[HN Gopher] Athena landed in a dark crater where the temperature...
___________________________________________________________________
Athena landed in a dark crater where the temperature was minus
280deg F
Author : 01-_-
Score : 62 points
Date : 2025-03-14 03:46 UTC (19 hours ago)
(HTM) web link (arstechnica.com)
(TXT) w3m dump (arstechnica.com)
| bell-cot wrote:
| At what point do you just fire your entire "Land on Moon"
| software team, and hire a couple young Neil Armstrong wanna-be's,
| who can hand-land your spacecraft remotely? (In spite of the
| moon-earth-moon signal lag.)
| ceejayoz wrote:
| You'd probably wanna make sure that's the problem area first.
|
| Considering the altimeter failed, that seems unlikely to be the
| case.
| dist-epoch wrote:
| Dumb question, but why can't it have a few simple telescopic
| sticks which extend to flip it over if it lands upside down.
|
| Seems it's the second time they fail in this mode.
| ragebol wrote:
| Moe parts, more complexity, more weight.
| hulitu wrote:
| Because: 1. It cannot fail in this mode. 2. Testing is done by
| the user, test results are sent by telemetry and the fix will
| be done, when the bug can be reproduced on developer's
| computers.
|
| /s
| somenameforme wrote:
| Definitely not a dumb question. The first lander to land on the
| Moon (after _many_ failures) is pretty amusing. [1] The Soviets
| a designed a lander that 'd be launched right into the Moon
| but, just before impact would jettison the lander which itself
| was a highly reinforced ball that was then designed to simply
| pound into the Moon at 54kph, but survive the crash. The egg
| then unfurled and finally humanity had achieved a 'soft'
| landing on the Moon. Somehow it kind of makes one think of a
| really elaborate egg drop contest paired with a 'what happens
| if you jump right before the elevator crashes.'
|
| Like another comment mentioned, complexity and size are big
| issues. Some more are power/mechanics (fluids, such as for
| hydraulics, and -280F aren't gonna play well together) and then
| there's the fact that there's not even a guarantee it'd work.
| Your legs could get damaged, you might end up in an orientation
| where none of the legs are appropriate, and so on. So you may
| be adding a whole bunch of complexity for stuff that might not
| even save you in the situation it was designed for!
|
| [1] - https://en.wikipedia.org/wiki/Luna_9
| notTooFarGone wrote:
| battlebots did it first!
| mystified5016 wrote:
| Mass. Each kilogram costs what, millions? Hundreds of millions?
|
| There's a small chance that navigation or landing fails in a
| way that would make those legs useful, and an even smaller
| chance that they'll save the mission.
|
| Given tight budgets, this is almost certainly not a gamble
| worth taking
| ceejayoz wrote:
| NASA paid $65M for the launch. It's about 2,000 kilos.
|
| $32k/kilo or so.
| tapotatonumber9 wrote:
| How about a parachute to keep it the right way up?
| appleorchard46 wrote:
| Not enough of an atmosphere.
| moffkalast wrote:
| Just give the RCS thrusters enough power to lift it sideways.
| Works every time in KSP.
| 1970-01-01 wrote:
| Still unclear what happened. Did they not anticipate a big moon
| hole or did navigation fail when the rangefinder failed?
| ceejayoz wrote:
| I'm not sure what you find unclear. Navigation was fine -
| "Athena knew where it was relative to the surface of the Moon"
| - but without a working altimeter it was kinda fucked for
| actually touching down.
|
| Hard landing, skid, tip.
| 1970-01-01 wrote:
| If navigation was fine, why was touchdown on a plateau?
| ceejayoz wrote:
| Because "where am I" and "how high am I over that position"
| are very different things.
|
| Visual demonstration of being at the wrong altitude in the
| right spot: https://www.f-16.net/f-16-news-article968.html
| walrus01 wrote:
| Was there no functioning laser or radar altimeter for the
| final descent phase?
| ceejayoz wrote:
| "However, the lander's altimeter had failed."
| 1970-01-01 wrote:
| Looking at this closely, it was working, however it was
| noisy. I speculate that they didn't correctly anticipate
| the moon dust problem. Laser rangefinders may not be a
| workable solution for future landings.
| So engineers at Intuitive Machines had checked, and re-
| checked, the laser-based altimeters on Athena. When the
| lander got down within about 30 km of the lunar surface,
| they tested the rangefinders again. Worryingly, there was
| some noise in the readings as the laser bounced off the
| Moon. However, the engineers had reason to believe that,
| maybe, the readings would improve as the spacecraft got
| nearer to the surface.
|
| https://arstechnica.com/space/2025/03/intuitive-machines-
| sec...
