Spaceflight Now: Minotaur

Newly-launched military research satellite healthy

Posted: July 24, 2000

  Mightysat 2.1
An artist's concept of Mightysat 2.1 orbiting Earth. Photo: Spectrum Astro
The U.S. Air Force Research Laboratory's Mightysat 2.1 spacecraft is making good progress in its orbital checkout after four days circling Earth, officials reported Sunday.

The $21.5 million satellite carries 10 different experiments, ranging from the space camera system to materials used to built the craft's structure, to gauge whether these advance technologies are worthy of being used by future military satellites.

As of late Sunday evening, the technology demonstration satellite had completed 65 orbits and communicated with ground controllers via 55 contacts. Mission authorities said about 95 percent of the initial activities planned in the satellite's Launch and Early Orbit period had been completed, with most all of the craft's subsystems having been characterized and checked. Overall, Mightysat 2.1 is said to be healthy and with no problems found.

To date, controllers have tested the satellite's ability to point toward the sun, run in mission modes, while also checking the solar array drive assemblies, reaction wheels, magnetometers, gyros, torque rods and the star tracker camera. The central processor unit, solid state memory and all other aspects of command and data handling system is also about finished.

Officials also say the electrical system is fully tested now, verifying generation of solar power, batteries and the charge control units. In the thermal management area, all temperatures are reported well within operational limits. The telemetry, tracking and commanding system is also working normally.

Monday's agenda calls for initial operation checkout for some of Mightysat 2.1's payloads: Shaped Memory Alloy Thermo-elastic Tailoring Experiment, Fourier Transform Hyperspectral and Quad-C40 processor.

By Day 2 of the flight, officials had already said all experimental bus component experiments were working nominally. This included the Multifunctional Composite Structure (MFS) with its integrated thermal management system, the Solar Array Concentrator (SAC), the Solar Array Flexible Interconnects (SAFI), the Mini SGLS Transponder (NSX), and the Solar Array Substrate (SAS).

The Minotaur rocket lifts off. Photo: Vandenberg AFB
Mightysat 2.1 was delivered into low-Earth orbit by the second Minotaur rocket launched from Vandenberg Air Force Base in California on July 19. The satellite's first communications session with ground controllers came through the Thule, Greenland some 80 minutes after launch.

Before the launch, Mightysat program manager Randy Kahn of Air Force Research Lab's Space Vehicles Directorate described the satellite's mission: "The 266-pound Mightysat 2.1 is a relatively low-cost satellite about the size of a small refrigerator and the second of its kind built and tested here at Kirtland AFB. Built by the Spectrum Astro Corporation under contract to AFRL, it will fly a number of advanced technology experiments that are not only critical to the future of spacecraft subsystems, but eventually, to the warfighter. Our highly successful MightySat 1, launched from the cargo bay of the Space Shuttle Endeavour on December 14, 1998, demonstrated five other forward-looking experiments that have improved our operational understanding of how new technologies actually work in space. We expect MightySat 2.1 will do the same."

Mightysat 2.1's primary payload is a Fourier Transform Hyperspectral Imager (FTHSI) able to detect and accurately discern different objects by recording their individual spectral "signatures," or the light they reflect. FTHSI will help the warfighter "see" more details on the ground and thus enable better planning and tactical decisions.

"Another onboard experiment is a solar array concentrator that increases the amount of energy solar cells convert into spacecraft power -- at half the cost and weight," Kahn said. "The array also reduces the number of solar cells needed to produce the same amount of power -- and less weight means lower launch costs -- always an important consideration in a business that spends tens of thousands of dollars for every pound placed in orbit," he added.

Another test is investigating the viability of a new device called a Shaped Memory Alloy Thermo-elastic Tailoring Experiment that could replace mechanically complex actuator mechanisms that previously have caused spacecraft failures because of their improper operation.

"To do this, we are using a heat-actuated, shaped-memory metal alloy on Mightysat 2.1 that will gently control the shape of certain spacecraft composite materials as needed," Kahn said.

The satellite also carries the high-speed Quad-C40 microprocessor that will not only process data collected by MightySat 2.1's hyperspectral imager, but increase the number of collected images that can be downlinked to a ground control station.

The Naval Research Laboratory's Miniature Space Ground Link System experiment is also onboard to test a small transponder approximately 70 percent smaller and lighter than used today.

Video vault
The U.S. Air Force Minotaur rocket lifts off from Vandenberg Air Force Base in California on July 19 with Mightysat 2.1.
  PLAY (292k, 32sec QuickTime file)
Download QuickTime 4 software to view this file.

Flight data file
Vehicle: OSPSLV Minotaur
Payload: Mightysat 2.1
Launch date: July 19, 2000
Launch window: 2009-2135 GMT (4:09-5:35 p.m. EDT)
Launch site: CLF, Vandenberg Air Force Base, Calif.

Pre-launch briefing
Launch timeline - Chart with description of events to occur during launch.

Minotaur - Facts and background information of OSP Space Launch Vehicle.

Mightysat 2.1 - A look at the satellite to be carried aloft by Minotaur.