AGS2

Project Milestones

NASA, Texas A&M, and the University of Texas embarked on the LONESTAR Autonomous Rendezvous and Docking Campaign in 2005. NASA tasked the two schools with three cooperative missions to test ARD technologies and techniques, and a fourth an ARD demonstration. The satellite pair, AggieSat2 and Bevo-1, comprised the first of these missions. Students from both schools formed the Mission Systems Engineering Team (MSET) to define mission requirements and shape the beginnings of the campaign. At this early stage, the mission was comprised of both GPS data and crosslink data taking

sessions between the two satellites. Realities of design and size would play a role in iterating this preliminary design during the course of the program. The Preliminary Design Review showcased the initial configuration and designs of both spacecraft for the AggieSat2/Bevo-1 mission. Lab students provided the briefings in front of NASA managers. NASA approved AggieSat2 for continued payload processing as part of the STS-127 payload. Texas A&M students briefed the shuttle safety review board at NASA Johnson Space Center in relation to mission critical items (such as electrical, RF and physical interfaces) and their impact on safe shuttle operations. Key topics at this review included the passive magnetic attitude systems and their effects on GPS reception, and the separation interfaces between Texas A&M and the University of Texas.

By this time, the mission had matured into a more robust, two orbit GPS data taking flight which involved redundant operations of the Texas A&M and University of Texas satellites. This refocusing was the result of trade studies and lessons learned from prototyping by the students on both teams. The Critical Design Review during October 2008 covered the final designs for the major subsystems of AggieSat2. This review was held at NASA Johnson Space Center.

Texas A&M students developed and built a functional replica of the Oceaneering Space Systems SSPL launcher to conduct a series of air bearing floor tests to prove the satellites could separate without interference. The series was 100% successful. Texas A&M and the University of Texas joined forces to test interfaces between the two cubesats. Each satellite featured inhibit pins and spring loaded antennas which were used to provide separation energy at deployment. The student team, with the assistance of mentor Joe Perez, spent long hours in the lab painstakingly assembling and testing these components. Additionally, all subsystem components, such as electrical power system or command and data handling, were integrated together into a final, working, flight unit. From December 2008 to February 2009 Texas A&M assembled and checked out the components of the flight unit AggieSat2 spacecraft.

Texas A&M delivered the AggieSat2 flight unit in February 2009 to Oceaneering Space Systems in Houston, Texas where it was integrated with the University of Texas Bevo-1 satellite and the SSPL launcher unit. During this time, final safety information was approved by the shuttle safety boards at JSC for flight. During these test, functional tests were completed continually. A shorting problem, induced by the last vibration axis, was discovered and corrected. Soon after, the spacecraft was deemed in good health and approved to ship to the Cape. Soon after delivery in March, AggieSat2 underwent combined vibration testing at NASA Johnson Space Center’s test facilities. The spacecraft went under a three axis vibration series to simulate the effects of a Space Shuttle launch. AggieSat2, BEVO-1, and the SSPL launcher were processed at NASA’s Space Station Processing Facility prior to installation in Space Shuttle Endeavour in Orbiter Processing Facility 2. Texas A&M lab members followed the AggieSat2 flight unit to Kennedy Space Center in March to perform one last aliveness test prior to integration with the Shuttle. Atlantis flew on STS-125, without need of rescue, and successfully maintained the Hubble Space Telescope for the last time.

In April, STS-127 Endeavour, with AggieSat2 on board, was rolled out to Pad 39B at Kennedy Space Center to serve as rescue shuttle for Atlantis on STS-125. At 39A, the primary payload for STS-127, the Japanese Exposed Facility, was installed and prepped for a 13 June launch. May, after rescue duty for Atlantis, Endeavour and AggieSat2 were rolled around to Pad 39A at Kennedy Space Center in final prep for STS-127. The AO-51 amateur radio satellite was received from near Panama, and heard through the Eastern United States and onto Canada in the first integrated RF and tracking test of the new facility. In late June, when AggieSat2 deployed from Endeavour, this station was seeking to receive flight telemetry and data. After approximately three months of preparation, the AggieSat2 ground station made its first satellite contact on 8 June.

NASA closed the payload bay of Endeavour for the last time. AggieSat2 was GO and ready for launch on 13 June 2009 at 7:17 a.m. Despite these delays, Lab members were elated at the liftoff; with many present during the launch in Florida. Additionally, those who were unable to travel to Florida gathered at the AggieSat Lab on campus at the Munnerlyn Building in College Station to witness the launch on NASA Television. After 5 launch scrubs, AggieSat2 finally launched aboard Space Shuttle Endeavour on attempt 6. Space Shuttle Endeavour took off at 5:03 p.m., central time, on a 16 day mission to the International Space Station to add an additional component to the Kibo Laboratory. Endeavour was dogged by a leaky seal on the fueling plate for liquid hydrogen on the Shuttle’s orange External Tank and a string of stormy Florida afternoons.