The U.S. Navy could shoot down an errant spy satellite as early as Wednesday night. Now a new computer model shows what might happen.
The spy
satellite USA-193, also known as NROL-21, was launched aboard a Delta II rocket
on Dec. 14, 2006 from Vandenberg Air Force Base in California. Shortly after
the satellite reached orbit, ground controllers lost contact with it. Though
the satellite's objective is secret, many believe it is probably a high-resolution
radar satellite intended to produce images for the National Reconnaissance
Office.
On Feb. 14,
senior U.S. government officials at a Pentagon press briefing described a Defense
Department plan to try and shoot down the defunct satellite, after becoming
convinced that the spacecraft's toxic hydrazine fuel posed an unacceptable risk
to people on the ground. The attempted strike could come Wednesday evening.
With this
press information, computer modelers Bob Hall and Tim Carrico at Analytical
Graphics, Inc. (AGI) put together a computer-generated
simulation of the missile-satellite collision. The model shows a
hypothetical deployment of U.S Navy ships in the Northern Pacific Ocean and the
firing of a Standard Missile 3 at the failed satellite.
Information
the modelers do know:
- The
satellite has a mass of about 5,015 pounds (2,275 kilograms).
- The
missile would be fired from a ship in the North Pacific Ocean.
- The
interception would occur at an altitude of about 149 miles (240
kilometers).
- The satellite
and missile would close on one another at a velocity of about 22,783 mph
(36,667 kph).
If left
alone, the satellite is expected to re-enter Earth's atmosphere some time between
the end of February and early March. About 2,500 pounds (1,134 kilograms) of
satellite material would survive re-entry (the rest would burn up), including
1,000 pounds (453 kilograms) of hydrazine, according to a statement from the
U.S. Department of Defense.
The
collision between the fired missile and the satellite would not only break the
massive hunk of metal into pieces but would also speed up its tumble through
Earth's atmosphere.
"If
you want to bring something down, you slow it down. You apply a force on it
which results in it being slowed down and decrease in its orbit," Carrico
told SPACE.com. "Right at that point where they want to engage [the satellite] is at
the edge of the atmosphere, so you're bringing it down faster."
The plan
comes on the heels of the intentional destruction last year of China's
Fengyun-1C weather satellite, which produced a flurry of concern over the
hostile-or-not nature of the firing as well as a serious load of shrapnel
littering Earth orbit. That debris is still in space, frustrating mission
managers and satellite operators forced to dodge the potentially debilitating
bits.
USA-193 is
already on its way toward Earth and the interception will take place at a much
lower altitude than that of the China satellite, presumably meaning that
whatever happens, there will not be a fresh load of small junk sent into
perpetual orbit.
If more
details were made public, the model results could change depending on several
factors, including the location of the ships and when the missile is fired.
"How
the missile hits the satellite will affect how quickly the debris re-enters and
what the velocity is between the objects and how they hit," Hall said.
"Are they attempting to get most of the debris to come down in the Pacific
almost immediately? Or ... over the course of two or three revolutions, is most
of it going to start to fall out? If we had different information about the
engagement we could re-run our model.
advertisement
