Minotaur rocket launches U.S. military spacecraft
BY JUSTIN RAY
Posted: April 11, 2005
Deploying tiny probes to inspect or service spacecraft in distress and flying satellites that can operate with limited human touch are the chief goals behind a state-of-the-art technology demonstration mission successfully launched into Earth orbit this morning.
Officials confirm that the XSS-11 spacecraft separated from the launcher as planned and has begun its initial activities.
"Everything looks good," an Orbital spokesman said. "Early preliminary indications look like (the satellite) is healthy. It was an accurate launch, right in the middle of the box."
Over the coming weeks, controllers will conduct a fundamental checkout of the satellite's main systems.
The first real test of the XSS-11's rendezvous sensors and technology is expected sometime in the next three to six weeks when the craft revisits the Minotaur fourth stage.
"That is really where we get the basic performance parameters for the sensors," said Harold Baker, XSS-11 program manager at the Air Force Research Lab.
The mission will last 12 to 18 months as XSS-11 demonstrates new autonomous satellite features during encounters with six or seven spent rocket stages and dead U.S. satellites. The microsatellite project is designed to test technologies that could allow quick visual examinations or maintenance of spacecraft in orbit.
"This satellite represents a significant advance of what's ever been done in space before," Baker said. "Proving these technologies could have considerable impact on the amount of money it takes to operate a satellite, to launch a satellite, to build a satellite."
At the heart of XSS-11 is a radiation-hardened Power PC 750 processor that serves as the master avionics box, enabling onboard autonomous operations and mission planning by the satellite itself.
"The real technology is in the autonomous planner onboard and the logic algorithms that are required to do that mission, as well as the ground tools," Baker said.
The U.S. military has spent $56 million creating the XSS-11 spacecraft. Another $6 million has gone into mission operations over the life of the program.
Ground controllers will be actively involved in the early rendezvous attempts, but hope to gradually wean XSS-11 from human intervention.
"From the beginning, safety has been foremost in our minds. If we collide with an object, we fail. So initially we let the planner plan, but it has many, many ground decision points that have to be reached before it can proceed on its own," Baker said.
"As we proceed through the mission, we take some of those points out as we get more confidence that the planner is doing the right thing and it's agreeing with what we are seeing on the tools on the ground. As we go through the mission, we will take more and more of those go/no go decision points out that are given from the ground. The objective by the end of the program is have as many of those, if not all those, out and tell it what you want it to do and have confidence it is going to succeed."
"All of the objects are U.S.-owned, dead or inactive space objects. We have several rocket bodies that have been expended for other space vehicles and two or three satellites that are no longer operating....I believe one of them is a dead NOAA satellite," Baker explained.
The exact mission length will be determined as the mission proceeds.
"It really depends how the objects work out as we go along," Baker said. "Fuel is the limiting factor on the flight."
Some space watchers have suggested that XSS-11 is actually testing anti-satellite, or space weapon, concepts to disable enemy craft.
"Our job at the Lab is to develop technology," Baker said. "This is really a demonstration of autonomy technology, not weapons."
"We can say categorically, there's nothing that ejects out of the satellite," said Col. Richard White, commander of Space and Missile System Center's Detachment 12. "There's no battering ram. The entire purpose of the software, the entire purpose of the mission, is to make sure -- I repeat -- not bump into something."
During the rendezvous events with the target objects, XSS-11 will close within 1.5-miles of a rocket body or satellite but will never touch them.
"To fulfill our requirements, we can do that from two-and-a-half kilometers away. Obviously, we move in somewhat closer just to validate some of the technologies and how well they perform," Baker said.
"If we collide with something, we fail. We have multiple layers of safety on this satellite, literally we have three or four layers of safety to make sure we don't collide with an object."
How the technology will be used in operational missions of the future is yet to be seen.
"There is no specific or direct military application. This is a technology demonstration. That is what the Lab is for. We're really looking at the technologies, tools, algorithms, how the onboard planner performs and validate those so that they can be put into future plans," Baker said.
XSS-11 is one in a line of demonstration test satellites. Air Force leaders will decide whether there needs to be a follow-up to this particular mission.
"I think if this flight is successful, we move some of this technology forward for future mission planning. There are other areas to be developed, so there may be a follow-on. But that is not really how we do our programs.
"This is one in a series of experimental satellites. Currently, we are planning the next one. We receive proposals from different organizations on what they would like to see and done in space. That goes to our high-level officers in the Air Force and at Space Command, they get vetted and they select a new demonstration. It doesn't have to be in the same area as this one, it could be in a totally different area. We are right in the middle of that process now. In the next three or four months, they will come out with what the next demonstration is going to be."
"It's a great reuse of old ICBM assets, taking those out of missile holes and using that to launch a small satellite," White said.
Minotaur successfully debuted in 2000, carrying out a pair of missions that lofted five small satellites.
Schedules call for two more Minotaur launches this year -- in July and December -- from Vandenberg. The first will deploy the STP-R1 research satellite for the Air Force; the second will carry spacecraft in the joint Taiwan-U.S. project called COSMIC to study the atmosphere.
For Vandenberg Air Force Base, today's launch was the site's first space mission in 2005. Next up is Orbital Sciences' air-launched Pegasus rocket with NASA's DART technology satellite slated for flight on Friday.