A more in-depth take a look at SpaceX’s Mars plan

Despite assembly all targets of the tenth Starship take a look at in August, SpaceX’s purpose of sending the primary Starships towards Mars this decade should still be out of attain. Jon Kelvey examines the proposed plan and the required applied sciences.

Over the years, Elon Musk has regularly revised his aspirational targets for SpaceX touchdown an unoccupied craft on the floor of Mars. In a 2016 discuss earlier than the International Astronautical Congress, he proposed touchdown a variant of SpaceX’s Dragon capsule by 2018, solely to shift a 12 months later and counsel the still-nascent Starship may contact down on the purple planet in 2022.

“I feel fairly confident that we can complete the ship and be ready for a launch in about five years,” he advised 2017 IAC attendees, which may have paved the best way for touchdown two crewed Starships on Mars by 2024. 

He shifted that focus on but once more in May, during a talk at SpaceX’s Starbase facility in Texas. But this time he gave extra particulars, describing the broad outlines of a step-by-step method for touchdown the primary people as quickly as 2029.

Five uncrewed Starships would carry off in 2026, the subsequent time the orbits of Earth and Mars are aligned. If all goes effectively, the craft would contact down on Mars in 2027, carrying an unspecified variety of the bipedal Optimus robotic made by Musk’s electrical automobile firm, Tesla. Another 20 Starships would carry off in the course of the subsequent switch window in 2028. Most of them would carry extra Optimuses to arrange Martian floor infrastructure and survey for sources, akin to water ice, however no less than one of many Starships would carry an unspecified variety of human passengers.

Plans then name for steadily growing the variety of flights each 26 months, in every subsequent launch alternative: 100 Starships in 2031, 500 in 2033, working as much as the eventual goal of “1,000 or 2,000 ships per Mars rendezvous,” Musk stated, with every crewed Starship carrying 100 to 200 passengers.

The normal plan is sound, in line with the ten specialists I spoke with for this piece, a number of of whom have been retired NASA staff who oversaw earlier Mars missions and contributed to the company’s plans for sending its personal astronauts to the purple planet.

“I like it. I like it a lot,” says Robert Moses, a retired aerospace engineer from NASA’s Langley Research Center in Virginia. Like many I spoke with, Moses in contrast the SpaceX structure favorably to NASA’s newest reference mission, although SpaceX’s plan contains tons of extra spacecraft and crew. “He’s checking all the boxes here that I would like to see checked.” 

What’s much less sure is whether or not SpaceX can follow the launch targets. Even Musk acknowledges that 2026 is bold, tweeting in early August that it was “more likely” the primary uncrewed Starships would launch “in ~3.5 years, next flight ~5.5 years with humans.”

That could be OK, Moses says, since pushing the primary uncrewed missions to 2028 “still gives him one more opportunity before 2033 to throw everything possible over to Mars.”

But maybe of biggest concern to Moses and the opposite specialists are the quite a few technical challenges SpaceX nonetheless wants to handle — a lot of which have by no means been demonstrated by any group — to make sure a profitable Mars transit and floor operations, any of which may flip right into a mission-swallowing morass. My emails to SpaceX requesting remark went unanswered, so for this report I drew on public paperwork and remarks by Musk and different executives describing the Mars plan.

Reaching orbit

For SpaceX’s plan to work, the behemoth Starship-Super Heavy design should attain orbit as reliably as the corporate’s Falcon 9 workhorse, which in July logged its five hundredth flight. For each autos, SpaceX has touted an iterative design method during which the designs are incrementally refined between a sequence of speedy flight checks. But with Starship, SpaceX might have reached the boundaries of this “build a little, test a little, fail a little” technique, says Scott Hubbard, former director of NASA’s Ames Research Center and now director emeritus of the Stanford Center of Excellence for Commercial Space Transportation.

With Falcon, “there was a distinct improvement from flight to flight, until it’s now 150 flights or something without a problem,” he says. “Starship is nowhere near that at this point.”

Starship has by no means reached orbit; as a substitute, SpaceX has adopted a suborbital trajectory for the ten built-in flight checks carried out to this point, during which the higher levels have been despatched towards managed splashdowns within the Indian Ocean. The most up-to-date Starship take a look at, carried out in August, was the primary to outlive the punishing trek by the environment and splash down intact since late 2024, ending a streak of failures that included three Starships exploding in flight and one other exploding on the bottom throughout a June static fireplace take a look at.

Once Starship reaches Earth orbit, the subsequent problem will likely be docking with a number of “tankers” to fill its tanks with the 933 metric tons of liquid oxygen and 267 metric tons of liquid methane required to achieve Mars. A full load of propellant is crucial for lowering the transit time to 3 to 4 months, in line with Moses, in order to reduce how lengthy the human crews are uncovered to hazardous galactic cosmic radiation.

