Power and Propulsion Element
Artist's impression of the PPE, attached to HALO, firing its engines in lunar orbit.
Asteroid Redirect Vehicle
Mission typePower and propulsion module
OperatorNorthrop Grumman / NASA
Mission duration15 years (planned)
Spacecraft properties
ManufacturerMaxar Technologies
Launch mass5,000 kg (11,000 lb) [1]
Power60 kW
Start of mission
Launch dateNovember 2025 (planned)
RocketFalcon Heavy
Launch siteKennedy Space Center, LC-39A

The Power and Propulsion Element (PPE), previously known as the Asteroid Redirect Vehicle propulsion system, is a planned solar electric ion propulsion module being developed by Maxar Technologies for NASA. It is one of the major components of the Lunar Gateway. The PPE will allow access to the entire lunar surface and a wide range of lunar orbits and double as a space tug for visiting craft.[2][3]

The PPE originally started development at the Jet Propulsion Laboratory as a part of the now cancelled Asteroid Redirect Mission, but is now led and managed by the NASA John H. Glenn Research Center, in Cleveland, Ohio. When ARM was cancelled, the solar electric propulsion was repurposed as the PPE for the Gateway.[4][5] The PPE is designed to be able to transfer the reusable Gateway to lunar orbit.[3] It will also serve as the communications center of the Gateway.[6] The PPE is intended to have a launch mass of 5,000 kg (11,000 lb) with propellant accounting for half that mass [1] and the capability to generate 50 kW [7] of solar electric power using Roll Out Solar Arrays for its Hall-effect thrusters, which can be supplemented by chemical propulsion.[8] It is currently planned to launch on a Falcon Heavy no earlier than 2025 along with the HALO module.[9]

The PPE will be compatible with the International Docking System Standard.[10] This means that any IDSS Spacecraft could theoretically dock to the PPE, such as Orion, the International Space Station, Dragon 2, Dream Chaser, and Boeing Starliner. The other modules of the Lunar Gateway will most likely also be IDSS compatible.


Asteroid Redirect Vehicle bus

Main article: Asteroid Redirect Mission

The Asteroid Redirect Vehicle was a robotic, high performance solar electric spacecraft for the Asteroid Redirect Mission (ARM). The mission was to send the spacecraft to a near-Earth asteroid and capture a multi-ton boulder from the surface with a grappling device. It would then transport the asteroid into orbit around the Moon where crewed missions to study it could be conducted more easily.[5][11] The mission was cancelled in early 2017 and the spacecraft's propulsion segment became the Power and Propulsion Element (PPE) for the Deep Space Gateway, now known as the Gateway.[4]

Reusable Space Tug missions

During the Asteroid Redirect Mission, space tug missions were purposed to separate Mars logistics that can spend a longer time in space than the crew into a separate mission, which could have reduced the costs by as much as 60% (if using advanced solar electric propulsion (ion engines) [12]). They would also reduce the overall mission risk by enabling check-out of critical systems at Mars before the crew departs Earth. This way if something goes wrong in those logistics, the crew is not in danger and the hardware can simply be fixed or relaunched.[13][14][15][16][17][18]

Not only would the solar electric propulsion (SEP) technologies and designs be applied to future missions, but the ARM spacecraft would be left in a stable orbit for reuse.[13][15][14] The project had baselined any of multiple refueling capabilities. The asteroid-specific payload was at one end of the spacecraft bus, either for possible removal and replacement via future servicing, or as a separable, reusable spacecraft, leaving a qualified space tug in cislunar space. This made adaption for Gateway easy, as the propulsion system was already designed to be multi-mission reusable.[19][20][21][22][23] When the ARM was cancelled however, development on the bus and any reusable tug ideas died, temporarily.[4]

Power and Propulsion Element

A diagram of the Gateway identifying the Power and Propulsion Element, along with the other modules planned.

