NASA Craft To Leave Vesta Heads For Dwarf Planet Ceres 116
DevotedSkeptic writes "NASA's Dawn probe is gearing up to depart the giant asteroid Vesta next week and begin the long trek to the dwarf planet Ceres, the largest object in the asteroid belt. The Dawn spacecraft is slated to leave Vesta on the night of Sept. 4 (early morning Sept. 5 EDT), ending a 14-month stay at the 330-mile-wide (530 kilometers) body. The journey to Ceres should take roughly 2.5 years, with Dawn reaching the dwarf planet in early 2015, researchers said. 'Thrust is engaged, and we are now climbing away from Vesta atop a blue-green pillar of xenon ions,' Dawn chief engineer and mission director Marc Rayman, of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. 'We are feeling somewhat wistful about concluding a fantastically productive and exciting exploration of Vesta, but now have our sights set on dwarf planet Ceres.'"
Re:Asteroid Vesta and dwarf planet Ceres (Score:5, Informative)
Re:Good luck Dawn (Score:2, Informative)
One tiny problem with that, though: Ceres is a bit further out from the sun than Mars... as in way the hell out there. [wikipedia.org]
It does have potential for fueling an orbital colony or, well, any colony that isn't at the bottom of a big gravity well. OTOH, if Mars is a screamer of a target to hit, I can only imagine what it would take to hit a relatively microscopic-sized target that's way further out, and somewhat surrounded by asteroids.
Sounds like fun, though.
Re:Asteroid Vesta and dwarf planet Ceres (Score:5, Informative)
How can an asteroid of only 330 mile wide have volcano that spewed out lava ?
Lot's of radioactive Aluminum-26, which melted all sorts of things in the very early solar system. (Vesta is thought to be near-primordial.)
Re:Good luck Dawn (Score:5, Informative)
Mars has water. A lot of it, right on the surface. Plenty to provide air and water for indefinite human habitation and fuel for the return trip, if you have the energy. That's the good news.
Mars also has a lot of gravity (.38 g). And it's the gravity that's a killer because it's not got enough atmosphere for a decent atmospheric brake. To land a significant (20 ton or better) craft on Mars in condition to lift off again demands that you set her down on the jets, and that is a very unforgiving process that costs a metric boatload of fuel. Whatever source of energy you use is going to have a lot of mass too. The 1 ton of Curiosity is actually as much mass as we can land on Mars right now. To get humans there in any condition to start a colony requires a vast quantity of fuel to shorten the trip and to land. And where are we going to get that fuel? Ceres!
Mars has too much gravity to be a good source of water for fuel in microgravity. You have to burn too much fuel to get it off of Mars. As it is on the return trip the humans are going to have to meet up in Mars orbit with a return booster fuelled by LH2/LO2 from Ceres.
Yeah, Ceres is a good bit further out and it takes longer to get there (to the GP). But the robots don't care. Planetary Resources should get us enough Near-Earth asteroid water to make the fuel to lift the craft out of LEO and send it swiftly on its way to Ceres. At 0.03 g, the water comes off of Ceres nice and easy. Once it comes back to lunar orbit (firing its LH2/LO2 jets) with its kilotons aquatic payload a lot of other things like Mars become realistically possible. There are just not enough near-Earth asteroids of the right type to provide the supply we need for this.
Ceres is the key to everything. If it really has the water.
Re:Good luck Dawn (Score:5, Informative)
There is no extra fire danger in a 100% Oxygen environment as long as the partial pressure of Oxygen is identical to typical seal level pressure or slightly less. The extra fire danger (as in what happened with the Apollo 1 fire) comes from a 100% oxygen atmosphere at standard sea level pressure. That is a fire just begging to happen with almost any material.
BTW, the Apollo spacecraft used a 100% Oxygen atmosphere because it was less mass to haul up to the Moon and back (thus more Moon rocks to bring back and more stuff to bring to the Moon in the first place). The Apollo astronauts seemed to have done just fine with that for a week or so in space at a time, and in fact the Skylab environment was also 100% Oxygen (with CO2 scrubbers in both cases to pull that gas out of the mixture as it was produced).
The reason the Space Shuttle went to a more normal 80/20 mixture of Nitrogen to Oxygen ratio had more to do with the electronics they were using than anything about the astronauts themselves. Since electronics are designed to operate here on the Earth, an assumption is made that other kinds of atmosphere environments won't be used by anybody using those components. Yes, milspec equipment can be made to overcome that problem, but sometimes things like test equipment and a whole bunch of stuff being used inside of the Shuttle simply can't be made economically with that strict standard.
Interestingly enough, the space suits used for EVAs still stuck with the 100% Oxygen environment. One of the reasons for that is because of the lower pressure made it easier to bend joints... something sort of important if you want a practical space suit. The downside is that it takes longer for astronauts to get in and out of the airlocks.