|
| https://www.space.com/nasa-moon-landing-dust-
| concerns.html
|
| https://en.wikipedia.org/wiki/Lunar_horizon_glow
| ceejayoz wrote:
| Noise at 30km altitude probably points more towards a
| sensor issue than dust.
| Aspos wrote:
| May it be that laser bounced off exhaust plume?
| JshWright wrote:
| The top-heavy design didn't help things either. I'll be
| shocked if they don't go three-for-three on landing sideways
| given IM3 has the same tall design.
| ceejayoz wrote:
| The company _claims_ it 's not as top-heavy as you'd think
| from pics:
|
| https://www.theregister.com/2025/03/07/intuitive_machines_l
| a...
|
| > At his press conference earlier today, Altemus defended
| the design, saying the spacecraft doesn't have a high
| center of gravity because most of its cargo attaches to the
| base of the vehicle. He said there were no plans for a
| radical rethink of his company's design.
|
| (We see this in returning F9 first stages, as well.)
| sandworm101 wrote:
| >> The top-heavy design didn't help things either
|
| Just wait for SpaceX to start _trying_ to land starships on
| the moon. Also vertically. Also doomed to tip over whenever
| the surface is slightly out of spec.
|
| https://www.spacex.com/humanspaceflight/moon/
| JumpCrisscross wrote:
| > _Just wait for SpaceX to start trying to land starships
| on the moon. Also vertically_
|
| SpaceX has done it. To date, other nation-states have
| tried and failed to replicate their achievements in this
| domain.
|
| IM's design is wrongly optimised and probably requires a
| rethink. That the CEO won't contemplate this isn't a
| great sign for the company.
| CamperBob2 wrote:
| _SpaceX has done it._
|
| SpaceX has landed Starship on the moon?!
| JumpCrisscross wrote:
| SpaceX has repeatedly and reliably landed vertical
| stacks. On any body. Out of the engineering problems
| inherent to HLS, sticking the landing isn't material
| because for them, for that team, it isn't as novel a
| problem as _e.g._ in-orbit refuelling or getting Raptors
| to relight on the Moon.
|
| Put another way, just because SpaceX has done it doesn't
| mean the same problem carries the same risk for a team
| like IM's.
| MegaButts wrote:
| Has SpaceX ever landed their rocket on a surface that
| isn't purposefully engineered to be flat?
| Seanambers wrote:
| Multiple sea landings, but I guess you'd argue those
| don't count since the vehicles tip over in water and
| explode.
|
| Moving barges in the sea should qualify though.
| hildolfr wrote:
| A moving barge with a known flat surface of a known
| hardness and stability is a whole different category of
| difficult than doing the same thing on naturally
| occurring terrain with unknown voids, hardness, roughness
| and consistency.
| sandworm101 wrote:
| Lol. SpaceX has landed on prepared surfaces, concrete
| pads on land or on large barges. They literally have a
| big X to mark the target. Let's see them land on some
| random beach, an uneven surface that may or may not
| subside. But that is still peanuts comparted to the
| moon's surface.
| JumpCrisscross wrote:
| > _that is still peanuts comparted to the moon 's
| surface_
|
| Sure. I'm not trivialising the problem in an absolute
| sense. Just going from floating barge or chopsticks to
| Moon is a simpler set of problems than reinventing the
| sort of translational velocity and attitude control
| needed to get to first base.
| sandworm101 wrote:
| For selecting and touching down on an unprepared surface,
| rockets are not the stepping stone. Start with
| helicopters. It is the same problem: can I land there and
| what will happen when I put weight on the surface. Try
| programing a large helicopter to identify and land on a
| random chunk of rocky terrain. It is not easy. And the
| bigger/taller the craft, the more difficult it becomes.
| Then add a 10-second time limit.
| Kye wrote:
| Are the sky cranes of Mars viable without an atmosphere?
| ted_dunning wrote:
| You say this based on your history of landing rockets on
| the moon?
|
| And on your history of dealing with the lunar regolith
| near the poles?
| tekla wrote:
| Why do people keep thinking this thing is top heavy just
| because its taller than wide?
|
| The heavy bits are at the bottom.
| timmg wrote:
| > Why do people keep thinking this thing is top heavy
| just because its taller than wide?
|
| Because it keeps falling over?
| tekla wrote:
| The landing leg broke. How does that show you its top
| heavy?
| timmg wrote:
| I didn't say it was top-heavy. I answered the question,
| "Why does everyone think it is top heavy?"
| tekla wrote:
| Ah complete total ignorance. Figures
| _bin_ wrote:
| i think this becomes somewhat less of an issue once SpaceX
| gets Starship fulfilling contracts at scale. they're
| limited in width by the max payload faring width for Falcon
| 9, which is like half that of starship. add to that an exec
| claimed it's tall but not necessarily top-heavy as mass
| isn't evenly distributed throughout.
