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admin
06-20-2006, 06:09 PM
From Space.com...


Military Microsatellites to Test Technologies in Wednesday Launch
By Justin Ray - posted: 20 June 2006 - 12:25 pm ET

An experimental U.S. military project to test whether the advanced technologies embedded in two miniature satellites and a new upper stage kick motor can operate through the rigors of spaceflight will launch into orbit Wednesday evening from Cape Canaveral aboard a Boeing Delta 2 rocket.

The Micro-Satellite Technology Experiment, or MiTEx for short, is slated for liftoff at 5:34 p.m. EDT (2134 GMT). A four-hour launch window is available through 9:34 p.m. EDT (0134 GMT).

"MiTEx will investigate and demonstrate advanced space technologies such as lightweight power and propulsion systems, avionics and spacecraft structures; commercial-off-the-shelf processors; affordable, responsive fabrication/build-to-launch techniques; and single-string components," DARPA officials explained in mission information provided to Spaceflight Now.

The 12-story rocket will roar away from pad A of Complex 17 with its main engine and six strap-on boosters firing to create 789,000 pounds of thrust. A minute later, the three remaining solid-fuel boosters will light as the six ground-lit motors burn out and fall away.

Heading eastward across the Atlantic, the blue and white Delta will leave a smoky contrail from the solid boosters until the final three are extinguished just over two minutes into flight and separate more than 30 miles above the ocean.

That will leave the RS-27A first stage engine, consuming refined kerosene and supercold liquid oxygen, to push the rocket onward for another two minutes to an altitude of 70 miles (112 kilometers) before shutting down. The spent stage then jettisons, allowing the hypergolic-fueled second stage to ignite.

Moments later, the two-piece nose cone that shrouded the payload during ascent through the atmosphere is commanded to spring open and separate.

The second stage engine will deliver the rocket into an initial orbit with a high point of 154 statute miles (247 kilometers) and low point of 103 miles (165 kilometers) when it shuts down at T+plus 10 minutes, 22 seconds after liftoff.

The vehicle will coast in that orbit for 12 minutes before the engine is re-started for a 73-second burn to reach an intermediate orbit with a high point of 1,380 statute miles (2,220 kilometers) and low point of 105 miles (168 kilometers). Tiny thrusters on the side of the rocket then spin up the third stage in preparation for separation. The two stages split at T+plus 23 minutes, 31 seconds, followed 37 seconds later by ignition of the solid-fuel third stage for its 86-second burn.

The third stage targets a highly elliptical geosynchronous transfer orbit with a high point of 22,490 statute miles (36 194 kilometers), low point of 115 miles (185 kilometers) and inclination of 25.24 degrees to the equator.

At T+plus 30 minutes and 24 seconds while cruising 375 miles (603 kilometers) above south-central Africa, the third stage releases from the MiTEx upper stage with its still-attached satellites. That will complete the Delta 2 rocket's role in the MiTEx mission.

The Defense Advanced Research Projects Agency (DARPA) is spearheading the MiTEx effort to evaluate the usefulness of small satellite technologies and the prototype upper stage to support future military programs.

But before the two satellites can begin their year-long missions, the stage has to place the craft into the intended orbit.

Developed by the U.S. Naval Research Laboratory, the experimental motor will put several new technologies to the test including:
Platinum/rhodium bi-propellant attitude control thrusters
High-performance coated columbium delta-V thruster
Commercial off-the-shelf manual valve tested to aerospace standards
Light-weight Inconel-718 composite overwrap pressure vessels
Lightweight titanium propellant tanks with internal propellant management devices
Triple junction solar cells
Lithium-ion batteries
A low-cost/high-performance star tracker

The stage will ferry the two MiTEx satellites from the egg-shaped geosynchronous transfer orbit reached by the Delta 2 rocket to the circular geostationary orbit 22,300 miles (35,888 kilometers) above the equator. That high orbit allows spacecraft to match the planet's rotation and appear fixed over one location.

Once arriving in geostationary orbit, the satellite pair will be deployed from the stage to begin independent lives examining the value of operating miniature craft from such a high vantage point above Earth. The demonstration will give military planners real-life experience to draw upon when designing new projects.

The MiTEx spacecraft weigh about 500 pounds (226 kilograms) each. Orbital Sciences built one satellite and Lockheed Martin the other.

"The satellites will conduct a variety of experiments in autonomous operations and maneuvering and station-keeping. MiTEx will also demonstrate the ability to launch multiple small satellites into GEO orbit," according to DARPA officials.

Geostationary orbit is the home to government and commercial communications satellites, plus spy spacecraft for eavesdropping reconnaissance missions and missile-launch detection.

