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NASA Probe Orbiting Asteroid Vesta
astroengine writes "Mission managers of NASA's Dawn asteroid probe had a long Saturday, waiting for news from the asteroid belt. Eventually they got the news they were hoping for: Dawn had entered Vesta orbit. This is the first time in history that an object in the asteroid belt has been orbited by an artificial satellite. It's taken four years for the ion thruster-propelled spacecraft to reach the asteroid and there was some uncertainty as to whether the probe had been captured by the asteroid's gravity at all. But after a long period of waiting, mission managers received the signal after Dawn was able to orientate its antenna toward Earth."
Wow, what loathsome editing by Discovery: they injected a video clip about a "Doomsday Asteroid" wiping out the earth into the middle of an article about Dawn visiting Vesta. The two are unrelated, but the juxtaposition somehow makes it sound like NASA is fulfilling some Hollywood fantasy about visiting the asteroid that will come smashing into Earth unless we send [current B-rate movie star] on the now-defunct Space Shuttle to nuke it.
Vesta is a Taliban stronghold.
Also not quite as bad as that curious predilection those in the UK have of ending a written sentence with a preposition.
Why are you so fixated on U.S. capabilities, it only matters that mankind can put people into orbit, and the U.S. space program has a large number of useful missions in progress or soon to launch, and many as collaboration with other nations. Patriotism has no place in science.
The possibility of successfully navigating an asteroid field is approximately 3,720 to 1.
Support Right To Repair Legislation.
FTFA:
Dawn will remain in orbit around Vesta for a year, before gently boosting away to begin the trip to Ceres, the second half of its asteroid belt adventure.
That was actually my first thought: "Why is this visiting Vesta and not Ceres?" Ceres (might) have surface water and an atmosphere, so it makes more sense as a base. Its also larger (about 4 times the mass/size, although, surprisingly, it has nearly the same gravity, .027g to Vesta's .022g) and looks one hell of a lot more interesting. I mean, both are just big rocks in space, but Ceres is actually dwarf planet class and looks like it could serve as a quite effective base for more missions past the asteroid belt.
Of course, visiting both makes sense. Vesta may have also been a nice test run for gravitational capture, since it doesn't have an atmosphere and its smaller, but has similar gravity. Establishing a (manned) base in the asteroid belt seems like it could be an enormous step forward in space. The asteroids could potentially be mined, providing a financial incentive to visit, plus their low gravity makes them easy to escape after loading up on fuel/ore or for constructing spacecraft (anyone else think the idea of a spaceship factory in the asteroid belts is pretty cool?). All in all, this is a pretty cool (if pretty small) step forward in getting off this rock. I can see why Obama wants to send an astronaut to the belt by 2025, even if I know it'll probably take till 2040 or so.
"None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
Bodies don't explore space, probes do.
We have centuries to perfect the robotic systems we MUST have for the utterly hostile environment of space (and for more efficient work on Earth).
"This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
To the science-abled fellas in here: How would conditions for astronauts/cosmonauts visiting this bodies be? Can they walk up there or would they need some sort of exo-skeleton or something with more space for sponsors...?
Well, from Wikipedia the asteroid's gravitation field is .022g or about 1/50th of Earth's, so its basically micro-gravity. You could probably escape the gravitational field by jumping really hard, so tethers are probably a must for working outside. Exo-skeletons would probably hurt, rather than help, unless you meant just a space suit, which yes, is absolutely required. Not sure what "space for sponsors" even means, so....
There are so many cool things about this mission! ION FREAKING ENGINES!
Yes. Ion engines are cool. Delta-v is a bit low though (0-60mph in 4 days, which makes it almost as bad as a Yugo... I kid, I kid). Very useful for deep-space missions, but I can't wait until we get plasma engines, which could potentially have the efficiency of ion thrusters AND the thrust of chemical rockets.
"None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
Patriotism has no place in science.
Heh, I actually agree with that, but ultimately there will be war between the space people and the earth people, exactly in the same fashion that we make war against our African/Middle East ancestors.
Mutiny on the Skylab
For justice, we must go to Don Corleone
I think I just had a small stroke while typing that.
Masturbation does seem to be a common part of this thread.
Science is all about firing a drunk pig out of a cannon just to see what happens.
