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Pathfinder Technology Demonstrator

Demonstrating Novel CubeSat Technologies in Low-Earth Orbit

photo of LISA-T in zero gravity

NASA’s Pathfinder Technology Demonstrator (PTD) series of missions will test the operation of a variety of novel CubeSat technologies in low-Earth orbit, providing significant enhancements to the performance of these small and effective spacecraft. Over the course of multiple planned PTD missions, the successful demonstration of new subsystem technologies will increase small spacecraft capabilities enabling direct infusion into a wider range of future science and exploration missions.

The PTD series of missions utilizes a new commercial spacecraft bus and state-of-the-art MK II avionics platform developed by Terran Orbital Corporation, of Irvine, California. The 6-unit (6U) spacecraft, named Trestles, is common to all PTD missions and easily accommodates different technology payloads being demonstrated without the need to completely redesign the spacecraft each time. In addition to providing the spacecraft, Terran Orbital also serves as the integrator for each technology payload into its respective spacecraft and performs in-orbit mission operations from the Terran Orbital mission operations center after each launch.

Pathfinder Missions by the Numbers

PTD-1 on a table.
The Pathfinder Technology Demonstrator-1 spacecraft during fit check and integration into a CubeSat deployer.
Terran Orbital Corporation

The PTD-1 mission launched on January 24, 2021 to demonstrate the Hydros-C propulsion system with a water-based propellant that was developed through a public-private partnership with Tethers Unlimited, Inc., of Bothell, Washington. Carrying approximately one pint of water in a flexible bladder contained within in a metal vessel aboard the CubeSat, the propulsion system separates water into hydrogen and oxygen propellants by applying an electric current through the water. The propulsion system uses power provided by the spacecraft’s solar arrays to operate the miniature water electrolysis system. The demonstration tested propulsion performance through programmed thrust events which change spacecraft velocity and altitude executed by the hydrogen and oxygen-fueled combustion. This propulsion system provides higher thrust compared to other propulsion technologies while requiring lower power input. The data collected during this flight demonstration will be incorporated in future Hydros-C and its larger Hydros-M systems. The Hydros-M system is planned for several missions including NASA Science Mission Directorate’s  Polarimeter to UNify the Corona and Heliosphere (PUNCH) mission. PTD-1 is the first mission to demonstrate a water-based electrolysis propulsion system on any type of spacecraft.

The completed TeraByte InfraRed Delivery (TBIRD) payload at the Massachusetts Institute of Technology Lincoln Laboratory.
The TeraByte InfraRed Delivery, or TBIRD, is a payload on the PTD-3 mission. It is a 3U payload, approximately the size of a tissue box.
Massachusetts Institute of Technology Lincoln Laboratory

The PTD-3 payload is the TeraByte InfraRed Delivery, or TBIRD, which is being developed by the Massachusetts Institute of Technology Lincoln Laboratory in Lexington in collaboration with NASA’s Goddard Space Flight Center. Funding for the TBIRD technology payload is provided by NASA’s Space Communications and Navigation (SCaN) program in the Space Operations Mission Directorate. NASA’s Space Technology Mission Directorate’s (STMD) Small Spacecraft Technology (SST) program provides funding for the spacecraft, mission operations, and launch. The communication system is intended to achieve an unprecedented 200 gigabit per second data downlink rate. PTD-3 launched on May 25 as part of SpaceX’s Transporter-5 rideshare launch.

PTD-4 in weightless simulation
Successful deployment of Pathfinder Technology Demonstrator-4’s Lightweight Integrated Solar Array and anTenna, or LISA-T, array during simulated weightlessness, parabolic flight testing.
NeXolve Holding, LLC

The PTD-4 mission will demonstrate a very high-power, low-volume deployable solar array with an integrated antenna called the Lightweight Integrated Solar Array and anTenna, or LISA-T, being developed by NASA’s Marshall Spaceflight Center in Huntsville, Alabama. Current LISA-T designs are scalable from 100 to 500 watts, with options to scale up to 1000 watts and beyond. Utilizing small spacecraft for missions in deep space will necessitate the need for more electrical power, and LISA-T’s thin film solar array offers lower mass, lower stowed volume, and 300% more power per mass and volume allocation than the current state-of-the-art thick film solar arrays. This mission is currently in development.

NASA’s SST program invests in partnerships and collaborations with industry to access innovative ideas for next generation small spacecraft. The PTD mission series is an example of industry-inspired small spacecraft innovation that offers affordable, rapid turn-around opportunities to demonstrate technologies needed to increase the capability and utility of small spacecraft.

Fast Facts: PTD-Mission Series

  • Each of the planned PTD missions consists of a 6-unit, or 6U, CubeSat weighing approximately 25 pounds and comparable in size to two stacked cereal boxes.
  • Each technology being demonstrated weighs no more than approximately 6.5 pounds and fits within a 3-unit volume.
  • Equipped with deployable solar arrays, the PTD spacecraft bus can deliver an orbit-average power of 45 watts and a peak power of 180 watts to payloads for each mission.

