Our solar system has more than 500,000 asteroids flying around. But don’t worry, the “big one” isn’t expected to end life here on Earth for several million years.
That doesn’t mean we shouldn’t study them. After all, there are more than 1,000 asteroids on a “potentially dangerous” watch list.
“We have to figure out how to nudge these objects out of the way,” said Kevin Conod, manager for the Newark Museum’s Dreyfuss Planetarium.
Conod gave a lecture, “All about Asteroids,” this past week during the North Jersey Astronomical Group’s monthly meeting at Montclair State University.
Conod spoke about the history of asteroids (scientists thought they were stars, hence the Greek word “aster” for “star” ), its characteristics (a majority are dark carbonaceous objects; some are stony and a small fraction are metallic), and the latest asteroid-related discoveries gathered by NASA’s Dawn mission.
Dawn is orbiting the asteroid Vesta, a 330-mile object located in our solar system’s asteroid belt. After mapping, photographing and further study of Vesta, Dawn will travel to Ceres, a dwarf planet.
Vesta and Ceres are two of the largest objects in the asteroid belt and they are quite different. According to the mission’s website:
The top-level question that the mission addresses is the role of size and water in determining the evolution of the planets. Ceres and Vesta are the right two bodies with which to address this question, as they are the most massive of the protoplanets, baby planets whose growth was interrupted by the formation of Jupiter. Ceres is very primitive and wet while Vesta is evolved and dry.
Conod showed various pictures taken from Dawn that shows Vesta’s rocky and impact-ridden surface.
This 3-D image of the giant asteroid Vesta obtained by NASA’s Dawn spacecraft shows the surface of the asteroid from an orbit of about 1,700 miles above the surface. Numerous impact craters illustrate the asteroid’s violent youth. By counting craters on distinct geological surfaces scientists can deduce relative ages of the asteroid’s surface. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
This image of Vesta, calculated from a shape model, shows a tilted view of the topography of the south polar region. This perspective shows the topography, but removes the overall curvature of Vesta, as if the giant asteroid were flat and not rounded. An observer on Vesta would not have a view like this, because the distant features would disappear over the curvature of the horizon. (In the same way, if you were standing in North America, you would not be able to see a tall Mt. Everest in the distance, because of Earth’s curvature.) Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
Questions were raised regarding some of the parallel grooves, or streaks, on Vesta’s surface. What could have caused those marks, audience members asked Conod. “They go on much longer than can be explained by impact,” Conod responded. “They are really quite long … It’s under investigation.”
This full view of the giant asteroid Vesta was taken by NASA’s Dawn spacecraft on July 24, 2011, at a distance of 3,200 miles. This view of Vesta shows impact craters of various sizes and grooves parallel to the equator. What caused those parallel grooves? Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Later this month, NASA will obtain more images (eight times higher resolution) of Vesta. We’ll keep you posted here on Space Oddities.
After its rendezvous with Vesta, Dawn will head out to the dwarf planet Ceres. “It’s going to be an interesting world to explore,” Conod said.
There are only five objects classified as dwarf planets in our solar system. Perhaps the most famous is Pluto, which was declassified from a planet to a dwarf planet in 2006.
Other interesting asteroid/Dawn facts:
- According to Conod, if you took all the asteroids in our solar system and mashed them other, their total mass would only be 4 percent of that of our moon. Wow.
- When thinking about the asteroid belt, people usually reflect on what they’ve seen on television: Spaceships quickly darting out of the way of thousands of incoming rocks. But, Conod said, the average distance between asteroids is about 2 million miles. Wow again. “Collisions aren’t that common,” Conod said.
- Dawn, launched in 2007, is the first solar spacecraft to travel past Mars.
- Dawn uses ion propulsion, or electrical fields for power; unlike chemical reactions that were used for the Space Shuttle Program. An example: Conod said for 5,400 pounds of chemical propellant, only 540 pounds of ions are needed. Ion propulsion will allow scientists to go deeper and deeper into space. Read more about that here.
- Of all the meteorites that have crashed onto Earth, 5 percent has come from Vesta’s crust.
- Some asteroids, like Ida, have moons. Crazy, right? Read more about Ida and its moon Dactyl here.