Arrival and departure safety system collects data on trajectory, other parameters

As SpaceShipOne rocketed over the Mojave Desert on October 4 to claim the famed Ansari XPrize, a team of engineers at Edwards Air Force Base collected data about the spacecraft’s trajectory thanks to the spaceport arrival and departure safety system.

In a partnership between the California Space Authority and the Air Force Flight Test Center, the system performed its first two technology demonstrations during SpaceShipOne’s flights on September 29 and again on October 4.

Space authority and center officials said they recognized a need for a multi-frequency, continuous-wave radar system that can simultaneously track multiple objects.

In an era when the sky is crowded with commercial aircraft -- and now space planes -- officials said the system offers a new potential for enhanced safety.

For the center, this technology could be an important asset for many programs, including monitoring unmanned aerial vehicles, bomb drops and possibly space shuttle flights, said Allen Khosrowabadi, the system’s program manager for the 412th Test Wing.

“We can take a product like this to a place on the other side of the lakebed ... range,” said Robert Selbrede, lead engineer contractor, “and set it up, so the aspect angles are the way we want them to be when they drop the bombs. Then (the aircraft) will fly by and drop a whole load of bombs, and this radar can actually see all the individual bombs, see them spin, see the fins come out [and] the whole works. That’s really where something like this excels."

“Think of SpaceShipOne as a bomb separating from the aircraft,” Selbrede said. “You would want to know if the bomb came back up and hit the plane. You would want to see if it came off and dropped off real quick or if it stayed parallel or started tumbling right away.”

The key component for the project is the radar. It tracks velocity differences as objects move toward or away from the radar’s scope, Mr. Khosrowabadi said.

“Everything in the beam with a velocity component will be detected,” said Edwin Rutkowski, lead systems engineer for a subcontractor. The velocity helps the system’s receiver detect changes in frequency and compute the range for each change, he added.

The radar, which includes one panel for transmitting and another for receiving, sits on a mobile kineto-tracking mount, which is actually 15 to 20 year-old technology. Engineers with the range operations and maintenance contractor for the 412th TW, installed the radar and modified the mount to accept the system.

Mr. Khosrowabadi said it was great to see the whole thing come together. The team had many obstacles to overcome, particularly in dealing with old and new technologies trying to communicate coherently within the same system.

In this first phase of development, Mr. Khosrowabadi said the team simply “wanted to get the radar, get familiar with it and do a demonstration” to see if it would work for the center or the range. “Apparently now the answer is ‘yes.’” he said.

The team plans to update the radar’s auto-track feature so that the system does not have to rely on an individual using visual tracking alone, officials said.

“Then the next step is to make this an operational system by doing the upgrades and getting a bigger radar,” Mr. Khosrowabadi said. “The long-term vision, once hypersonic [flight] starts happening, is to increase our range by having a couple of these strung along miles apart. When one loses visual, another one picks it up. As far as the data (are) concerned, you won’t see any holes.”

(Thanks to Capt. Kelly George, Air Force Flight Test Center Public Affairs)

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