Post #396,365
11/15/14 2:29:45 AM
11/15/14 6:33:55 AM
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Day 3 summary from Telegraph/UK
Here. Pity.. that 10 years ago they had not the battery power-density of today :-/ Cosmic ill-Humour re the recalcitrant Two! gadgets.. for screwing-In instead of -Up. :-/ (They were Right that these devices were bloody-necessary; +1 for foresight.) [Optional, some comments exchanged with a physics cohort And a suggestion.. tyrellcorporation • 14 hours ago
Just a wild idea but if they located the lander could they re-orient Rosetta to reflect sunlight onto it? Apparently the solar panels are the length of 3 double deckers. And an opinion.. daviecrockett • 2 days ago
I find the entertainment and interest value of the Rosetta project much greater than that of all the Football World Cups, Formula One meetings, Olympic Games and Superbowls together, so for that reason alone it's justified. Sorry for the thickies who can't appreciate that, just move over for once. And mine: me too.. What an exquisitely choreographed crash-course in the genius of Newton and the n-folk standing on his shoulders, since.. We'll never know fershure IF.. the screw-in device really could have functioned [torque!] as tested, hoped--but only in our 1 G grav. field--(I guess..) How Do you simulate a .001 G field? More accurately: simulate such, within a static field 1000X stronger. A game of pocket billiards with dandelions? Lastly, a bit of Econ: Barry Kort moscowhead • 2 days ago
1.4 billion euros over 10 years works out to less than 2 euros per person, or a measly 20 cents a year per European taxpayer.
The average person will spend 2 euros on a cup of coffee and the daily paper, just to sit down and read the story.
Compare that to the $3 trillion Americans paid for 10 years of pointless war in Afghanistan and the Middle East. That cost each American $10,000, or $1000 a year. I'd say the Europeans got a much better return for a whole lot less money. Thou. sayest.
Edited by Ashton
Nov. 15, 2014, 02:52:00 AM EST
Edited by Ashton
Nov. 15, 2014, 06:33:55 AM EST
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Post #396,371
11/15/14 1:06:45 PM
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How to test the screws
Suspend the lander and a comet-analogue sideways by very long wires. The longer the wires, the more consistent the artificial gravity as the objects move. Move the suspension points closer or farther apart to simulate different gravities. See if the screws push them apart or dig in.
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Post #396,375
11/15/14 4:59:41 PM
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Tan 90° is handy for that, of course.
Nicely reasoned.
Prelude:
You have a massless, infinitely strong 'wire' with mass M attached.
Theoretically a gnat's wing brushing this (infinitesimally-thin) wire produces an infinite force.
Did everyone get that 'Problem' in a test?
Yeah, for a mere 0.001 G (and lots of calibrations of the non-ideal Osmium tungstate wire's modulus/elasticity): could get you some ballpark results.
'Course that's in 2-D. Should make a lovely physics Final Q. But in 3-D when the torque, screw config/shape are added-in.
Wonder how they modeled it, because when you try to estimate any "realistic" volume avge. density for the comet
ya gets a family of possible solutions re the pitch, necessary length of the drill-bit. Some Problem!
Guess: maybe they did use 'wires', after the computer simulations? with all the various moduli in a humongous equation Pity about the Mass problem (for every piece of equipment aboard): you must have wanted to bracket the solutions and have a bizarre screw shape, starting with thin at the point and going to gradually coarser 'threads' along the permissible length. I see, too: 'radius of gyration' amidst the clutter.
Betting that aerogel was one medium employed.
Base-problem: Time! Ya gots to get the gadget to function during the initial n Sec of compressive contact; embedding must complete ... before the whatever tensile strength of the surface gets tested! Pisser.. not now to know if all their machinations were close-enough.
(Let's do it again, but heavier modules, more boost into orbits than planetary slingshots, etc.) Use the entire dis-US Military Budget: make jobs/but with no collateral-deaths in the expenditures.
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Post #396,378
11/15/14 5:38:18 PM
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"Soil Type: Hardness ranging from fluffy snow to basalt"
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Post #396,379
11/15/14 7:41:17 PM
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Quite interesting. Thank you.
"Religion, n. A daughter of Hope and Fear, explaining to Ignorance the nature of the Unknowable."
~ AMBROSE BIERCE
(1842-1914)
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Post #396,380
11/15/14 7:42:17 PM
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Is Rosetta close enough to get pics of Philae? Could it *get* close enough?
I know nominal mission end is in January, because Philae is expected to be too hot by then. If Rosetta is also expected to burn up, I'd really love for them to fly her in close enough for an actual photo of Philae on the surface first.
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Post #396,383
11/15/14 8:52:00 PM
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Doesn't sound like that is part of the plan.
http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questionsHow long will the Rosetta spacecraft operate?
Rosetta’s planned lifetime is about 12 years. The nominal mission ends in December 2015, after the comet reaches its closest point to the Sun (in August 2015) and starts heading back towards the outer Solar System.
How long will the lander operate on the comet nucleus?