As needed as it’s, that refueling course of entails lots of logistics. “Starship needs 1,200 tons of propellant, and you’ve got a tanker that takes 100 tons at a time,” says Donald Rapp, a chemical engineer and advisor for NASA’s Jet Propulsion Laboratory for the Mars 2020 mission. That works out to 12 tanker launches to gasoline every Mars-bound Starship.

By these calculations, the 5 Starships leaving Earth in 2026 would require 60 tanker launches, says Rapp — ample alternative to check Murphy’s legislation, and an unprecedented stress take a look at of floor infrastructure.

That refueling maneuver itself is sound in concept, however there may be scant proof from observe. “There’s been a lot of models that have been developed,” says William Notardonato, a former NASA engineer and now CEO of Eta Space, a Rockledge, Florida, firm growing spacecraft for small-scale cryogenic propellant transfers in Earth orbit. But “nobody’s really been able to accurately anchor those models in flight data using a real cryogenic fluid.”

SpaceX transferred an undisclosed quantity of liquid oxygen between two inner tanks throughout a 2024 Starship take a look at, however nobody has but tried giant switch between two spacecraft. SpaceX plans to take action in 2026, per Musk, pitting SpaceX’s iterative design philosophy straight towards his bold timeline.

Among the elements to be decided in these checks is how a lot of the cryogenic propellant will evaporate upon first contact with the comparatively heat traces and empty tanks, in line with Notardonato. These “parasitic” losses pose one other problem for SpaceX: Lose an excessive amount of, and extra tanker launches may very well be required to gasoline up every Starship.

“You might have to launch one or two more refueling missions,” Notardonato says, “and nobody really knows how many refueling missions they’re going to have to do yet.”

Sticking the touchdown

Transit to Mars is simply step one of the journey. Once arriving in orbit, Starship should navigate entry, descent and touchdown. At 200 tons or extra, relying on payload, every Starship will likely be 200 instances extra huge than any craft that’s beforehand touched down, and subsequently requires a unique touchdown approach.

NASA spacecraft, together with the Perseverance rover, relied on single-use, ablative warmth shields to guard them in the course of the searing journey to the floor. By distinction, every Starship will depend upon a reusable warmth protect fabricated from hexagonal metallic-ceramic tiles for aerobraking within the Martian environment, utilizing friction to sluggish from 7.5 kilometers per second to round 1 kilometer per second.

“No one has ever developed a truly reusable orbital heat shield,” Musk stated in his May discuss. He famous that the skinny, carbon dioxide-rich environment of Mars, when ionized by the warmth of entry, generates extra free oxygen than Earth’s, which is able to eat away at protect tiles.

For Flight 10, SpaceX technicians put in tiles of varied compositions on totally different elements of the Starship higher stage, and the automobile’s reentry trajectory was “designed to intentionally stress the structural limits of the rear flaps” that may steer the automobile by the environment, SpaceX stated on its web site.

Then there’s the touchdown itself, which Hubbard predicts may pose an excellent larger problem as a result of Starship’s top of 52 meters. There’s a cause, he says, that NASA utilized parachutes and airbag-cushioned landings for a lot of of its landers and rovers, which have been comparatively squat autos with low facilities of gravity.

“Landing vertically looks very slick,” Hubbard says, “but look at the failures to land on the moon with a tall, slender vehicle.” He pointed to the Odysseus lander constructed by Intuitive Machines that “tipped right over” in early 2024 after a laser altimeter failure led it to land sooner and on a steeper slope on the lunar floor than anticipated.

“A lower center of gravity would always add stability,” Hubbard advised me in a follow-up e mail, noting that there aren’t any flat, well-prepared touchdown pads awaiting the primary Starships touchdown on the moon or Mars.

Establishing the Mars metropolis

Once the primary Starships attain Mars, the job of organising camp for human astronauts will fall to Optimus. The bipedal humanoids are to put in energy crops and different infrastructure, in addition to scout for sources akin to water ice. In May, Musk confirmed a picture of Optimus ironworkers constructing the Empire State Building, sitting on a girder consuming lunch.

Hubbard, who in 2000 grew to become NASA’s first Mars Program director, has doubts Optimus can do the job. He notes that lots of the demonstration movies present the robots in well-prepared environments — a pointy distinction to the barren Martian floor. Tesla has additionally been criticized over movies it’s shared of Optimuses seemingly cooking or interacting with folks at occasions, the place it later turned out the robots have been no less than partially distant managed.

Instead, “Why not take a whole bunch of rovers of a design you’re pretty sure will work?” Hubbard asks. The six-wheel design used for Perseverance and Curiosity has confirmed “capable of adapting to almost any kind of surface with enough clearance.”

Another possibility is to take to the air. Optimus is “inferior as an exploration platform to a scaled-up Ingenuity helicopter, which can fly,” says Robert Zubrin, an aerospace engineer and longtime Mars mission optimist, referring to the small rotorcraft that rode together with Perseverance and accomplished 72 flights in three years.