| strangattractor wrote:
| Or use New Glenn which works now and has a larger faring.
| nomel wrote:
| > "Athena knew where it was relative to the surface of the
| Moon" - but without a working altimeter it was kinda fucked
| for actually touching down.
|
| Z is an axis that exists in our 3d world, and a required
| value for any relative position, which means it _DID NOT_
| know where it was, relative to the moon.
| martin_drapeau wrote:
| Scott Manley has a great video explaining what he thinks
| happened. https://youtu.be/ISZTTEtHcTg?si=0LZFyiCysBiFZrMz
| 1970-01-01 wrote:
| Scott Manley and I agree that altitude signal shouldn't
| matter if navigation is correct. Athena simply risked
| touchdown, and it didn't find a flat spot, it found a hole.
|
| https://youtu.be/ISZTTEtHcTg&t=1158
| ceejayoz wrote:
| Can you quote the bit you think is relevant here?
|
| He's saying modern spacecraft _can_ null out the horizontal
| velocity to land, but without an altimeter, you don 't
| necessarily know _when_ to do so, nor when to give the
| thrusters a little boost to avoid an obstacle you 're about
| to hit, like a plateau.
| russdill wrote:
| It touched down with a large horizontal velocity component
| areoform wrote:
| If you take the time to study the documentation from the 1950s &
| 1960s, the engineering culture of that era _appears_ to be
| markedly different from the engineering culture prevalent today.
| And I think it 's deeply rooted in the symbiotic relationship
| between computing, Baumol's cost disease and our obsession with
| precision, results-oriented, MBA-style-min-maxing, "good enough
| for government work" engineering.
|
| Robert Truax, the designer of the Sea Dragon, loved to promote
| the design paradigm of Big Dumb Boosters. Instead of many small,
| sophisticated rocket engines, what if we made one big robust one
| that can take a lickin' and keep on kickin'.
|
| The idea was to relax the mass margins and to create big. dumb.
| boosters. It's the approach TRW explicitly followed for the Lunar
| Module engine, > "There was an amusing but
| instructive side to this program. TRW farmed-out the fabrication
| of the engine and its supporting structure, less the injector
| that they fabricated themselves, to a "job-shop" commercial steel
| fabricator located near their facility . The contract price was $
| 8000. Two TRW executives visited the facility to observe the
| fabrication process. They found only one individual working on
| the hardware, and when queried, he did not know nor care that he
| was building an aerospace rocket engine." > " I had
| arrived late to witness the test, and only saw the firing. I was
| told by others who witnessed the entire test procedure that the
| engine was pulled out of outdoor storage where it lay unprotected
| against the elements. Before it was placed on the launch stand,
| the test crew dusted off the desert sand that had clung to it.
| This unplanned inlcusion [sic] of a bit of an environmental test
| also demonstrated hardware ruggedness of the kind no other liquid
| rocket eingine [sic] could approach."
|
| The Surveyor program managed to make it "just work" 5 out of 7
| times by adopting this approach. It had robust landing legs and
| RADAR. They would decelerate and then shut off the engine 11'
| above the surface. The wide, sturdy legs would then absorb that
| final impact of coming stand still from free fall.
|
| These programs had a lot of capital behind them. Some components
| required precision engineering, but there's a very clear through
| line and embrace of the "we gotta make stuff that can take a
| lickin' & keeps kickin'" philosophy.
|
| Modern engineering approaches seem to be the opposite of that. I
| think we've become so accustomed to living in a silicon driven
| world where our personal devices are engineered at microscopic
| level that we've forgotten how to do things the Apollo-era way.
|
| For example, to the best of my knowledge, IM-2 doesn't use RADAR
| -- they're using LIDAR and optical navigation instead. Perhaps it
| is to save on mass and power so that more payload reaches the
| surface. Perhaps optical navigation was declared to be "good
| enough." Perhaps it doesn't make sense from a minmaxing of
| capital perspective. But this philosophy may not be suited to an
| untamed frontier.
|
| China adopted the Surveyor / Apollo-era philosophy. Their first
| successful lander, Chang'e 3, used the same hover & fall
| technique as Surveyor. > The vehicle will hover
| at this altitude, moving horizontally under its own guidance to
| avoid obstacles, and then slowly descend to 4 m above the ground,
| at which point its engine will shut down for a free-fall onto the
| lunar surface. The landing site will be at Sinus Iridum, at a
| latitude of 44o.
|
| It chose the terminal landing sites with the help of LIDAR and
| its cameras, but it relied on RADAR and a suite of sensors to
| have robust navigation.