I would not begrudge our soldiers in Afghanistan small comforts. But still I was taken aback by the news that Pentagon spends more on airconditioning barracks in Afghanistan than the entire NASA budget. If Pentagon bought some more efficient air conditioners without compromising comfort, may be we could fund a few more of these missions. Quite sad to see the congresscritters make grand statements about government waste and then ram their pet pork projects through defense appropriations.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
When the ion drive isn't running, there is plenty of power. There's no reason to not gather as much data as possible. After all, if something went bung during insertion (when the probe was out of comms with Earth) it would be the only data they have. Given the detail in the last image (from ten days ago), what prevented them from at least getting a full surface sequence?
Other NASA probes take images from distant approach, trying to milk as much data as they can before the arrive, as well as PR for the mission. I can't find an explanation of why the Dawn team have been so reticent to image their target. It doesn't bode well for the rest of the mission.
I can think of a theoretical reason that may or may not have any application to reality.
We know the asteroid's orbit and our (the earths) orbit from a zillion years of position observation. We don't know the vehicle's relative velocity to the asteroid, and thats kind of important to put it in orbit. In ye olden days the stereotypical way to figure orbits was to put what amounts to a crossband linear repeater on the vehicle and spend inordinate amounts of effort on the earth measuring the doppler shift of signals transmitted thru the repeater. In ye olden days that was best done using an continuous information free carrier CW tone. Now a days the youngin's probably use some sort of spread spectrum solution to avoid ionospheric scintillation or just to plain ole be cool? At any rate the radios would probably be busy doing the navigation-thing as opposed to the science-thing.
Now a "news for nerds tech site" could make an interesting article about how this mission did navigation...
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
If it makes you feel any better, (it did for me) that number ($20 billion) for air conditioning in Afghanistan is highly debatable and was put forward by a guy who was a brigadier general but now is in the private sector, selling technologies branded as energy-efficient to the Defense Department. More from the source article (http://www.npr.org/2011/06/25/137414737/among-the-costs-of-war-20b-in-air-conditioning): "Now it's important to note that wrapped up in Anderson's $20 billion figure are all kind of other expenditures – for instance, the cost of building and maintaining roads in Afghanistan, securing those roads, managing the security operations for those roads. That all costs a lot of money and is part of the overall war effort in Afghanistan." And, "The Pentagon disputes the calculation made by Anderson about air conditioning costs. Defense Department spokesman Dave Lapan says that in fiscal year 2010, the Pentagon spent approximately $15 billion on energy for all military operations around the world. The Pentagon says when it comes to Afghanistan, it spent $1.5 billion from October 2010 to May 2011 on fuel. That fuel was used for heating and air conditioning systems, but also for aircraft, unmanned aerial systems, combat vehicles, computers and electricity inside military structures."
"....Patriotism has no place in science."
Patriotism may have no place in science, but science unquestionably has a place in patriotism.
I'm proud that my country built and operates the Tevatron which discovered the top quark, I'm proud we built the world's most powerful laser, the National Ignition Facility which is on the verge of demonstrating controlled thermonuclear fusion in a laboratory, I'm proud we were the first to decipher the 3 billion letter sequence of the human genome, I'm proud we invented the transistor, the laser, the nuclear reactor and the Polio vaccine that is on the verge of wiping that disease from the face of the Earth forever, I'm proud we engineered the microcomputer revolution and invented the internet those machines operate on, I'm proud we were the first to robotically explore every planet in the solar system with the exception of Venus and sent probes into interstellar space, and I'm proud of a thousand other things my country did to push back the darkness of ignorance about the physical world, thereby elevating the human condition to previously unimagined heights. And I hope that someday, instead of being proud of something as stupid as military might, or the number of gold medals we win in the Olympics, that my countrymen can join me in the more nuanced and altruistic flavor of patriotism that I am proudly guilty of indulging in. My style of patriotism is anything but the last refuge of scoundrels, and scientific achievement plays a central role in its maintenance.
- "Hear that?! The percolations are imminent! Cease your ingress!"
Maybe the quarter second signal lag vs the 30 minute signal lag has something to do with it? You cannot effectively remotely pilot things much beyond the Moon's orbit; and Vesta is definitely much beyond the Moon's orbit.
When our name is on the back of your car, we're behind you all the way!
First orbit of an asteroid *in the belt*.
Eros was the first discovered near-Earth asteroid.