Given Starship’s touted 100-metric-ton payload capability, Zubrin believes that SpaceX may ship a military of rovers and rotorcraft, “like the troops coming off the landing craft at Normandy Beach,” he says, and conduct extra Mars science in two years than NASA has been in a position to in a long time. 

Neither Musk’s remarks nor SpaceX’s public supplies point out to what extent science elements into the targets for the early Mars landings. But Zubrin and different specialists agree that if Musk is to realize the self-sustaining metropolis of his desires, some type of robotic automation will likely be important.

NASA’s planning has lengthy assumed in situ useful resource utilization will likely be key to human Mars missions. The newest idea, Design Reference Architecture 5 (DRA-5), requires pre-positioning strong oxide electrolysis cells on Mars forward of astronauts’ arrival. Essentially a gasoline cell run in reverse, strong oxide electrolysis cells would break up atmospheric carbon dioxide into carbon monoxide and oxygen through electrical present.

Operating over 16 months, the electrolysis unit would produce 25 tons of liquid oxygen to energy the Mars Ascent Vehicle, together with 6 tons of liquid methane propellant that the astronauts would have introduced from Earth. Once fueled, this rocket would return astronauts to Earth on the finish of their mission.

NASA in 2021 proved this normal idea with the MOXIE experiment aboard the Perseverance rover, which produced 122 grams of oxygen over 30 months. Scaling MOXIE as much as make tons of liquid oxygen wouldn’t be troublesome, in line with Michael Hecht, the experiment’s principal investigator, nevertheless it wouldn’t come free.

“It takes a lot of energy to pull a carbon dioxide molecule apart,” he says — a couple of kilowatt per kilogram of oxygen produced.

In NASA’s plan, a nuclear fission reactor can be required to provide the 25 kilowatts of energy essential to create 25 tons of liquid oxygen. By Hecht’s calculations, Starship would want extra: roughly 600 kW to provide 600 tons of liquid oxygen for every automobile returning to Earth, if stuffed to capability.

Unlike NASA, SpaceX plans to depend on solar energy — “a lot of solar power,” Musk has stated, although he hasn’t elaborated on the mechanism for gathering and storing that power.

The approach may work, Hecht says, however once more, at a price: “The solar arrays are going to be more massive, certainly, than the reactors would be,” Hecht says. NASA’s DRA-5 estimated that producing 25 tons of liquid oxygen would require round 1,450 sq. meters of photo voltaic panels, placing the potential SpaceX equal at 38,400 sq. meters — about seven American soccer fields.

That’s lots of infrastructure for Optimus to arrange and preserve forward of human crews. But the choice — sending people to set issues up with out already having propellant saved and prepared for a return mission — “strikes me as dangerous beyond belief,” Hubbard says.

And except SpaceX additionally needs to fly lots of further liquid methane to Mars, it might want to make the most of a unique course of than MOXIE to create that methane on Mars, in line with Rapp: the Sabatier response, which makes use of electrical energy and carbon dioxide, but in addition requires water. The primary premise is to run an electrical present by the water to separate it into oxygen and hydrogen. Take the hydrogen and react it with carbon dioxide at round 300 levels Celsius to acquire methane and extra water, with the water fed again into the loop.

“It’s a very simple process,” Rapp says, “It’s almost risk free.”

But SpaceX would want to search out lots of water on Mars, he notes, and whereas orbital information suggests ample subsurface water might exist, there’s no concrete proof but. But let’s assume there may be 15% water in Martian regolith, he says, based mostly on a February paper within the journal IgMin Research. That means to create 5 tons of propellants per day, Optimus or another equipment would want to course of 33 tons of floor materials.

The highway forward

All that taken collectively, the percentages {that a} Starship will launch to Mars in 2026 is almost unattainable, Zubrin says.

“The notion they’re going to land a Starship on Mars that they launch next year is not true. If you disagree, I’ll bet you $1,000.”

He agrees with Moses that 2028 appears extra possible, however he additionally warned towards ready too lengthy, lest the Trump administration or Congress change its priorities, inflicting SpaceX to lose momentum.

“I don’t think Apollo could have been accomplished in a 20-year schedule,” he says. “It had to be accomplished on an eight-year schedule,” or else the political and financial circumstances that led then-President Richard Nixon to cancel this system after the Apollo 17 touchdown may have overtaken this system sooner.

Politics could be the greatest unknown of all relating to SpaceX’s plans. Between Musk’s public falling-out with President Donald Trump and the proposed cuts to NASA funding, it’s not clear there’s authorities help for the public-private, NASA-SpaceX partnership that the majority specialists I spoke with consider is critical to realize a human Mars mission.

“A lot of people take it as a given that it will work, and there’s really no guarantee,” says Casey Dreier, chief of area coverage on the Planetary Society, about SpaceX, Starship and Mars. But “you never want to bet against SpaceX as a company, because they are, frankly, incredibly capable.”

Opening picture: A SpaceX Starship plunges by the Martian environment on this illustration. Credit: SpaceX