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Athena spacecraft declared dead after toppling over on moon

theguardian.com

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Re: Athena spacecraft declared dead after toppling over on moon

#321

Post by weebull »

sfblah wrote: post #318
somenameforme wrote: post #283

Earlier quoted context omitted.

It's not just the center of gravity. I think people really underestimate how hard landing on the Moon is, because counter-intuitively, the lack of an atmosphere makes things harder, not easier. Landing on Mars (or even Venus (!!) - which is the first other planet we ever landed on) is easy mode by comparison. With the lack of atmosphere is that there is no 'natural' attitude/orientation correction. If you're tilted 5…

So are you saying that landing the lunar lander in 1969 was substantially harder than SpaceX landing its boosters back on Earth?

In 1969 they used a pilot, and a very good one too.

Surveyor 1 in 1966 is a much better comparison.

Re: Athena spacecraft declared dead after toppling over on moon

#322

Post by renewiltord »

carabiner wrote: post #3

Jesus. It really is that hard. With all the bajillion in extra compute and simulation time from Apollo era, we can't do hard things anymore. We don't know how.

Apollo is like 200 billion dollars adjusted from 1973. This cost about as much as 40 public toilets in SF. They can just keep trying.

Re: Athena spacecraft declared dead after toppling over on moon

#323

Post by havelhovel »

ndr42 wrote: post #249
celsius1414 wrote: post #81

Earlier quoted context omitted.

You are likely aware of the English language's feature of multiple adjectives (that are modifying the same noun) needing to appear in a certain order to sound "correct". So for example "yellow big balloon" sounds wrong but "big yellow balloon" sounds right. This is because SIZE is supposed to come before COLOR in standard English phrases. In this case, "robotic" and "private" could be similar enough in category to be…

In other languages (e.g. German) you can "fine-tune" the order and hierarchy of the attributes with a comma. private, robotic spacecraft (with comma) -> private and robotic are attributes to spacecraft, the order could be changed but as in english you have an order that is more likely used private robotic spacecraft (without comma) -> the attribute private refers to a robotic spacecraft If you would like to emphasize…

It’s the same in English. There was supposed to be a comma between both words because they’re coordinate adjectives.

Re: Athena spacecraft declared dead after toppling over on moon

#324

Post by dreamcompiler »

astar1 wrote: post #280

These 2 failures could have been easily avoidable both times. I really wish there was a push in the US government to create and stockpile plutonium-238 and ensure it's readily available, subsidized, and offered for all US probes/rovers/other scientific instruments in space (whether it be for NASA's use who currently has to ration because of how little they have left, or for private use after approval). Like, why aren…

One reason all space scientific instruments are not powered by RTGs is that prior to each launch NASA has to run a very involved and time-consuming risk analysis program to determine just how much of the state of Florida becomes uninhabitable for the next 10,000 years if the rocket blows up on the launch pad.

I used to conduct said risk analysis.

Re: Athena spacecraft declared dead after toppling over on moon

#325

Post by JoeAltmaier »

ForOldHack wrote: post #202
JoeAltmaier wrote: post #105

Earlier quoted context omitted.

I think that is entirely irrelevant. It just changes the speed of the topple. Does not affect at all the tendency to tip over?

Physics 1A: the center of mass does not change. It is irrelevent. The tendancy to tip over is how wide the base is: look at the LEM. Big wide base. Did not tip over. None of them tipped over. They tip over faster on earth due to larger Earth's gravity and mass.

That is exactly a description of why center of mass is the important variable. If the center of mass wanders outside the support point, it tips over. That's the whole deal right there!

Re: Athena spacecraft declared dead after toppling over on moon

#326

Post by ForOldHack »

echoangle wrote: post #187
ChicagoDave wrote: post #173

I seriously do not understand why moon or mars landing structures aren’t some kind of dodecahedron. It can always correct itself after landing and then “unpack” itself. Someone tell me why we’re not doing this.

Because making a lander that’s wider and lower like the Firefly one is simpler and you have to control attitude for the landing anyways. Making it not tip over is easier than making it spherical and unpacking it after landing. But IM apparently chose to do neither of the 2 options…

Difficult to get into or it, but assemble in orbit... Read Digital Apollo. The moon is rocky. Really really rocky. You need enough fuel/thrust for your remote sensing to idle while Houston proceses you options.

What if spherical comes up against a rock or crater wall as big as it is? Splat.

Re: Athena spacecraft declared dead after toppling over on moon

#327

Post by [deleted] »

sfblah wrote: post #318
somenameforme wrote: post #283

Earlier quoted context omitted.

It's not just the center of gravity. I think people really underestimate how hard landing on the Moon is, because counter-intuitively, the lack of an atmosphere makes things harder, not easier. Landing on Mars (or even Venus (!!) - which is the first other planet we ever landed on) is easy mode by comparison. With the lack of atmosphere is that there is no 'natural' attitude/orientation correction. If you're tilted 5…

So are you saying that landing the lunar lander in 1969 was substantially harder than SpaceX landing its boosters back on Earth?

[deleted]

Re: Athena spacecraft declared dead after toppling over on moon

#328

Post by ForOldHack »

ZeWaka wrote: post #136
aabiji wrote: post #131

Earlier quoted context omitted.

No, sound needs a medium to pass through and there isn't (ok fine, yes there is, but it's not sufficient) an atmosphere on the moon. Interesting philosophical questions though :)

Wouldn't the crash make a vibration in the lunar soil? I know it's actually quite dry, thin, and dusty, but half the density of common Earth rock (~1.6 v. ~2.7g/cm³) should still conduct some sound. If you put your ear (or more likely, a microphone) on the ground...

Look up the earth material with the closest density. It's a type of cheese,and yes, the sound will propigate through Christmas. Wtf? Firefox I said Cheese. . (Myth) Actually the closest rock is silicate basalt. Sharp and dusty.

What if we had sticky landing pads? And literally glued the probe to the surface? ( No. You would either have to find a rock or you would simply collect dust. )

There are many brilliant ideas here.

Re: Athena spacecraft declared dead after toppling over on moon

#329

Post by ForOldHack »

ForOldHack wrote: post #253
trhway wrote: post #176

given the low gravity and $200M+ cost of mission, one would think that 3-4 thin spider-like-wide legs would be a must, especially after similar failure several months ago. Or just an inflatable "donut" around the lander (which would be deflated once the lander is standing upright).

This is brilliant but for the very wrong reasons. Make it a rescue mission. All you have to do is to have one mission pick up the first mission.

I realise that it is a lot more difficult. What if it landed on a sea of smooth pool balls? I bet there is going to be a good long laugh when we find it.

Re: Athena spacecraft declared dead after toppling over on moon

#330

Post by ForOldHack »

carabiner wrote: post #3

Jesus. It really is that hard. With all the bajillion in extra compute and simulation time from Apollo era, we can't do hard things anymore. We don't know how.

We sent up the best and brightest pilots. One of them went around a crater. We do not know how to replace a trained pilot with a remote computer.

We can do hard things,and we do them because they are hard. Listen to JFKs Rrice U speech.

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