Hubble Space Telescope nickel-hydrogen batteries testing and flight performance

The Marshall Space Flight Center (MSFC) has several ongoing tests relating to the Hubble Space Telescope (HST). A six-battery test has been running for over 2 years and is producing excellent data on the operation of a simulated HST electrical power system (EPS). A 22-cell 'flight spare' battery (FSB) has also been on test for almost 2 years. Since this battery is comprised of cells identical to those in orbit, it is the best ground-based simulation of the operation of a flight battery. The authors not only discuss the results of the HST Ni-H2 six-battery and FSB tests but also describe the operation of the HST EPS and give an overview of the flight batteries' performance.