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Rosetta, the Comet Hunter
Roland Piquepaille writes: "After being delayed for about a year because of a failure of the Ariane-5 rocket, the Rosetta spacecraft is scheduled to be launched on February 26. Rosetta is a special spacecraft, including an orbiter and a lander. And it will take up to 2014 before landing on Comet 67P/Churyumov-Gerasimenko -- with the help of a harpoon. Then, as says the European Space Agency (ESA), Rosetta will help to solve planetary mysteries. This news release looks at the goals of Rosetta's mission and explains why it will take more than ten years to reach the comet. But here the 'funny' part of the story: the landing. 'In November 2014, the lander will be ejected from the spacecraft from a height which could be as low as one kilometre. Touchdown will be at walking speed, about one metre per second. Immediately after touchdown, the lander will fire a harpoon into the ground to avoid bouncing off the surface back into space, since the comet's extremely weak gravity alone would not hold onto the lander.' This overview contains more details and includes illustrations of the Rosetta's spacecraft and its landing on the comet."
Harpoon... check
Name I can't pronounce... check
10 years before getting some... check
I just have the class not to make a big deal out of it.
Is this truly the only Earth I can live on?
Phase 2 will be sending Bruce Willis and the rest of his rigger pals in their awful corduroy space-suits to "kick comet ass" of all the ones found by Rosetta.
Don't blame Durga. I voted for Centauri.
The timeline states that in 2014, Rosetta will orbit the comet for six months before it lands, mapping the comet to find a suitable landing spot. Then it goes on to say:
Immediately after touchdown, the lander will fire a harpoon into the ground to avoid bouncing off the surface back into space, since the comet's extremely weak gravity alone would not hold onto the lander..
My question is, if the comet's gravity is so weak, how is the Rosetta supposed to orbit this thing for six months?
The World is Yours.
...given that we probably know little about the surface of the comet.
Given that it could be porous (or even lots of shatterable ice), I hope that the harpoon has the force to bury itself deeply enough to actually anchor itself in something solid.
libertarianswag.com
given that we probably know little about the surface of the comet....Given that it could be porous (or even lots of shatterable ice)
If the world works according to Bruckheimer rules, the impact of a harpoon is likely to make the comet go up like the Death Star.
Don't blame Durga. I voted for Centauri.
I know that landing on Mars is a very tough thing, lots of variables to consider.
But this seems like it would be exponentially harder.
Ya know, landing on something that doesn't have gravity and they don't know what it's made of.
Maybe this is a good way for humans to travel thru space while conserving fuel. Comments?
I'm curious. How big does an object have to be to have gravity that'll hold say, a person to it?
I'm thinking say, if I were standing on a rock the size of NYC out in space, would I just drift away from its surface without any noticeable gravity, or could it hold me there? How about something the size of a state like Oregon? or something only 2miles in diameter?
shouldn't this be banned under the international whaleing treaty?
We're whalers on the moon.
We carry our harpoons,
but there ain't no whales
so we tell tall tales
and sing this whaling tune.
"You IDIOT! That was no whale you just harpooned. That was Baron Harkonnen!"
Don't blame Durga. I voted for Centauri.
And it will take up to 2014 before landing on Comet 67P/Churyumov-Gerasimenko -- with the help of a harpoon.
What makes them think they'll be able to land an unmanned probe on a small rock in deep space that way when here on earth, countless bigger, manned ships have tried the same feat on whales for decades and failed?
They're just gonna kill that poor little comet. For nothing. Just like that. Somebody calls green-piss ferchrissake!
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
But I don't wanna work in SourceForge sales. I imagine selling a free product is pretty hard.
The French had a very reliable launch vehicle, the Arianne IV, which they decided to "upgrade" with the Arianne V. After failing on 4 of the first 13 missions, they introduced an upgraded version with an extended nozzle. The failure of that launch led to the (highly justified) delay of the Rosetta launch on a similar Arianne V because of the failure investigation. Turns out that the nozzle had a design flaw which led to the failure.
ESA did pretty well on their 1st trip to Mars, as the Mars Express is an unqualified success, but the Beagle II didn't work for whatever reason. All this is just to reiterate that space is hard, and there will be successes and failures. No one's at 100% (Russians have a worse track record on Mars than anyone, and NASA lost Contour--not a JPL mission-- last year due to an obvious design flaw).
Whenever a new technique is tried in space for the 1st time, the odds increase. That Pathfinder worked on its first attempt at a bouncy landing, and Sojourner roved Mars without a hitch speaks to the talent & luck of the JPL crew. Hopefully the Europeans will do as well with their harpoon, and hopefully they haven't made obvious mistakes like those made by NASA and the APL did in the Contour comet mission.
Since there's not much gravity there, it should be. Even though I wonder how rugged the surface will be and how they will determine a landing spot. I think an American probe has already successfully landed on an asteroid, even though it wasn't part of the mission plan. It didn't do much when it landed. I think they did it just to see if they could.
Very slowly? Staying in orbit is just like falling, but you "move out of the way of" the body (comet in this case) you want to orbit so you move next. Repeat this thought-experiment for the new position and so on.
.. so you move next to it. My humble appoligies.
It should of course read
"It's too bad that stupidity isn't painful." - Anton LaVey
"Towards thee I roll, thou all-destroying but unconquering comet; to the last I grapple with thee; from hell's heart I stab at thee; for hate's sake I spit my last breath at thee. Sink all coffins and all hearses to one common pool! and since neither can be mine, let me then tow to pieces, while still chasing thee, though tied to thee, thou damned comet! Thus, I give up the spear!"
are you saying you cant pronounce rosetta?
girls are the least of your problems...
