Landing large lunar landers such as SpaceX’s Starship HLS and Blue Origin’s Blue Moon is going to be risky until we better understand and can account for plume surface interactions. How the gas from rocket engines interacts with regolith will determine how we proceed with large landers and permanent infrastructure on the Moon or Mars. From NASA’s Artemis III to human settlements on Mars, plume effects and surface science need to be well understood for landing safely.
Thumbnail background image credit: SpaceX
In-video image and video credit: SpaceX, Blue Origin, NASA, UCF, Masten Space Systems / Astrobotic, ICON
Lunar Surface Science Workshop LSSW 25: Plume Surface Interactions playlist: https://www.youtube.com/playlist?list=PLKg3EyXg9SjrQvyf8HjZtQFJeTeWfQ9b8
NASA: Plume Surface Interaction (PSI): https://www.nasa.gov/directorates/stmd/plume-surface-interaction-psi/
UCF: The Science of Plume Effects: https://sciences.ucf.edu/class/landing-team/the-science-of-plume-effects/
The Damage to Lunar Orbiting Spacecraft Caused by the Ejecta of Lunar Landers: https://arxiv.org/abs/2305.12234
Grow your business in space: https://astralytical.com/
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That was interesting
How much programming do you do when modelling?
I’ve never done much in ABAQUS…
Thanks for the nerd invitation on the important subject of plume interaction Laura. Love it! This video has taught me a lot and you've explained the principles very well.
Lunar SS 5000t landing mass?
You could use a very high intensity short duration xray source to fuse the surface into the lunar equivalent of trinitite.
I was under the impression thatSpaceX's Luna lander had its Landing rockets place HIGH up the hull near the nose, To negate the Plume effect. Any thoughts?
Looks like we need anti-gravity mechanisms to address this issue and we need it sooner than later 😉
Laura,
Great video! Does anyone know if China has conducted similar studies? They have really ambitious lunar plans for the2030s and beyond, which will require frequent flights.
Starship HLS won't use it's Raptor Engines to land on the Moon, it instead uses Draco thrusters near the nose cone to try and avoid any cratering.
You can't put anything in stable orbit by firing it from the surface. All such orbits will intersect with the surface.
Stuff could be kicked off the planet, which might put it in orbit around the earth, but it's unlikely. The difference between escaping the moon and escaping the earth-moon system is small.
I wonder if anyone has thought of sintering lunar dust using a laser in orbit around the moon. (Is lunar-stationary orbit a thing?) There's no atmosphere to interfere with the laser beam or convect heat away from the work site. You can make many landing sites without needing fuel for landing or for moving around on the lunar surface.
Its the most Stupid Desing for Landing , yuo will see
However SpaceX will do it, this problem would only exist for few years. Just look at China's Mars landing. They were propulsive landing, digging up a decent hole in the landing site they were in. Whatever SpaceX will do, all of it will be ruined in few years when China will arrive on the moon, putting a lot of debris into orbit. At some point, all spaceships trying to land on the moon, or space stations orbiting Moon will just have to have some kind of armor to defend from bigger pieces of regolith, and at that point, SpaceX will have landing pads on the moon anyway, which will completely eliminate the problem of kicking up dust.
I did not quite believe you about dust in orbit so I looked up the numbers and yes, space x rocket exhaust exceeds lunar orbital velocity. That's gonna get messy.
That’s a lot of different…
21.35 metric tons Blue Moon Mk1
16.0 metric tons Blue Moon Mk2
50.0 metric tons Starship Human Lander
Lauren, I would draw your attention to the time of 5.25 in Marcus House's video on the Starship HLS. He goes into not using the Raptors for the Luna landing to avoid blowing up dust.
https://youtu.be/e4Ymh5KCgi0?si=izcmtcILthELNs4e
Would gas molecules orbit like dust particles? How exactly do gas atoms or molecules behave in a vacuum? It seems to me molecules should have the same kinematics as very tiny particles, but I know nothing.
Unless the moons surface is flat, that tall a rocket is going to fall over!
There's a reason the original moon landers were so low and wide.
