Approaching Asteroid 1998 QE2 has a satellite Moon

First radar images of asteroid 1998 QE2 were obtained when the asteroid was about 3.75 million miles (6 million kilometers) from Earth.

CREDIT: NASA/JPL-Caltech/GSSR

A huge asteroid set to sail past Earth on Friday has its own moon, NASA scientists have just discovered.

Researchers obtained a series of radar images of the approaching asteroid 1998 QE2 late Wednesday (May 29) using the Deep Space Network antenna at Goldstone, Calif.

Images captured over the course of two hours showed that the asteroid is actually a binary system.

The main space rock is the size of nine ocean liners, roughly 1.7 miles (2.7 kilometers) across, and the satellite that orbits it is estimated to be 2,000 feet (600 meters) wide, according to NASA.

Binary systems are quite common among near-Earth asteroids. Of space rocks at least 655 feet (200 meters) across, about 16 percent are binary or triple systems, NASA officials said.

1998 QE2 poses no threat of hitting Earth during the flyby, space agency officials assure. Its closest approach will occur at 4:59 EDT on Friday (May 31) and it is expected to pass at least 3.6 million miles (5.8 million kilometers) away from the planet.

The asteroid won't be visible to the unaided eye as it zips by.

Though harmlessly far away, this will be the nearest 1998 QE2 gets to Earth in the next two centuries.

As it passes, the asteroid will be closely watched by astronomers. In addition to the 230-foot-wide (70 meter) Deep Space Network antenna, astronomers will also be using the Arecibo Observatory in Puerto Rico to observe 1998 QE2 until June 9.

NASA WISE mission finds lost asteroid family members

This artist's conception shows how families of asteroids are created. 

Over the history of our solar system, catastrophic collisions between asteroids located in the belt between Mars and Jupiter have formed families of objects on similar orbits around the sun. 

Image credit: NASA/JPL-Caltech

Data from NASA's Wide-field Infrared Survey Explorer (WISE) have led to a new and improved family tree for asteroids in the main belt between Mars and Jupiter.

Astronomers used millions of infrared snapshots from the asteroid-hunting portion of the WISE all-sky survey, called NEOWISE, to identify 28 new asteroid families.

The snapshots also helped place thousands of previously hidden and uncategorized asteroids into families for the first time.

The findings are a critical step in understanding the origins of asteroid families, and the collisions thought to have created these rocky clans.

"NEOWISE has given us the data for a much more detailed look at the evolution of asteroids throughout the solar system," said Lindley Johnson, the program executive for the Near-Earth Object Observation Program at NASA Headquarters in Washington.

"This will help us trace the NEOs back to their sources and understand how some of them have migrated to orbits hazardous to the Earth."

The main asteroid belt is a major source of near-Earth objects (NEOs), which are those asteroids and comets that come within 28 million miles (45 million kilometers) of Earth's path around the sun.

Some near-Earth objects start out in stable orbits in the main asteroid belt, until a collision or gravitational disturbance flings them inward like flippers in a game of pinball.

The NEOWISE team looked at about 120,000 main belt asteroids out of the approximately 600,000 known.

They found that about 38,000 of these objects, roughly one third of the observed population, could be assigned to 76 families, 28 of which are new.

In addition, some asteroids thought to belong to a particular family were reclassified.

An asteroid family is formed when a collision breaks apart a large parent body into fragments of various sizes.

Some collisions leave giant craters. For example, the asteroid Vesta's southern hemisphere was excavated by two large impacts.

Other smash-ups are catastrophic, shattering an object into numerous fragments, as was the case with the Eos asteroid family.

The cast-off pieces move together in packs, traveling on the same path around the sun, but over time the pieces become more and more spread out.

More information: Paper: dx.doi.org/10.1088/0004-637X/770/1/7

Dangerous Near Earth Asteroids: Is Nuking them the Best Protection?

Recent Russian space rock explosion and same day close flyby of an asteroid is stirring up talk about dealing with the near-Earth object threat.

CREDIT: Texas A&M

If a dangerous asteroid appears to be on a collision course for Earth, one option is to send a spacecraft to destroy it with a nuclear warhead.

Such a mission, which would cost about $1 billion, could be developed from work NASA is already funding, a prominent asteroid defense expert says.

Bong Wie, director of the Asteroid Deflection Research Center at Iowa State University, described the system his team is developing to attendees at the International Space Development Conference in La Jolla, Calif., on May 23.

The annual National Space Society gathering attracted hundreds from the space industry around the world.

An anti-asteroid spacecraft would deliver a nuclear warhead to destroy an incoming threat before it could reach Earth, Wie said.

The two-section spacecraft would consist of a kinetic energy impactor that would separate before arrival and blast a crater in the asteroid.

The other half of the spacecraft would carry the nuclear weapon, which would then explode inside the crater after the vehicle impacted.

The goal would be to fragment the asteroid into many pieces, which would then disperse along separate trajectories.

Bong Wie

Bong Wie believes that up to 99 percent or more of the asteroid pieces could end up missing the Earth, greatly limiting the impact on the planet.

Of those that do reach our world, many would burn up in the atmosphere and pose no threat.

Wie's study has focused on providing the capability to respond to a threatening asteroid on short notices of a year or so.

The plan would be to have two spacecraft on standby — one primary, the other backup — that could be launched on Delta 4 rockets.

If the first spacecraft failed on launch or didn't fragment the asteroid, the second would be sent aloft to finish the job.

Wie admitted that sending nuclear weapons into space would be politically controversial.

However, he said there are a number of safety features that could be built into the spacecraft to prevent the nuclear warhead from detonating in the event of a launch failure.

A nuclear weapon is the only thing that would work against an asteroid on short notice, Wie added.

Other systems designed to divert an asteroid such as tugboats, gravity tractors, solar sails and mass drivers would require 10 or 20 years of advance notice.

Near Earth Asteroid Missed by 17,000 miles

Talk about a close shave. On Feb. 15th an asteroid about half the size of a football field will fly past Earth only 17,200 miles above our planet's surface. There's no danger of a collision, but the space rock, designated 2012 DA14, has NASA's attention.

"This is a record-setting close approach," says Don Yeomans of NASA's Near Earth Object Program at JPL. "Since regular sky surveys began in the 1990s, we've never seen an object this big get so close to Earth."

Earth's neighborhood is littered with asteroids of all shapes and sizes, ranging from fragments smaller than beach balls to mountainous rocks many kilometers wide. Many of these objects hail from the asteroid belt, while others may be corpses of long-dead, burnt out comets. NASA's Near-Earth Object Program helps find and keep track of them, especially the ones that come close to our planet