In 2017, a year after the Artemis program came into existence, the ARM space tug/propulsion bus was dusted off and repurposed as the main propulsion system for the Gateway space station, and officially became known as the Power and Propulsion Element or PPE.[4] The PPE will be a smaller version of the Asteroid Redirect bus.[4][24] In 2018, the Gateway was split off from Artemis as a separate program to allow a Moon landing by 2024 without having to wait for the Gateway to be completed.[25][26]

Commercial company studies

On 1 November 2017, NASA commissioned 5 studies lasting four months into affordable ways to develop the Power and Propulsion Element (PPE), hopefully leveraging private companies' plans. These studies had a combined budget of US$2.4 million. The companies performing the PPE studies were Boeing, Lockheed Martin, Orbital ATK, Sierra Nevada and Space Systems/Loral.[27][7] These awards are in addition to the ongoing set of NextSTEP-2 awards made in 2016 to study development and make ground prototypes of habitat modules that could be used on the Gateway as well as other commercial applications,[28] so the Gateway is likely to incorporate components developed under NextSTEP as well.[7][29]

Contract awarded

In May 2019, Maxar Technologies was contracted by NASA to manufacture this module, which will also supply the station with electrical power and is based on Maxar's SSL 1300 series satellite bus.[30] The PPE will use Busek 6kW Hall-effect thrusters and NASA Advanced Electric Propulsion System (AEPS) Hall-effect thrusters.[31][32][33] Maxar was awarded a firm-fixed price contract of US$375 million to build the PPE. Maxar's SSL business unit, previously known as Space Systems/Loral, will lead the project. Maxar stated they will receive help from Blue Origin and Draper Laboratory on the project, with Blue Origin assisting in human-rating and safety aspect while Draper will work with trajectory and navigation development.[6] NASA is supplying the PPE with a S-band communications system to provide a radio link with nearby vehicles and a passive docking adapter to receive the Gateway's future Utilization Module.[6] Maxar stated they are experienced dealing with high power components from making satellites. They did mention that their satellites are around 20 to 30 kilowatts, while the PPE will be about 60 kilowatts, but they say much of the technology they have already developed will still be applicable.[6] After a one-year demonstration period, NASA would then "exercise a contract option to take over control of the spacecraft".[26] Its expected service time is about 15 years.[25]

To be launched with HALO

In 2020, NASA announced that the PPE would be launched with the Habitation and Logistics Outpost (HALO) (the renamed Utilization Module).[34]

