Operational uncertainty follows a 'perfect' launch

The Multispectral Thermal Imager (MTI), the product of Sandia’s first full satellite development program, was successfully placed into orbit early Sunday morning, March 12, by a Taurus rocket launched from Vandenberg Air Force Base, Calif.

The Air Force Space and Missile Center (SMC) launched the satellite at 2:29 a.m. MST using an Orbital Sciences Corp. Taurus rocket. Twelve minutes later, at about 2:41 a.m., the satellite was alone in space as the final booster of the four-stage rocket separated, leaving the MTI on its planned sun-synchronous orbit some 310 miles above Earth.

By Monday morning, March 13, operators in Sandia’s ground control station had reported that the satellite appeared to be in good working order after four passes over Albuquerque.

As of Lab News press time Wednesday morning, March 22, however, the Sandia MTI team was struggling to understand a problem with the satellite’s power system.

MTI project manager Brian Brock (5711) says the unexpected technical difficulty appears to be serious. But, he says, there is a good chance a solution can be found.

The MTI team has been concerned about the problem since Wednesday, March 15, when telemetry data during one pass over Albuquerque indicated that an "undervoltage" had occurred, meaning the satellite had shut power off to its nonessential functions. The satellite does this automatically when its battery gets too low due to unexpected voltage loads.

Since then the team has been powering various components on and off and analyzing data to understand the source of the problem.

It’s still too early to tell, Brian says, but the team hopes that adjusting the operating parameters of some power system components will compensate for the faster-than-expected voltage drops the battery experiences when the satellite’s solar panels lose sight of the sun.

Some good news

Despite the setback, the mission has achieved some important milestones, says Brian. About 400 seconds after separation from the launch vehicle, the satellite’s solar paddles deployed and the satellite aimed them at the sun, allowing MTI’s battery to be recharged.

During the first pass over Albuquerque at 11:45 MST Sunday morning, March 12, the Sandia control station sent commands to MTI and verified that the satellite had received them, verifying good uplink and downlink signals.

And on the Tuesday following the launch, the Sandia team turned on the primary payload (the Sandia imager) and the S-Band transmitter (a four-lane data highway that allows MTI’s imaging data to be downlinked) for the first time.

Assuming the power system problem can be solved this week, MTI will begin taking its first daytime snapshots of the ground in the coming weeks. Once that is done, the MTI team plans to cool the telescope’s focal plane to liquid nitrogen temperatures, allowing nighttime infrared images to be taken.

After the approximately two-month test period, MTI will begin its three-year mission of acquiring images useful to DOE and more than 100 researchers from more than 40 national defense and civilian agencies that are part of DOE’s MTI Users Group.

MTI’s mission objectives

MTI carries a sophisticated telescope that collects day and night ground images in 15 spectral bands. The unique camera, designed and built by a government and industry team led by Sandia and calibrated at Los Alamos National Laboratory, gives the satellite the ability to photograph light and heat patterns on Earth that are not visible to the human eye.

The satellite will make two or three passes over the Sandia ground station (on the 3rd floor of Bldg. 890) each day. If all goes well, it will transmit six images to the ground daily.

The images will be of DOE sites in the US that have been instrumented with sensors by the Savannah River Technology Center, and of other sites similarly instrumented by other government agencies. To evaluate MTI’s capabilities, the sensor data taken on the ground will be compared with the satellite imagery data.

Los Alamos National Laboratory will process MTI’s images to produce standard data products for distribution to various researchers.

A picture perfect launch

Although the current technical problems are worrisome, the launch itself was "picture perfect," says Brian. "The Air Force and Orbital have done a great job," he says. "The orbit parameters are well within our specifications, based on the data from NORAD."

The Air Force Space and Missile Center funded and managed the launch, and Orbital Sciences Corporation provided the launch vehicle.

Brian says from his seat in the Vandenberg control center watching the launch on a TV monitor, the combination of emotions he felt while watching the satellite leave the launch pad were indescribable, something like watching the birth of your first child.

"There were tears in my eyes and in the eyes of the others too," he says. "It was joy and relief and postpartum sorrow all at once. I’ve never felt such an emotion during my career. And I’m not the only one." Watch the Lab News and Sandia Daily News for updates about the MTI mission.

Last modified: March 24, 2000