Itokawa is an Apollo and Mars-crosser asteroid.
sr
His ignorance covered the whole earth like a blanket, and there was hardly a hole in it anywhere. - Mark Twain
Science is a collaborative effort. Nearly every advance the parent cited can be traced back to development work done by people who were not born in the US. Von Braun, Tsiolkovsky, and Fermi come to mind immediately, along with Einstein, Turing, Goedel, Bohr, Pauling, Dirac, Mendeleev, and Roentgen. National pride is fine, but it rings kinda hollow when one is aware of just how connected all scientific advancement is. The idea that all of those achievements are somehow the sole purview of the US is absurd.
I thought probes explored bodies?
http://www.rootstrikers.org/
Thanks for the information. Oddly I feel better knowing that Pentagon is not wasting that much. Sorry to have fallen for some marketers' spiel.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
There is no such thing as a good form of patriotism, unless it is dissent. The US has plundered the world to enrich an astonishingly small minority, and you're saying it's okay because a dollar or two fell into the science bucket along the way? Our contributions fo human suffering dwarf our contributions to knowledge. Patriotism is evil, just one more way to deny our common humanity and place ourselves above others.
Allow me to quote:
Every gun that is made, every warship launched, every rocket fired, represents, in the final analysis, a theft from those who hunger and are not fed, who are cold and are not clothed. This world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children. -- Dwight D. Eisenhower
America has nothing to be proud of. We are tyrants, criminals, and murderers all, not to mention the way we've polluted the earth so that our children's children will curse our names. Altruistic patriotism? The third world thanks you for your most benign munificence. It's a thin shroud to drag over two centuries of violent imperialism; you delude none but yourself, and display only conceit. You have allowed yourself to fall into comfortable ignorance, an ignorance of the world outside your borders, an ignorance not only free from want or suffering but free from their conception. The world entire is brimming with pain, and has no use for armchair altruism or fools who rest on the laurels of others and naively hope for change. They sow the wind, that shall yet reap the whirlwind.
Those who advocate genocide deserve every protection afforded by law, and none afforded by common human decency.
*sigh* So much misinformation floating around here...
GP said
That's because the only images they have are from the low-res navigational imager. They will fire up the high res camera and other instruments now that they're in Vesta orbit.
Which is absolute bullshit, because there's only one science camera (well, two identical cameras, for redundancy), and it's currently getting crap resolution because it's ~2x10^7m away, while science orbits will range from 2x10^6 to 2x10^5m altitude. There's also the star trackers, which while technically cameras, are not used for imaging Vesta or Ceres at all.
When the ion drive isn't running, there is plenty of power. There's no reason to not gather as much data as possible. After all, if something went bung during insertion (when the probe was out of comms with Earth) it would be the only data they have. Given the detail in the last image (from ten days ago), what prevented them from at least getting a full surface sequence?
Other NASA probes take images from distant approach, trying to milk as much data as they can before the arrive, as well as PR for the mission. I can't find an explanation of why the Dawn team have been so reticent to image their target. It doesn't bode well for the rest of the mission.
(It's not a power issue, it's an attitude issue -- each of the three ion thrusters is gimbaled in a narrow range, and the high-gain antenna and cameras are fixed completely -- same result, though.)
The mission's design duty cycle for the IPS (ion propulsion system) is 95%; the remaining 5% of the time is divided between imaging Vesta and relaying data to DSN ground stations. There's certainly time for more pics than they've taken, but allocating more time for imaging and less for thrusting means postponing your arrival, which reduces your time for doing high-quality science in orbit.
Unlike many other missions, which use a chemical rocket to perform a Hohmann or similar transfer into a near-final orbit, with relatively small deltaV reserved for orbit adjustments, Dawn will be gradually spiraling in under power to reach any given orbit. It's completely free to stop thrusting at any point and coast in a nearly-circular orbit while doing science observations, then resume spiraling in later, though they will likely stick to the mission plan of 3 orbits (2700km, 950km, and 460km radius -- subtract ~280km to get altitude). So there's very little to gain from more low-res approach images that we won't already get from the two full-rotation sets already scheduled (and I presume completed) during approach, and especially the full surface mapping that will be done in the first (highest) orbit. For more info on the navigation imaging strategy, see the latest Dawn Journal.
The main issue is that they're not releasing the pictures they have -- particularly the full-rotation sets mentioned above, As I understand it this is mainly a manpower issue, but I certainly wish they could set up a low-overhead nerd-ready channel separate from their press-ready channel, so they could just dump all the images and let the bloggers sort 'em out.