Moon & Mars Mondays · your week on the Moon and Mars

From The Decisional Pass

Every machine we have ever put on the surface of Mars got there inside something else. Airbags, a lander, a skycrane. Ingenuity rode down bolted to Perseverance's belly and spent its first days on Mars as cargo.

Last Thursday NASA put three helicopters under contract that skip all of that. They don't ride a lander down. They are the landing.

"They're going to get tossed overboard"

On August 27, JPL awarded AeroVironment a contract to co-design and co-build three Mars helicopters for a mission called SkyFall. Jeff Foust had the details at SpaceNews two days later. The value wasn't disclosed.

Here's the maneuver the thing is named after. The entry capsule comes in, rides out the hot part of entry, and then, still descending, opens up and throws the helicopters out. Each one takes a position fix from the capsule and from its own cameras, falls, pulls up, spools to a hover, and sets itself down. No parachute of its own. No lander. No skycrane.

Will Pomerantz, who runs space ventures at AeroVironment, put it plainly: they're going to get tossed overboard.

I've spent a lot of time thinking about entry, descent and landing as a mass problem. On Mars the landing system is the thing that eats your budget. Curiosity's descent stage ran about 1,370 kg fuelled, against 899 kg of rover, and the full entry, descent and landing stack came to 2,401 kg. The gear that put the rover down outweighed the rover almost three to one. Every kilogram of descent stage is a kilogram of science you didn't bring, and it's hardware you have to qualify for a job it performs exactly once, on another planet, with nobody watching in real time.

SkyFall's answer is to make the landing gear the payload. The rotors you need to fly on Mars are the same rotors you need to land on Mars, so stop paying for both.

Not an Ingenuity rerun

These are bigger. Each runs 2.5 to 2.7 kg against Ingenuity's 1.8 kg, with enlarged rotors to haul the extra mass. That mass buys instruments Ingenuity never carried:

• a ground-penetrating radar with a flexible, fabric antenna, reading 12 to 60 cm down
• high-resolution imagers
• a dosimeter
• temperature sensors

They can cover more than a kilometre per flight, talk straight to Mars relay orbiters without a rover in the middle, and fly in pairs for stereo imaging. The job is hunting near-surface water ice and scouting ground for future crewed landings. Arcadia Planitia is the design reference case, which tracks. It's low, flat, midlatitude, and long suspected of holding shallow ice.

Ingenuity was a demo that had to ask a rover for permission. This is a survey.

The ride is the other headline

SkyFall flies as a payload on Space Reactor-1 Freedom, which is a whole story by itself. Roughly 12,000 kg. A fission reactor burning high-assay low-enriched uranium, feeding a 20-kilowatt closed Brayton power loop, driving a 12-kilowatt Hall thruster. NASA and the Department of Energy are targeting late 2028 and that year's Mars window.

If it flies, it's the first fission-powered interplanetary spacecraft anybody has flown. The reactor also doubles as a rehearsal for surface power at the Moon Base. Which means the helicopters are hitching a ride on a technology demonstration, and that's a slightly nervous seat to be sitting in. Worth remembering as 2028 gets closer.

Meanwhile, in High Bay 2

The Moon side of the week was quieter and a lot more physical.

On August 24, technicians at Kennedy started lowering RS-25 engines into the Artemis III core stage of the SLS. Four of them: E2054, E2057, E2048, E2052. Each weighs about 7,700 pounds and makes close to 500,000 pounds of thrust, and together they drink roughly 1,500 gallons a second for more than eight minutes.

E2048 is the one I keep coming back to. It flew on Atlantis for STS-129, and on Discovery for STS-95, in 1998. That engine is older than plenty of the people who'll be watching it launch.

Elsewhere on the vehicle: booster stacking is past halfway, started in early July. Orion's crew and service modules got their umbilicals mated and took first integrated power. Randy Bresnik, Andre Douglas, Frank Rubio and ESA's Luca Parmitano, named to the crew on June 9, are running water survival and sims. Launch is targeted for next year.

One kilometre up

Small last item. On August 26, JPL noted that Curiosity has now gained one vertical kilometre since it left the floor of Gale Crater. Fourteen years, one kilometre of elevation.

The panorama marking it is 323 Mastcam frames shot on August 1 and 2, sols 4,972 and 4,973, looking out across a valley called Valle Grande with the crater floor going hazy in the summer dust. Mount Sharp is five kilometres tall. Curiosity has been climbing it since 2014 and is a fifth of the way up.

Slow is a strategy. Ask anybody who's driven one of these.

References

• NASA and AeroVironment advance work on SkyFall Mars helicopters — SpaceNews, Jeff Foust, 29 August 2026
• Space Reactor-1 Freedom mission page — NASA, accessed 31 August 2026
• NASA Starts Artemis III Engine Install; Boosters, Crew Training Advance — NASA, 27 August 2026
• Curiosity Reaches 1-Kilometer Elevation Gain — NASA Science, 26 August 2026
• Mars Science Laboratory mission data, EDL and rover masses — Gunter's Space Page, accessed 31 August 2026

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