Tactical Satellite-3’s Secondary Payloads Provide Operational Backup and Data Dissemination

Two of the Tactical Satellite-3’s trio of payloads may be called secondary, but their importance to the success of the spacecraft’s year-long mission is primary.

Employing plug-and-play technology, the Space Avionics Experiment will provide backup downlink capability for TacSat-3’s main experiment, the Advanced Responsive Tactically-Effective Military Imaging Spectrometer, and the Satellite Communications Package will transmit sea-based and space-generated data to ground stations.

Led by the Air Force Research Laboratory’s Space Vehicles Directorate here, TacSat-3, planned to launch May 5 from the from the Mid-Atlantic Regional Spaceport, located at NASA Wallops Flight Facility, Wallops Island, Va., will serve as the inaugural demonstration of plug-and-play avionics operating in the cosmos environment. In September 2007, the technology flew for a few minutes into near space onboard a sounding rocket and the stand-alone trial achieved performance expectations. The AFRL-funded SAE payload features plug-and-play components similar to desktop computer Universal Serial Bus components, which, if required due to a system failure, will perform data transfer to enable downlink of ARTEMIS sensor data, as well as will provide TacSat-3 with global positioning system information.

“This will be the first spacecraft demonstration of plug-and-play technology. The purpose of the technology is to significantly reduce spacecraft development time from years to months to weeks, as well as to lower production costs,” said Maurice Martin, responsive systems group lead, the AFRL’s Space Vehicles Directorate. “Our plan during TacSat-3’s flight is to evaluate the Space Avionics Experiment on an occasional basis to ensure the components’ reliability in case they are called upon to function in full operational mode.”

Managed by the Office of Naval Research, the Satellite Communications Package will collect data from ocean buoys and then TacSat-3’s onboard processor will download the details to a ground station. In addition, the U.S. Army Space and Missile Defense Command/Army Forces Strategic Command will utilize the SCP experiment’s ultra high frequency radio link known as the Army Tactical Data Link.

“USASMDC/ARSTRAT is going to use the Satellite Communications Package Payload’s
ATDL to provide a direct tactical downlink of onboard processed information from the ARTEMIS to the joint force commander. The JFC will have direct access to task the spacecraft as it appears over the horizon, while the satellite is still in view, the requested information will then be transmitted back to the JFC,” said Allen Kirkham, Army Space and Missile Defense Command Battle Lab technical lead for the TacSat-3 Joint Military Assessment, Peterson AFB, Colo. “We will coordinate with the TacSat-3 program team to utilize the SCP’s ATDL for a few two-week periods during the spacecraft’s 12-month mission. We also intend to use the SCP’s ATDL during a major exercise to allow us to collect data and perform a Joint Military Utility Assessment of the satellite and sensor’s capabilities to support the joint force commander in the field.”

As a significant team member in the program, the Space and Missile Systems Center’s Space Development and Test Wing, also situated at Kirtland AFB, is providing the Orbital Sciences Corp.’s Minotaur I launch vehicle. The four-stage rocket consists of two structures taken from retired Minuteman intercontinental ballistic missiles, and another two stages from Orbital’s Pegasus booster. In addition, the Dept. of Defense’s Operationally Responsive Space office is underwriting the launch and will be heading the Military Utility assessment to determine the operational value of the low-cost satellite and its three payloads. SMC’s Space Development and Test Wing will also assist mission operations during TacSat-3s flight in Low Earth Orbit at approximately 425 kilometers (264 miles) altitude.

TacSat-3 also features a spacecraft bus, developed by ATK Space Systems, which
includes standard interfaces, side access panels that enable rapid integration, a three-axis, fixed stabilization system allowing payload sensors to collect precision data on orbit, and modular power options tailored for specific mission requirements.

With TacSat-3’s liftoff rapidly approaching, project staff have been working around-the-clock to ensure the 880-pound spacecraft is ready to roll. “The past few weeks leading up to launch have been very critical, but the program team has achieved small victories with each passing day such as the mating of the spacecraft to the rocket body,” said Dr. Thomas Cooley, TacSat-3 program manager, the AFRL’s Space Vehicles Directorate. “Since TacSat-3’s inception five years ago, we have been striving to reach the launch date, and at this point, all the preparatory groundwork has been accomplished and we’re now just anticipating a successful lift off and mission.”