|
| The follow up missions up-ed the ante every time, but they seem
| to have consistently focused on the robustness of their craft
| over precision, MBA-spreadsheet-oriented minmax-ing.
| dylan604 wrote:
| > Perhaps it is to save on mass and power so that more payload
| reaches the surface.
|
| It doesn't matter how much mass was saved and how much more
| payload that allowed to reach the surface if the landing isn't
| successful. Successful landing is mandatory for anything else
| to matter. The obviousness of this baffles me that it is taken
| so haphazardly.
| ordu wrote:
| I believe that the thing you are missing is Intuitive
| Machines aims at landing a lot of spacecrafts, not just one.
| They hope to have a limited number of failures to land which
| will teach them how to do it reliably. We might doubt will
| this work or not, but if we accept the plan then it becomes a
| rational decision to increase the engineering complexity and
| risks of failure by saving on mass, because in the long run
| less missions will allow to land more payload.
|
| Though, of course, I wonder how many landings they are
| planning to do, and how many of them they need to do to
| compensate for each failure to land.
| dylan604 wrote:
| Again, if you can't stick the landing, you might as well
| not have any payload on it. So if you're worried about
| cost, keep testing until you can stick the landing with
| dummy mass. Once that works, send the real payload.
| Otherwise, you're just wasting payload.
|
| The mindset difference seems to be that if there's no human
| on board, so no problemo wasting a lander if something goes
| wrong. That's just a bad attitude (as well as yaw and
| roll). If you designed everything with "baby on board"
| hanging in the window, you'd probably not cut so many
| corners so sharply. Otherwise, why not just light your
| cigars with hundred dollar bills. How would you feel if you
| were on the team building the payload, but the lander guys
| keep fucking up so you just wasted however much time you
| spent because "meh, we're just testing". In sports, there's
| a saying "practice like you play because you play like you
| practice".
| cratermoon wrote:
| Okay but successfully landing an inanimate carbon rod is
| easy, but why?
| dylan604 wrote:
| Who said it was easy? I'm saying they are not giving it
| enough respect because of the attitude of "it's only a
| test". That's bad. It's still expensive to get to that
| point. They have become complacent/lazy with the luxury
| of being able to iterate. Rather than spending money on
| engineering testing, they just build "real things" that
| don't work and improve the failed things. Never mind that
| if procedure 10 failed, you never get to test procedure
| 11+. So your next launch fails at procedure 11. It's just
| a bad attitude.
| cratermoon wrote:
| To a point. Landing a solid brick of aluminum isn't much
| good, unless the entire goal of the exercise is to get a
| successful landing of something.
| j_bum wrote:
| This reads like a "comment" version of Destin's speech to a
| NASA group a few years ago [0]. The loss of institutional
| knowledge and fundamentals philosophical differences seem like
| they'll need to be overcome.
|
| [0] https://youtu.be/OoJsPvmFixU?si=EUxpp6C9vRAYD3kA
| somenameforme wrote:
| What an absolutely phenomenal speech and video. Just a sort
| of +1 highly recommended thing. That video was crazy
| _insightful_.
| antonvs wrote:
| The talk was to the American Astronautical Society, not
| specifically a NASA group. But Destin talked as though he
| imagined everyone in the audience worked at NASA. It actually
| bothered me a bit - if I had been at that talk I would have
| been a bit pissed off, because he was basically using it as a
| channel to talk to people who probably weren't actually even
| there.
|
| Just youtubers doing youtube things, I guess.
| somenameforme wrote:
| > "I think we've become so accustomed to living in a silicon
| driven world where our personal devices are engineered at
| microscopic level that we've forgotten how to do things the
| Apollo-era way."
|
| This is a really interesting point. I think a practical issue
| in modern times as well is that companies are being inspired by
| SpaceX while forgetting that it took SpaceX _alot_ of work to
| get to the point of being able to do things like casually land
| a 20 story tower in the middle of the ocean on a barge, let
| alone the even more ridiculous 'stunts' they're doing with
| Starship.
|
| Apollo was starting from the perspective of trying to do
| something where it was even debatable about whether it was
| possible. And so I think there was a lot more 'humility' in
| design, for lack of a better word.
| jjmarr wrote:
| You're criticizing the prioritization of cost, not the concept
| of trying to solve for constraints. Engineering is about
| constrained optimization to meet customer needs.[1] Learning
| this is a core part of the curriculum at my accredited
| engineering school.
|
| > Engineering design is a process of making informed decisions
| to creatively devise products, systems, components, or
| processes to meet specified goals based on engineering analysis
| and judgement. The process is often characterized as complex,
| open-ended, iterative, and multidisciplinary. Solutions
| incorporate natural sciences, mathematics, and engineering
| science, using systematic and current best practices to satisfy
| defined objectives within identified requirements, criteria and
| constraints.
