Second live test of US raygun jumbo delayed by glitch

The United States' radical jumbo jet mounted ICBM-blasting laser cannon was set for its most ambitious test yet last night, in which it would have fried a missile in flight from more than 100 miles off. However technical hitches have delayed the test until the weekend.

The trial was announced by the US defence department in a statement on Tuesday, at which time it was expected that the laser jumbo would shoot down its second missile above a Californian firing range early yesterday morning. Thus far the raygun has shot down just one missile (in February) at a relatively close range, which would be inconvenient in operational use - the plane would have to fly dangerously close to the enemy missile silo or pad, penetrating defences to do so.

Here's a vid of the test:

However it has now been announced that this week's longer-range firing has been delayed "due to a problem with the tracking camera cooling system". The Missile Defence Agency (MDA) expects to have rectified the fault in time for the next range slot on Saturday.

The 747-carried energy weapon, formerly known as the Airborne Laser (ABL) and intended as the forerunner of an operational fleet, was downgraded by the incoming Obama administration to the status of an experiment. It is nowadays known as the Airborne Laser Testbed (ALTB), and no fleet of similar aircraft is to be built.

Nonetheless the MDA still expects to deploy directed-energy weapons as a means of knocking down the possible enemy ballistic missiles of the future.

“Directed energy may be a viable missile defense technology in the future,” insisted agency spokesman Rick Lehner this week.

However the ALTB's chemical laser technology, which uses hazardous fuels to generate the beam (and generates equally hazardous exhausts) is nowadays seen as unacceptably cumbersome. It remains the only way right now to generate a truly powerful ray - the ALTB is said to put out a "multimegawatt" amount of energy - but is heavy and very troublesome to refuel.

The MDA is thought to be carrying on with the ALTB not so much as a weapon but as a means of validating the technologies which aim and control the beam, and as a means of finding out just what is required in terms of beam power and duration to shoot down real missiles.

The possible operational war rayguns of the future are more likely to use new electrically powered solid-state technologies which have been going from strength to strength in recent times. For now, however, such kit remains well down in the sub-megawatt realm - in large part due to cooling difficulties. Present day rayguns tend to release far more energy inside themselves than they send down the beam, and this self-heating is a major problem for designers.

The ALTB's chem-laser, as it generates its beam within a gas, is easier to cool than a solid assembly. Comments made lately by the head of the MDA suggest that some US raygun boffins are now looking at some kind of combo gas/solid-state system for the future.

There doesn't, however, appear to be much urgency any more in the MDA's ICBM-busting mission compared to the days of the Bush administration.

“The reality is [the Iranian missile threat] did not come as fast as we thought it’d come,” said General James Cartwright, vice chairman of the US Joint Chiefs of Staff, last year.

Meanwhile North Korea, the other primary ICBM worry for the US and the other major powers, has so far failed to get its erratic Taepodong-2 missile ("space rocket") to work. The Nork threat would probably have been the main point of action for the planned ABL fleet, as patrolling blaster-jumbos could lurk without too much difficulty above international waters and yet within range of the missiles' launch sites.

In the absence of any actual working Nork (or Iranian) missiles able to reach more than one or two countries away, however, the back-burnering of the US raygun programme would seem reasonable. ®