NASA's Dawn Spacecraft Enters Orbit Around Asteroid Vesta

July 17, 2011, JPL/NASA
NASA's Dawn spacecraft, illustrated in this artist's concept, is propelled by ion engines. Image credit: NASA/JPL

NASA's Dawn spacecraft on Saturday became the first probe ever to enter orbit around an object in the main asteroid belt between Mars and Jupiter.

Dawn will study the asteroid, named Vesta, for a year before departing for a second destination, a dwarf planet named Ceres, in July 2012. Observations will provide unprecedented data to help scientists understand the earliest chapter of our . The data also will help pave the way for future human space missions.

"Today, we celebrate an incredible exploration milestone as a spacecraft enters orbit around an object in the for the first time," Administrator Charles Bolden said. "Dawn's study of the marks a major scientific accomplishment and also points the way to the future destinations where people will travel in the coming years. President Obama has directed NASA to send to an asteroid by 2025, and Dawn is gathering crucial data that will inform that mission."

The spacecraft relayed information to confirm it entered Vesta's orbit, but the precise time this milestone occurred is unknown at this time. The time of Dawn's capture depended on Vesta's mass and gravity, which only has been estimated until now. The asteroid's mass determines the strength of its . If Vesta is more massive, its gravity is stronger, meaning it pulled Dawn into orbit sooner. If the asteroid is less massive, its gravity is weaker and it would have taken the spacecraft longer to achieve orbit. With Dawn now in orbit, the science team can take more accurate measurements of Vesta's gravity and gather more accurate timeline information.

Dawn, which launched in September 2007, is on track to become the first spacecraft to orbit two solar system destinations beyond Earth. The mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif., for the agency's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Ala.

The University of California, Los Angeles, is responsible for the overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are part of the mission's team. JPL is a division of the California Institute of Technology in Pasadena.

Explore further: NASA spacecraft to enter asteroid's orbit today

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not rated yet Jul 17, 2011
Some recent photo of the Vesta asteroid. It looks like typical asteroid.

not rated yet Jul 17, 2011
What is the benefit of landing a person on an asteroid?
5 / 5 (3) Jul 17, 2011
Probably a few benefits. Most importantly there are ramifications for future commercial missions (e.g. asteroid mining). If one can show that its possible to land on one and mine valuable minerals it could open up a commercial space race.
1 / 5 (1) Jul 17, 2011
Future space weapon, drag one back to earth and put on a planned trajectory to hit foreign countries we don't like.
1 / 5 (1) Jul 17, 2011
There really is no point to landing a man on an asteroid. Space mining is never going to profitable, even for high value metals like rhodium or uranium, unless they develop advanced propulsion systems that are orders of magnitude cheaper than conventional rockets.
4.7 / 5 (6) Jul 17, 2011
The idea is to mine materials for use in space, not to return to Earth. Avoiding the cost of boosting one kilo of anything out of Earths gravity well results in huge savings for, say, LEO colonies.
not rated yet Jul 17, 2011
Future space weapon, drag one back to earth and put on a planned trajectory to hit foreign countries we don't like.

A true M.A.D. idea if I ever saw one.
not rated yet Jul 17, 2011
But to send humans to asteroids by 2025? The word "optimistic" sounds like an understatement to me. Here we are in 2011 barely achieving the first orbit insertion. How many craft are on the way now? Right. And it took this one almost 4 years just to get there. One way.
not rated yet Jul 18, 2011
The idea is to mine materials for use in space, not to return to Earth. Avoiding the cost of boosting one kilo of anything out of Earths gravity well results in huge savings for, say, LEO colonies.

Asteroids in the main belt have a far higher return delta-V cost to go to and from LEO than it costs to come from the surface of the Earth.

Remember, moving through gravity wells costs whether you're going out or coming back. To get to the main belt, you have a pretty far climb out of the Sun's gravity well, and just as decent a climb to get back down the well.

True, some near Earth asteroids have fairly low LEO round-trip delta-Vs, but it's not as if cheap extended habitation and mining in space is anywhere near feasible in the next several decades.

No, the real reason to 'land' on an asteroid is the same as it has always been: because it's there.
not rated yet Jul 18, 2011
What is the benefit of landing a person on an asteroid?

Seeing if they bounce? Astronauts (or more likely Taikonauts) will have a hard time walking on asteroids because the surface gravity is so low. Only on the biggest ones can you be reasonably certain not to fly off into space with each step (e.g. Ceres and Vesta which have a surface gravity of 0.028g and 0.022g respectively)

While they probably won't manage the 350m/sec or so speed you need to get to to reach escape velocity the height achieved by any inadvertent move could be significant. Falling from such a height will not be a problem - but the amount of time you spend heplessly drifting might mean that your horizontal speed will carry you into a crater wall.

Drilling might also be difficult. We rely a lot on gravity to do manual drilling chores on Earth.
not rated yet Jul 18, 2011
"two solar system destinations beyond earth"... close but not quite. There is a craft that was orbiting a Lagrange point (destination 1) and then shifted to moon orbit... just a few weeks ago - but I can't recall when. I think it may have been a Chinese craft though.
"two solar system objects beyond earth" would be accurate.

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