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Comet Probe Philae Unanchored But Stable — And Sending Back Images
An anonymous reader writes with an update to the successful landing of the ESA's comet probe Philae, which (as mentioned yesterday) had problems attaching to the surface of the comet's Rosetta: "BBC now reports that Philae is stable on the surface. Although no source claims so, we can all imagine a faint humming of 'Still Alive' coming from the probe." Not just stable, but sending pictures while it can. From the article: The probe left Rosetta with 60-plus hours of battery life, and will need at some point to charge up with its solar panels. But early reports indicate that in its present position, the robot is receiving only one-and-a-half hours of sunlight during every 12-hour rotation of the comet. This will not be enough to sustain operations. As a consequence, controllers here are discussing using one of Philae's deployable instruments to try to launch the probe upwards and away to a better location. But this would be a last-resort option.
New submitter Thanshin notes that the persistent Philae bounced a few times, and actually performed 3 landings, at 15:33, 17:26 & 17:33 UTC.Thanshin adds links to a handful of relevant Twitter feeds, if you want to follow in something close to real time: Philae2014; esa_rosetta; and Philae_MUPUS (MUlti PUrpose Sensor
One).
Now Philae seems to be sideways and under the shadow of a cliff that only let's it have sunlight 1,5h per 12h cycle.
That amount of sunlight may not be sufficient to keep Philae operating beyond its 60h battery autonomy.
Most info seems to appear first in BBC news
Why did we get away from that technology for space exploration? If you're going to spend the money to conduct a mission of this sort why limit yourself to the power provided by solar panels? It would be a pisser to have come this far only to have the mission fail because the probe can't get enough power to carry on operations.
I want peace on earth and goodwill toward man.
We are the United States Government! We don't do that sort of thing.
Why does every science-illiterate newsreader think that the most amazing part of the mission is that "the comet is moving at thousands of miles an hour?" This was amazing months ago, when Rosetta moved into its station-keeping formation with the comet. Right now, it is stationary with respect to Gerasimenko. What's incredible now is the deployment of Philae and its fight for survival in a totally unknown environment.
I don't know how much heat an RTG emits, but if you're trying to land on a comet, it would be a real pain if you melted away the surface you had landed on.
politicians are like babies' nappies: they should both be changed regularly and for the same reasons
"Unanchored But Stable — And Sending Back Images"? Let's call the next comet probe "Kim Kardashian". Then again, Philae is stable.
You are lucky to get 10% efficiency from an RTG with a thermoelectric element, and proper Stirling engines or steam turbines are not popular in space for some reason.
However, Philae only needs 32W apparently.
Finally! A year of moderation! Ready for 2019?
"The lander weighs about 220 pounds and is the size of a domestic washing machine"
I'm waiting for the Saturday Night Live skit..
Due to a terrible mix-up. a Maytag washing machine was inadvertantly placed in the cargo hold of the Rosetta spacecraft.
"My socks have been missing for 10 years!" said Matt Taylor. He also added that now he knows why the washing mashine in Mission control does such a horrible job on the rinse cycle and has stymied the Maytag repairmen/women for the last 10 years.
"In hindsight we should never have put the washer next to the Phileas unit", Matt stated as he scratched at his wrinkled shirt. "On a positive note we now have a washing machine (!) on the comet and have mangaged to contact the circa 2003 unit and initiate a spin cycle".
Matt refused to comment on the Ulyssus launch in 1990 where his daughter's "Easy Bake" oven was mistakenly put into orbit for a mission relating to Polar observations.
At the moment, the Philae mission is a partial, or qualified, success. They'll be receiving the passive science data and imagery, but let's be realistic: they have no way of anchoring Philae to the comet, they can't drill, and any attempts at "bouncing" it are at the mercy of how much gyro range is available to keep it stable while it follows the ballistic arc - and whether it'll come down anywhere safe enough to keep itself upright. The gravity is so small that the lander could "impact" the comet upside down and it wouldn't damage it, it'd just make its orientation useless for the deployment of drilling instruments. Heck, it may be that the gyros have enough oomph to roll the Philae if it ends up upside-down, although it'd probably tumble for a while before setting in some other random orientation, possibly still a wrong one.
They have to weigh the battery life against science returns - and right now there's no battery recharging to speak of. That's the hard part of rocket science - it's not through any fault of mission design, it's simply a bad luck. So, I bet they'll keep Philae where it is up to say 48-50hr mark, and then they'll re-enable the gyros and attempt a bounce, and they'll get one shot at it due to the time the bounce will take, and the link availability constraints due to Rosetta's orbit. I really wonder if the harpoons didn't work due to insufficient contact forces and a sequencer step to shoot the harpoon not being triggered, or if it's due to a failure of the harpoon deployment mechanism itself. It wouldn't hurt to reattempt a harpoon firing once the bounce ends with a recontact.
I'm still wondering why they couldn't get the Rosetta spacecraft itself to be the lander. It's a much bigger platform, it has a proper RCS system and could easily land and take off to scout multiple locations on the comet. Not having a stand-alone lander would give enough available weight to put the instruments on Rosetta itself, and take the extra fuel to do repeated landings and take-offs. That's at least according to my back-of-the-envelope fuel budgeting, I may be way off, though...
