Why it's so challenging to land upright on the moon
nytimes.com
nytimes.com
I expect if astronauts aboard HLS lose their altimeter they'd have to abort the landing immediately -- to proceed without it would be the height of recklessness. But Odysseus had no abort-to-orbit capability so was committed to landing.
I have never once read about abort-to-orbit capability as a concept, let alone a requirement for Artemis HLS.
Here’s a 4 year old video detailing past abort systems and why Starship won’t have one: https://m.youtube.com/watch?v=v6lPMFgZU5Q
ATO was an abort mode [1] on the Shuttle program and is notably the only abort mode that was successfully used in the entire program, on STS-51f [2] . Challenger suffered an engine anomaly on liftoff that resulted in a lower orbit than was intended, but otherwise the mission went off without a hitch.
[1] https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes#Abor... [2] https://en.wikipedia.org/wiki/STS-51-F
Per the links: “A particularly significant enhancement was bailout capability. Unlike the ejection seat in a fighter plane, the shuttle had an inflight crew escape system[12] (ICES). The vehicle was put in a stable glide on autopilot, the hatch was blown, and the crew slid out a pole to clear the orbiter's left wing. They would then parachute to earth or the sea. […] Before the Challenger disaster, this almost happened on STS-51-F, when a single SSME failed at about T+345 seconds. […] A second SSME almost failed because of a spurious temperature reading; however, the engine shutdown was inhibited by a quick-thinking flight controller. If the second SSME had failed within about 69 seconds of the first, there would have been insufficient energy to cross the Atlantic. Without bailout capability, the entire crew would have been killed.“
Why is the naming scheme of shuttle launches so bad
I always wished it at least included the orbiter name in it. But I suppose the orbiter choice could change closer to actual launch.
STS-41B-ATL2
Ouch, shortly after they get standardized and consistent flight numbers, the shuttle program gets cancelled. I guess computer science doesn’t have a monopoly over the difficulty of naming things.
Apollo 14 had a piece of loose solder in the button triggering abort-to-orbit, so it occassionally triggered itself. This wasn't a problem en route to the moon, but the second the descent phase started it would have been a Poisson-timed bomb that would prevent the landing.
There was a bit of memory that could be set to ignore the state of the abort button (this bit was the reason the abort sequence wasn't triggered en route). The problem was this ignore bit was reset by the landing sequence (to allow aborting once landing started), and they did not believe the astronauts would be quick enough to set the bit again before the button shorted out and triggered the abort.
(Ignoring the abort button was fine because an abort could be triggered in the computer instead. Takes a little longer but was determined a better option than scrapping the mission.)
Don Eyles came up with a clever hack. Setting the program state to 71 ("abort in progress") happened to both allow descent to start and prevented the abort button from being effective. So this program state was keyed in just before descent.
The drawback was that it obviously put the computer in an invalid state so some things were not scheduled correctly but Eyles and colleages had figured out which things and the astronauts could start those processes manually.
Then once the computer was in a reasonable state again the ignore abort bit could be set and the program mode set correctly and it was as if nothing had happened.
This was basically a lawn-chair rocket for two which would utilise a disabled LEM's (lunar excursion module) fuel tanks, and would be hand-piloted without any guidance computer to an intercept orbit with the Apollo Command Module, with the hope that a rendezvous and crew transfer could occur within the four-hour window of space-suit oxygen supplies. Given that the CM's orbital period was two hours, this meant at best two chances for a successful intercept.
<https://en.wikipedia.org/wiki/Lunar_escape_systems>
(I'd run across this from the recently submitted MOOSE article, "Man out of space, easiest", a strap-a-foam-mattress-to-your-ass reentry concept: <https://en.wikipedia.org/wiki/MOOSE>.)
It does still leave the system without a means of aborting if the ship's main engines have trouble, although I suppose they do have a good bit of redundancy there.
I'm no expert, so this is a question to confirm my understanding: Starship does have a booster. So, doesn't that make it a dual stage?
https://www.zenger.news/2023/11/27/elon-musk-reveals-simple-...
Even if it's a bit more than doable by hand a ratchet jack should make short work of it.