See also


  1. ^ a b Boyle, Alan (23 May 2019). "NASA says Maxar will build the first big piece for Gateway station in lunar orbit". GeekWire. Retrieved 28 August 2023.
  2. ^ "NASA Awards Artemis Contract for lunar Gateway Power, Propulsion" (Press release). NASA. 23 May 2019. Archived from the original on 20 September 2019. Retrieved 11 December 2019. Public Domain This article incorporates text from this source, which is in the public domain.
  3. ^ a b "Deep Space Gateway and Transport: Concepts for Mars, Moon Exploration Unveiled". Science News. 4 April 2017. Archived from the original on 30 May 2019. Retrieved 30 May 2019.
  4. ^ a b c d e "NASA closing out Asteroid Redirect Mission". SpaceNews. 14 June 2017. Retrieved 30 May 2019.
  5. ^ a b "Asteroid Redirect Robotic Mission". jpl.nasa.gov. NASA. Archived from the original on 30 May 2019. Retrieved 30 May 2019. Public Domain This article incorporates text from this source, which is in the public domain.
  6. ^ a b c d Clark, Stephen. "NASA chooses Maxar to build keystone module for lunar Gateway station". Spaceflight Now. Archived from the original on 5 June 2019. Retrieved 30 May 2019.
  7. ^ a b c Foust, Jeff (3 November 2017). "NASA issues study contracts for Deep Space Gateway element". SpaceNews. Retrieved 11 December 2019.
  8. ^ Chris Gebhardt (6 April 2017). "NASA finally sets goals, missions for SLS – eyes multi-step plan to Mars". NASASpaceFlight.com. Archived from the original on 21 August 2017. Retrieved 9 April 2017.
  9. ^ Dunbar, Brian (18 December 2023). "Gateway". NASA. Retrieved 25 December 2023.
  10. ^ Robinson, Julie A. (11 October 2018). "Update on Gateway with Science and Technology (Utilization) Discussion" (PDF).
  11. ^ Greicius, Tony (20 September 2016). "JPL Seeks Robotic Spacecraft Development for Asteroid Redirect Mission". NASA. Archived from the original on 17 June 2019. Retrieved 30 May 2019. Public Domain This article incorporates text from this source, which is in the public domain.
  12. ^ Tate, Karl (10 April 2013). "How to Catch an Asteroid: NASA Mission Explained (Infographic)". Space.com. Retrieved 26 March 2015.
  13. ^ a b Cassady, J.; Maliga, K.; Overton, S.; Martin, T.; Sanders, S.; Joyner, C.; Kokam, T.; Tantardini, M. (2015). "Next Steps in the Evolvable Path to Mars". Proceedings of the IAC.
  14. ^ a b Craig, D. (10 June 2015). Evolvable Mars Campaign.
  15. ^ a b Troutman, P. (30 July 2014). The Evolvable Mars Campaign: the Moons of Mars as a Destination.
  16. ^ Howell, E. (8 May 2015). "Human Mars Plan: Phobos by 2033, Martian Surface by 2039?". Space.com. Retrieved 9 October 2016.
  17. ^ McElratht, T.; Elliott, J. (January 2014). "There and Back again: Using planet-based SEP tugs to repeatably aid interplanetary payloads". Advances in the Astronautical Sciences (152): 2279–2298.
  18. ^ Price, Humphrey W.; Woolley, Ryan; Strange, Nathan J.; Baker, John D. (2014). "Human Missions to Mars Orbit, Phobos, and Mars Surface Using 100-kWe-Class Solar Electric Propulsion". AIAA SPACE 2014 Conference and Exposition. doi:10.2514/6.2014-4436. ISBN 978-1-62410-257-8.
  19. ^ Manzanek, D. (20 May 2016). The Asteroid Redirect Mission. ((cite book)): |work= ignored (help)
  20. ^ Gates, M.; Manzanek, D. (28 June 2016). Asteroid Redirect Mission (ARM). ((cite book)): |work= ignored (help)
  21. ^ Manzanek, D.; Reeves, D.; Hopkins, J.; Wade, D.; Tantardini M.; Shen, H. (13 April 2015). "Enhanced Gravity Tractor Technique for Planetary Defense". IAA-PDC.
  22. ^ NASA RFI: Spacecraft Bus Concepts to Support the ARM and In-Space Robotic Servicing- Section "Separable Spacecraft Architecture ARRM Concept".
  23. ^ "Will April 2020 be the last month on this Earth? NASA told the whole truth". Big 11 News. Archived from the original on 20 March 2020. Retrieved 20 March 2020.
  24. ^ Foust, Jeff (30 March 2018). "NASA considers acquiring more than one gateway propulsion module". SpaceNews. Retrieved 11 December 2019.
  25. ^ a b Crusan, Jason (7 December 2018). "Gateway Update: NASA ADVISORY COUNCIL Human Exploration and Operations Committee" (PDF). Retrieved 12 November 2022.Public Domain This article incorporates text from this source, which is in the public domain.
  26. ^ a b NASA updates Lunar Gateway plans Archived 6 August 2019 at the Wayback Machine, Philip Sloss, NASASpaceFlight.com, 11 September 2018
  27. ^ Jimi Russell (November 2017). "NASA Selects Studies for Gateway Power and Propulsion Element". nasa.gov. NASA. Archived from the original on 12 January 2018. Retrieved 2 November 2017. Public Domain This article incorporates text from this source, which is in the public domain.
  28. ^ Robyn Gatens, Jason Crusan. "Cislunar Habitation and Environmental Control and Life Support System" (PDF). nasa.gov. NASA. Archived (PDF) from the original on 31 March 2017. Retrieved 31 March 2017. Public Domain This article incorporates text from this source, which is in the public domain.
  29. ^ Erin Mahoney (9 August 2016). "NextSTEP Partners Develop Ground Prototypes to Expand our Knowledge of Deep Space Habitats". nasa.gov. NASA. Archived from the original on 10 April 2017. Retrieved 6 November 2017. Public Domain This article incorporates text from this source, which is in the public domain.
  30. ^ "NASA Awards Artemis Contract for Lunar Gateway Power, Propulsion" (Press release). NASA. 23 May 2019. Archived from the original on 20 September 2019. Retrieved 11 December 2019. Public Domain This article incorporates text from this source, which is in the public domain.
  31. ^ Foust, Jeff (23 May 2019). "NASA selects Maxar to build first Gateway element". SpaceNews. Retrieved 23 May 2019.
  32. ^ Status of Advanced Electric Propulsion Systems for Exploration Missions Archived 13 June 2019 at the Wayback Machine R. Joseph Cassady, Sam Wiley, Jerry Jackson; Aerojet Rocketdyne, October 2018
  33. ^ "Maxar and Busek Thruster System for NASA Lunar Gateway Passes Critical Milestone". www.prnewswire.com. Retrieved 28 April 2021.
  34. ^ Northrop Grumman outlines HALO plans for Gateway’s central module Aug 2020