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Comet Probe Philae To Deploy Drill As Battery Life Wanes
An anonymous reader writes With less than a day of battery life left, The European Space Agency's Philae probe will begin to drill for samples even though the drilling may dislodge it. From the article: "Philae is sitting in the shadow of a cliff, and will not get enough sunlight to work beyond Saturday. Friday night's radio contact with the orbiting Rosetta satellite will be the last that engineers have a reasonable confidence will work. The team is still not sure where on the surface the probe came to rest after bouncing upon landing on Wednesday. Scientists have been examining radio transmissions between the orbiter and the lander to see if they can triangulate a position. This work has now produced a 'circle of uncertainty' within which Philae almost certainly lies."
Drill baby, drill!
Join us at 2 for #cometlanding briefing with @ESA_Rosetta and @Philae2014 experts from @esa @DLR_en @CNES @NASA
Why was this designed to use mainly solar instead of a radioisotope thermoelectric generator like the voyager probes?
A comet's trajectory out of the solar system would have been interesting thing to ride on, but then solar wouldn't be a viable option.
What state would the man be in after 10 years in space?
How big would the initial launch have had to be to keep a man alive for 10 years in space?
Watch this Heartland Institute video
Part of the problem is that some of the systems intended to help the probe land properly aren't working, like the thruster on top.
Some of it seems like just poor planning though. How hard would it have been to install a bright LED on the top that Rosetta could see from a few km away? LEDs don't weigh much and you only have to run it while Rosetta is taking the picture so the power budget would be nominal. It seems better than not being able to find the lander because it is in shadow.
I read the internet for the articles.
"It seems to me the design and/or planning of this mission were poorly thought out"
Is the funniest fucking thing I've heard all day. Do you have any idea how well thought out this mission was? FFS look at the trajectory it took 10 YEARS(!) to get to the comet. And you think they overlooked the fact that the comet is craggly?
Jesus-Dunning-Kruger-Christ.
http://www.esa.int/esatv/Video...
Another stunning image of my new home taken by ROLIS during #CometLanding yesterday, when I was just 40 m from #67P pic.twitter.com/I8OZ5kXjXA
> What state would the man be in after 10 years in space?
The "Bored" state.
---- MISSING MISCELLANEOUS DATA SEGMENT --- [sigdash] trolololol
Radioisotope thermoelectric generators (RTGs) are big, heavy, and emit radiation that screws up some of the instruments.
The ones on Voyager are about the size of Philae. from Wikipedia: The GPHS-RTG has an overall diameter of 0.422 m and a length of 1.14 m.[1] Each GPHS-RTG has a mass of about 57 kg and generates about 300 Watts of electrical power.
Philae:
Launch mass 100 kg (220 lb)[1]
Payload mass 21 kg (46 lb)[1]
Dimensions 1 Ãf-- 1 Ãf-- 0.8 m (3.3 Ãf-- 3.3 Ãf-- 2.6 ft)[1]
Power 32 watts at 3 AU[2]
Unfortunately, RTGs don't come in multiple sizes, so you can't get a 1/10th scale RTG that weighs 6kg and is 15 liters in volume.
I don't know if ESA has access to RTGs in the first place, or if public policy would allow launching with a radiation source. The Cassini RTGs causes a huge public relations problem when it was launched in 1998.
There's also limited Pu240 available to make the RTGs.
All hail the armchair asteroid mission planning experts. Why they keep hiring professionals to do these jobs is beyond me.
Philae bounced twice, the first bounce was about two hours, the second one 7 minutes. If the gravity on the comet is 1/200,000th that on earth (a reasonable estimate, it varies around the comet because it's *way* not round) then the first bounce was about 1,000 feet off the surface, but the second one was only about three feet. Seven minutes to fly up and down three feet; that's almost impossible to imagine.
I love Mondays. On a Monday, anything is possible.
I think we've been spoiled by the various Mars missions, and having rovers lasting well beyond the expected lifetime. We should not assume that all missions will be like that. We should revel in the fact that the probe is working at all after 10 years in space, and that it wa sable to land on the comet at all.
What an insulting thing to say about the astronaut!
I think that's pretty unfair.
