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Athena landed in a dark crater where the temperature was -280° F / -173° C

arstechnica.com

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Re: Athena landed in a dark crater where the temperature was -280° F / -173° C

#121

Post by strangattractor »

_bin_ wrote: post #81
JshWright wrote: post #40

Earlier quoted context omitted.

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.

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.

Or use New Glenn which works now and has a larger faring.

Re: Athena landed in a dark crater where the temperature was -280° F / -173° C

#123

Post by PantaloonFlames »

nomel wrote: post #117
ceejayoz wrote: post #8

Earlier quoted context omitted.

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.

> "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.

Ya the wording was not quite … satisfactory. I think they meant , it could tell X and Y, but not Z.

But all three are important.

Related - I’m not clear how the article can describe that landing as “not crashing”. If that was not a crash, what was it? Will they call it a crash only if there are Hollywood-style explosions?

Re: Athena landed in a dark crater where the temperature was -280° F / -173° C

#124

Post by dietr1ch »

abdullahkhalids wrote: post #116
dietr1ch wrote: post #62

Earlier quoted context omitted.

Which is hard to grok since a third of something warm doesn't seem to be extremely cold.

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 p…

It's hard, I can imagine the average kinetic energy slowing down, but can't imagine heat halving since there's no halving we can feel without dying.

Humans should experience something within -50°C to 50°C for most, if not their entire lives, but that's just 223K to 323K, maybe that's the range we can understand as a warmth difference, so getting to that temperature might feel like that super wide, in human warmth terms, drop in temperature twice, which still feels unimaginably cold.

Re: Athena landed in a dark crater where the temperature was -280° F / -173° C

#125

Post by Frederation »

JumpCrisscross wrote: post #61
sandworm101 wrote: post #56

Earlier quoted context omitted.

>> 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/

> 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.

Keep that Musk copium going, man!

Re: Athena landed in a dark crater where the temperature was -280° F / -173° C

#126

Post by PantaloonFlames »

russdill wrote: post #85
1970-01-01 wrote: post #7

Still unclear what happened. Did they not anticipate a big moon hole or did navigation fail when the rangefinder failed?

It touched down with a large horizontal velocity component

That’s another thing that bothered me about this story. They said they knew where the craft was , relative to the surface of the moon. Wouldn’t that also mean they should know of any substantial horizontal (x/y) component of velocity?

Re: Athena landed in a dark crater where the temperature was -280° F / -173° C

#127

Post by nomel »

sandworm101 wrote: post #80
JumpCrisscross wrote: post #61

Earlier quoted context omitted.

> 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.

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.

For any of these landings, it's a problem of 3d positional/velocity precision. SpaceX has prove that they can reliably land on a target, usually within meters, with negligibly delta velocity on contact.

In other words, they've proven they have the control systems in place for placing a craft at a precise location, with a precise velocity. What requirement do you see outside of this that are far outside of placement and velocity? Autonomous mapping and adjustments for approach maybe?

Let's not assume they're going to try to use their current earthly landing legs.

> land on some random beach,

They did this I believe two starships ago, when they landed in the ocean. Came to zero xyz velocity some target distance above the water, and hovered for a bit. Unfortunately, the surface tension of the sea couldn't support the weight once they lowered for touchdown.

Re: Athena landed in a dark crater where the temperature was -280° F / -173° C

#128

Post by PantaloonFlames »

accrual wrote: post #26
ck2 wrote: post #17

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. A…

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 gra…

First time encountering the phrase “gravitationally lumpy”. I can imagine what that is. But why? I suppose it would naturally occur if the moon were not more or less consistent density. But how would that be possible given the moon’s age and shape. (Roughly spherical I am assuming)

Re: Athena landed in a dark crater where the temperature was -280° F / -173° C

#129

Post by PantaloonFlames »

bell-cot wrote: post #2

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.)

In this domain, Signal lag seems to be an insurmountable problem, when using remote control. 2.7s delay will be hard to mitigate in a dynamic system.

Unless I am misunderstanding something.

Re: Athena landed in a dark crater where the temperature was -280° F / -173° C

#130

Post by driggs »

Is there any sort of international body with regulatory power over the moon, or is it completely lawless and unrestricted?

This startup has already crashed two pieces of space junk onto the lunar surface. Can any startup able to get there do whatever they want?

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