Plus, you've got to get the whole jacking operation done without damaging any of your main or control thruster rockets, and without tipping past the upright point over to the other side, or just effectively rolling onto an adjacent side.
I wouldn't want to go on a craft where [jacking it back upright] was in the top ten on the list of recovery options to get home.
For a counter, I wouldn't want to be on a lander so fragile[0] that being manipulated upright is infeasible. Something will go wrong, maybe not on that lander, but when it does go wrong it'll have to get duct taped together.
[0]Not just mechanically, but in terms of operation scope. Planning that everything must go perfectly or people die is a recipe for the latter.
(And yes, I've done a fair amount of wrangling vehicles, gear, etc. in snow, dirt, mud, & rocks, and eventually it can often be gotten out. But on a different planet/moon, it really should be not be anything close to a primary option. OTOH, if it's got a set of 6+ pop-out lever-legs to upright itself, tested, etc., that's a different solution)
For comparison, a craft built for earth launch mass fractions probably wouldn't survive falling over in the first place - when that happened to a Falcon 9, the whole rocket simply exploded.
I don't think that is an assumption you can make. In the worst case scenario the lander lands on the door. In which case the only way to disembark is to lift the lander.
In addition to the obvious, it should be taken into account that the absence of atmosphere makes very difficult to assess distance and scale. Videos of approach seem like a fractal browser.
With both Crew Dragon and Starship, there will have been _many_ successful missions involving un-crewed variants of the spacecraft (Falcon 9 and Cargo Dragon were both well-proven systems before crew was a possibility).
The advantage of SpaceX's Starship--and the reason NASA chose it for the first HLS--is that it has an insane mass budget. It's literally designed to land 100 people on the surface of Mars (TBD whether it will ever meet that goal, but that's the design point).
Starship is so hilariously large that there's enough mass budget to solve almost any problem.
https://www.nasa.gov/history/diagrams/apollo.html
1: https://www.nasa.gov/wp-content/uploads/static/history/diagr...
That was a concept called "Earth Orbit Rendezvous" which was discarded early on during the Apollo program in favor of "Lunar Orbit Rendezvous" where the Command and Service Module (CSM) and the Lunar Module (LM) was launched on a single Saturn V. You can see this in the movie Apollo 13.
What? Have you watched any Apollo mission media ever?
Watch Apollo 13 the movie at least and get the most basics of facts straight.
Starship gets refueled in orbit (by a fleet of Saturn V-class rockets). A Saturn V could put about 8 metric tons on the lunar surface. With refueling, Starship can land 100 metric tons on the moon.
SpaceX plans to stretch the second stage to increase fuel carrying capacity for tanker flights, so the actual number is TBD until both the revised Starship and its engines (Raptor 3) are built and tested.
It's the refueling that potentially gets a huge usable payload to the Moon. A second Starship whose only payload is fuel would launch with the first and they'd rendezvous and transfer fuel. Ostensibly if something went wrong with the refuel rendezvous the payload (or personnel) carrier would still be able to abort back to Earth.
> Symmetrically, almost all problems can be solved by increasing the mass budget: more fuel to loiter longer, redundant systems, etc...Starship is so hilariously large that there's enough mass budget to solve almost any problem.
Also incorrect. Mass budget does not change fundamental Newtonian physics, nor does it alter the issue of instability caused by a high center of mass. The engineers at SpaceX are very smart and I'm sure they're hard at work trying to engineer out this solution, but it's a bit like saying that you can prevent a car from rolling over if you make it heavy and powerful enough. Sure, but that causes problems and challenges of its own. It would have been easier to engineer the car to have a lower center of mass, i.e. it would be easier to land on the moon with a lander that had its mass spread out over a larger surface area and didn't have an angular moment of inertia significant enough to where topple was a concern -- like the Dynetics or BO proposals.
The size of the ship solves some problems. Illustrations depict landing gear taller than a person, which means small rocks and holes are less of an issue.
... A surprisingly kerbal solution. Wouldn't the engines be firing to control the vertical speed though? Otherwise it'll end up lithobraking at hundreds of meters per second instead of gently touching down at 1 or 2 m/s. At least that's what happens to me if I don't burn retrograde.