It was launched 10 years ago, and has been spiraling around the solar system doing fly-bys to get going fast enough to match speed ... and then it got close enough to land, even though it wasn't perfect.
I'm more inclined to think this is a demonstration of just how damned hard something like this is, and that no matter how much you try to plan for stuff, you can't know everything until after it's happened.
I think a bunch of whiny nerds saying this was poorly thought out is some pretty lame arm chair quarterbacking.
Tell you what, when your probe lands on a comet, we'll all line up to tell you what a shitty job you've done.
Oh, wait, you don't have a probe and wouldn't know how to make one, right?
Lost at C:>. Found at C.
Still more capable than a useless arduino in a shoebox that cost a billion euros.
And when something doesn't go as planned, as inevitably happens at some scale, we get to listen to people complaining about the useless person stuck there that costs 100 billion euros. An the question shouldn't be if a person is more capable than a $1 billion euro robot if the person would cost way more to get there, the question should be if a person would be more capable than 100 $1 billion euro robots. For quite a lot of science work, that is a hard sell, even if a significant fraction of the robots failed, because then we could send them to many different comets and adapt and do different things with them in ways that a person couldn't even do if they were there (e.g. new instruments that require more than just duct taping together parts a person would have).
Drilling and have it become dislodged for an hour or two, hopefully landing in a better place sounds like a feature -- I hope they fire the harpoons a few hours before the batteries are discharged to take the chance of repositioning it in an open area
"How hard would it have been to install a bright LED on the top that Rosetta could see from a few km away?"
If you were to drop the LED frequency into the radio spectrum you could reduce the power requirement further.
They really aren't exactly sure where it is or what the surrounding terrain is like. It is quite likely that by the time the lander gets direct sunlight it will have failed due to prolonged cold.
BUT, the gravity is extremely low and it's not tightly anchored to the ground, so it could (accidentally or on purpose) throw itself into a new location that might work better. They want to accomplish as many objectives as possible first because it could also face plant.
Look, unless you're a friggin' rocket scientist, or believe they had additional information they didn't use ... summarizing anything as "the whole problem" is kind of childish.
Based on your vast experience of landing on comets after a 10 year journey, do you think you have a better sense of what the assumptions about the hardness of the ice should have been? Maybe you should have shared that with them.
Lots of smart people worked on this, took all they knew and could surmise, and made choices with the best available information, and using the technology and money available to them.
I'm sure as heck not going to say "well, if only they'd done this it would have worked". I know I'm not qualified to do that, and I'm quite certain most of us on Slashdot aren't either. In fact, I'm betting the people who are qualified are all thinking this was a monumentally difficult task. NASA isn't sitting around going "Ha ha!"
To me, even what they did is some pretty mind-boggling engineering. But in interviews I heard over the last few weeks, they still knew there were risks and uncertainties.
It sucks, but unless you're more qualified than the entire team who did this, you have to realize this is still an incredible feat.
I won't even claim this to be an accurate analogy: But this is kind of like hitting a target in China from New York, using a home made gun, in the dark, and while both you and the target are moving.
Me, I'll applaud the ESA and everyone involved. Success for this kind of engineering includes all of the stuff that got you there. Getting far enough to have a failed landing is still a huge undertaking.
Lost at C:>. Found at C.
That's why they gave it batteries that last long enough to fulfill the primary objectives of the lander.
The solar panels were for the icing on the cake. Or rather the icing on the icing of the cake - most of the scientific relevant data is collected by the orbiter.
GP is right - there's no other place where the gap between actual and imagined capabilities is so dramatic as on Slashdot. I really wonder where this overestimation of the own capabilities coupled with an uncalled-for arrogance comes from.
"It seems to me the design and/or planning of this mission were poorly thought out"
Is the funniest fucking thing I've heard all day. Do you have any idea how well thought out this mission was? FFS look at the trajectory it took 10 YEARS(!) to get to the comet. And you think they overlooked the fact that the comet is craggly?
Jesus-Dunning-Kruger-Christ.
http://www.esa.int/esatv/Video...
And Philae bounced twice, finally settling in two hours after first touching the comet, which is enough time for the comet to rotate almost 60 degrees. The two systems meant to prevent bouncing - the thruster and the harpoons - failed, so it ended up some kilometer away from the carefully chosen site. That we are getting any science at all after that potentially mission-killing news is just fantastic.
