End of an Era for SAMS


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On April 19, 2001, two payloads of the Space Acceleration Measurement Systems (SAMS) Project were installed on the International Space Station (ISS) as part of the cargo on STS-100. The SAMS-II measured high frequency accelerations in support of microgravity science experiments. The Microgravity Acceleration Measurement System (MAMS) measured very low-frequency accelerations in support of microgravity science experiments. Both systems also supported other users such vehicle dynamics, ISS operations, EVAs, exercise countermeasures, etc.

On November 1, 2005, the SAMS-II and MAMS were intentionally powered off due to lack of current microgravity science on-board the ISS. The SAMS-II and MAMS are being put into a dormant state in anticipation of future microgravity-based research to be conducted on ISS. The SAMS project has been dissolved as a funded project at GRC, ending nineteen years of microgravity environment research. When SAMS-II and MAMS are re-activated, operations will be conducted by those research payload teams.

In 1986, the idea of a single acceleration system to support research experiments on microgravity platforms was conceived and the Space Acceleration Measurement System (SAMS) project was conceived. Previously, specialized accelerometer systems were built or were planned for individual experiments. SAMS was developed as a multiple sensor, multiple mission instrument to serve the needs of microgravity science payloads.

The first flight of a SAMS system was 1991 on STS-40. The seven SAMS flight systems flew on over twenty shuttle missions in the Spacelab modules, in the middeck, on MPESS cargo bay carriers, and in the SPACEHAB modules. All these missions were successful with the exception of SPACEHAB-3 where the SAMS system suffered an inexplicable fuse failure early in the mission.

One system was retrofitted for operation on Mir and spent three and a half years on-board as part of the NASA-Mir Science Program. It became the longest residing U.S. hardware of that program and that SAMS system now resides at the National Air and Space Museum. In the fall of 2005, that SAMS unit was put on public display in the Udvar-Hazy Center of the National Air and Space Museum.

A specialized SAMS version was developed for free-flyers which was used on Shuttle missions, sounding rockets, drop towers, ground facility characterization, and parabolic-flight aircraft.

The atmospheric research accelerometer systems, Orbital Acceleration Research Experiment (OARE) and High Resolution Accelerometer Package (HiRAP), both of which were developed by JSC and LaRC were absorbed into the GRC microgravity accelerometer program to serve microgravity payloads. In a tragic coincidence, one HiRAP instrument was lost on the Challenger accident and the OARE instrument and a SAMS unit were lost on the Columbia accident.

After a brief stint at MSFC, the data analysis, distribution, and archival functions were consolidated with SAMS & OARE at GRC as the PIMS project. Multi-terabytes of data have been obtained and archived as a result of microgravity measurements from 1991 to the present. The software developed for this purpose won awards, including an IR-100 award.

A new and improved SAMS system was developed for the Int'l Space Station and utilizes features of the ISS for long-term use. The SAMS-II and MAMS payloads to date have collected over four years of data on ISS and during that time, PIMS has published those data in near-real-time on the internet and reports. Much of the data has been analyzed for investigators, ISS systems organizations, Russian colleagues, international investigators, and others. Over fifty gigabytes of data were collected on over twenty Shuttle flights and on Mir, while three terabytes of data have been collected on ISS to date.

SAMS and PIMS have served countless PI's and systems personnel to help understand the microgravity environment. Training about the microgravity environment has been provided over the years to principal investigators, Shuttle and ISS crew, microgravity researchers, and astronaut candidate classes. These have been by microgravity environment conferences, meetings, classroom tutorials, and presentations.

As an end to an era comes to a close, the SAMS-II and MAMS subsystems on-board the ISS will be placed in a safe mode until such time as future payloads that require microgravity environment characterization arrive on ISS.

All this success was brought about by a small, dedicated team of NASA civil servants and contractors at NASA Glenn Research Center. This team worked with the mission integration teams at MSFC, JSC, KSC, and Russia to implement the missions.

While the SAMS and MAMS are 'mothballed' on-orbit, they will be revived to serve investigators in the future.

Richard DeLombard & William Foster
Past Project Managers for SAMS and PIMS

NASA Glenn Research, Cleveland, Ohio

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