Fast Facts: PTD-1

  • The use of traditional high-performance rocket fuels presents risks that include high toxicity, flammability, and extreme volatility. Water is a desirable fuel alternative for some applications to address these risks.
  • Launch vehicles commonly generate thrust by burning hydrogen and oxygen in a rocket nozzle. The Hydros-C propulsion system generates thrust in the same way, after splitting water in orbit to produce hydrogen and oxygen propellants.
  • The size and configuration of the propulsion system’s water tank can be tailored to fit the requirements of small spacecraft missions.
  • Water is a “green” resource for propulsion. It is non-toxic, stable, and inexpensive.
  • Water is also a safe fuel for personnel to use during spacecraft integration and poses no significant risks to other payloads during launch.
  • Burning hydrogen and oxygen gas in a rocket nozzle generates more propulsive thrust than using “unsplit” water as propellant.
  • The water electrolysis system demonstrated on PTD-1 may be applied in future deep-space missions using water resources found off Earth such as from comets or the Moon and Mars.

Fast Facts: PTD-3

  • The TeraByte InfraRed Delivery (TBIRD) is a small satellite – CubeSat – that will demonstrate optical communications downlink at 200 gigabits per second- the fastest the aerospace industry has ever seen.
  • Radio waves have been used in space communications since the beginning of space exploration; however, as space missions generate and collect more data, the need for enhanced communications capabilities becomes paramount. Optical communications will provide significant benefits for missions, including bandwidth increases of 10 to 100 times more than radio frequency systems.
  • Optical communications systems provide decreased size, weight, and power requirements. TBIRD is a 3U payload, meaning it is three 10-centimeter cubes put together – roughly the size of a tissue box. TBIRD is hosted on a 6U CubeSat, which is six 10-centimeter cubes. Altogether, the CubeSat is the size of two stacked cereal boxes.  
  • CubeSats like PTD-3 offer the aerospace industry a cost-effective way to test technologies and capabilities. Their miniaturized size makes possible cost saving in areas like fuel and hardware development. In addition to being small, TBIRD is built from existing telecommunications hardware products that were repurposed for space flight. The team took commercial, off-the-shelf hardware, and redesigned it for space operations. Leveraging existing components also introduces cost savings. 
  • TBIRD will downlink data to Optical Ground Station – 1 in Table Mountain, California. The location was chosen for its clear weather conditions and remote, high-altitude. TBIRD shares this optical ground station with NASA’s Laser Communications Relay Demonstration and the upcoming Deep Space Optical Communications payload.
  • TBIRD is helping demonstrate a networking concept known as delay/disruption tolerant networking (DTN). DTN allows data to reach its destination despite disruptions or unavailable data paths.
  • TBIRD is planned to operate for six months, enabling NASA and the aerospace community to gather as much information as possible about optical communications and DTN on small satellites.​

Partners: PTD-Mission Series

  • NASA’s Ames Research Center in California’s Silicon Valley manages the PTD mission series.
  • NASA’s Small Spacecraft Technology program within the agency’s Space Technology Mission Directorate is sponsoring the PTD mission series. The program is based at Ames.
  • Terran Orbital Corporation of Irvine, California is developing the PTD spacecraft bus and performing payload integration and mission operations for each mission.

Partners: PTD-1

  • NASA’s Glenn Research Center in Cleveland managed the development of PTD-1’s propulsion system.
  • Spaceflight Inc. of Seattle provided integration and rideshare services for the PTD-1 spacecraft, which was launched on a SpaceX Falcon 9 rocket from Cape Canaveral Space Force Station in Florida.
  • PTD-1 was launched as part of NASA’s Educational Launch of Nanosatellites 35 (ELaNa) mission, which was managed by the Launch Services Program based at NASA’s Kennedy Space Center. Selection of the payloads for ELaNa missions is provided by NASA’s CubeSat Launch Initiative (CSLI).
  • Tethers Unlimited, Inc., of Bothell, Washington developed the Hydros-C propulsion system demonstrated during the PTD-1 mission.

Partners: PTD-3

  • The Massachusetts Institute of Technology’s Lincoln Laboratory in Cambridge, Massachusetts is developing the optical communications system to be demonstrated on the PTD-3 mission. This technology is funded by NASA’s Space Communications and Navigation (SCaN) program.
  • NASA’s Goddard Space Flight Center in Greenbelt, Maryland manages the TBIRD project, in addition to multiple other optical communications projects, demonstrating NASA’s optical capabilities for future missions.

Partners: PTD-4

  • NASA’s Marshall Space Flight Center in Huntsville, Alabama, is developing the deployable solar array and integrated antenna technology planned for launch on PTD-4.

Learn more:



For investigators:

Investigators interested in funding opportunities with the Small Spacecraft Technology program please visit here.
For technical inquiries about the PTD series, contact:

For news media:

Members of the news media interested in covering this topic should reach out to the NASA Ames newsroom.