NASA's Cooperative Autonomous Distributed Robotic Exploration (CADRE) project is developing small robots programmed to work autonomously as a team to explore the lunar surface.

A team of shoebox-size rover scouts was recently put to the test at a NASA Glenn Research Center lab. The facility, called the Simulated Lunar Operations lab (or SLOPE) is designed to mimic lunar and planetary surface operations. The mini-rovers traversed simulated lunar soil—called regolith—to better understand the types of challenges that lunar rovers of this size will face on the Moon's surface. The results of the tests will be used to characterize small rover performance and improve the rovers' mobility design.

In the 1998 Hollywood blockbuster "Armageddon," Bruce Willis and Ben Affleck race to save the Earth from being pulverized by an asteroid.

While the Earth faces no such immediate danger, NASA plans to crash a spacecraft traveling at a speed of 15,000 miles per hour (24,000 kph) into an asteroid next year in a test of "planetary defense."

The Double Asteroid Redirection Test (DART) is to determine whether this is an effective way to deflect the course of an asteroid should one threaten the Earth in the future.

NASA provided details of the DART mission, which carries a price tag of $330 million, in a briefing for reporters on Thursday.

"Although there isn't a currently known asteroid that's on an impact course with the Earth, we do know that there is a large population of near-Earth asteroids out there," said Lindley Johnson, NASA's Planetary Defense Officer.

Four astronauts could leave the International Space Station on Sunday without their replacement team having arrived to take over, NASA announced Thursday, but the timing remains uncertain due to weather conditions.

The four members of the Crew-2 mission, including a French and a Japanese astronaut, are due to return to Earth this month after spending about six months on board the ISS.

Normally they would have to wait for four other astronauts—three Americans and a German from the Crew-3 mission—to arrive aboard the space station to take their place.

But the takeoff of the next mission's rocket, which had already been postponed several times and had been rescheduled for this weekend, was once again canceled because of unfavorable weather conditions, NASA said in a statement.

As a result, the space agency is now considering returning Crew-2 to Earth before Crew-3 launches.

"The earliest possible opportunity for undocking" the capsule to bring Crew-2 back to Earth would be at 1:05 pm Sunday Florida time (1705 GMT), NASA said.