As the U.S. government reviews its policy toward the military uses of space, the most serious concern raised by some activists is the potential to put a weapon in space that could attack targets on earth.  VOA Defense Correspondent Al Pessin reports on the debate over what some see as the ultimate weapon and others see as a destabilizing and dangerous concept.

It is not a complicated idea.  Satellites orbit the earth approximately every 90 minutes.  Put a weapon on a satellite that can hit targets on earth, and it can strike almost anywhere within that short timeframe.  Put several such satellites in orbit, and the owner would have the ability to hit any target, anywhere on earth, within just a few minutes.

So why has no country done so?  The answer can be summed up in one word:  Cost.  And that refers to both the huge expense of developing and deploying any space weapon, and the political cost.

"There is not going to be any other nation on earth that is going to accept the U.S. developing something they see as the 'Death Star,'" said Theresa Hitchens, vice president of the Center for Defense Information, a Washington research organization.

"I do not think the United States would find it very comforting if China were to develop a 'Death Star' - a 24/7, on-orbit weapon that could strike at targets on the ground anywhere in 90 minutes," she added.  "What if we develop such a weapon, and we orbit it, and China decides to follow suit?  Are we going to shoot it down before they get it in space to prevent them from being on equal footing with us?  And if we did that, what kind of follow-on would come from that?"

It sounds like a scary scenario. 

U.S. defense officials say they have no plans for such a weapon.  But Randall Correll, a Pentagon consultant who served five years as an officer at the U.S. Air Force Space Command, says a space-based weapon is not necessarily scary, and could be very useful.

"Is this basically a scary weapon?  I do not know about that," he said.  "If we construct an operational scenario where we have these launch vehicles that once or twice a year do an exercise.  They do a launch.  We work with our allies and other countries and have, kind of, worked out the operational and political agreements on how and when we would use these. I think you can, kind of, manage the fear or the concern over their misuse.  Now, that is easier said than done.  Clearly, there would be a lot of work to do that.  But I think that is the direction we are going."

Mr. Correll says a space-based weapon, or an earth-based weapon that can attack a satellite in space, could provide the president of the United States with a decisive option in a critical situation.

"If the choice is to destroy an enemy's ground station, where there will be people, maybe in an area where there are civilians.  Maybe destroying a machine, or damaging a machine, in space might be the preferred option," he added.

Mr. Correll says in such a situation, the space weapon would be well worth its political and financial cost.

U.S. officials say they are a long way from developing any such weapon, and efforts in other countries even to develop an anti-satellite weapon have failed.

The vice commander of U.S. Air Force Space Command, Lieutenant General Daniel Leaf, says he cannot simply "presume away that possible threat," but for now he stresses other ways of controlling an adversary's ability to use space against the United States, or against U.S. forces around the world.

"We need the ability to deny access to space capabilities," he said.  "There are a variety of ways to do that.  We always prefer localized, temporary and reversible means of doing that.  And I won't go into the specifics, of course, but you don't have to necessarily act directly upon the space system.  You can disrupt a link.  You can address the ground segment, the ground control segment.  They are not limited to this, sort of, 'Star Wars' picture that's been painted by some people that I think is a significant amount of hyperbole."

And General Leaf points out that an adversary that is using space may not even actually have its own rockets, satellites or ground stations.

"You do not have to be a space power to have access to space capability," he explained.  "You can have access to space capability with a credit card.  So even nations that are small, or organizations like al-Qaida, have potential access to space capabilities.  They can buy imagery, for example, on the Internet that is high quality and reasonably fresh, without having a single satellite of their own."

That makes Space Command's mission to deny adversaries access to space even more difficult, and involves other U.S. government agencies monitoring all sorts of space and Internet activity.

And at the same time, Space Command is looking for new ways to use space, ways U.S. adversaries might want to block.  Among them is a growing list of space capabilities designed to directly help U.S. troops involved in conflicts and peacekeeping around the world.