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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).
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...
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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