NASA Craft To Leave Vesta Heads For Dwarf Planet Ceres

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.'"

Comments

Good luck Dawn

[symbolset]

We're all counting on you...

Seriously though, Ceres is an awesome target and much more exciting than Vesta. Vesta is a rock. Ceres is half water ice by volume, in low g. Obviously some serious upside potentials there. A vastly superior target to Mars, or just about anywhere else in the solar system.

Re:Good luck Dawn

[symbolset]

Space is cold, and dry. It can be pretty hard to find water out there, and gas stations are far between.

Planetary Resources is a company in Seattle set up to mine asteroids. The big deal at first is asteroid-borne water, which comprises up to 30% of some asteroids. They are going after asteroids that pass near the Earth at first.

The big deal is what potentials this opens up for expoloration of our solar system and the stars. With energy water can be converted into LH2/LO2 fuel. The problem is that lifting up the fuel from our deep gravity well makes this prohibitively expensive.

Ceres may have 200 million cubic kilometers of water ice, almost all of it relatively pure and on the surface, 100km thick. That's more water than all of the fresh water on Earth. Ceres has a surface gravity of 0.03 g, so getting the ice or fuel away from there is no big deal. There may be other volatiles there as well - Xenon would be a great find. We've found water on the moon and Mars, but getting the water away is nearly impossible because the gravity on these bodies is just too high. Small asteroids aren't plentiful enough for a huge explosion of exploration and manned habitation in space.

Abundant water and energy are the two essential keys to human and robotic exploration of the solar system. If we can somehow with robots bring energy and equipment to this ball of water we can bring back enough fuel to scoop much larger payloads out of much cheaper near Earth Orbits and move them anywhere from there. That enables larger habitations with centrifugal simulated gravity, water ice mass shielding from radiation, million-kilo LH2/LO2 rockets that start in microgravity and so don't have to spend 90% of their fuel lifting up out of our gravity well.

Ice makes a great construction material too, so if we found a way to put humans on Ceres they need not worry too much about radiation or building materials. It's also a great thermal insulator, and we've learned how to carve habitats out of ice in Antarctica.

In short if that water is really there it is the key to humans establishing a permanent occupation of space, and maybe the fuel we'll use to send the first probes to nearby stars. We'll know in about 30 months.

Re:Good luck Dawn

[symbolset]

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

[symbolset]

This is an interesting point. A sufficiently deep subsea human habitat that was self-sufficient might be enough to preserve mankind against even a planet-killer asteroid, if it survived the initial shock wave. Certainly many aquatic species survived the last dinosaur killer, including sharks. If you put it at the equator it should be safe from ice ages. Geothermal energy would be persistent enough, even if the uranium from seawater thing didn't work out. It would have to be a subsea city with pop > 100k though to provide a persistent level of science and culture.

There's probably a good trilogy of books in this one if you want to develop it.

Not proof against nuclear war though. If I know anything about my fellow men, they're griefers and when the shit hits the fan a subsea survival habitat is going to have several torpedos with its name on them, some of them nuclear.

Re:Good luck Dawn

[Teancum]

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.

Re:Good luck Dawn

[symbolset]

Colonization of Ceres requires that the humans live in a huge centrifuge because humans don't bear up well under such a tiny gravity in the long term and centripetal force is a fair substitute. Construction of such a centrifuge on Ceres would require considerable resources we don't have because Ceres has both significant gravity and spins on an axis. Ultimately a human habitat on orbit of Ceres seems more likely to me than one burrowed into the ice for this reason, as the centrifuge is simpler on orbit. In fact, the operation of human habitat polar centrifuges would alter the poles of Ceres and be self-defeating. But given such a habitat on orbit, short-term surface ventures and shelter from solar storms are trivial with a surface gravity of 0.03 g and unlimited available fuel from refinery operations. A space elevator on Ceres though, that would make better sense than anywhere else in the solar system.

No, I'm excited about Ceres only as a source of water for LH2/LO2 fuel, O2 for breathables, water for drinking, minerals for refining and fabrication - not as habitat. It may be 50 years or more before we put people there and that will be out of scope for me.

Orbiting an asteroid

[tomhath]

This kind of control just amazes me. Orbiting a dinky little asteroid, just amazing.

Vesta flyby video

[Narishma]

Here's a cool video generated from pictures taken by the probe as it orbited the asteroid.

Dear Slashdot:

[fustakrakich]

When posting NASA news, it's always best to go to NASA itself. Avoiding ad cluttered sites will help reduce excess traffic on our limited bandwidth.

Re:Asteroid Vesta and dwarf planet Ceres

[reverseengineer]

From further down in that link you posted, "it appears to have a surface of basaltic rock -- frozen lava -- which oozed out of the asteroid's presumably hot interior shortly after its formation 4.5 billion years ago, and has remained largely intact ever since." So no volcanic activity anymore, though meteorites believed to originate from Vesta are believed to have been formed in the impact that produced the Rheasilivia crater, which possibly ejected material as deep as the mantle.

Re:Asteroid Vesta and dwarf planet Ceres

[mbone]

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.)