Lets not go overboard with the claims we make about government contracting.
> instability caused by a high center of mass
The center of mass is low as the engines are by far the heavies part of the rocket.
That's more or less true though?
There's no need to debate semantics when the criteria NASA used are very clearly laid out in the source selection statement [0]. It is plain that SpaceX was selected because it met the technical requirements, provided the best value for the government, and fit within NASA's budget for the program (indeed, was the only proposal that did so).
There's also the GAO report which more or less says the same thing with more detail and confirms NASA's judgement [1].
And, I'm no expert on contracting, but it is my understanding that "meeting requirements" and "achieving the best value" are criteria that are supposed to underpin all government contracts, not something unique to that particular contract.
[0]: https://www.nasa.gov/wp-content/uploads/2019/04/option-a-sou...
No it isn't. It was done correctly in this case. But if you study the history of NASA and DoD contracting the idea that they always perfectly evaluate is nonsense.
Literally during the very selection process you talk about, a NASA employ was fired because he tried to give Boeing an unfair advantage. How many times in history was this not caught?
Often the selection documents aren't public. The idea that lobbying and politics have no influence of government selection is just being naive.
Just recently in commercial Crew Starliner was selected over Dreamchaser. Despite Dreamchaser being considerably cheaper, and offering much more utility. NASA just assumed that Starliner would be done fast because it was Boeing. The reality many believe without Boeing CommercialCrew would have failed.
We can go threw history, as far back as you like. The Supersonic transport, you basically had Boeing proposing an absurdly complex incredibly ambitious design, despite being the company with the least amount of experience. They were selected despite the other projects being much more reasonable and much cheaper.
These can often be at odds. It is surprisingly difficult to award a govt contract under the guise that it provides better value (and there are specific contract mechanisms to that effect). However, from a contracting officer's perspective, it can be riskier (to them personally, even if it's less risky to the taxpayer). The govt also has other goals, like reducing the risk of putting all their eggs into one contractor's basket. All this to say, there are enough competing aspects to undermine a claim that "value" is baked into the primary goals of every contract.
It's kind of weird that someone would select a launch architecture that is meant to go to Mars and whose company CEO thinks the moon is a waste of time for a moon mission. Yeah sure, SpaceX is going to Mars, but are they going to the moon?
Considering the massive delays at SpaceX, their Starship will turn into another SLS type boondoggle. At the current rate of development, it is not obvious that the schedule of Artemis 3 is going to be meaningfully ahead of Artemis 5. If it takes Blue Origin 2-3 years to launch their New Glenn rocket, then all they have to do is build the lander and they are pretty much set, because it only takes 3 New Glenn rockets, which could launch simultaneously to minimize time in orbit and thereby reduce boil off. Reusability is a nice to have cost optimization for Blue Origin. When it comes to the Artemis 3 architecture, it is impossible to stay under $1 billion per launch without some form of reusability.
Also, it's ironic you're saying that BO could do it faster, their lander is basically just a Hydrogen fueled Starship.
a) for launch you want your rocket to be slender and tall. For a stable landing you want your vehicle to be broad and flat.
b) The engine is at the bottom (moon-wards), by definition. The fuel is above the engine. As you land, the fuel tank depletes significantly which shifts the center of mass towards the top of the vehicle which makes it less stable.
c) The lunar (mun-ar?) surface is really uneven and gravity is low. What you want to land is a steamroller but what you actually have is a springy, ultra-light, top-heavy contraption that's more likely to bounce off of then to flatten moon rocks.
Unless the rest of the vehicle's mass (all the other equipment, and crew if it is a manned mission) has more mass than the engine & landing apparatus of course, which I think (caveat: no deep thinking involved here) is likely for manned missions but less so for others? I'm assuming the mission mass is above the fuel (having the fuel on top would presumably be less safe/reliable/practical/other).
The Apollo's "lunar module descent engine" weighs a mere 180 KG vs the approx. 4200 KG of the rest of the craft (dry mass). Just the fuel for the descent is then roughly 8000 KG.
Obviously, landing on the moon is possible but I do think that the inherent requirement to have engine(s) and fuel tanks below the payload makes landing in a vacuum a bit of a challenge.
