NASA Plum Brook Station gearing up B-2 facility for future upper stage, lander rocket tests

Michael Cole

Spacecraft Propulsion Research Facility (B-2). Photo Credit: NASA

NASA’s Plum Brook Station test facility in Sandusky, Ohio, is continuing a series of upgrades that may gain Plum Brook the reputation as the premier spacecraft testing facility in the world.

In recent years, a $66 million upgrade to Plum Brook’s Space Power Facility, with its enormous thermal vacuum chamber, vibration table, and powerful reverberant acoustic test chamber, have made it the space environment and launch-stress test center for the Orion spacecraft. Tests are currently in progress on the European-built Orion service module.

Now, a series of repairs and upgrades to Plum Brook’s Spacecraft Propulsion Research Facility, known more commonly within the agency as the B-2, will soon make the B-2 the most versatile upper stage rocket testing facility in the agency.

“It is the third largest thermal vacuum chamber in the agency,” Gerald Hill, facility manager of Plum Brook’s propulsion test complex, told SpaceFlight Insider. “But it can handle stage-level quantities of propellants. If you think about putting a stage in there with 5–10 thousand [U.S.] gallons of liquid hydrogen and 4–8 thousand [U.S.] gallons of oxygen, you really can’t do that anywhere else. With other existing large thermal vacuum chambers, you can’t go back and add that propellant capability. This place was designed for that.”

The B-2 was built in the early 1960s as the run-up to the Apollo program began. Its design consists of a series of powerful pumps, boilers, tanks, and spray bars geared to the purpose of diffusing and venting the exhaust of a rocket engine undergoing a hot-fire test within the facility. Assembled on top of this exhaust system was a 62 feet (18.9 meters) high by 39 feet (11.9 meters) wide thermal vacuum chamber. Coupling these two systems was necessary to effectively test an upper stage rocket.

Compared to the testing of launch vehicles, testing upper stage rockets presents additional complexities. Launch vehicles, by definition, ignite their engines at or near to sea-level atmospheric conditions and exert their thrust through a continuously thinning atmosphere as they gain altitude. They can, therefore, be effectively tested outside in the open air.

Upper stage rockets, however, must be able to ignite in the conditions of the upper atmosphere or in the near vacuum of orbital space. They must, therefore, be tested in a pumped-down vacuum chamber to simulate those conditions, with the addition of a simulated thermal environment that the engine will experience during upper atmosphere or orbital ignition.

“B-2 extends that capability,” Hill said. “They put a thermal vacuum chamber on top of it. If you can imagine how the launch vehicle takes off and it gets to a certain level, then the booster drops off, now the second stage lights off at about 100 thousand feet, and then it gets to what we call on-orbit loitering. That’s where B-2’s vacuum chamber can simulate on-orbit loiter. That’s at about 200 nautical miles up in space. I can go to –320 degrees Fahrenheit (–195.6 °C). I can simulate the Sun’s intensity hitting one side of the stage. That’s what makes B-2 unique. What is unique is that we can simulate the engine re-start after it is in orbit.”

B-2 was once a busy facility, but it fell into disuse after testing on the Boeing Delta III upper stage in the late 1990s. No repairs or upgrades had been done to the facility since its initial construction; however, a series of refurbishments are currently underway.

Most recently completed were the replacement of three 1,000 hp (745.7 kW) pumps for the exhaust system. The work was completed through a $2 million grant from the state of Ohio to Sierra Lobo, Inc., a technology company based just a few miles south of Plum Brook Station in Milan, Ohio. The grant demonstrates the importance the state believes Plum Brook Station holds for the economic and technological future of northeast Ohio.

Other upgrades are underway, notably the future integration of three large boilers, already in storage at Plum Brook. Installation of the boilers will allow Hill and his engineers to bring the facility and the larger 11,000 hp (8202.7 kW) pumps of its deluge system into operation to vent the potential 400,000 lbf (1779.3 kN) of thrust from an upper stage rocket test.

In the meantime, B-2 is well on its way to becoming a versatile test center for small robotic lander rockets as well, beginning with tests on a vehicle called Morpheus.

“We were down at Johnson [Space Center] asking where we could get a tank or two that we could put in the facility with an engine to do a hot fire test,” Hill said, referring to the propellant tanks on Morpheus. “And they said why don’t you consider using the whole vehicle. They said they would work with us because they would love to get a test on it in a thermal vacuum. So it has become kind of a collaborative thing.”

Morpheus is a prototype planetary lander vehicle, capable of both vertical landing and takeoff. The Morpheus project and lander prototype serve as an experimental testbed. The vehicle provides a platform for bringing new lander technologies from the laboratory and integrating them into an existing flight system at relatively low cost.

“We’re going to run a small hot fire test this fall,” Hill said. “That will demonstrate this limited propulsion capability, so we can get some of this in-space small thruster work going, while we complete our upgrades for the bigger tests.”

Hill sees B-2’s capability to test the small lander engines as a broadening of B-2’s value to NASA, and also as a bridge to the future testing of larger upper stage rockets.

“A stage test doesn’t happen very often,” Hill said. “It’s very expensive. It can be on the order $15 million to do that kind of test. A lot of people are looking at in-space small ascent and descent vehicles to preposition materials on Mars or the Moon. We think there is a real good niche here for that work. A lot of the work we’ve been doing recently, like getting our water pumps together and other things, has all been geared toward that.”

Hill said the other repairs must be completed to bring on the facility’s full steam capabilities. Those steam capabilities are essential to venting the exhaust of the upper stage engines. Once those repairs are completed, the venting system and the thermal vacuum chamber will be ready to simulate any mission profile that is needed.

“We can simulate sitting on orbit for as long as necessary,” Hill said. “It can be three hours or it can be 10 days. Whatever they require. Then, if they need to demonstrate re-ignition, then we would have already re-charged our steam system, pulled the water out, cooled it back down, and then we would equalize the pressure, open the valve and fire it up.”

The timeframe for completion of the remaining repair work is uncertain, depending on future budgetary allocations. However, once completed, the B-2 will be a tremendous testing resource and an added jewel to the testing capabilities at Plum Brook Station.

NASA Plum Brook Station Spacecraft Propulsion Research Facility (B-2). Image Credit: NASA