The Space Propulsion Laboratory (SPL) at the Massachusetts Institute of Technology (MIT) features state-of-the-art experimental facilities that complement our educational and research programs. MIT students, staff, faculty and approved visitors are eligible to work at SPL, provided that safety training requirements are met and users are familiarized with the laboratory environment.
Vacuum Chambers and Thruster Testing
Astrovac
Astrovac is the laboratory’s largest vacuum chamber. It is located in room 37-462. The steel vacuum vessel measures about 1.5 m in diameter by 1.6 m long and is pumped down by two cryo-pumps. Astrovac is bakeable, and when empty capable of reaching ultimate pressures of about 1e-7 Torr, with a pumping speed of 7000 liters/sec of Xenon. This tank can accommodate additional hardware such as plasma diagnostic probes, energy analyzers, motorized stages, etc. Several windows located around the chamber allow visual inspection of the working equipment. Astrovac is used for testing plasma and electrospray thrusters developed at SPL. It is also used to host the Maglev Cubesat Testbed (MCT).
Maglev Cubesat Testbed
The Maglev Cubesat Testbed (MCT) was designed and built by MIT students to provide a realistic environment to test nanosatellite hardware. The MCT makes use of magnetic levitation to suspend a cubesat-sized satellite inside the Astrovac vacuum chamber. Magnetic levitation allows rotational motion around the vertical axis. This motion is practically frictionless, such that the satellite can rotate freely without contacting chamber materials. The MCT is used to explore the way a small satellite will behave in space once it is equipped with thrusters, electronics, sensors, actuators, batteries, on-board computer, radio and payload. Spacecraft charging, rotational motion due to thrust, and integrity of all components in a vacuum environment can be investigated with the MCT.
Sputnik
Sputnik is a vacuum chamber attached to the Astrovac that improves research and testing capabilities, especially of electrospray thrusters. Although small (30 cm DIA), this chamber has ample accessibility through a variety of instrumentation feedthroughs. Sputnik is pumped down by one 70 liters/sec turbomolecular pump, but since it is attached to the larger chamber through an isolation gate, the pumping speed can be increased to >5,000 liters/sec while adding the flexibility of using characterization instruments inside the bigger chamber, e.g. time-of-flight mass spectrometer or a retarding potential analyzer. Depending on the particular experiment, different equipment would be installed in this chamber. For example, a 3-axis translational stage with sub-micron resolution, micro-channel-plate/phosphor screen beam visualization system, and linear manipulation stage effectively turn Sputnik into a loading dock for the Astrovac.
Turbovac
Turbovac is a medium-sized vacuum facility and one of the primary vacuum chambers used in the SPL to test and characterize full electrospray thrusters. It is pumped down by one 700 liters/sec turbomolecular pump and one 70 liters/sec turbomolecular pump, providing ultimate pressures of under 1e-8 Torr. This chamber houses a full suite of ion beam diagnostic, including a 1.1-meter-long time-of-flight mass spectrometer (TOF), a retarding potential analyzer (RPA), faraday cups, precision rotation stages, and a residual gas analyzer (RGA). Many signal, power and fluid feedthroughs are available, and with two turbopumps the turnaround time is fast, reaching high vacuum from atmosphere in as little as 1-2 hours.
Flightvac
Flightvac is a medium-sized vacuum facility used to test and characterize full electrospray thrusters. It is pumped by one 450 liters/sec turbomolecular pump, providing ultimate pressures of under 1e-7 Torr. Flightvac, like Turbovac, is equipped with all of the state-of-the-art diagnostic equipment required to fully characterize electrospray performance, including TOF, RPA, and angular control.
Flangevac
Flangevac is a medium-sized vacuum facility used primarily for long-duration propulsion system testing. It is pumped by one 700 liters/sec turbomolecular pump to ultimate pressures of under 1e-6 Torr. Named for its many flanged ports, Flangevac was fully torn down and refurbished in 2023, making it the SPL’s most recently upgraded vacuum testing facility.
Minivac
Minivac is a smaller vacuum facility dedicated to test single emitter electrosprays. It is pumped down by one 70 liters/sec turbomolecular pump, providing ultimate pressures of under 1e-6 Torr. This chamber houses equipment used for ionic liquid meniscus quenching experiments using cryogenic liquid nitrogen. The turnaround time of this facility is fast, and ample signal, power and fluid feedthroughs have been provided.
Megavac
Megavac is the SPL’s smallest high-vacuum facility, primarily used to test electronics and materials. It is pumped down by one 70 liters/sec turbomolecular pump, providing ultimate pressures of under 1e-6 Torr. Multiple electronic feedthroughs are available to route power and communications.
Fabrication Tools and Facilities
Clean Room
SPL has a clean room (class 10,000) located in room 35-405a currently used to support the laboratory’s research in electrospray thrusters. Processes and materials that are sensitive to debris and particulate matter, such as assembly of microscopic ion source arrays, are handled in the clean room. The clean room also houses a nitrogen-purged desiccator cabinet for storage of fueled propulsion units and moisture-sensitive ionic liquids.
In addition to a variety of equipment and work benches, this room includes the following:
- Several inspection and assembly stations for fabricating thrusters.
- Tube furnace for the synthesis of materials.
- Keyence digital microscope.
- Scanning electron microscope (SEM).
- Energy-dispersive X-ray spectroscopy (EDX).
- Oxygen plasma asher for cleaning substrates.
Laser Micromachining Facility
The Laser Micromachining Facility (LMF) is located in room 35-405, It is comprised of a KrF excimer laser, a beam delivery system, and a precise x-y-z stage that allows precise ablation of a large number of materials.
Sputter Coater
The SPL sputter coater is an RF magnetron sputtering system made by AJA International. It houses two 2″ target holders with space for three additional holders to be installed. It can deposit thin films of a variety of materials onto substrates up to 6″ in diameter. Common materials used in the sputtering system include titanium, silver, cerium oxide, PTFE, and more.
Additional Facilities
Chemicals Processing
The SPL has two standard fume hoods capable of handling a large number of processes. These hoods are used to synthesize materials and ionic liquids for propulsion research, and also for miscellaneous chemical reactions and cleaning steps.
Optics Bench
The SPL has a standard perforated and isolated table bench used as a generic platform to test optics systems and devices. Lasers, lenses, mirrors and detectors are available for this bench.