk’s impatience to reach the red planet...

“I wonder what things will be like in 8 years… I think we will have landed on Mars and I think we will have sent people to the moon.” ~ Elon Musk

Rocket Cargo

As previously discussed, delivering military cargo with Starship is a huge opportunity for SpaceX, because it allows them to develop point-to-point transport with financial support from the military. Initially the US Space force want to use Starship to place cargo in orbit or land at austere sites, which suggests they won’t want to reuse these vehicles. Hence expendable launches would seem ideal for the early proving flights at the very least. The military would receive vitally needed cargo in less than an hour anywhere on Earth, giving them significant tactical advantage on any battlefront. Talk about shock and awe when a rocket delivery appears out of the blue…

Catch-all Capabilities

The future is uncertain, which suggests many more applications for Starship could arise, given its unique capabilities and rapid availability. Here are a few examples for how it could prove invaluable in a number of possible scenarios: -

Asteroid defense – the Near Earth Asteroid (NEA) Apophis should barely miss Earth in 2029 but if its perceived trajectory shifts towards us for any reason, urgent action maybe required to avert a disaster. In this scenario SpaceX could quickly launch an unladen Starship, refill it at the propellant depot then send it to intercept Apophis in deep space. The closing velocity would be >10km/s, and given the vehicle mass is over 100 tonnes, the impact should transfer sufficient momentum to alter Apophis’s trajectory away from Earth.

Hubble replacement – SpaceX plan to repair and reboost the Hubble Space Telescope, but if this venerable instrument should fail for any reason they could easily provide a replacement. Elon Musk has talked with Saul Perlmutter about converting the entire cargo section of Starship into a reflecting telescope, using conventional mirrors built for ground telescopes. The resultant Starship telescope would have roughly 10 times the resolution of Hubble, allowing far better imaging of exoplanets to determine potential new Earths.

Commercial Space Station – at present there are some early efforts to develop a commercial space station to replace the International Space Station (ISS), after it retires in 2030. However, if these efforts are delayed or the ISS needs to be evacuated for any reason, SpaceX could fit Starship with equipment racks and solar panels, effectively turning it into a substitute space station to allow this vital research to continue. Starship has comparable internal volume to the ISS (~1,000 cubic meters) and a robust Environmental Control and Life Support System (ECLSS) developed for HLS missions. Crew could use a Dragon spacecraft to access the Starship station, which could be retained in orbit as long as necessary, hence no need for it to be recovered.

In Conclusion

While it seems wise to temper our expectations for Starship reusability in the short term, it still retains some prodigious capabilities, even when partially or fully expended. Essentially expendable Starship should be fine for most applications, such as missions to the moon and Mars; technically reusability would only be required to actually colonize these new worlds.

As Starship prepares for its epic fourth flight, a successful launch and landing at sea seems more than possible given SpaceX’s unrivaled ability to overcome technical challenges. Then we enter that period when Starship stretches its legs and shows its true worth – reusability will just be a bonus!

Chris Prophet