The price tag for MiTEx has not been released. And the exact parking spots in geostationary orbit for the two spacecraft aren't being revealed.

admin
06-23-2006, 08:56 AM
From Space.com...


Experimental Military Microsatellites Reach Orbit
By Justin Ray - posted: 22 June 2006 - 10: 47 a.m. ET

An experimental U.S. military project to characterize the performance of two micro-satellite trailblazers operating 22,300 miles above Earth and a prototype maneuvering motor for small spacecraft began with a beautiful blastoff from Cape Canaveral Wednesday evening.

The Micro-Satellite Technology Experiment, or MiTEx, was successfully delivered into space by Boeing's workhorse Delta 2 rocket. Launch from pad 17A occurred at 6:15 p.m. EDT (2215 GMT) after a short delay to clear both a technical issue with the payload and any boats from the restricted waters under the rocket's flight path.

The swift half-hour ascent by the three-stage rocket put MiTEx into an elliptical geosynchronous transfer orbit to mark the 67th consecutive successful Delta 2 mission dating back to 1997 and the 120th success overall in 122 flights since 1989.

The Delta's job has been completed but the year-long missions for the two 500-pound micro-satellites of MiTEx can't begin quite yet. The miniature spacecraft are relying on their Naval Research Laboratory-developed upper stage rocket motor to boost them from the current launch orbit to the final destination -- a circular geostationary orbit over the equator.

The Defense Advanced Research Projects Agency, Air Force and Navy have collaborated to fly this space mission to test technologies that could be incorporated in future military programs. MiTEx will prove whether the technologies -- for satellites and upper stages -- are deemed worthy or simply need more work.

According to information about MiTEx provided to Spaceflight Now by DARPA officials, the major goals of the project include:

Develop and flight-test a new experimental upper stage

Investigate and demonstrate advanced space technologies such as lightweight power and propulsion systems, avionics, and spacecraft structures; commercial-off-the-shelf processors; affordable, responsive fabrication/build-to-launch techniques; and single-string components

Demonstrate a one-year lifetime for small satellites built using these new technologies and techniques

Demonstrate the ability to insert small satellites into geostationary orbit

Gain experience in the operations and determine the potential utility of small satellites for future Defense Department missions in a geostationary orbit

The new upper stage burns monomethylhydrazine and nitrogen tetroxide. It is equipped with a 90-pound-force engine as well as a half-dozen five-pound-force engines.

Specific technologies being tested on the stage include:

Platinum/rhodium bi-propellant attitude control thrusters

High-performance coated columbium delta-V thruster

Commercial off-the-shelf manual valve tested to aerospace standards

Light-weight Inconel-718 composite overwrap pressure vessels

Lightweight titanium propellant tanks with internal propellant management devices

Triple junction solar cells

Lithium-ion batteries

A low-cost/high-performance star tracker

The micro-satellites are bound for geostationary orbit, a unique vantage point 22,300 miles above the equator that allows spacecraft to match the planet's rotation and appear fixed over one location.

Geostationary orbit is the home of government and commercial communications satellites, plus spy spacecraft for eavesdropping reconnaissance missions and missile-launch detection.

Once the MiTEx upper stage achieves that orbit, the micro-satellite pair will be deployed from the motor to begin running their experiments for the benefit of military planners.

"The satellites will conduct a variety of experiments in autonomous operations and maneuvering and station-keeping. MiTEx will also demonstrate the ability to launch multiple small satellites into GEO orbit," according to DARPA officials.

Orbital Sciences built one satellite and Lockheed Martin the other.

"Since (they were) built by different companies, they are not identical, but both will investigate and demonstrate high payoff technologies. Immediately after release, the spacecraft will commence independent operations," DARPA officials said.

Meanwhile, the Delta launch team has little time to savor Wednesday's success. About 60 workers and managers involved in the MiTEx liftoff must get in position to support next Tuesday's Delta 4 rocket launch from Vandenberg Air Force Base, California. That classified liftoff carrying a national security spy satellite will happen sometime between 7 and 9 p.m. local time (10 p.m. - 12 a.m. EDT).

For the rest of the Cape crew, assembly of another Delta 2 rocket is underway at pad 17B to launch NASA's STEREO solar observing probes July 22. The first stage and some of its strap-on solid boosters have been erected at the pad. Now that MiTEx is on its way, preparations for STEREO can proceed in full force.

"We've taken a break in the action while we get MiTEx (launched). Everything is secured and we're ready to resume STEREO the day after we launch MiTEx," Rick Navarro, Boeing's director of Delta launch operations, said in an interview this week.

Pad 17A will be cleaned up from the MiTEx launch and readied to support the next Global Positioning System satellite liftoff currently planned for September.

"Busy and exciting times," Navarro said.