Comet-Chasing Probe Wakes Up On Monday 67
Hugh Pickens DOT Com writes "Jason Major reports that after nearly a decade of soaring through the inner solar system, flying past Mars and Earth several times and even briefly visiting a couple of asteroids for a gravity assist, the European Space Agency's comet-chasing spacecraft, Rosetta, is due to 'wake up' on January 20 after 957 days of hibernation. The probe is awakening to prepare for its upcoming and highly-anticipated rendezvous with comet 67P/Churyumov-Gerasimenko in August. The spacecraft was designed to be put in hibernation for the coldest part of the journey that took it close to the orbit of Jupiter, because even with massive solar panels the size of a basketball court, Rosetta would not have enough power to complete its mission without this energy-saving strategy. Once Rosetta enters orbit around the comet — the first time a spacecraft has ever done so — it will map its surface and, three months later in November, deploy the 220-lb (100-kg) Philae lander that will intimately investigate the surface of the nucleus using a suite of advanced science instruments. 'It's the first time we've made a rendezvous with a comet — that's never been done before — and it's going to be the first time we've escorted a comet past its closest approach to the Sun,' says ESA project scientist Matt Taylor."
units (Score:5, Insightful)
"massive solar panels the size of a basketball court,"
can we please have proper units for measuring things in space?
Re:units (Score:5, Insightful)
"massive solar panels the size of a basketball court,"
can we please have proper units for measuring things in space?
And confuse half of the american audience? Basketball courts they know, meters they don't.
Re: (Score:3)
"massive solar panels the size of a basketball court,"
can we please have proper units for measuring things in space?
And confuse half of the american audience? Basketball courts they know, meters they don't.
FTFA "...have a total span of about 32 metres tip to tip." Or 105 feet; a basketball court is 94 feet long.
On behalf of the USA, you're welcome.
Re: (Score:1)
the solar panels are over 2 x the size of 1/2 of an american basketball court.
Re:units (Score:4, Informative)
The page on the ESA website [esa.int] says there are two panels, each 32 m^2.
I'm not familiar with basketball courts, but I assume they're quite a lot bigger than that.
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Hence the probe had to hibernate.
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420 m^2, to be exact. In fact, both panels together make a badminton court!
Re:units (Score:4, Insightful)
Only that was what was said. They said they were the same size as a basketball court which is not the same as saying they are the same length as a basketball court's diagonal. You are twisting numbers to fit your idea.
The area of the solar panels is approximately 32 m^2. The area of a basketball court (which is played is countries other than america) is about 420 m^2. Not the same size at all.
Re: (Score:3, Interesting)
Only that was what was said. They said they were the same size as a basketball court...
Actually, that's not what they said. They said that the probe would not have been able to power itself even with solar panels the size of a basketball court. It's a hypothetical statement. My car would not be able to lift itself, even if it was filled with hydrogen. This is true, but in saying this, I'm not saying my car is actually filled with hydrogen, just pointing out that it wouldn't have enough lift even if it was.
Granted the way they said it unfortunately implied what you said. But it's not what
Re: (Score:2)
They forgot to say "The size of a basketball court for hamsters", it's the favourite sport at ESA, you should see new power forward, maaan! the critter is awesome, MVP for two consecutive seasons:
https://encrypted-tbn0.gstatic... [gstatic.com]
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Re: (Score:1)
Err, since it's an ESA project it would be "football fields". "Soccer" is not a word frequently encountered in Europe, except from the lips of the more impressionable of Britain's youth, few if any of whom actually understand the rules of American Football but a distressing number of whom use American terminology for the game they themselves actually play.
Balls to them and their habit of playing football on my lawn!
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"Soccer" is not a word frequently encountered in Europe, except from the lips of the more impressionable of Britain's youth
And Saturday morning Sky Sports coverage [wikipedia.org].
Re: (Score:2)
Spot on mate!!!
FOOTBALL is the name of the #1 sport on the planet, played by 11 vs 11 guys with spike in their shoes a _round_ ball and some guys in black that nobody cares about... and hooligans wrecking havoc in the town.
This sport that USians call "football" where an undefined number of guys stay for hours deciding how to place themselves and were everybody is covered in cushions should be called more appropriately "Fluffyball" or "sissy-rugby".
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How much is that in FIFA approved football fields?
It sure was asleep! (Score:1)
...flying past Mars and Earth several times...
That sounds like a sleepy driver to me!
Unless....are they using ethanol to fuel this thing?! Does MADS (Mother Against Drunk Space exploration) know about this?
Wake Up (Score:5, Funny)
is due to 'wake up' on January 20 after 957 days of hibernation
If successful, this will be a new record for the onboard Windows XP.
I can tell you what it's gonna find (Score:5, Funny)
You know that ice that's in the corner of the parking lot covered in black dirt and is the last piece of ice to melt? That's what's that probe is going to find.
Re: (Score:2)
don't worry, there is an US military probe following it, if there is oil in it it will first bomb the fuck out of it and then set up a puppet government on it to get full rights to drill.
RTG? (Score:2)
Why didn't they just use an RTG? http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator [wikipedia.org]
Re:RTG? (Score:5, Informative)
I presume because a large solar array with some battery backup meets their power needs over the mission for less money than an RTG, and they only need to operate for a short period out near the outer limits of what is feasible for photovoltaics (roughly the orbit of Jupiter).
