Laser Retroreflector Array (LRA), on the lander¶
Griffin Mission One · manifested · NASA payload
A passive optical marker: eight small glass corner-cube prisms in a dome-shaped aluminum frame, mounted on the lander. Laser altimeters on orbiters or landers can range to it, so it marks the lander's position on the Moon for decades. It needs no power. NASA's TO20A page names it as Griffin-1's NASA payload.
PI: Xiaoli Sun (NASA Goddard)
Built by: NASA Goddard Space Flight Center (NASA center)
| Technology | passive navigation marker (laser retroreflector) |
| Moon Base need | #0101, #1101 (The study's reading, as for the earlier CLPS arrays. No NASA gap names the LRA; the knowledge base files it as a navigation aid. NASA says LRAs could later guide landings in the dark near the South Pole (#1101) and build a network of fixed markers for positioning (#0101). NASA's June 2026 Moon Base release frames the LRA as part of 'a global network of ... location markers'. Griffin's array would add one at Mons Mouton, near the Moon Base sites.) |
| Route onto CLPS | other NASA; No payload call. The LRA was developed under NASA's CLPS program and is added to most CLPS landers. NASA's IM-2 page already listed an LRA for task order TO20A, Astrobotic's Griffin delivery of VIPER, awarded in June 2020. VIPER moved to Blue Origin in September 2025; NASA's TO20A page now names the LRA as the NASA payload Griffin-1 delivers to Mons Mouton. When this unit was assigned is not in public sources.; 2020-06 |
| Timeline | first funding not in public sources (the design was space-qualified at Goddard in 2018); first flight test 2019-02-21 (the design, on Beresheet); selected not in public sources (rides under task order TO20A, awarded June 2020); launch target late 2026 (NASA, Aug 2026); landing not in public sources |
| On the Moon | not yet flown |
| FO | none |
Flights before the Moon¶
- earlier lunar mission: SpaceIL's Beresheet lander (the same Goddard LRA design, metal-coated version), 2019-02-21. The first flight of the design: the first NASA instrument on a non-governmental mission to the Moon. How Beresheet ended is not in these sources.
"LRALL was integrated with the SpaceIL Beresheet spacecraft prior to its February 21, 2019 launch and became the first NASA instrument to fly on a non-governmental mission to the Moon."
— NTRS 20205001993
- earlier lunar mission: ISRO's Chandrayaan-2 Vikram lander (an uncoated version), 2019. A space-qualified uncoated version, integrated in April 2019. The landing attempt is not described in these sources.
"one of which was integrated in April, 2019 with the Indian Space Research Organization (ISRO) Vikram lander, a part of the Chandrayaan-2 mission"
— NTRS 20205001993
- earlier lunar mission: ISRO's Chandrayaan-3 Vikram lander (NASA LRA), 2023-08-23. The design on the surface. LRO's laser altimeter (LOLA) first ranged to it on 12 December 2023; by December 2025 about a third of daytime attempts succeeded.
"Vikram lander, with a NASA retroreflector on it, touched down on the Moon on Aug. 23, 2023."
— Laser Instrument on NASA’s LRO Successfully ‘Pings’ Indian Moon Lander - NASA Science"At 3 p.m. EST on Dec. 12, 2023, NASA’s LRO"
— Laser Instrument on NASA’s LRO Successfully ‘Pings’ Indian Moon Lander - NASA Science"32% daytime and 9% nighttime for CH3"
— hou.usra.edu: 1707.pdf
- earlier lunar mission: JAXA's SLIM lander (a NASA retroreflector), 2024-01. A NASA LRA on a lander resting in an off-nominal attitude. LOLA has ranged to it, but rarely.
"including one on JAXA’s (Japan Aerospace Exploration Agency) SLIM lander, due to land on the Moon on Jan. 19, 2024"
— Laser Instrument on NASA’s LRO Successfully ‘Pings’ Indian Moon Lander - NASA Science"The number of opportunities and success rate to SLIM were low given the off-nominal lander attitude."
— hou.usra.edu: 1707.pdf
- Earth orbit or deep space: Astrobotic's Peregrine Mission One (a NASA LRA on the lander deck), 2024-01-08. Nothing: the LRA is passive and works only on the surface, and Peregrine did not land. Same lander company as Griffin.
"As NASA’s LRA (Laser Retroreflector Array) instrument is a passive experiment, and operations could only take place"
— NASA Science, Astrobotic Peregrine Mission One Concludes - NASA
- earlier lunar mission: Intuitive Machines' IM-1 (Odysseus), a NASA LRA, 2024-02-22. The design on a CLPS lander. Odysseus tipped over and its LRA sits on a solar panel almost facing the horizon; LOLA had no returns from it as of December 2025.
"It landed on February 22, 2024."
— Commercial Lunar Payload Services (CLPS) Deliveries - NASA Science"So far, no returns have been received from IM-1"
— hou.usra.edu: 1707.pdf
- earlier lunar mission: Intuitive Machines' IM-2 (Athena), a NASA LRA, 2025-03-06. The design at Mons Mouton, Griffin's target area. The lander came to rest on its side; no ranging to this LRA is reported in these sources.
