Thursday, November 24, 2011

OTV-2: When will the X-37B land?

The U.S. Air Force's reusable OTV-2 (Orbital Test Vechile 2) automated space plane is nearing it's 270 day orbital design life. Launched on March 5 from Cape Canaveral on an Atlas V booster, the OTV-2, which is the second X-37B spaceplane built, has now been in orbit for 264 days.

Will the OTV-2 land soon? Maybe yes, maybe no. It's possible the mission may be extended. While the X-37B uses solar panels for electrical power, it's orbital lifetime is limited by consumables, such as fuel. If flight controllers have managed to conserve fuel, then the mission may be extended.

Commenting on the possibility that the mission may be extended Lt. Col. Tom McIntyre, Air Force X-37 systems program director said in October, "On-orbit experimentation is continuing, though we cannot predict accurately when that will be complete" and “We are learning new things about the vehicle every day, which makes the mission a very dynamic process." He also said that controllers "will try to extend it as circumstances allow." See Space Insider - Space.Com

If the Air Force follows the same procedures as they did in the landing of OTV-1 in December 2010, they will announce a few days in advance the approximate landing date of the vehicle.

Is it possible to see the X-37B land?  The X-37B's primary landing site is Vandenberg AFB on the California coast north of Los Angles. The backup landing site is Edwards AFB, about 150 miles to the East. While both site's are restricted, there is public access nearby.

Assuming the X-37B uses a path similar to the Space Shuttle, an approach Vandenberg AFB's runway 30 would probably come from the west-south-west on the upward node of it's orbit, fly just north of the runway and make a sweeping 240 degree turn to the right around the heading alignment circle to align with runway 30.  Observers in Lompoc and along California Hwy 1, east of Vandenberg would probably be able to spot the craft, given the right conditions.

An approach from the west-north-west on the downward node of it's orbit would probably fly to the west of the runway, over the ocean, and make 160 degree left turn to align with runway 30. Again observers in Lompoc should be able to spot it under the right conditions.

Right now the upward node of the X-37B's orbit passes over Vandenberg AFB about an hour before dawn each day. In another 10 days or so it will passing over around dawn, prime viewing time. But catching a glimpse of it gets more interesting.

Because of the X-37B's cross-range ability, the distance it can fly to the right or left of it's orbital path while reentering, the craft probably has landing opportunities on 4 or 5 consecutive orbits each day. That's a 6 hour window! So it's going to be tough to spot.  Best advice, if you're near Lompoc and hear a sonic boom in the morning hours, look towards Vandenberg's runway and maybe you'll catch a glimpse of OTV-2's landing.

By the way, this will be only the third time a spacecraft returning from orbit has made an automated runway landing.  Can you guess the first two? Post a comment if you know.

Image credits: Top two - NASA; Bottom - USAF