SpaceX HLS: Why NASA is taking a Starship to the Moon

Before the stars and before Mars comes the Moon. That’s the order of the day for space agencies and commercial space companies alike.

NASA plans to return humans to the lunar surface by 2025 through the Artemis program, which is much more than a reboot of the Apollo program. Astronauts will speed weeks on the lunar surface, eventually construct a Moon base, and practice with technology and operations necessary to land humans on Mars one day.

NASA already has a new, powerful Moon-shot rocket, the SLS, and a new spacecraft, the Orion space capsule, a much more advanced Apollo-like craft. But the space agency only finally settled on its choice of Human Landing System vehicle, a vessel to carry astronauts from lunar orbit to the Moon’s surface and back again, in April, awarding a contract to SpaceX.

After some delays, spurred by legal challenges from SpaceX rival Blue Origin, SpaceX is now back to developing an HLS variant of its Starship rocket and spacecraft. When American astronauts return to the Moon in Artemis III, it will be in a decidedly retro-looking Starship, resting on its tail like a silvery rocket from the cover of 1950s pulp science fiction novels, but pointed up into the future.

What is the Artemis human landing system (HLS)?

The Artemis HLS is the contemporary equivalent of the Apollo program’s Lunar Excursion Module, or LEM.

The Artemis III astronauts will travel to lunar orbit in NASA’s Orion spacecraft, but like the Apollo command module, Orion will never touch the Moon itself. Instead, Orion will rendezvous with the Starship HLS and both vehicles will dock with NASA’s Gateway — a small space station planned for lunar orbit.

Artemis astronauts will then transfer to the Starship HLS and descend to the Moon’s surface in the SpaceX vehicle, serving as their base of operations for six days. At the end of their mission, the Starship HLS will return the astronauts to orbit and Gateway, where they will transfer back to Orion for their journey home to Earth.

Who won the HLS contract?

In April, NASA awarded a $2.89 billion contract to SpaceX to develop an HLS for Artemis, choosing the SpaceX proposal over bids by competitors Blue Origin and Dynetics.

NASA explained in a source selection document that a primary factor in its decision was cost. The space agency would have liked to have contracted with two companies but could only afford one, and the SpaceX bid was the lowest of the three by a wide margin.

NASA has yet to award an HLS contract for Artemis IV and beyond, so Blue Origin or other companies might yet get a chance to carry astronauts back to the Moon — but they won’t get there first.

The Blue Origin lawsuit and the HLS

Blue Origin and Dynetics did not take the loss to SpaceX well and filed a joint protest with the Government Accountability Office, putting any SpaceX work on a Starship HLS on hold pending the outcome.

The GAO ruled in favor of NASA and SpaceX in July, but Blue Origin refused to let go, mounting a social media campaign criticizing SpaceX and NASA for choosing SpaceX for the HLS contract.

Then, in August, Blue Origin sued NASA, again putting Starship HLS development on hold.

Blue Origin lost its lawsuit on November 4, so Starship HLS is back on — but not on schedule.

On November 9, NASA Administrator Bill Nelson said that the Artemis III mission, initially scheduled for October 2024, will launch no sooner than 2025, blaming, in part, the “nearly seven months” lost in the litigation over the SpaceX contract.

What is the Starship HLS design?

The Starship HLS variant is just that — a variant, not a radical redesign. But SpaceX has already announced some significant changes over the main Starship spacecraft.

SpaceX will ditch the typical aerodynamic fins and heat shielding for the Starship HLS variant since once launched, it will not be returning to Earth for a landing. The Starship HLS will also have wide legs for landing on the rocky lunar surface and some form of elevator for lowering astronauts and material up and down its 164 feet height.

Operations-wise, the Starship HLS will launch into low-Earth orbit, where it will dock with another Starship variant — this time a fuel tanker — and take on fuel for its journey to the Moon. The Starship tanker variant is still under development. It will require as many as 10 additional Starship launches to fill up with fuel for a Starship HLS mission to the Moon, an operational complexity Blue Origin criticized heavily in its social media campaign against the SpaceX HLS contract.

Will Starship be more powerful than SLS?

NASA’s SLS is a big, powerful rocket designed to carry NASA missions to the Moon and far beyond — that’s the Congressional mandate for the launch system per the NASA Authorization Act of 2010.

Between its two solid-fuel boosters and four main stage RS-25 rocket engines burning liquid hydrogen and liquid oxygen, SLS will generate more than eight million pounds of thrust and deliver more than 95 tons of mass to orbit. It’s a historically large rocket, outclassing the Saturn V of the Apollo era, which generated a little more than 7.5 million pounds of thrust at lift-off.

But the Starship launch vehicle, if it works as planned, will nearly double the SLS’s power at lift-off. Consisting of a Super Heavy Booster using 33 Raptor rocket engines, the Super Heavy will produce 12 million pounds of thrust. The Starship spacecraft will function as a second stage, and together with the Super Heavy, will be capable of lifting more than 100 tons of mass to orbit.

But beyond raw power, Starship also boasts more cargo and crew capacity than SLS plus Orion. Where Orion can carry four crew, for instance, SpaceX claims Starship will one day carry up to 100 people into space.

Laura Seward Forczyk, the founder of space consulting firm Astralytical, previously told Inverse that Starship could theoretically launch NASA astronauts, carry them to the Moon, land them, and return them to Earth using just one vehicle, rather than using SLS, Orion, and Gateway. It’s possible that SLS eventually fades away in favor of the powerful and efficient Starship.

When will Starship launch?

So far, no version of Starship has launched to orbit, a somewhat critical test of the whole enterprise. SpaceX is targeting March 2022 as the first orbital test flight for Starship and the Super Heavy booster combo.