|
| > Constraints to be considered may include (but are not limited
| to): health and safety, sustainability, environmental, ethical,
| security, economic, aesthetics and human factors, feasibility
| and compliance with regulatory aspects, along with universal
| design issues such as societal, cultural and diversification
| facets.
|
| It's not an MBA philosophy but is intrinsic to the profession.
| Apollo didn't go up because of vibes, it went up because
| engineers knew the goals going in and to figured out how much
| fuel was needed to go to the moon. It also went up because the
| United States was willing to spend over a quarter of a trillion
| dollars (adjusted for inflation) on getting there,[2] and
| ignored the arguments that it was a giant waste of money while
| there were social problems at home.[3]
|
| [1]https://egad.engineering.queensu.ca/wp-
| content/uploads/2023/...
|
| [2] https://www.planetary.org/space-policy/cost-of-apollo
|
| [3] https://en.wikipedia.org/wiki/Whitey_on_the_Moon
| areoform wrote:
| This comment isn't directed at you jjmarr, I appreciate your
| take, but I think it's important to point out that,
| > constrained optimization to meet customer needs
|
| is MBA-capture in action.
|
| For most of its existence as a formal field, engineering
| wasn't about making geegaws that "meet customer needs." It
| was about building stuff that matters. Houses that didn't
| collapse. Roads and machines that made it possible to
| traverse vast distances. Toys that delighted us. Aquaducts
| that delivered clean water. Drainage that helped remove muck.
| Plumbing that cleaned our cities. Threshers that helped us
| harvest crops. Lights that vanquished the dark.
|
| The story of engineering is the story of creating technology
| that helps alleviate want.
|
| You can say that there was a "customer" for each, which is
| great and all, but that's not why we did it. We did it so
| that we could move out of the caves and not be in filth and
| muck all the time.
|
| We did it because it felt good. And we did it because it was
| the right thing to do.
| cratermoon wrote:
| The constrained optimization part is good, though.
| s1artibartfast wrote:
| I think you are presenting a romanticized fictional
| narrative, especially when it comes to aerospace.
|
| When engineers were working on Apollo and lunar landers,
| they were working on a set of customer requirements a mile
| long. Roving tinkerers didn't build the moon rockets.
| Engineers spent countless hours in design reviews with the
| customer, in this case, NASA.
|
| Roman engineers didn't build aqueducts and colosseums on a
| lark, or some sense of poetic destiny.
| tremon wrote:
| I don't understand what you are objecting to. Is it just
| the phrasing that's bothering you? Because from my point of
| view, "houses that don't collapse" and "machines that can
| travel vast distances" are all formulations of customer
| needs. And dealing with contraints is pretty much
| engineering 101, every project is at the very least
| constrained on two of these axes: cost, construction time
| or material availability.
| rout39574 wrote:
| Not GP, but I think the objection is: the engineer wants
| to build a thing cheaply enough that it functions, and
| then cheaply as can be while maintaining function.
|
| The MBA wants to build a thing as cheaply as can be while
| extracting maximum value from the process. Maintaining
| function is only relevant inasmuch as is necessary for
| marketing. Enshittification is offensive to the engineer,
| and is a deliberate calculated tactic for the MBA.
|
| We're replete with case studies, but my favorite is
| Kitchen-Aid mixers which accumulated a reputation when
| they were the small version of Hobart mixers, and have in
| succeeding decades become a cheap pile of crap because
| the optimization does not care about quality of function
| so long as the appearance of quality can be maintained.
| And it's cheaper to look quality than it is to be so.
|
| A close second is Singer in the '70s, which for a while
| decided to ship items with 100-hour motors because "Folks
| don't usually spend much time _actually_ sewing".
| Contrast with the machines built a centuryish before.
| We've got an early electric model which is still doing
| fantastic precise work. The engineer would enthuse over
| the superb work that went into building such a tool, and
| the MBA would focus on the foregone sales, the value not
| extracted.
| appleorchard46 wrote:
| I was watching this documentary Happy People, about people
| who live in the Siberian Taiga (by Werner Herzog, would
| highly recommend). A man is talking about making a new set
| of skis, and it shows the incredibly long and careful
| process of selecting the perfect trees, chopping them down
| in the right way, treating the wood and so on. He mentions
| how mass manufactured skis are light and cheap and will
| work fine for a while, but when one breaks and you're in
| the Siberian wilderness you can't just go to the store for
| a replacement. That really stuck with me.
