The NASA plan to "shoot" an asteroid with a rocket spacecraft

When American government representatives asked NASA head Charles Boden this year what the best response to a large asteroid headed towards New York City would be, his answer was simple - “Prayer”.

But NASA’s Jet Propulsion Laboratory is quietly working on a computer-piloted spacecraft that might help us understand how to blast an asteroid into a different orbit.

The idea sounds like science fiction - but the space agency is already running simulations of the planned mission to fire a high-velocity spacecraft into a rocky asteroid half-way across the solar system.

The ambitious plan could yield information on how to steer deadly space rocks away from Earth - but it will not be easy.

Shyam Baskaran of NASA siad, “Hitting an asteroid with a spacecraft travelling at hypervelocity is like shooting an arrow at a target on a speeding race car.”

The“arrow” NASA aims to fire is a ring-shaped spacecraft, piloted bycomputers, which will close on a 1600ft asteroid at incredible speeds - around eight miles per second.

The impact would blast a 100ft crater into the surface of the asteroid - and explode with the force of nine tons of TNT.  

The mission will provide information on what makes up the asteroid, but also how its orbit reacts to being hit by a spacecraft. It's one of several NASA missions targeting asteroids - including an ambitious plan to "capture" an asteroid and land humans on it by 2025.

“While the effect on the orbit of asteroid 1999 RQ36 will be miniscule, it will be measurable,” said Steve Chesley, a near-Earth object scientist at JPL. “Once we know how its orbit changes, no matter how small, we can make better assessments and plans to change some future asteroid’s orbit if we ever need to do so. Of course, we have to hit it in the first place.”

“High-speed impacts on asteroids can tell you so many things that we want to know about asteroids,” said Chesley. "They can tell you about their composition and their structural integrity - which is how they hold themselves together. These are things that are vital for mission designers working on ways to potentially move asteroids, either for exploitation purposes or because they may be hazardous to Earth.”

The impactor would “hitchhike” on a robotic NASA Mars mission, Insight, then loop round Mars to bear down on the asteroid RQ36. It’s not the first time NASA has hit a fast-moving object - a 2005 mission, Deep Impact, hit the surface of a comet.

Asteroids pose entirely different challenges, says Bhaskaran, who was also the navigator on the successful 2005 comet mission.

“Asteroids hardly ever resemble perfect spheroids,” said Bhaskaran. “What you’ve got floating around out there are a bunch of massive objects that look like peanuts, potatoes, diamonds, boomerangs and even dog bones - and if the spacecraft’s guidance system can’t figure out where it needs to go, you can hit the wrong part of the asteroid, or much worse, miss it entirely.”

The robotic spacecraft will pilot itself in the crucial last moments of the mission - the planned impact would be half-way across the solar system, so sending commands by radio would take too long.

Bhaskaran says, “With Earth so far away, there is no chance to send new commands in time. The "pilot", AutoNav, is essentially a cyber-astronaut that takes in all the pertinent information, makes its own decisions and performs the actions necessary to make sure we go splat where we want to go splat.”

In the crucial last two hours of the mission, Autonav will operate entirely on its own.

“AutoNav’s imaging system and its orbit determination algorithms will detect the asteroid and compute its location in space relative to the impactor,” said Bhaskaran.

“Without waiting to hear from us, it will plan for and execute three rocket burns at 90 minutes, 30 minutes and then three minutes out. That last rocket firing will occur when the asteroid is only 1,500 miles away. Three minutes later, if all goes according to plan, the spacecraft hits like a ton of bricks.”

"We expect the crater excavated by the impact of ISIS could be around 100 feet across,” said Chesley. “We will be able to determine how big a hole there is, but also analyse the material thrown out during the impact.”

“We have confidence that whenever called upon, AutoNav will do its job,” said Bhaskaran. “The trick is, we just don’t tell AutoNav it’s a one-way trip."