I'm hoping they make some last-ditch effort to have Philae try to jump over to another part of the comet to get more sunlight, though I'm not sure what kind of resources they have to try it. Can they command the drill and/or the legs to jab downward relatively quickly? Command the harpoons to fire? I don't know, but you can bet this will be part of the design on future missions. I actually did some work on this, which made hopping around a key part of the mission.
I doubt that anyone who worked in any serious capacity for the Mars Rover program would mock these folks. They know everything that could go wrong in ten years of space travel.
That's a strange assumption. Whence did it come?
I did intend to say maybe 10-100 billion, but went with the higher end because of how expensive it is to get people just considering how expensive it is to get people to near-earth orbit and inflation adjusted prices for the Apollo program. It could easily cost a lot more than that, but even if you take the lower bound of $10 billion, that still can buy a lot robots for ten times the price, especially since a large fraction of the cost is development costs. With few exceptions, space agencies seem to focus on using money to develop new and better probes instead of producing a few of the same type, even though that is an option.
Probably yes.
And from someone complaining about assumptions. It really comes down to what science goals you are trying to achieve. If your goal is to move manned flight ahead, then of course you need to do things with more people, although don't need to disguise it as being done to improve success rate of missions like this. If your purpose is to do composition analysis of materials, and measure mass distribution in comets and asteroids, especially in some sort of comparative sense, then a boring probe would be great at doing repetitive scans.
At this price and success rate, hardly.
Seriously, are you dense enough to think that a sample size of one is a great estimate of success rate? Which is also not perfect for manned missions either? And also think that we could send a person for the same cost as a single unmanned mission, and couldn't send multiple unmanned missions for the price of a single manned mission?
I wasn't specifically asking for you to go, there are quite a few people who have more skills than being able to duct tape.
I only design and build high resolution spectrometers for a living, including ones that get used in laser induced breakdown spectroscopy. The issue is not that I only know how to use duct tape, but that I know exactly how much equipment and tooling is needed to build such instruments, considering I've built them from scratch in a machine shop myself. Once constructed, a lot of instruments will have very limited flexibility to be changed with portable tools. They won't have a full machine shop there, and even then a lot of specialized components can't be made in a normal machine shop and require a lot of other special tools and services. A person could still tweek something in situ. But considering even a robot mission like this has over a dozen different instruments, it isn't just about knowledge of how to service all of them, but also time. It is bad enough screwing around with alignment on an optical device for a whole day because of a spec change or design fault when you have a nice open lab and that is the only instrument you are working on at the moment. At some level, regardless of the skills of the person, they're options will be limited to banging on something a few times before moving on to something else with less risk of eating up too much time.
But as you said, I guess I don't have enough skills to have an opinion on such things, and am sure that you aren't making any assumptions or superficial judgements despite the lack of content in your post.
To be honest, the trajectory calculations aren't that difficult. It's fairly cut and dry math and there have been computer programs to calculate this stuff for decades. It's cool, don't get me wrong, and the margin for error is a lot smaller than trying to hit Jupiter, but it ain't exactly rocket science.
Wait...
We don't have a state-run media we have a media-run state.
"It seems to me the design and/or planning of this mission were poorly thought out"
Is the funniest fucking thing I've heard all day. Do you have any idea how well thought out this mission was? FFS look at the trajectory it took 10 YEARS(!) to get to the comet. And you think they overlooked the fact that the comet is craggly?
Jesus-Dunning-Kruger-Christ.
http://www.esa.int/esatv/Video...
True, it's easy to throw snide comments at the people who designed this mission but until now nobody really even knew any details of what the surface of a comet looks like. Furthermore landing on Mars is difficult enough, the success rate for landings on the Martian surface is something like 30%. Getting a probe to rendezvous with a comet and land on the surface is a way bigger achievement. Finally I'm not exactly surprised that some systems failed after almost a decade in space. I just hope they manage to milk the maximum amount of data out of this probe.
Only to idiots, are orders laws.
-- Henning von Tresckow
That's a strange assumption. Whence did it come?