|
| 1960s US is hardly Siberia and I don't think any NASA
| engineers had their heads on the chopping block if their
| designs failed. But engineering philosophy was still rooted
| in survival; the primary goal was to make something that
| wouldn't kill you because it fails.
|
| You hear stories about artisans in the old days refusing
| work because they don't believe what they're being asked to
| make is safe or reliable enough for the person asking for
| it. Maybe it's romanticized and idealized, maybe it's just
| them covering their ass so they don't get blamed. But that
| philosophy of personal responsibility not just for making
| things according to the constraints, but for the outcome
| too, is something that served society well for a long time
| before slowly disappearing over the past century or so.
|
| It hasn't left without reason. As the things being made
| became less key to survival and more key to thrival, as the
| world became more interconnected and safe, it didn't make
| as much sense. Just think of how many crazy, inventive
| concepts we use every day wouldn't have been made if they
| could only be made to work reliably! Our entire modern
| existence is based off things that don't work reliably.
| It's a blessing and a curse.
|
| But when we're exploring the final frontier we need
| frontier thinking and frontier technology; things that,
| from the ground up, are built to work first with all other
| constraints secondary. Unfortunately spaceflight endeavors
| today must invariably build off the 'good enough, when it
| breaks just make a new one' foundation that permeates
| modern design at every level. Even if you want to make
| something nowadays with the sole purpose of working, as
| long as you're using any technological advancements made in
| the past 50 years chances are you're using something that
| wasn't made with that goal in mind.
| FredPret wrote:
| > stuff that matters
|
| Matters to whom?
|
| Answer: that's the definition of a customer in an
| engineering project
|
| Matters how / why?
|
| Answer: those are the requirements / user stories.
|
| Helping people by doing engineering feels good and is the
| right thing to do, but formalizing this process a bit does
| not detract from it.
| Macha wrote:
| > If you take the time to study the documentation from the
| 1950s & 1960s, the engineering culture of that era appears to
| be markedly different from the engineering culture prevalent
| today. And I think it's deeply rooted in the symbiotic
| relationship between computing, Baumol's cost disease and our
| obsession with precision, results-oriented, MBA-style-min-
| maxing, "good enough for government work" engineering.
|
| I wonder how much of that is because of public attitudes to
| government spend. Like if a SpaceX rocket blows up, they're
| taking innovative, risk-taking approaches to rocket
| development. If a NASA rocket blows up they're wasting tax
| payer funding.
|
| Similarly the pressure on NASA to have fewer programs for cost
| saving is similar. If NASA has two rocket programs, one of
| which is at a "good enough" level for launching satellites
| economically into space and one of them is a "safety conscious"
| rocket for manned launches at a higher per-mission cost, then
| people look at this and think why is NASA duplicating work and
| spending. So now they get only one program, so then even
| launching a GPS satellite is the expensive, human-safe rocket.
| 1970-01-01 wrote:
| >It chose the terminal landing sites with the help of LIDAR and
| its cameras, but it relied on RADAR and a suite of sensors to
| have robust navigation.
|
| I think this is the smoking gun. RADAR is usually successful,
| while LIDAR has a poor record.
| dmurray wrote:
| > China adopted the Surveyor / Apollo-era philosophy. Their
| first successful lander, Chang'e 3, used the same hover & fall
| technique as Surveyor.
|
| Dropping the last 4 metres isn't a sign of having a ruggedized,
| over-speced "takes a lickin' and keeps on kicking' approach".
| In lunar gravity, you could drop a raw egg from that height and
| not perturb the chick inside.
|
| Instead the aim is to avoid throwing up too much moon dust with
| retro rockets.
|
| Luna 9 (1966) really did need to withstand a bit of a bump, but
| it was 22km/h, comparable with a fast running pace or a car in
| first gear, not a high speed impact.
| ck2 wrote:
| Kinda explain why Neil Armstrong burned up all their fuel except
| for a few seconds scoping out the landing site in paranoia.
|
| Instead of building all these expensive to launch big landers,
| why not get some pizza-box sized probes into earth orbit AND THEN
| do like a slo-mo golf shot arcing to where the moon will be for a
| super slow/soft landing?
|
| Some will fail but if you launch 100 and get 20-30 working, there
| you go.
|
| As technology progresses, get it down to a shoe-box sized probe
| and then in 10 years smartphone sized (in 100 years tic-tac
| sized).
| btbuildem wrote:
| Combine that with leaving the long-range comms (and higher-
| powered equipment) in lunar orbit as the "master" for all the
| probes scattered on the surface, and maybe the problem becomes
| simpler by breaking it in two.
| mapt wrote:
| Space applications of all sorts are screaming out for mass
| production approaches. With so much design work and
| verification the actual manufacturing cost tends to be trivial
| by comparison, the work readily adapted to concurrent
| manufacturing processes.
