where is the cliff?
European Space Agency (ESA) boffins reckon they may have located the final touchdown site for their comet-intercepting Philae lander, after its bouncy landing caused them to lose track of it temporarily. Philae's bouncing touchdown seen in Rosetta NAVCAM pics Philae's touchdown site seen by Rosetta's navigation camera. The …
It would have been nice to to have some sort of a scale on the photo, but given that the pics are only 5 mins apart and show that philae is climbing and has moved at least 20-30 times its diameter mean that it must have been 500-1000 times its diameter further away when it hit the second time and moved again before its final landing place many times the width of the photo off to the right.
I guess at least they now know where to have a proper look.
If civilization doesn't collapse before we get a next time, can I make the following suggestions as a non-rocket scientist, but a keen observer of history:
1. Send two craft. It worked for Voyager, Pioneer, Viking, Mars Rovers etc. If one fails, you've got a second attempt. It's probably not even twice the price!
2. Redundancy. Did no-one think the comet might have the density of merange, and that pressure-sensitive feet might not work? Two independent thrusters - one a backup? (see above) Maybe a laser rangefinder for landing?
Good job though, at least we go something back. If the EU could maybe trade in a couple of Eurofighters the ESA could send another 4 probes or so...
"1. Send two craft. It worked for Voyager, Pioneer, Viking, Mars Rovers etc. If one fails, you've got a second attempt. It's probably not even twice the price!"
You appear to be under the impression that the landing was a failure. Why? It didn't go as planned, but the team got all the data that they wanted. It succeeded. It did what it was supposed to do. we won! Celebrate!
We've been spoiled by the successes beyond specification of our recent robot invasions and the media is always much more keen to focus on failure than success. As a result, people are getting the impression that the mission 'should have' vastly exceeded all perimeters. That would have been nice, but this time we'll just have to settle for it doing the job it was supposed to, even if it didn't perform it HOW it was supposed to.
Anyway, sending two vehicles to do the same job risks getting the same results twice, which wastes several billion dollars of very precious budget. It's a much better idea to split the money and do two things. That way you hopefully get two sets of results about two different things and expand mankind's knowledge twice as much.
"2. Redundancy. Did no-one think the comet might have the density of merange, and that pressure-sensitive feet might not work? Two independent thrusters - one a backup? (see above) Maybe a laser rangefinder for landing?"
I imagine that the PhD-toting literal rocket scientists will have done a better design job than you or I, and will have considered many factors that we are not aware of.
Bear in mind that rocket payload is a very delicate balancing act, and the vast additional about of fuel needed in the stack for every extra kg of payload. As demonstrated by one of the better named equations in engineering:
You can't just add spare things because they *might* be used. Especially given that the lander was not a critical part of the mission. I suspect any available mass for redundant systems was front-loaded and used on components that got us to the comet in the first place, rather than on proverbial cake-icing.
Landing a failure? As you say the scientist seem to have got what they wanted (seems that it was planned that they would have enough time on battery power to do the important science stuff) ... and if it had landed better and got solar power to charge the batteries we doubtless end up with the opportunity style articles along the lines of "lander only designed to work for 60 hours still working after 3 months"
>Superglueing a cat to the bottom of it might do the trick.
>Oh, on second thoughts, that wouldn't help - it would spend even more of its time in sleep mode.
The cat would fall asleep in a sunbeam, though, allowing the batteries to recharge.
If a cat is super-glued to the underside of a space probe and there is no one there to observer it then it is in both a state of aliveness and deadness. As such, cats can survive in space without any viable form of life support making them far better suited to exploration of the cosmos than man.
"I'm no rocket scientist but if they did manage to find the lander, how about re-positioning Rosetta's solar panel array to reflect sunlight down to the shadows in which lander resides?"
This was put to the panel during the google hangout on Friday lunchtime. All three of the panel laughed. One of them did then give a fuller answer which included the fact Rosetta is orbiting, not geo-stationary, you couldn't make it geo-stationary, it wouldn't reflect enough light and a few others besides.
Hmm...Rosetta has solar arays to do what ?....absorb the light at the best wavelengths to turn it into electricity.
So how much is going to be reflected off? not a lot.
Then you have to steer them precisely, and the spreading 'spot' will be much larger than the lander's panels...which will be a the wrong angle most of the time.
a replacement battery that may cost five times what even Halfords would dare to charge but does come with a slightly extended guarantee
The batteries are all the same.
I briefly worked for a parts distribution company. When we had batteries to deliver, the order sheet would specify which guarantee the customer had ordered. We would then stick the guarantee sticker for that to the battery of the appropriate shape/size/capacity spec, and deliver it to the motor factor.
 ADS, in case you were interested. They're gone now...
He meant AA. Or RAC, Green Flag or other roadside breakdown repair and recovery service. Unless he meant AA or AAA 1.5v cells, enough of which would power the probe.
AA is the Automobile Association in the UK, though we do have meetings of Alcoholics Anonymous too, apparently.
To be fair, the AAA - the American Automobile Association - is just as close to Rosetta as its British equivalent... but seeing as this is a European mission...
Startling how all the smaller features change between the 2 shots. I'd assumed it was either the shadow angle changing or a pack of Clangers running for cover, but with only 5 minutes between shots the shadow theory seems weak.
Now if we knew the scale we could estimate the top speed of a Clanger in an emergency, good science and terrific PR. What a mission this is turning out to be.
...Re: ...for the nth time....
Building them and getting them to only explode in the direction you want them to is indeed engineering.
But getting them to fly to where you want them to is science.
Building them and getting them to fly ANYWHERE is engineering.
Deciding where to fly them and why is science.
er .. contrary to what it says in this article, ESA haven't yet identified the final touchdown point of Philae. The photo shows the initial landing place and captures Philae mid-bounce. They've also located the probable second bounce point, but not yet the final position. More info here:
Two images taken at 15:30 and 15:35? With so many subtle pixel shifts and differences between the two posted images unrelated to the landing site, the ESA's press releases and celebrations seem premature. Were there other images in between like 15:31, 15:32, 15:33 or 15:34? Or, after 15:35? On another website, I saw lower resolution images from a different vantage point (?) taken supposedly at 15:18 and 15:43 with different results.
...into the idea that Philae has gathered the data it was supposed to gather.
This is not true, as a glance at the Mission Aims statement will show you. Philae was meant to touch down on the surface, and then send back data AS THE COMET STARTED OUTGASSING on its way to perihelion. That would be next summer.
The initial data set is fine, and it's a great achievement to have placed the craft on the surface of a comet. But, because they were relying on solar power, and because of the poor landing, Philae will probably not be able to fulfill its primary mission.
Just thought I'd mention this...
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