Overall, the biggest lessons learned are about things didn't work. Any further low-gravity comet lander designs will need to use designs that include fixes for whatever didn't work this time. I really wish they did, for example, store a duplicate thruster fuel supply system on Earth, in cryogenic conditions, for the decade Rosetta was out there - I bet it'd fail on Earth just as it failed out there, and it'd be an easy thing to post-mortem. But that time has passed, so we may never know what went caused the failure of the puncture pin system...
A successful API design takes a mixture of software design and pedagogy.
You are lucky to get 10% efficiency from an RTG with a thermoelectric element, and proper Stirling engines or steam turbines are not popular in space for some reason.
I presume that reason is water weight, in the case of steam turbines, and the lack of free atmosphere to work with in the case of stirling engines. If you could somehow get the water there, though, a recirculating steam system seems perfectly cromulent. Certainly the system efficiency is dramatically better than an RTG, and it doesn't require any especially exotic materials.
If you had unlimited mass to work with (ha!) and you were using water for reaction mass anyway, it might actually make sense. Not here in the real world of today, but it's an interesting idea anyway :) Perhaps it makes sense in an asteroid mining context, which we're nowhere near probably in large part due to our failure to expand our operations in space. We could have built a pretty big station out of the space shuttle main tanks, for example.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
I have a question... Does anyone know why are the photos in black and white? Is that for higher resolution, because of low/high light situations?
Ok nvm, found my answer here: Why are images from space probes always in black and white?
Still think they should take photos with RGB filters too so we can see what it would actually look like, you know, for PR photos...
Hmm, the humour and sarcasm seem to have been be lost on you.
This is so cool. ... Isn't that freakin' amazing? ... I'm getting goosebumps all over and feel like back in the 70ies when we'd been to the moon. (my Grandpa worked at Grumman as a Engineer on the Lunar Lander btw.)
We've landed on a friggin' Comet! This is so awesome!
F*ck yeah! YAY! Go, space exploration, go!
We suffer more in our imagination than in reality. - Seneca
Wait, you actually watched MSNBC? I didn't know people actually DID that...
Those aren't pictures from the surface(as of right now). They were taken by rosetta from orbit.
If this were an American probe, would the commentor also have dismissed this landing as easily?
On MSNBC, yes. It would have also been declared waste of money that should have gone toward wage-inequality.
Not sure who "they" is but from a quick look at Fox's coverage it seems as good as other sites (and yea, they have the usual "comet is traveling really fast" comments).
A lot of problems do seem to be caused by trying to do to much in unknown environments. A Russian Mars lander in the early 70's even had a little rover. This was before anybody knew what the surface of Mars was even like: rocky? sandy? dusty? If they focused instead on making it simple and robust, they could have had the first successful landing.
Same with UK's Beagle lander. If they had made it simpler and smaller, they'd have enough money left over for more parachute tests, which they regret skimping on now.
In a new environment or if you are a newbie space nation, it's usually best to follow K.I.S.S.
The US sent a small simple rover to Mars, Sojourner, before sending bigger rovers, and this is partly the reason for the rover successes.
Table-ized A.I.
That may be true, but I would argue that is entirely CNN's fault for making themselves into such a joke of a network the last several years, rather than a success of MSNBC.
EDIT4 : It's resting on "hard" ground, with a layer of dust about 30cm, and that's good news because it allows measurements to proceed as planned. As in, it's not burried into soft soil.
EDIT5 : Solar panels are deployed, radio link is up and running, but the fact the probe is slanted/in a hole/random ground limits the time it can communicate with the orbiter, altho that's not jeopardizing the mission. There's already a lot of things transmitted successfully to the orbiter. Contact between the orbiter and the probe can be done twice per day. EDIT6 : The first place it touched the comet was exaclty where it was planned, flat and cosy, too bad it didn't harpoon there. EDIT7 : Next contact will be near 19:30GMT, until 23:45GMT approx. This night they made contact with the probe (from the orbiter) at about 4:00GMT, and at 5:30GMT they had safely recovered all the data from the first batch of tests. From the ESA blog :
The team are ensuring that Rosetta maintains an orbit that is optimised for lander communication support; they are planning a manoeuvre (thruster burn) today to be conducted on Friday that will help keep Rosetta where it should be. Rosetta already conducted a burn last night as part of this effort.
Rosetta is presently sending signals to the ground stations at about 28 Kbps; Ignacio says that the spacecraft's own telemetry downlink uses about 1 or 2 Kbps of this, so the rest is being used to download science data from Rosetta and lander science and telemetry from the surface.
Important press conference from ESA at 13:00GMT. Over now. http://rosetta.esa.int/ EDIT8 : So there was more photos, and details. Important bit, they're planning on righting the lander, studying the best way to do it. First rebound was about 1000m long, 0.38m/s up, lasted 2 hours. 2nd rebound was 0.03m/s, 7 minutes long. Then it stuck itself in the side of the crater at the 3rd impact.
EDIT9 : Harpoons received the signal to fire, but didn't activate. There's no indication of damage on solar panels. The lander can hibernate and may likely still work several monthes from now, even if under limited power. They confirmed the orbiter will make adjustement tomorrow morning (friday) to optimize communication time with the lander. Operations are prioritized, from the less risky to the most.
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