On July 7, a spacecraft will launch from Cape Canaveral, Fla., to embark on an eight-year mission led by UCLA professor of geophysics and space physics Christopher Russell to explore two planetary bodies between Mars and Jupiter.
This endeavor, known as the Dawn mission, is conducted in collaboration with NASA and the Jet Propulsion Laboratory, or JPL.
The mission’s objective is to orbit the main belt asteroids Vesta and Ceres, said Marc Rayman, project systems engineer on the mission.
It is the first space mission ever to orbit two different bodies and the first to orbit a main asteroid in the belt.
Russell, who has been a professor at UCLA for more than two decades, came up with the idea for the mission.
“In 1992, I started to investigate how we might explore small bodies in the solar system by using ion propulsion engines that use fuels more efficiently,” Russell said.
The advanced technology of the ion propulsion system used in Dawn’s spacecraft engines makes this possible.
In ion propulsion, gas is neither heated up nor put under pressure as in regular propulsion systems. Instead, atoms that are given electric charges are shot out of the thruster of the spacecraft. This action causes a reaction that pushes the spacecraft in the other direction.
“By using this kind of engine,” said Britney Schmidt, a graduate student in the earth and space sciences department and collaborator on the mission, “we can fly out, go into orbit around Vesta, and then do something that’s never been done: leave the object we were orbiting and then orbit another object.”
The ions are emitted from the spacecraft at a very high speed of 35 kilometers per second, resulting in a big push per ion emitted.
In ion propulsion, only one-tenth of the amount of fuel is needed to achieve the same change in velocity as compared with conventional propulsion systems, making the engines extremely efficient, Rayman said.
Previously, scientists have only had a rough idea of the nature of the asteroids from images obtained from telescopes. Russell believes that the firsthand high-resolution photographs and precise measurements that the spacecraft will gather during its orbit around the asteroids will bring with it many scientific breakthroughs.
“Like Lewis and Clark, they know that there is a big country, but they don’t really know what’s out there until they go and see the rivers and mountains that are there,” Russell said. “They get a much better understanding than just by getting reports from Indian settlers as to what is really there.”
Dawn will collect various kinds of data, Schmidt said, including information that will provide details about the composition and the interior of the bodies. In addition, a high-resolution camera will take photographs of the mountains, craters, lava flows on Vesta, and ice on Ceres.
The science operations for the mission are headquartered at UCLA.
The spacecraft will transmit data to JPL, which will turn it over to the Dawn Science Center at UCLA, said Steven Joy, manager of the center. The university will then send the data to various investigators and instrument teams. These teams then send their analyses back to the center, which will distribute the information to various communities.
The novelty of the mission is that it will be an exploration in both space and time, Russell said.
“On one level, we are flying off to two asteroids to explore their present state,” Russell said. “On another level, we are trying to explore how the solar system formed by looking at two bodies that formed very close to the beginning of the solar system.”
In the asteroid belt, Ceres and Vesta both underwent planetary formation processes but never quite became planets due to the formation of other planets, particularly of Jupiter, Russell said.
Without reaching full planetary size, Ceres and Vesta were not affected by large-scale planetary processes that might alter their chemistry, Joy said.
This halt in development is what will allow researchers to use data gathered from these bodies to study the early formation of the solar system.
Vesta formed early enough in the history of the solar system such that the heat from radioactive material boiled all the water off, making the asteroid dry, while Ceres formed late enough so that it still contains water, said Paul Hayne, a UCLA graduate student in the department of earth and space sciences.
“If we go back in time, we can see the distinction,” Hayne said.
While Vesta is like the rocky bodies of the inner solar system, such as the Earth’s moon, Ceres is reminiscent of the icy bodies of the outer portion of the solar system, Russell said.
Dawn is scheduled to fly by Mars in April 2009, arrive at Vesta in September of 2011, and orbit the asteroid for seven months. The spacecraft will then arrive at Ceres in February 2015 and spend five months there, at which point its primary mission will conclude, Rayman said.
Russell anticipates that the new technologies that Dawn will employ will bring researchers new discoveries.
“Something that you learn in science is that if you increase your ability to do things,” Russell said, “you will find surprises and make important advances.”