The solar panels will produce 850 watts at the rendezvous point -- roughly the same as the Cassini probe's RTG at launch. Those panels will produce prodigious amounts of power at the spacecraft's action-packed perihelion, which may be useful. For example a huge power budget would allow faster transmission of data [wikipedia.org].
The drawback I see is reliability. The spacecraft's systems have to be kept dormant for a long time when it's out near its aphelion.
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You do know that the US uses nuclear reactors to power it's aircraft carriers and nuclear submarines?
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as well as, nearly every other spacecraft we've put up.
The 12-year Journey (Score:5, Informative)
For the curious, here's a video showing Rosetta's path: Rosetta's Twelve-Year Journey to Land on a Comet - ESA Space Science HD Video [youtube.com]
Re: (Score:2, Interesting)
Nice. We can also see that the submitter claim "briefly visiting a couple of asteroids for a gravity assist" is bunk. The asteroid flybys didn't change the orbit in any useful amount -- only the planet flybys did.
Re: (Score:3)
You are correct.
It should have read:
" flying past Mars and Earth several times for a gravity assist and even briefly visiting a couple of asteroids"
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Really SlashDot, I'm disappointed. I expected to see this observation making up half of the discussion thread, instead just a bunch of whining about the size of a basketball court. Sigh.
Actually, it's an incredibly cool accomplishment. This has already been one of the most productive deep space probes in years, and now the show really starts.
Chickens before they hatch? (Score:3)
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If you had to qualify statements with modifiers like that, you'd never get anything said.
Monday morning & the alarm clock goes (Score:3)
Poor space probe, I sympathise with it. What a day to wake up on!
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ESA: "Rosetta will prepare for its upcoming rendezvous with comet 67P/Churyumov-Gerasimenko"
Probe: Groan, mumble. "Whatever... where's my coffee?"
Exciting stuff (Score:3)
I remember staying up late to watch Giotto's close approach to Halley. That we're now planning to *land* on a comet, is very impressive.
All These Worlds... (Score:3)
Attempt No Landings There.
Amazing Picture from Rosetta of Asteroid Lutetia (Score:5, Interesting)
http://www.nasa.gov/images/content/468180main_2_Lutetia_and_Saturn_946-710.jpg [nasa.gov]
With Saturn hanging in the background. Stunning. It's worth it already!
Re:Amazing Picture from Rosetta of Asteroid Luteti (Score:5, Informative)
Wow, I don't remember seeing that pic before (must be from the 2010 flyby) but it's just about to become my desktop wallpaper. Thanks!
On a side note, for anyone who's not looked at the night sky before through a telescope, you can see Saturn somewhat like it is in that image, with an entry level (ish) telescope from your back yard. I first saw Saturn through an old TAL-1 newtonian that can be bought for as little as £100 here in the UK and on a good night you'll get a sharper view of Saturn than shown in that image. Or you could pop along to your local astro meet (there's bound to be one near you) and have a look at some of these objects through varying sizes and designs of telescopes.
Seeing Saturn for the first time through a telescope is, in my experience and from what others frequently say too, jaw dropping amazing. Then take a look at Jupiter with the same telescope and you should be able to make out Jupiter's bands and some of its moons, maybe even the great red spot if you time it right. We've all seen them in photos but there's nothing quite like the knowledge that your eye is at the receiving end of actual photons being reflected by the planets, or being emitted from galaxies.
orbital parameters (Score:5, Informative)
I dug around ESA's pages and finally found details on the orbital parameters: on Comet Rendezvous [esa.int], under "Comet mapping and characterisation (August 2014)" (halfway down) it says: "...the spacecraft is inserted into orbit around the nucleus at a distance of about 25 kilometres. Their [sic] relative speed is now down to a few centimetres per second. "
That slow orbital speed (OK, slow compared to what we're used to dealing with) is due to the small mass of the comet (again, compared to things like the Earth or Moon), which Wikipedia [wikipedia.org] gives as about 3e12 kg. Checking the math, the equation for circular orbital velocity v[circ] = sqrt(GM/R) ~= sqrt( (7e-11)(3e12) / 25e3 ) = 0.09 m/s = 9 cm/s, cool. (Even if the quoted 25 km is to the surface rather than the centre, using that figure for R is OK since the comet's radius is only about 2 km.)
FWIW, at the surface, escape velocity sqrt(2)*v[circ] = sqrt( 2(7e-11)(3e12) / 2e3 ) = 0.5 m/s. You could easily jump off of that comet!
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... Their [sic] relative speed ...
Why the [sic]? 'Their' is the correct word. It certainly wouldn't be 'there', and when talking about relative speed there have to be two objects, hence the plural - 'its' would not be correct either.
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Comet-chasing probe wakes up on Monday... (Score:2)
...decides it hasn't recovered from the weekend yet, calls in sick, goes back to sleep and rolls in on Tuesday at about 09:30.
"Gravity Assist" (Score:2)
briefly visiting a couple of asteroids for a gravity assist
Gravity assist for whom, the probe or the asteroids?
I'm curious (Score:2)
excited jabin jay trapp (Score:1)
Breaking news: wakeup is going well (Score:3)
I was following the webcast [esa.int], a few minutes ago they received the signal from Rosetta, so the wakeup has succeeded, if a bit behind schedule.
(unfortunately I can't see a way to rewind, so you'll have to wait for the video to become available on the archive section of the webcast page)
Did it yesterday, what's the problem? (Score:2)
I also woke up this Monday, what's the big deal?