Too bad they didn't call the craft Ishmael or Ahab.
Stop using I.E.
Ishmael?
Or would Captain Ahab been more appropriate?
I'm not sure if you deliberately write it as you pronounce it, but in case you don't: it's "Ariane", not "Arianne". If that is a typo, it's a frequent one. And Ariane is clearly not french. There is substantial french contribution, no doubt -above all the launch site- but Ariane is a European project. I agree with you that Ariane 4 was abandoned with too great a haste- however, that step was inevitable sooner or later. Ariane 5, plus extensions, will be able to carry much larger payloads, and for smaller launches the Vega will take over for Ariane 4.
If /. and Spaceflightnow are still running in 2014, I will look foreward to the coverage
Y'know, for a troll, that was actually kind of funny. Well the first sentence anyways. I wonder how much force it takes to crush an Oreo anyways... ?
Ah well, don't mind me. Mod the thing down into hell, i've had my laugh.
I vote we call it YT!
Don't go to a brothel if you want to buy broth
Then I remembered I was on Slashdot. News for nerds. Since I'm married, I claim that I'm no longer a nerd, just a plain old geek.
I'm just hoping Rosetta survives the trip. I can just picture it getting Beagle-2'd by an asteroid on one of it's 2 trips through the asteroid belt. I mean, I know it's a longshot, but you never know. I hope ESA's luck improves with this one. Thie could be realy cool.
You are not the customer.
So after the lander fires a harpoon, the rigid comet breaks into hundereds of pieces and a single "oops" by mission control will echo around the Houston room.
Whats wrong with superglue? Still stuck with the "lets go GET it" thinking?
Rants aside. I really hope it works, and we get high res public domain pictures of it to make our desktop wallpapers out of.
I wonder if it would be cheap enough to steer the whole comet towards the earth into an orbit, and just bring it right next to the IIS. Spacewalking astronauts could then harpoon it to their hearts content
"Give orange me give eat orange me eat orange give me eat orange give me you." -Nim Chimpsky
Over the building, through the window, around the telephone pole, off the wall, around Saturn, through the asteroid belt, near Mars, between Earth and the Sun, nothing but net. Err.. harpoon.
that is retarded
Whatever happened to NASAs "Deep Space" project. Y'know the craft with the ion acceleration engine? IIRC Deep Space IV was supposed to attempt a comet landing but I'm reaching back to about 1998 here. Was this scrapped? I know that DS I was considered a success.
You're correct: NEAR
In the absence of significant gravity, won't a significant amount of the force used to launch the harpoon serve to actually propel Rosetta *away* from the asteroid? Can someone explain what's to keep the harpoon from going "boink" against the comet and Rosetta from not just bouncing but actually being propelled into space by the harpoon launch?
Cheers
-b
If I wanted a sig I would have filled in that stupid box.
As mentioned, you have to be moving slower than the escape velocity to be in orbit around something. The formula is v = sqrt(2GM/r). G is 6.67x10^-11 m^3/s^2kg everywhere.
For Earth, M is 6x10^24 kg, and the highest relevent velocity as at the surface, so r = 6x10^6 m. That's 11.2 km/s. Very fast. Which is why it's hard just to get into orbit.
Now for the comet. If it's 4 km across, r = 2000 m. I can't find a value for the mass, but based on the common description of comets as dirty snowballs let's guess the density is about that of water, or 1000 kg/m^3. The volume of a sphere is 4/3 r^3 so our guess for M is 3.35x10^13 kg.
That makes the escape velocity for 67P/Churyumov-Gerasimenko at 1.5 m/s which pretty much the same brisk walking-speed which which the lander is expected to hit the comet, especially if our guess at the density is high. Thus, the lander could easily bounce off, and a person could with some effort jump off, fast enough that the comet's gravity wouldn't bring them back. On the other hand, an rocky asteroid (denser) the size of Manhattan (bigger) would probably be hard to get away from under your own power. This comet is right on the edge.
The so-called great voyages of discovery of the past were never undertaken for the sake of idle science all. Always there was that search for the elusive El Dorado or that secret shortcut to the spice capital of the world. While most voyages failed to recoup the wood and slave labor invested on them, enough returned with if not the silver and gold then things that would prove more valuable, like coffee, cannabis or the claims to a "New" World.
The pure science mission ("Is there life on Mars?") is a modern invention. While the altruism is admirable, the only way to justify to taxpayers the continued exploration of space is to turn these missions into hunts for precious metals and minerals. Follow not just the water (a valuable space resource in its own right) but also the platinum.
Presumably the harpoon will have waaay lower mass than the lander, and the comet waaaay higher mass than either. Low acceleration for the lander = no problem in the time scale we're talking about. High mass (approaches 0 accel.) for the comet means that the harpoon buries itself. I think...
Corruptissima re publica plurimae leges.
"Towards thee I roll, thou all-destroying but unconquering whale; to the last I grapple with thee; from hell's heart I stab at thee; for hate's sake, I spit my last breath at thee. Sink all coffins and hearses to one common pool! and since neither can be mine, let me then tow to pieces, while still chasing thee, though tied to thee, thou damned whale! Thus, I give up the spear!"
Decade long hunt... Harpoons... Big ass prey...
I think I've heard this story before
http://www.aaplblog.com/ - News about Apple Inc.
Yeah, sure its a comet probe. Or the romulans are invading. Just compare this:
p acecraft.jpg
http://radio.weblogs.com/0105910/images/rosetta_s
With THIS!!!
http://home.arcor.de/torran/3ds/BOP3.jpg
"YT" is a reference to the novel Snow Crash and harpoons. You are expected to understand this.
...why don't they shoot the harpoon first and use it to reel the probe in?