STPSat-1 End of Life

(7 Oct 2009) On October 7th 2009, the STPSat-1 satellite was decommissioned after 2 1/2 years of successful on-orbit operations. Tiger Innovations personnel transmitted the final commands to shut down the spacecraft at 1730 UTC from the Blossom Point Tracking Facility. The United States Air Force launched STPSat-1 in March of 2007 and operated it for the initial 13 months on the mission. Following the designed 13 month mission life, the USAF transferred spacecraft control authority for the STPSat-1 Spacecraft to the Naval Research Lab on 1 June 2008. Under contract with the NRL, Tiger Innovations provided its StreamLINK Ground Control System (SGCS) and engineering support to autonomously operate STPSat-1 during the mission extension period.

The StreamLINK system was deployed to support the life extension mission and includes a flight operations version of our Integrated Test Rack (ITR). The SGCS consists of the Tiger Innovations Frame Sync/Command Formatter, and automated operations package that allows 24/7 "lights out" operations. The SGCS utilizes the same StreamLINK backend that was used during integration and test of the vehicle, which allowed us to field a working ground system in less than 2 weeks. It is currently integrated with the Blossom Point Tracking Facility, which provides the RF interface, automated antenna operations, and engineering support during the operational phase of the mission. In addition to providing the StreamLINK system, Tiger Innovations has developed scripts to autonomously take passes, record data, upload commands, and generate email and phone alerts in the event of an anomaly. The 17 month mission extension went very well, with no SC failures and a smooth transition from 24/7 ops to a fully automated ground station. Tiger Innovations is pleased that we were able to contribute to the successful STPSat-1 mission extension and congratulates all organizations involved with the program.

Experiment Accomplishments

The primary experiment, SHIMMER, has now measured the PMC diurnal variation for the two northern seasons of 2007 and 2008, and surprisingly, the variation is quite different. Even though a semidiurnal signature, that is two peaks per day -- one in early morning and one in the late afternoon -- was observed in 2007; in 2008, the variation was diurnal or one peak per day. This result has important implications for the inference of long-term trends from historical, space-based PMC observations because NASA and NOAA satellites that have observed PMCs over the last 25 years have all been launched into sun-synchronous orbits with different, fixed local times. Until the diurnal variation of these clouds is better understood, the SHIMMER data show that it is premature to make firm conclusions about multi-decadal trends in PMCs.

About STPSat-1

STPSat-1 was launched in 2007 on board an Atlas-V rocket as part of the STP-1 mission. Tiger Innovations designed the Integrated Electronics Module which provides all C&DH and EPS functions for STPSat-1. Additionally, we provided the spacecraft EGSE and engineering support services to the mission. The primary experiment, Spatial Heterodyne Imager for Mesospheric Radicals (SHIMMER), is a high-resolution ultraviolet spectrometer based on the optical technique known as Spatial Heterodyne Spectroscopy (SHS). SHS facilitates the design of low mass, low power, high throughput spectrometers for space-based remote sensing. The secondary experiment, the Computerized Ionospheric Tomography Receiver in Space (CITRIS), investigated irregularities that affect propagation of satellite-to-ground links for GPS and communications.