The Rosetta lander, called Philae, will touch down on the comet's surface on 12 November 2014. The science observations will start immediately. During the first 2.5 days the first series of scientific measurements will be completed. During this phase the lander will operate on primary battery power. In a second phase that may last up to three months, a secondary set of observations will be conducted, using backup batteries that will be recharged by the energy from the solar cells on the lander. However, no one knows precisely how long the lander will survive on the comet.
Could activity on the comet's surface damage or destroy the lander?
Survival of the lander depends on a number of factors, such as power supply, temperature, or surface activity on the comet. For example, dust may cover the solar panels, preventing the battery from recharging. In any case, by March 2015, when the comet is closer to the Sun, it is likely that the lander will become too hot to operate. It sounds like they will be doing science with Rosetta even after Philae stops working. Apparently the camera on Rosetta has a resolution of 2 cm per pixel at its normal operating conditions. November 15 report: From now on, no contact will be possible unless sufficient sunlight falls on the solar panels to generate enough power to wake it up. The possibility that this may happen later in the mission was boosted when mission controllers sent commands to rotate the lander’s main body with its fixed solar panels. This should have exposed more panel area to sunlight.
The next possible communication slot begins on 15 November at about 10:00 GMT / 11:00 CET. The orbiter will listen for a signal, and will continue doing so each time its orbit brings it into line-of-sight visibility with Philae. However, given the low recharge current coming from the solar panels at this time, it is unlikely that contact will be re-established with the lander in the near future.
Meanwhile, the Rosetta orbiter has been moving back into a 30 km orbit around the comet.
It will return to a 20 km orbit on 6 December and continue its mission to study the body in great detail as the comet becomes more active, en route to its closest encounter with the Sun on 13 August next year.
Over the coming months, Rosetta will start to fly in more distant ‘unbound’ orbits, while performing a series of daring flybys past the comet, some within just 8 km of its centre. Maybe they'll find it during one of the 8km "fly bys". Fingers crossed. Cheers, Scott.
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Post #413,378
9/5/16 3:40:22 PM
9/5/16 3:40:22 PM
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They finally found Philae!
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Post #413,381
9/5/16 6:42:03 PM
9/5/16 6:42:03 PM
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Best video game in the world
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Post #396,388
11/16/14 4:26:12 PM
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"I. Apathy and A. Peter" are boffins of the 'DIM' module"
Love. It. (Wish the pics were better quality.) Thanks for the sleuthing.
While their comments don't state specifically, does it not look as if they indeed tried to anticipate the fact that the largely un-testable landing MO had many ways to send the sucker all golly-wampus?
And given their use of a Primary-cell for initial power (presumably for max. energy density) it looks as if quite enough of the roster got attended-to, from first contact; haven't yet checked-in today, to see if that snazzy sample probe got somehow to acquire some evanescent samples
The ESS (elect. support sys.) must have been a test of all logic yet explored re. Fail-safe, redundancy, idiot-proofing; hope they pass on whatever was innovative (12? 14 years ago) to see if it could have been built any better, at all(?)
Maybe a benign confluence, free via warming-assistance can reposition the lander enough for enough energy to try clever commands.. like using the legs' K.E. as "rockers", pushers etc. Anyway, deeming this to be some sort of massive failure, is an insult to all responsible for this near-perfect field-trip, ongoing.
Beats the NYT Crossword for Science Suspense..
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Post #396,459
11/20/14 3:25:56 AM
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Kudos and some grumbling over reports to date..
at least the kibitzers are literate, as the Standard Model predictions, recaps of the inertial-hammer & screw are dissected (in the pop-up blogs for each Topic.) Kibitzers here seem disdainful of the performance (after 10 Years! in stasis..) and are already imputing some cover-ups within esa's offered interpretations of the first data releases; seems a bit pissy to me. After this long a wait and all those n! risks, I deem this attitude churlish; after all, the assumptions in overall design are today 13+ years out of date. Pity about the failures in harpoons, but such was well within the long-Odds, byotches. Tonight on PBS, a reprise: To Catch a Comet. So far, some good pics, comments. Nice lab demo of sublimation (there was some surprise that a coma was forming this early on G.) They had to do a record-long burn to accelerate closure. Etc. Then the nascent coma stopped! Suspense.. One thing is unarguable: these Euro guys know how to compute celestial mechanics to a fare-thee-well; had a couple small things occurred with Curiosity's check-list ... well, you know.
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Post #396,463
11/20/14 8:43:15 AM
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Re: how to compute
It helps to use only one system of measurements. In this case it's metric.
Furlongs per fortnight for speed and mousefarts for force might work also. But, I have my doubts. :) Alex
"There is a cult of ignorance in the United States, and there has always been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that "my ignorance is just as good as your knowledge."
-- Isaac Asimov
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Post #396,508
11/21/14 5:31:07 PM
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Given that...
I consider myself lucky I can get the snowblower to fire up without having to take it apart to the de-ice the carburator, having some things not wanting to move after 10+ years in the ultimate deep freezer is not all that shabby.
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