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Laser Retroreflector Array (LRA)

IM-1 · landed · NASA payload

A passive optical marker: eight small glass corner-cube prisms set in a gold-painted aluminum dome about 5 cm wide and 20 g. Laser altimeters on orbiters or landers can range to it, so it marks the lander's position on the Moon for decades. It is too small to range to from Earth.

PI: Xiaoli Sun (NASA Goddard); deputy PI Daniel Cremons
Built by: NASA Goddard Space Flight Center (NASA center)
Technology passive navigation marker (laser retroreflector)
Moon Base need #0101, #1101 (The study's reading. No NASA gap names the LRA; the knowledge base files it as a navigation aid, not a data gap's subject. 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 put LRAs on all four Moon Base science landings it ordered in June 2026.)
Route onto CLPS other NASA; No payload call named. The LRA was developed under NASA's CLPS program itself and is added to most CLPS landers. It is not on the February 2019 NPLP list; NASA's January 2020 manifest put one LRA on each of the first two landers, Peregrine and IM-1.; 2020-01-22
Timeline first funding not in public sources (the design was space-qualified at Goddard in 2018); first flight test 2019-02-21 (on Beresheet); selected 2020-01-22 (January 2020 manifest); launch 2024-02-15; landing 2024-02-22
On the Moon no data: lander failure
FO none

Flights before the Moon

  • earlier lunar mission: SpaceIL's Beresheet lander (same Goddard LRA design), 2019-02-21. The first flight of this array design: integrated on Beresheet in November 2018 and launched in February 2019, 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 (a total-internal-reflection version of the design), 2019. A space-qualified uncoated version, integrated in April 2019. The launch and Vikram's landing attempt are 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, NASA-ISRO partnership), 2023-08-23. The design on the lunar surface. On 12 December 2023, LRO's laser altimeter ranged to it from about 100 km: the first laser ranging from lunar orbit to a small array on the surface, two months before IM-1.

"ISRO's (Indian Space Research Organization) 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

  • earlier lunar mission: JAXA's SLIM lander (a NASA retroreflector), 2024-01. A NASA LRA due to land on 19 January 2024, a month before IM-1. LRO has since ranged to it, though rarely, because SLIM came to rest in an off-nominal attitude.

"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, LPSC 2026 abstract 1707

  • Earth orbit or deep space: Astrobotic's Peregrine Mission One (its NASA LRA), 2024-01-08. Nothing to test in transit: the LRA is passive and works only on the surface, and Peregrine did not land.

"As NASA's LRA (Laser Retroreflector Array) instrument is a passive experiment, and operations could only take place on the lunar surface."
— NASA Science, Astrobotic Peregrine Mission One Concludes - NASA

Heritage hardware

  • design heritage: Similar small arrays flew on the ExoMars and InSight landers. The design differs from the large Apollo arrays: smaller cubes and a dome shape, so orbiters, not Earth stations, can range to it. Small retroreflectors are also used on the ISS as docking markers.

"Similar small LRAs were placed on the ExoMars and InSight landers"
— NTRS 20205001993

"On the International Space Station, they're used as precision markers that help cargo-delivery spacecraft dock autonomously."
— Laser Instrument on NASA’s LRO Successfully ‘Pings’ Indian Moon Lander - NASA Science

Funding before the lunar flight

  • NASA's CLPS program (with a NASA Postdoctoral Program fellowship for the optical tests) (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

How it got onto CLPS

"Laser Retroreflector Arrays for Lunar Landers (LRALL) developed under the Commercial Lunar Payload Services (CLPS) program"
— NTRS 20210010915, LPSC 2021 poster

"Laser Retro-Reflector Array (LRA): LRA is a collection of eight approximately half inch (1.25 centimeter) retro-reflectors"
— First Commercial Moon Delivery Assignments to Advance Artemis - NASA, 22 Jan 2020, under Both Partners

"They will be attached to most of the landers from United States companies"
— How NASA Uses Simple Technology to Track Lunar Missions - NASA

On the Moon

The array landed intact as far as is known, but the lander tipped over, and the LRA sits on a solar panel that now faces almost to the horizon. LRO had received no returns from it as of December 2025, while it has ranged to the arrays on Chandrayaan-3, SLIM and Chang'e-6. The array is passive and could still be found later.

"So far, no returns have been received from IM-1, but this is not surprising given its off-nominal landing and the location of the LRA on a solar panel"
— hou.usra.edu: 1707.pdf, LPSC 2026 abstract 1707

"LOLA has successfully ranged to the LRAs on the CH3, SLIM, and CE6 landers"
— hou.usra.edu: 1707.pdf

"LRA is mounted on Intuitive Machine's Nova-C lander top deck solar array"
— NASA press kit, Commercial Lunar Payload Services Intuitive Machines IM-1 Mission

FO's role

Grade: none. No FO project, flight or report mentions the LRA or its Goddard team. A passive marker had no need of a suborbital test; its proof came from earlier landers and LRO ranging. The study's earlier traceback grade (none found) stands.

"No FO record or report names SCALPSS, ROLSES, LN-1, the retroreflectors"
— earlier finding of this study (not a public source)

Who built it

"Payload Principal Investigator: Dr. Xiaoli Sun, NASA Goddard Space Flight Center"
— NASA press kit, Commercial Lunar Payload Services Intuitive Machines IM-1 Mission

"deputy principal investigator for the"
— How NASA Uses Simple Technology to Track Lunar Missions - NASA, Daniel Cremons

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

Open questions

  • The LRA program's cost and the cost per array: not in public sources. USAspending shows no award tied to these arrays.
  • How did Beresheet (2019) and Chandrayaan-2's Vikram (2019) end, and did their arrays reach the surface intact? Not in these sources.
  • Has LRO ranged to the IM-1 array since December 2025? Not in public sources.