Plus, since the engine is typically one of the heaviest parts , and the lander isn't a two-part design like Apollo, the fuel tanks are mostly empty upon landing, and therefore the center of mass is low due to the engine.
In re "mun-ar", maybe you meant "monthly".
Etymology of "lunar": Middle English, from Latin lunaris, from luna moon; akin to Latin lucēre to shine [0]
Etymology of "moon": Middle English mone, from Old English mōna; akin to Old High German māno moon, Latin mensis month, Greek mēn month, mēnē moon [1]
You the Anglophones have this tendency to forget about the noble origins of your languages, just to reinvent it badly ;-)
[0] https://www.merriam-webster.com/dictionary/lunar [1] https://www.merriam-webster.com/dictionary/moon
Mexicans forgetting about Latin is even worse than native English speaker doing the same!
Genuinely asking because I think I might learn something: wouldn't a depleting fuel tank above the engines shift the center of mass toward the bottom of the vehicle?
This is especially the case with things like landers and geostationary satellites, where you want as much fuel as you can afford for station keeping, to keep the satellite operable for as long as possible.
Half of Nova-C's mass was fuel (~900kg), payload was 100kg. Starship's payload is ~100t, dry mass is ~150-200t but fuel mass is ~1200t.
"The Apollo's "lunar module descent engine" weighs a mere 180 KG vs the approx. 4200 KG of the rest of the craft (dry mass). Just the fuel for the descent is then roughly 8000 KG."
Like the article said in the last line, the margin of error is only manageable if all the systems are functioning correctly. The argument over the height of the lander is as nonsensical as arguing over any of the thousands of other design decisions. Second guessing literal rocket scientists is silly.
The lander was designed as a whole, any single change - redundant systems, extendible legs, etc., etc. - would have required other changes due to weight or space constraints, requiring other changes, ad nauseum.
The specific thing that killed this landing is a failure in quality control/checklists which if done better would have ensured all the systems operated correctly and a successful landing.
For that matter, the Space 1999 "Eagle" for the same reason, just good design. https://news.ycombinator.com/item?id=39484015
If a human lander tips over for any reason, that could be disastrous.
> Of particular concern is the significant weakness within Dynetics’ proposal under Technical Area of Focus 1, Technical Design Concept, due to the SEP’s finding that Dynetics’ current mass estimate for its DAE far exceeds its current mass allocation; plainly stated, Dynetics’ proposal evidences a substantial negative mass allocation. This negative value, as opposed to positive reserves that could protect against mass increases at this phase of Dynetics’ development cycle, is disconcerting insofar as it calls into question the feasibility of Dynetics’ mission architecture and its ability to successfully close its mission as proposed.
You can read NASA’s full thoughts on that link. But the basics are, they thought there were good ideas, but they weren’t comfortable picking a lander that went far above the allotted budget, while the team who made the lander wasn’t able to come up with a way that it would work yet.
[1] https://www3.nasa.gov/sites/default/files/atoms/files/option...
“Intuition that’s based on Earth is now a liability,” Dr. Metzger said. He gave the example of trying to push over the refrigerator in your kitchen. “It’s so heavy that a slight push is not going to push it over.” But you replace it with a piece of Styrofoam in the shape of a refrigerator, mimicking the weight of a real refrigerator in lunar gravity, “then a very light push will push it over.”
When landing, the horizontal velocity (side drifting) should be very very minimal, otherwise it would topple over.
Doesn't help on the moon, though, where the surface is soft, and may contain boulders.
What if airbags inflated around the lander? The external shape of the lander-with-inflated-airbags and the internal weight distribution could make it self-righting, while shielding the external fixtures and the hull.
Just throwing ideas around and role-playing spacecraft designer.
https://en.m.wikipedia.org/wiki/Sky_crane_(landing_system)#/...
https://www.space.com/jaxa-slim-moon-lander-lev-2-ball-robot
There's also the method of dropping a ball of airbags that deflate and detach, so you aren't limited to being a ball.
I assume it's more efficient and versatile (lots of tools on these things) to not be a ball.
You basically want a small truck loaded with equipment and a solar panel on top.
