Washington — Two NASA science missions — one to Jupiter, the giant of the solar system, and the second to the dwarf planet Ceres — are passing important benchmarks as August turns to September.
The Juno spacecraft bound for Jupiter successfully performed its first deep-space maneuver since its launch in August 2011 with a half-hour engine burn that changed the spacecraft’s velocity, putting it on track for an upcoming Earth flyby.
The Dawn spacecraft is preparing to leave the asteroid Vesta to begin a more than two-year journey to Ceres, also in the asteroid belt. Dawn began what will become a journey of almost 5 billion kilometers in 2007 to visit the two largest bodies in the solar system’s asteroid belt.
Dawn’s journey to the two bodies — which NASA calls cosmic fossils — is gathering data for a better understanding of asteroids. That body of knowledge may eventually inform a mission taking a crew of astronauts to the asteroids.
“We went to Vesta to fill in the blanks of our knowledge about the early history of our solar system,” said Christopher Russell, Dawn’s principal investigator, based at the University of California, Los Angeles (UCLA), an institution partnered with NASA’s Jet Propulsion Laboratory for this mission. “Dawn has filled in those pages and more, revealing to us how special Vesta is as a survivor from the earliest days of the solar system.”
Dawn photographed Vesta from a close vantage point, revealing that the asteroid had completely melted in its past, and is now a layered body with an iron core, and bears the scars of collisions with other bodies.
“We now can say with certainty that Vesta resembles a small planet more closely than a typical asteroid,” said Russell.
Dawn begins the journey to Ceres on September 5, and in doing so, it will be the first probe to orbit and study two destinations.
UCLA is responsible for the science activities of the Dawn mission. 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 team.
JUNO TO JUPITER
Juno was more than 480 million kilometers from Earth August 30, when JPL navigators and mission controllers watched their computer screens to see the craft fire its main engine for an accurate burn. The craft will perform a second burn on September 4 to set a course for an Earth flyby, which will boost the craft’s velocity to almost 7.5 kilometers per second, sending it on the proper flight path to reach Jupiter, the giant gas planet that dominates its corner of the solar system. But the destination still has four years and 2.2 billion kilometers to go, said Scott Bolton, Juno’s principal investigator from the Southwest Research Institute in San Antonio.
“We need to go to Jupiter to learn our history because Jupiter is the largest of the planets, and it formed by grabbing most of the material left over from the sun’s formation,” said Bolton. “If we want to learn about the history of the elements that made Earth and life, we need to first understand what happened when Jupiter formed.”
The Southwest Research Institute is JPL’s partner in the Juno mission.
When the spacecraft reaches Jupiter, it will circle the planet 33 times from pole to pole and use the scientific instruments on board to probe beneath the cloud cover that obscures the planet. The craft will be gathering data that will help researchers better understand Jupiter’s structure, atmosphere and magnetosphere.
Both the Dawn and Juno missions are part of NASA’s planetary science program, which also encompasses the Curiosity rover’s mission on Mars. The program has spacecraft exploring the innermost planet of the solar system to the very edge of the sun’s influence.
The NASA website outlines the goals of the program: “With an exploration strategy based on progressing from flybys, to orbiting, to landing, to roving and finally to returning samples from planetary bodies, NASA advances the scientific understanding of the solar system in extraordinary ways, while pushing the limits of spacecraft and robotic engineering design and operations.”
More information on NASA's mission to the planets is available on the NASA website.