You can't make this stuff up! The latest idea from NASA sounds like a "space western." In this case one cowboy, played by a robotic spacecraft, is sent to lasso a small asteroid and bring it back to a spot near the moon. Once parked by the moon other cowboys, played by astronauts, would explore the space rock. This sounds like a great subject for a film, but the plot seems a bit weak.

Just last Friday, Senator Bill Nelson of Florida endorsed the plan and said it would speed up existing NASA plans to land astronauts on an asteroid by four years. In other words, a robot could travel to an asteroid and bring it close to Earth in much less time than sending astronauts to a rendezvous that is well beyond our geocentric environment.

The robotic spaceship is envisioned as capable of capturing a half-million-kilogram asteroid travelling in a heliocentric orbit, and then dragging it into the Earth's sphere of influence. NASA's plan calls for this to happen in about six years. About two years later an Orion space capsule with a crew of several astronauts would rendezvous with the rock in order to conduct exploration activities.

Apparently, President Obama is planning to provide $100 million in the 2014 NASA budget to support the accelerated asteroid mission. Presumably, this money would be used to find the right small asteroid. Although this seems a lot of money to find a rock, the people in charge think it a clever idea.

Well, when you compare it to the 17 trillion we already owe, it seems only a pittance. After all, this would be the first time humans would have captured and manipulated a space rock of this size.

To paraphrase Sen. Nelson: "Rather than going to the mountain, why not bring the mountain to us?"

This whole discussion begs the question: "If it costs $100 million to find a rock, how much can it cost to bring it back?" The Keck Institute for Space Studies recently proposed a similar mission with an estimated price tag of $2.6 billion. However, NASA has not released its cost numbers.

Of course, the other question we must ask is: "How does one lasso an asteroid?" There are apparently literally thousands of near-Earth objects (NEOs) that might fit the bill, but finding one that passes near Earth at just the right time for capture may not be easy. Nevertheless, once the "right" NEO is found, the robot would throw a lasso, similar to a baggie with a drawstring, around the rock.

In the words of Donald Yeomans, head of NASA's NEO Program: "You bag it. You attach the solar propulsion module to de-spin it and bring it back to where you want it." Of course, there are the problems of lassoing a half-million-kg rock travelling at a relative speed that might be several km/sec with a several-hundred-kg spacecraft and then slowing its speed to allow capture by Earth's gravitational field.

Clearly, the robotic spaceship will require a good deal of new technology to capture and bring back the rock. So, the final question seems to be: "If we can build a robot to rendezvous with a NEO and capture it, why not simply let the robot explore it, sample it and bring a piece of it right to NASA?"