End is nigh for Rosetta: Spacecraft will meet its end by crashing into a comet | Hacker News Reader

End is nigh for Rosetta: Spacecraft will meet its end by crashing into a comet

arstechnica.com

116 pointsTomte21 comments

The press release itself is more informative: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rose...

"Commands uploaded in the days before will automatically ensure that the transmitter as well as all attitude and orbit control units and instruments are switched off upon impact, to fulfill spacecraft disposal requirements."

Is there a scientific reason for doing this? Keeping the instruments on seems to be a far more logical option, just in case it survives 50cm/s descend.

I read somewhere (sorry, no link handy) that the ITU requires the frequencies to be vacated as soon as the experiments end. My guess is, that they're afraid that it'd still be transmitting but is unable to receive the command to cease doing so.

According to http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2007002...

  In 1995 NASA released the first detailed set of orbital
  debris mitigation guidelines [...] One of NASA’s policy
  objectives is to control the amount of orbital debris
  generated by accidental explosions. [...] The NASA safety
  standard goes on to identify typical systems that should
  be passivated, [...] electrical power systems, [...] the 
  discharge of all batteries and their disconnection from
  charging circuits

TLDR: Standards written for satellites being left in orbit want to avoid explosions. This means dumping all fuel and compressed gas - and draining and disconnecting any batteries.

Doesn't seem all that relevant in the disposal in question, of course; I can't imagine the standard will make much difference to the amount of debris if the craft is crashing into a comet anyway.

Huh, i heard them say "controlled descent". That is, they would try to land the probe on the surface, rather than slam-crash it intentionally.

With the kind of gravity comets have, crashing might be trickier than landing.

Crashing and Landing are the same operation. It's subjective from the lander's point of view which occurred. Gravity's role in either is identical :p

Crashing and landing are about as similar as dying and sleeping.

So very alike except in intensity and duration?

As far as the individual parts are concerned, it is not at all alike.

And also the fact that your organs are still operating in sleep as opposed to not in death.

I do believe that was his point; not at all similar, and missing an /s, like yours.

I would define crashing as "camera and/or essential hardware broken", and landing what it's not.

That is, if it returns surface pictures, then it landed. Otherwise - crashed.

What would be badass is if they try to knock Philae out of its perch so that it can be in a better solar position.

Hmmm... The orbiter is about 10^3 kg, the comet about 10^13 kg, so 10 billion times heavier. We're gonna need to build up some speed somehow!

Philae is the lander, not the comet.

I was thinking cosmic billiards... in retrospect I probably shouldn't have posted :)

To what end? Philae requires Rosetta as a 'repeater'. Even if it did knock Philae into a better position, we would never know.

Maybe we'll see a follow-up frame on xkcd's play-by-play:

https://xkcd.com/1446/

This appears to have the full list of frames:

http://www.explainxkcd.com/wiki/index.php/1446:_Landing/All_...

A flipbook of the second link would be great.

Badass; that's how I wanna go.

Seconded. A one-way trip to another heavenly body sounds great.

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