| AStonesThrow wrote:
| When I signed on to a Mars mission in 1999, the scientists
| told me that's JPL's approach: instead of extremely
| expensive, robust, redundant craft, they would begin to make
| leaner stuff and worry less when it failed...
|
| Around the same time, Mission Control was replacing their
| bespoke hardware with COTS and trying to minimize the "glue"
| HW/SW for space systems.
|
| You'll also see that expertise on a particular instrument
| package is leveraged over and over across multiple missions.
|
| NASA still has amazing educational outreach and makes
| incredible software, even for mere mortals.
| accrual wrote:
| It's definitely possible to target a certain surface location
| on the moon from low Earth orbit and set off on a trajectory to
| get there with a single burn. However, as the craft(s) approach
| the moon and enter its sphere of influence, gravity will kick
| in and increase their relative velocity to the surface. Another
| burn (suicide burn if you're feeling lucky) would be needed for
| the soft touchdown.
|
| The moon is also gravitationally very "lumpy", so some small
| corrections might be needed along the way as well.
| 1970-01-01 wrote:
| Here's the hole it fell into:
|
| https://www.lroc.asu.edu/images/1408
| dang wrote:
| Related. Others?
|
| _Athena spacecraft declared dead after toppling over on moon_ -
| https://news.ycombinator.com/item?id=43292471 - March 2025 (340
| comments)
|
| _The Moon Lander Athena 's Fate on the Lunar Surface Is
| Uncertain_ - https://news.ycombinator.com/item?id=43283136 -
| March 2025 (1 comment)
| Koshkin wrote:
| https://en.wikipedia.org/wiki/IM-2
| littlestymaar wrote:
| Can someone ELI5 why it's at that temperature?
|
| I mean, because it's in the dark I'd expect it to reach
| equilibrium with space background thermal radiation which is
| around 3K. Yet its 100K. Where does that heat comes from? It
| radiates from earth? Conduct through the floor coming from the
| inner of the moon itself? (Is there some kind of geothermal
| gradient on the moon BTW?)
| antonvs wrote:
| There are multiple factors. The biggest ones are reflected
| sunlight; infrared and thermal conduction from surrounding
| rocks; and the Moon's internal heat (the region between the
| core and the mantle has a temperature of over 1,300 C).
| shadowgovt wrote:
| > As a result, the privately built spacecraft struck the lunar
| surface on a plateau, toppled over, and began to skid across the
| surface. As it did so, the lander rotated at least once or twice
| before coming to a stop in a small, shadowed crater.
|
| Oh yeah, we've all Kerbaled it in like that at one point or
| another.
| dang wrote:
| [stub for offtopicness]
| ThePowerOfFuet wrote:
| -173degC.
| oneshtein wrote:
| 100K
| muzani wrote:
| This actually puts it into perspective, knowing it's closer
| to absolute zero than room temperature.
| layer8 wrote:
| It's roughly a third of room temperature.
| dietr1ch wrote:
| Which is hard to grok since a third of something warm
| doesn't seem to be extremely cold.
| layer8 wrote:
| It's sort-of the point to realize that it actually is (a
| third of something). The lander is receiving a third of
| the thermal energy that it would receive at room
| temperature.
|
| Warm-blooded mammals of course have a reference point
| based on their thermal homeostatic capabilities (ability
| to maintain body temperature). "Warm" and "cold" is in
| relation to that.
| ted_dunning wrote:
| I don't think that black-body radiative transfer is a
| linear process.
|
| The Stefan-Boltzman relation says power scales with the
| fourth power of temperature. So 1/3 absolute temperature
| would be 1/81 the inbound radiative energy. If you are
| getting 800W inbound at room temp, you would get 10W
| inbound at 100K (=300K/3).
| abdullahkhalids wrote:
| This is an interesting explanatory challenge.
|
| Temperature is roughly how fast molecules are moving,
| vibrating etc. And the impact of low/higher temperature
| are really how fast molecules are knocking you. For an
| ideal gas, temperature is proportional to the square of
| the velocity.
|
| So at room temperature (300K), the speed of the molecules
| is roughly 300^0.5 = 17.3 in some arbitrary units. If you
| drop down to freezing point of water, (273K), speed is
| 16.5. And that is starting to get cold. -40C (as cold as
| most humans will experience) is 15.3. So each drop of 1
| in speed is pretty drastic.
|
| At 100K, the speed is 10, or 7 drops from 17. That should
| be a lot colder than room temperature. But not cold
| enough. Most of the speed is still there, we haven't even
| cut it by half. It's the next few 1/3rd cuts of the
| temperature that will start to get us closer to zero
| speed.
