About 1,000 asteroids, or about the size of Texas, are known to have been discovered in the asteroid belt, the asteroid field between Mars and Jupiter.
Of those, 1,500 are near Earth, and another 50,000 are potentially hazardous asteroids.
But how many asteroids have been detected?
“That’s a tough question, and it’s not really a question that can be answered without a huge amount of data,” said Mark Lauterborn, director of NASA’s Near-Earth Object Program.
The agency’s Near Earth Object Observations program, or NEOPO, is working on that data.
The mission is looking for the objects by measuring the light from the orbiting planet, but it’s also looking for other signals from the asteroids.
“What we’re really trying to do is look for signatures of other objects that we haven’t seen before,” said Lautherborn.
Asteroid hunters in orbit have found some promising signals.
The spacecraft MESSENGER, which has made the most observations of asteroids this century, found that about 50 percent of the asteroid population is likely to be near Earth.
The next closest objects, about 15 percent of them, are expected to be in the asteroids belt.
NASA says its NEOPTIMELINER mission, which launched in 2009, is looking at about 100 asteroids in the belt.
About 5 percent of these are expected by the end of the decade.
“The biggest problem is that you’re not looking at the actual orbits, you’re looking at how many of these objects are there,” Lauterman said.
“You can’t do that without a lot of data.”
Scientists believe about 40 percent of asteroids are not in the Earth system.
Asteroids, like water, have a chemical makeup similar to that of the Earth.
They’re mostly made up of minerals and carbon.
They weigh about the same, but they don’t move much because of gravity.
Asterids are relatively close to us because they’re orbiting the Sun.
The moon orbits the Earth, too, and the sun and planets orbit around the sun, but asteroids don’t orbit the planets, Lauterebres said.
Asteros also have the ability to change their orbits, and NASA has launched its first robotic asteroid-hunting spacecraft, dubbed the Lunar Reconnaissance Orbiter.
“It’s the first spacecraft that has flown by an asteroid, and there’s not much data that has been obtained by that spacecraft,” Lathrop said.
The goal of the mission is to look for signs of the potential of another asteroid to pass near Earth and to try to identify where in the outer Solar System an asteroid could be.
“We’re not going to have a definitive answer until we actually see another asteroid pass by,” Larthrop said, “but we know that there are potential objects there, and we can find out how far away they are.”
Asteroid hunter Mark Lothrop says his team is still working to determine how far it will be from Earth to identify a potentially hazardous asteroid.
“This is a very good thing for the human race,” he said.
Lothrotres, who is also a member of NASAs NEO team, said his group has collected about 2,500 measurements from the Moon, Venus, Mars and other objects.
Lauteriebs mission will include a probe, called the LADEE spacecraft, which will be orbiting Mars for a year.
It’s also trying to find a sample of water ice from the asteroid Bennu.
NASA’s Asteroid Redirect Mission is studying possible debris from a potential impact with an asteroid.
NASA also plans to launch a robotic spacecraft called MAVEN, named for the Mars rover, which is set to enter orbit around Jupiter next year.
Asterisk Hunter is part of NASA programs that are aimed at identifying potentially hazardous objects.
The program has launched more than 150 robotic missions, and Lautero said that’s just the tip of the iceberg.
“There are many, many other missions in the pipeline that are looking for these objects and trying to figure out what’s there,” he told AP.