Well, a mannad mission to mars is estimated to need roughly 800 Mg of equipment lifted into space, and then slung out onto a mars intercept orbit. The orbit required for this comet intercept is thankfully pretty similar (it needs only to get around mars to do a gravity assist back to earth, for a few more gravity assists to get out to jupiter). But a mission to mars would take only 2 years, this requires 10. That means 5 times as much food, and I'd bet a bunch more equipment. So lets conservatively guess at 1.6Gg of stuff that needs to be lifted into space.
Meanwhile, the launch mass for the robotic longer was a mere 100kg. So, even if you assume that you can scale the amount of fuel needed to get all the stuff up there linearly (which you can't), you're looking at 16000 times the cost, i.e. $1.6 trillion.
To me, it appears that the above poster underestimated quite a lot, not overestimated as you'd like to believe.
It seems to me the design and/or planning of this mission were poorly thought out, it's obvious the comet has a rough surface, they knew there would be shadows.
The planning for this mission was started 30 years ago - in 1984; 5 years before the Berlin Wall came down, 7 years before the Soviet Union was dissolved, 3 years after the first IBM PC was released. This mission has been compared to "throwing a hammer from London and hitting a nail in New Delhi".
Imagine that - the IBM PC with its 16 KB of RAM was advanced, for gods' sakes! It may be that it is easy to sit in front of your top-of-the-bloody-range games PC and imagine that 'it can't be that hard', but the fact is that it would be very hard even today, and the fact that we actually have anything man-made touching the surface of an actual comet at this moment is mindblowing. It was only really designed to run a few measurements on its main battery, and even that was considered beyond what we could reasonably expect; the secondary battery and solarpanels were more of a "you never know, we might get lucky". This mission has already been a huge success.
Hey Kerbal has taught me a lot about this kind of thing
1) Solar panels everywhere..hates it when I run outta power
2) Put a protruding strut on the top of the lander just in case your lateral motion causes you to topple
3) To stick the landing a bit of mystery goo can me most efficacious.
4) Get some mods...Philae looks like it was crafted from Vanilla parts.
Well, apparently they planned to launch with the gravity assists and eddies needed, and to intercept the comet's trajectory. That's macro-scale planning: "I'm going to go grocery shopping at Big K-Mart".
They apparently didn't plan back-ups for parts failure (thruster on top), landing anomalies (bounces around), losing track of the probe, or landing in shadow (couldn't make it mobile enough to move to a lighter place). They also didn't consider the cost in delivering a payload, versus the cost in delivering a slightly larger payload--two probes, which is less than two probes and two launchers and two fuel loads. That's micro-scale planning: "I need to carry a second credit card in my wallet in case I run low on cash or the first has a mag strip failure".
It's certainly easier to plan a mission that can get there and do its work if all goes well compared to if things go wrong. Realizing that something can be done and drawing up the plans to point-and-shoot isn't "well thought-out"; risks and contingencies are what make a plan well thought-out.
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We're all glad you're here to share your wealth of experience in space probe design with us.
In 1984 no one bought an IBM PC with 16k of RAM. 256K was normal, larger sizes less so, but not entirely unheard of. 640K was growing common within a couple of years, but the great RAM price spike of the late 80s (something like $1k a meg) put a little bit of a damper on that.
HBI's Law: Frequency of calling others Nazis is directly correlated with the likelihood of the accuser being Communist.
The battery life is good enough for the primary mission which is to plunge a drill into the comet. After they've accomplished the mission they will probably try something, but give them time to analyze things and accomplish the primary goal before they try.
Keep in mind they try to jump and they might jump into deep space.
Because that's all science ever is, some scam to get money. Understanding the universe better is just an annoying side effect that they don't give a shit about.
What state would the man be in after 10 years in space?
With adequate life support, as good as new,
Hardly. Cosmonauts returning from Mir after only one year in space could barely function once they returned to earth. I kind of doubt that anybody would physically survive 10 years in zero-G, even assuming they've survived the long-shot odds of no fatal spacecraft malfunctions in 10 years.
Not to mention that they would gone bat-shit insane by that time, after they realized that they've sat in a tiny tin can eating stale cat food and being blasted by cosmic rays for over a decade just so they get a sample of some crappy small-time comet; a job that could be easily done by a robot.