I guess the concept would be to surround the motors in a electrostatic force that results in propulsive removal of particulates away from the drivetrain.
I don't know if it has been practically used.
For example, at some point you need to be in the right position for your communication and power needs. The payloads need to handle rolling around. Lots of reasons.
Its a very invasive solution for one particular problem but doesn't help and makes other things harder. If you don't slow down, being round want help you when splatting on the ground.
At the end of the day, we can make landing of the moon reliable with other methods that are less invasive and thus less costly. The solution you suggest is one that you use if you don't have any good options left.
But it also occurs to me and therefore probably the actual engineers they should be throwing these landers out of an airplane over a rough, rocky earth desert many times before trying the moon?
The Surveyor probes used radar ranging to get relative altitude/velocity measurements. They were not very precise in where exactly they landed. The Apollo landers were semi-manually flown visually in the terminal guidance phase which probably helped with their accuracy.
The vision-based systems used today are much more capable of doing precision landings autonomously once you are close to the surface.
The Soviets started landing on the moon in the 1950s. It wasn't pretty, it was primitive, but it has been done. We (as a species) have since landed on asteroids and planets of sulphuric acid.
Space is hard, but we're literally trying to replicate what has already been done.
What was lacking then was precision. The landers from the 60s (Soviet and US) targeted landing areas that were massive. You basically ensured that the initial descent trajectory would intersect a certain area (using ground-based orbit determination) and the terminal landing sequence just ensured a soft-landing ... wherever that might be.
What is even more impressive is that they did all that without any digital computer on board. For example, in the Surveyor lander, the landing guidance was made up of analog electronics, using the radar signals to command a thrust-vector and throttle to the gimbaled rocket engines. Here is an interesting read about NASA's surveyor probe, if you want to know more: https://www.sciencedirect.com/science/article/pii/S147466701...
In contrast, the new commercial landers are trying to land at very precise locations within hundreds, if not tens of meters of a certain point. And they are doing that with a fraction of the budget of the programs from the 60s. For example, the entire Surveyor program (with 7 landers) cost ~$469 million in 1966. That is nearly 4.5 billion in 2024 dollars with a large part of that going into R&D. The IM-1 lander in contrast, was awarded $118 million. The Japanese SLIM lander cost $121.5 million.
So for what they have, they are doing really well!
I think there are plans for better relays situated around the moon, but a lunar gps system is not likely given the costs and engineering difficulties.
Another idea is to let the lander “spring” on the moon surface. Because the gravity is so small, a free fall from 50 m or so will be like nothing. Cutting off the engine early and accept a certain down fall velocity will help stabilize the landing axis as well. With a wider base, the landing can be further stabilized.
Allowing the lander to take a bit of a hit is kind of what IM-1 ended up doing :P but jokes aside, the legs add a bit of tolerance for this, and it has been done on Mars (wrapping rovers in inflatable balloons to absorb the impact), but I guess the logic with the Moon is that you need to do a controlled propulsive descent anyway (and with heavy/large payloads you have no other options), so might as well focus on doing it properly. With Mars there's an atmosphere to help, reducing how controlled the descent needed to be for lighter things.
So then here's my luddite take. Can't they just unfurl wider stabilizers from the legs that increase their footprint? At slow speeds in low gravity it seems like they wouldn't need to be heavy or strong.
So much cheaper just to have an altimeter and no extra stabilizers. Sadly, their altimeter didn’t work. They forgot to turn it on correctly.
Honestly, they’re lucky that it got so close to landing correctly; if it had been going faster the damage would have been even worse than just a crumpled landing leg.
If I throw a pencil 1000 times and 999 times it lands on its side, I would use that feature instead of hopen this is the 1/1000 chance..
The Apollo LM weighed 15-16.5 metric tons at launch. Not exactly a Mylar balloon.
Obviously much more complex, but probably cheaper than redundant everything.
It's not only a matter of adding complexity, mass, money, etc. This kind of solution is simple on its face, but it is akin to being ignorant of why a car has windows (for the driver to see), doors (for the passengers to enter/exit) or a cooling system (to not overheat), and then reading that Jeeps (or to be more fair, a new Jeep prototype) are prone to tipping over on a trail after driving 1000km on a highway to a trailhead, and then commenting on how Chrysler should just make a dodecahedron Jeep with 20 wheels instead of 4.