| tempodox wrote:
| Exactly, the Kelvin unit makes it easy to see that. I
| can't believe they used fucking Fahrenheit in the title.
| shadowgovt wrote:
| "You know how hot you feel when you're running a fever?
| Well, it was nearly _three times_ that cold! "
| elviejo wrote:
| I know I'm a snob... but I can't read science news using the
| imperial system.
| ggm wrote:
| You would think either they could parameterise all units or a
| plausible browser extension could convert elephants to
| swimmingpools and King's thumbs to badly measured fractions
| of a diameter.
| rufname wrote:
| I made this, but have not tested it yet with this website:
|
| https://github.com/rufname/metricPlease
| jdminhbg wrote:
| Well, the definition of 0oC is based on the freezing point of
| water at one atmosphere of pressure, which isn't super
| relevant on the Moon. You could give it in K but that's not
| very relatable.
| 0cf8612b2e1e wrote:
| -280F, -173C, or 100K is not relatable to anyone except
| niche researchers. Maybe slap in the extra few people who
| happen to work with liquid helium and you are still talking
| about 0% of the population.
| nntwozz wrote:
| Everyone knows feet and British stones is the way to measure
| things in space. Just ask any scientician:
|
| https://m.youtube.com/watch?v=nRnt3TE-V-Y
| nextts wrote:
| Ahhhh...
| samstave wrote:
| Speaking of "feet" as a measurement - Randall Carlson has
| an AMAZING video[0] on the source of the 12 inch foot.
|
| And how its all related to the measurement of the
| precession of the earth. And yes - its specifically how to
| measure things in space. And its all from Sacred Geometry.
|
| [0] https://www.youtube.com/watch?v=R7oyZGW99os
| shmerl wrote:
| I agree, especially scientific articles should just stick to
| metric, period.
|
| At least inside the article both units are actually used,
| just the title is imperial only.
| ninalanyon wrote:
| But it only looks like Imperial, it's almost certainly
| actually US Customary.
| kiicia wrote:
| No sane person can
| Koshkin wrote:
| -280F = -173.33333C +280F = +137.77777C
| chairmansteve wrote:
| Wow. Cosmic resonance man...
| scotty79 wrote:
| I refuse to believe anyone knows how cold -280F is.
|
| When you have such extreme temperatures you think in Kelvin
| or at least Celsius.
| usrnm wrote:
| It's not like using Kelvin or Celsius helps you grasp these
| temperatures. -173C is very, very cold, but how cold? What
| can you compare it to? Not many humans have any experience
| with something of this scale
| alwayslikethis wrote:
| Liquid nitrogen (boiling at -196 C) is a semi-common
| substance that people would have heard of, though not
| everyone would have seen or interacted with it.
| mncharity wrote:
| That's the example Copilot used when asked to make a list
| of temperatures in 50 C steps with an example or two of
| something around that temperature that people might have
| heard of. Also cryogenic freezing of biological samples.
| inetknght wrote:
| I've seen liquid nitrogen, briefly, as it was sprayed out
| of a hose. It immediately boiled into a (quite cold) gas,
| of course. I was told not to play with it too much
| because they would have to evacuate the building. Oh the
| joys of "bring your kid to work" days in manufacturing
| facilities
| Vilian wrote:
| You compare to 0 kelvin, you know where it's on the
| Celsius scale, not on F
| mordechai9000 wrote:
| Maybe the Rankine temperature could be provided, as well.
| NikolaNovak wrote:
| Fair, but in Celsius or Kelvin I know how close it is to
| absolute zero. In Fahrenheit I have no idea!
| wnoise wrote:
| Got it, I should use Rankine.
| kiicia wrote:
| -173C is just twice your typical winter in Yakutia
| nextts wrote:
| Anyone who has done cryotherapy?
| trhway wrote:
| Or you can think that way - you at 36 C radiate 900 W away
| while from our usual environment you get 800+ W radiated
| (and also transferred by air) at you (with your body
| producing that 50-100W difference), and at 280F you'd get
| only mere watts radiated at you from the environment while
| you still would start radiating at 900 and going quickly
| downhill from that as you surface quickly cools down (that
| is supposing you don't have some performance enhancing
| stuff Expanse style to generate 900 watts boiling you blood
| to bring those 900 watts non stop to the skin) until coming
| into equilibrium with the environment.
| jdlyga wrote:
| Minus 173deg C. The US does use Fahrenheit, but not for
| science.
| accrual wrote:
| > For the second mission in a row, the lander's altimeter failed
|
| That's a bummer. Altimeters are relatively simple and defined
| hardware as far as I know. Send a ping, receive a ping,
| calculate. Too bad they didn't incorporate a backup solution.
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