NASA’s SERT II: ‘A Proper Spot Success Epic’

“A accurate put success memoir,” is how Experiments Manager William Kerslake described NASA’s 2nd Spot Electric Rocket Test (SERT II), the vital long-length operation of ion thrusters in put. SERT II supplied researchers with information for years past its expected lifetime and used to be a uncommon example of an entire mission – including the originate, propulsion scheme, spacecraft, and succor watch over center – being dealt with by one organization: NASA’s Lewis Analysis Center in Cleveland (these days, NASA Glenn).

The theorem that of electric propulsion thrusters dates support to the early Twentieth century, but on story of they must characteristic in a vacuum, there used to be no handy application for these systems unless the put program a protracted time later. In the leisurely Fifties, researchers at NASA Lewis began investigating sorts of electrical propulsion and analyzing missions that can possibly utilize these systems. They invent low quantities of thrust by constructing and accelerating dinky particles at high velocities, and over time, can scuttle spacecraft at very high charges of scuttle. Their skill to characteristic continuously for years at a time with tiny propellant makes them ideally suited for long-length missions or conserving satellites in orbit.

This work was expanded in the early 1960s with the introduction of Lewis’ Electromagnetic Propulsion Division and the construction of modern vacuum facilities, including the Electric Propulsion and Energy Laboratory (EPPL). Lewis engineer Harold Kaufman’s electron bombardment ion engine, which used liquid mercury as its propellant, was the most promising option. While Kaufman’s thruster was undergoing extensive testing in the EPPL tanks, Lewis engineers began constructing a spacecraft to test the thruster. During the 50-minute suborbital SERT I flight on July 20, 1964, the Kaufman thruster became the first ion engine to operate in space.

Lewis continued improving the thruster design, and in August 1966 received approval for SERT II. Researchers wanted to verify that the thrusters could operate for extended periods in space, assess their impact on various spacecraft systems, and measure the degradation of solar arrays over time.

The center began simultaneous development of the SERT II ion thruster system and the spacecraft that would carry it into orbit: a Thorad-Agena rocket. SERT II featured two 15-centimeter diameter electron bombardment thrusters mounted at the rear and a 5-by-40 foot solar array, the largest ever flown by NASA at that time, on the opposite end.

After a series of tests within the EPPL, SERT II blasted off on February 3, 1970. Mission Manager Raymond Rulis called the launch “one of the smoothest operations I’ve seen.” SERT II was positioned into a circular polar orbit that provided its solar arrays with the precise daylight hours required to power its thrusters and electronic systems.

On February 14, 1970, Lewis engineers activated the vital thruster, starting its six-month operational check. Three weeks later, operators shut the thruster down unbiased correct earlier than the auto passed via the crawl of a voice voltaic eclipse. It used to be restarted with out explain afterwards and continued operation as the spacecraft encountered the eclipse a 2nd time later that day.

The thruster operated efficiently for five months unless an electrical short within the grid introduced about it to fail on July 22, 1970. Two days later, the 2nd thruster used to be activated. It operated smoothly for three-and-a-half of months unless a the same short came about in mid-October. Even supposing the SERT II thrusters didn’t fulfill their six-month wishes, they did characteristic for extended periods, confirming information obtained in Lewis’ vacuum tanks.

The mission continued when Lewis engineers reactivated SERT II in 1973 to demonstrate cathode restarting, and the following year, they resolved an electrical short in one of the thrusters. During periods of intermittent sunlight, operators demonstrated restarting the thruster with less than an hour of power available. SERT II’s return to an orbit in full sunlight in 1979 provided Lewis researchers the opportunity to conduct over 500 restarts. They operated the thruster for 18,000 hours before the propellant ran out in the spring of 1981.

Over eleven years, SERT II supplied information on an entire bunch of thruster restarts, restarts after shutdowns as long as 18 months, ion beam neutralization of 1 thruster by the diversified, and discovery of a brand modern plasma thrust mode. SERT II additionally verified that thruster operation had no contaminated affect on spacecraft and voice voltaic arrays.

Silent, SERT II continued to be an asset to NASA researchers. In the leisurely Eighties, Lewis engineers realized that an auxiliary experiment on SERT II that analyzed the end of micrometeoroids on voice voltaic mirrors is also helpful to study on voice voltaic dynamic systems to vitality put stations. One day of six months in daylight hours in 1990, the Lewis team particular that after twenty years in orbit, there used to be no degradation of the voice voltaic contemplate’s optical properties.

Many technological components of the SERT II thruster system have been integrated into subsequent generations of ion thrusters. By the time the mission was terminated, Lewis was already ground testing thrusters twice the size of those on SERT II. The center has continued to lead NASA’s electric propulsion efforts, developing an array of technologies, including the NEXT-C thrusters that powered the Deep Space 1 and Dawn spacecraft. In support of the agency’s Artemis missions, NASA Glenn recently tested the thrusters that will power GatewayNASA’s future lunar space station.

Further Recordsdata:

Pattern and Flight History of SERT II Spacecraft

NASA Glenn Solar Electric Propulsion