These spacecraft also made it past 99% of the hurdles, the next try will probably make it and overcome the final 1% without starting from scratch and adding all kinds of complexity that are far more likely to add failure.
I work in the industry and opinions are mine and not of my employer.
Obviously N-way redundancy isn't optimal, but it would seem potentially simple if you had a modular design with multiple instances of the same "omniface" component. Perhaps use 1/2 of each redundant face for radiator and 1/2 for solar panel?
I'm not suggesting a rolling design - just one with legs on every side such that if it did tip over (or worst case tumble if landing on an incline) from preferred engine-down orientation then it would not make any difference.
Seeing as Intuitive Machines wanted to avoid deployable (spreadable) legs as a way to achieve a more stable low center of gravity, another alternative would seem to be to shrink the design (lose the height) to better work within the width of the faring, although I don't know how viable that would be given amount of propellant needed for the landing.
"Just put 1/2 radiator and 1/2 solar" and "just put legs on every side" is still really simplistic and nobody even mentioned thermal insulation yet, which is normally a much higher proportion of surface area compared to radiators and solar, at least if all three are on the main spacecraft body. I was being extreme in my last comment to make a point, but you still sound to me like a guy suggesting 20, and now 12 wheels on a Jeep instead of 4.
No - on a lunar lander, not on a jeep. It makes a difference (I'm really not sure why you started talking about Jeeps).
The difference is the cost to test a lunar lander (on the moon) vs cost to test a jeep, and the fact that we're only going to build one lunar lander vs a production run of millions for the jeep.
For the Jeep it's cheap enough to iterate and test (on earth), and end up with an optimized design that has 4 wheels and not 12 or 20. Not only is this relatively cheap to do, but there's a huge incentive to do so since we're going to mass produce the Jeep and would therefore like to reduce build cost and maximize profit.
In contrast, the lunar lander is very expensive to "test" since that means a failed mission to the moon. Maybe that mission costs $5M, so if we fail twice before getting it right we've added $10M to the cost. If we can avoid those failed tests by instead adding $1M of redundant hardware that makes it work first time, then we've saved a lot of money. We're only building one lunar lander, so there's no multiplier in front of that $1M we added to the hardware cost.
Of course it's a more complex design in a way given that you deploy this airbag at low altitude - something else to go wrong. It's interesting though that NASA has used that and the even more complex air-crane technique on Mars both successful first attempt. Even though they seem complex I'd assume NASA determined they were the least-complex approaches that had a high likelihood of success.
Maybe the economics of doing this on the moon, and with a cheaper lander, are different - better to have a simpler system with higher chance of failure, and redo the mission if it fails ?
If you know it's difficult, shape a thing so it can not go wrong?
Not even very much like my home planet at all ;)
Edit: My point being: spacex is already doing it on earth, dealing with stronger gravity and air non linearity.
More seriously, the humans in question were very skilled pilots with huge amounts of general flight experience and specific lunar training; they also had access to hardware that had already been expensively tested in the lunar environment. Neither of those were available to this project.
It probably would have landed upright if the LIDAR worked. It is impressive that it landed as intact as it did
[0] https://arstechnica.com/space/2024/02/it-turns-out-that-odys...
https://en.wikipedia.org/wiki/Mars_Pathfinder#/media/File:Pa...
Having an atmosphere helps, though and that's not available on the Moon.
50-60 years of history, crazy advances in technology from materials to computers to everything else, yet its still objectively a difficult, "unsolved" problem.
I really like the idea of a mission to build infrastructure though.
But mostly by obstetricians and context-unaware autocorrect software?
https://dictionary.cambridge.org/dictionary/english/birthing
https://dictionary.cambridge.org/dictionary/english/berthing
Apollo 11/Eagle landed something like 4 miles off from their target site, but SpaceX nowadays routinely lands on target.
Landing on the moon is easier. It just looks hard because it's so expensive to get there that you don't get many attempts.