"IM-2 touched down at approximately 11:30 a.m. March 6"
— NASA Receives Some Data Before Intuitive Machines Ends Lunar Mission - NASA"will remain affixed to the top deck of the lander"
— NASA Receives Some Data Before Intuitive Machines Ends Lunar Mission - NASA
Heritage hardware¶
- design heritage (CLPS LRA line, flight-proven): The same miniature design that has flown since 2019: eight 1.27 cm fused-silica corner cubes in a 5 cm aluminum dome, about 20 g, no power. Goddard space-qualified it in 2018 and optically tested 13 units. NASA calls the LRA flight-proven. Similar small LRAs flew on the ExoMars and InSight landers.
"These devices consist of a small aluminum hemisphere, 2 inches (5 centimeters) in diameter and 0.7 ounces (20 grams) in weight"
— How NASA Uses Simple Technology to Track Lunar Missions - NASA"The metal-coated version of LRALL underwent space qualification and optical testing at Goddard Space Flight Center in 2018"
— NTRS 20205001993"All 13 LRALL units tested met the design specification"
— NTRS 20210010915, LPSC 2021 poster"These three payloads are flight-proven"
— NASA Awards More Moon Base Science, Previews New Opportunities - NASA"Similar small LRAs were placed on the ExoMars and InSight landers"
— NTRS 20205001993
Funding before the lunar flight¶
- NASA's CLPS program (with a NASA Postdoctoral Program fellowship for the optical tests). No amount public for the program, the LRA line or this unit. (NASA CLPS; not in public sources): amount not in public sources
"Funding National Aeronautics and Space Administration (NASA) Commercial Lunar Payload Services (CLPS)"
— NTRS 20205001993, Funding"developed under the Commercial Lunar Payload Services (CLPS) program"
— NTRS 20210010915, LPSC 2021 poster
How it got onto CLPS¶
"Voyager's Griffin-1 lander will deliver NASA's Lunar Retroreflector Array (LRA) to Mons Mouton (South Pole)."
— TO20A Science Payloads - NASA Science"Task Order: CLPS TO2-IM (2/20C/OP), TO2-AB, TO20A-VIPER, and PRIME-1"
— TO2-IM Science Payloads - NASA Science"June: NASA names Astrobotic as CLPS"
— NASA press kit, Commercial Lunar Payload Services Initiative: Astrobotic's Peregrine Mission One…, 2020 timeline"They will be attached to most of the landers from United States companies"
— How NASA Uses Simple Technology to Track Lunar Missions - NASA"VIPER and its instruments will be delivered to Mons Mouton by a Blue Origin Blue Moon MK-1 lander as part of task order CS-7"
— TO20A Science Payloads - NASA Science
On the Moon¶
Manifested on Griffin Mission One. If Griffin lands upright, LRO's LOLA, the only lidar in lunar orbit, could range to the array; LOLA locates small arrays to tens of meters for now.
"LOLA is one of the six operating science instruments on LRO and the only lidar in lunar orbit at present"
— hou.usra.edu: 1707.pdf"The observed LRA location uncertainty is 10s of meters peak-to-peak"
— hou.usra.edu: 1707.pdf
FO's role¶
Grade: none. No entry in the earlier traceback for Griffin's LRAs (the study's earlier traceback lists Griffin Mission One with no NASA payloads), but the study's earlier traceback found no FO link for any of the five earlier CLPS LRAs, and none was found here: no FO project, flight or report names the LRA or its Goddard team. A passive marker needs no suborbital test; its proof has come from earlier landers and LRO ranging.
"No FO record or report names SCALPSS, ROLSES, LN-1, the retroreflectors,"
— earlier finding of this study (not a public source)"Nothing in the FO sources (a passive reflector)."
— earlier finding of this study (not a public source)
Who built it¶
"PI: Dr. Xiaoli Sun, GSFC"
— TO20A Science Payloads - NASA Science"Laser Retroreflector Arrays (LRA), developed by NASA’s Goddard Space Flight Center"
— Moon Base Phases - NASA
Moon Base need¶
"Navigation aid, not a data gap's subject."
— Moon to Mars knowledge base: Architecture data gaps: all 25, Moon Base science awards table, LRA row"LRAs can eventually be used to help spacecraft land in otherwise pitch-dark places close to permanently shadowed regions near the lunar South Pole"
— How NASA Uses Simple Technology to Track Lunar Missions - NASA"this growing network will allow scientists to gauge the location of key landers and other points of interest more and more accurately"
— How NASA Uses Simple Technology to Track Lunar Missions - NASA"build out a global network of environmental data and location markers on the Moon"
— NASA Awards More Moon Base Science, Previews New Opportunities - NASA
Open questions¶
- Where on Griffin is the array mounted? NASA's TO20A page still shows the Peregrine photo and caption.
- NASA's Moon Base page lists two LRAs for Griffin-1 without saying where they go; reading one as on the lander and one on FLIP is this study's.
- When was this unit assigned to Griffin-1, and is it the unit first assigned with VIPER? Not in public sources.
- The LRA program's cost and the cost per array: not in public sources.