Surprised at your failure to mention the design feature of the lunar Starship that is meant to avoid cratering and other nozzle blast effects, namely the thrusters high on the cylinder that are angled out ~45° for that last leg of the descent
Even from a hundred meters away, the Raptor engines will exert a lot of force on the moon's surface. There's no air to interact with and decelerate the gas. Lots of supersonic particles will fly in every direction, including upwards. Again, there's no air and low gravity so the particles that head upwards are going to hit the engines with full velocity. After the regolith has been carved by the Raptors, the resulting surface will be unpredictable. It may get flattened. It may be uneven. Then Starship attempts to land and not fall over but its all up to chance.
The difference with other landers is that they generally have a lower center of mass relative to their footprint, so they're harder to tip. Plus if you want more safety then you need to either have the ability to hover and rotate, just sweeping the regolith sideways, or ideally you need a lander where the engines can be gimballed sideways so as to push the regolith sideways. Starship doesn't have this feature.
And Mars is entirely different. Starship will be landing with its Raptor engines pointed directly at the ground. Point blank range. Let's see how big a crater that will create and how much damage is done to the engines/lower tankage. If it doesn't tip over, its also likely to suffer critical damage and be non reusable.
the fan fictions at 5:06 is telling. Starship will blast the regolith with the full force of it's engines. The particles from the regolith head out at supersonic velocities. There is low gravity and very little air to slow it down. Therefore a lethal rain of bullets will hit any structures within many kilometers of the landing/launch. Even if you survive the landing and the preceding 5 or 6 gs of deceleration (likely debilitating) you're going to have to then travel a long distance to your base.
The thin Mars atmosphere tends to contain the plume of then engines and direct more of it downwards? I'm not sure that's of much consequence if you're landing something with mega Newton class engines and they're going to be meters from the surface. Note that the forces will even higher after Starship hypothetically refuels.
On the issue of a landing pad. We're talking hundreds of tonnes (Earth weight force equivalent) for a Starship ascent. You're talking dozens if not hundreds of tonnes of steel for the pad. And it will erode. So a massive robotic mission for each landing pad, using expendable vehicles.
ADDITIONAL INFO: Thank you to all who pointed out that Starship will be landing with angled thrusters, not Raptor engines. I had forgotten this detail. It will change the physics, but not completely eliminate the concerns.
From what I seen of computer graphics regarding the starship, the landing thrusters are way up the ships fuselage not at the bottom it doesn't use the primary engines for landing. So regolith isn't going to be as big a factor in landing. Now take off there will probably be dust kicked up because the main engines are more than likely going to be used. I think spacex took regolith into consideration when designing the craft to land on the moon that's why the landing thrusters are way up the fuselage and not using main engines for landing.
As someone who couldn't afford to go to school to learn about these things I am so glad there are videos like this available. I'm not smart, but I am curious. 😂
Starship HLS according to the artwork has the engines high up to mitigate the problem.
I'd love to hear more about how a Lunar lander might create an "instant" landing pad just prior to landing, as you mention at about 5:50 into the video. Would a quick-drying glue-like substance or mesh be dropped onto the surface to stabilize and fix the regolith just before touch-down? I wonder if a scheme like this might be simpler than the extra landing thrusters that SpaceX is planning to install close to the top of the Starship HLS lander, to avoid the six Raptors at the bottom blasting regolith into Lunar orbit. Thank you, this was an excellent video.
It sounds as though some small experimental vehicles of various types need to be landed on a range of surfaces to clear up some of the issues. They need to match pressures, mass to rocket pressure ratios, &c.
Would the SkyCrane idea be applicable to this kind of landing? You might have to do it a bit differently, as you're trying to land a large cylinder in an upright position, but it might still work.
Longer term, a prepared pad, largely free of dust, would have major advantages. Not sure how completely dust-free you could make the pad area.
4:55 absolutely LOVE that you left this moment in your edit — as you said, very appropriate 🚀
Nice video, Laura! My company has a design for a landing pad manufacturing process.
I think the Viking landers had 18 small nozzle exhausts on its 3 landing engines.
Cool 😎 👍
A starship with a dry mass of 5 tonnes??? The 6 raptors on their own would be around twice that mass.
SpaceX lander is also closer to 1000 tons (you said 5 but wrote 5000) altho I'm not trying to over analyze here just thought u may want to know