I'm not an expert but I think landing on Mars with no atmosphere would be harder, because you'd need so much more fuel for a controlled descent.
On the moon?
SpaceX has not yet attempted to land anything on the moon.
There had been upgrades to software and procedures since Apollo 11 -- most notably, a new guidance parameter the astronauts could enter ("noun 69") to correct for deviations between the planned lunar orbit and the one in which the spacecraft actually was, before descent.
https://www.forbes.com/sites/davidmindell/2019/11/19/apollo-...
The topic was exactly that: landing pad preparation solutions. Here's a summary slide for one of the winning proposals: https://www.nasa.gov/wp-content/uploads/2022/03/lustr2021_qu...
The Autonomous Site Preparation: Excavation, Compaction, and Testing (ASPECT) Project will develop tools and methods to clear, level, and compact the lunar surface. ASPECT is a fully autonomous rover with equipment for regolith excavation, boulder moving, and surface compaction.
Someone proposed doing something similar with a lander, where a landing-site-prep robot gets dropped first. But that sounded like a lot of hovering to me, and a solution that would be very specific to lunar landing. I can't see that being successful on anything with higher gravity.
Better perhaps to send a separate stage or a scouting mission to do the work, then land later.
If Flight 3 explodes again, my completely armchair prediction is that stage 1 will get something similar, but to stop sloshing on boostback.
edit: er, forget that.
My landers are designed to land sideways.
I wonder how SpaceX will solve this reliably for Starship?
the past is a foreign country
The jumps (4 feet) and bounds (15 feet) are pretty good by everyday standards, but like half of the Earth-bound records.
The revenue for this would pay for several Starships.
Maybe a sport like Quidditch could become a reality
It's a nice place to visit, but I wouldn't want to live there.
Seems pretty sweet to me.
I'd probably be fired when they found out I hadn't read anything written since the 70s....
The Soviet Union is even more foreign with 50's tech and no human to aid primitive computers.
Better failure rate than the last 12 months of international moon landings.
At some point I wanted to go to places or in an amount of time or with cargo that a bike wouldn't allow.
The Artemis program is doing something similar but not the same as Apollo. It's different so it requires a change in the architecture which in turn means a series of problems because change is hard. Which truthfully is the exact same thing Apollo went through. Apollo was only six for six if you ignore everything that went before it. If you look the events before Apollo 11 it's easy to see that there were difficulties.
Because after every failure we must find excuses ? /s
They did it right 55 years ago. With people on it.
https://gymnasium.farama.org/environments/box2d/lunar_lander...
An algorithm designed by people who know what they're doing is usually better. More effort, yes, but rockets are a lot of effort! We can afford to pay the cost for a reliable landing system.
Best I could do was a 970 point crash.
That's not how statistics work. We don't have a "sudden epidemic", we just happened to get unlucky a few times in a short period.
The exact same underlying risks and chances of success could have led to a long period of everything working fine, or (the least likely outcome) a perfectly spaced series of accidents occurring at whatever the mean rate is.
Not understanding this is part of how we let people get away with lax safety standards. Nothing gets mass attention until enough people get unlucky in a short period, despite the safety standards being lax the whole time. (I think many people reading this could name a company this has happened to recently -- but will attention stay on them for long when random chance gives us a period of no problems?)
flatten a landing pad
make a moon highway
Moon GPS (2 votes)
stupid-wide landing legs
Dynetics lander
spherical lander
mechanism to push itself into upright
land sideways (ok this was a joke right?)
I couldn't find the relevant XKCD but I remember one along the lines of "why did they just do Y?". I say all of this in jest, as this is what we do here at HN: give our opinion on areas outside our expertise.
It is very odd however to see no mention of the fact that China is about a decade ahead, having completed the Chang'e 3, 4 and 5 missions. which included a successful return of Moon rocks to the Earth. Two more missions are in the works.
The article mentions a Japanese effort, but the omission of China's successes seems fairly deliberate. I wonder what the motivation was?
Seems like that would save a lot of fuel too if you don't care how you come down, just not too incredibly fast.
(wasn't there a Mars landing like that)
How exactly do you define a successful landing? What if you're upright but all four legs collapsed and the spacecraft crushed your primary science payload?