Caught in Orbit Tonight with Ion Drives – Vesta and Dawn

Vesta as seen from Dawn spacecraft
Image of Vesta taken during approach of NASA's Dawn spacecraft. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

If years of planning and work pay off, NASA’s Dawn space craft was just now gravitationally captured, as of 10pm PST, by an asteroid that lives in the wide region of our solar system between Mars and Jupiter. The asteroid is named Vesta.

It’s thought that Vesta, which is only 326 miles in diameter, once had lava flows. If Vesta did once have lava flows, it makes no sense with our current understanding, since Vesta is too small to contain a molten interior. The Dawn spacecraft will spend a year orbiting Vesta investigating its composition in an attempt to shed some light on this puzzling situation.

Some people believe Vesta may have a high concentration of radioactive elements, such as Aluminum-26, that fell together from a nearby supernova explosion, and worked its way to the core of the asteroid, resulting in geologies similar to what we find on Earth and Mars. Hopefully, we’ll know soon enough.

After a year, Dawn will depart from Vesta heading toward the nearby dwarf planet Ceres. This will mark the first time any spacecraft has managed to orbit one celestial body, then move away to orbit another.

Ion EngineNASA accomplishes this feat through the use of ion propulsion drives rather than chemical rocket drives. The Deep Space 1 mission years ago proved the viability of using ion propulsion drives for space exploration. Ion drives allow spacecraft to travel considerably faster than chemically-propelled rockets. Although chemical rockets produce a lot more up-front force, ion drives produce a small force over thousands of days, which gives you much faster speeds, and incredible “gas mileage”. In fact, at full throttle, the ion propulsion drives will produce little more force than a piece of paper does when held in your hand.

Tomorrow night around this time we’ll know for certain if Dawn was captured by the gravitational field of asteroid Vesta, and the science will begin. It could well be we will learn some important facts about how our solar system coalesced into this big ball of dust we’ve come wandering out from. Here’s hoping!