Skip to content

Laser Retroreflector Array (LRA)

Peregrine Mission One · failed to land · NASA payload

A passive optical marker: eight 1.25 cm glass corner-cube prisms set in a gold-painted aluminum dome, mounted on the lander deck. 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, as for the IM-1 array. No NASA gap names the LRA; the knowledge base files it as a navigation aid, not a data gap's subject. Goddard says the arrays can guide future landers and rovers back to a site in any lighting (#1101) and build a network of fixed markers (#0101). NASA put LRAs on all four Moon Base science landings ordered in June 2026.)
Route onto CLPS other NASA; No payload call named. The arrays (Laser Retroreflector Arrays for Lunar Landers, LRALL) were developed under the CLPS program itself and go on most CLPS landers. 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 (the design, on Beresheet); selected 2020-01-22 (January 2020 manifest); launch 2024-01-08; landing not in public sources
On the Moon no data: lander failure
FO none

Flights before the Moon

  • earlier lunar mission: SpaceIL's Beresheet lander (metal-coated version of the same Goddard design), 2019-02-21. The first flight of this array design, and the first NASA instrument on a non-governmental Moon mission. 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, total-internal-reflection version), 2019. A space-qualified uncoated version, integrated in April 2019. The landing attempt's outcome is not 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. A NASA array on the lunar surface. On 12 December 2023, four weeks before Peregrine's launch, LRO's laser altimeter ranged to it from orbit.

"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), in flight when Peregrine launched, 2024-01-19 (landing). A NASA array on a lander already on its way to the Moon; it landed eleven days after Peregrine's launch. Listed for completeness: it could not inform the Peregrine unit.

"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

Heritage hardware

  • design heritage: Similar small arrays flew on the ExoMars and InSight landers. Goddard space-qualified the design in 2018 and tested 13 units. The cubes have one tenth the area of the Apollo cubes, so orbiters, not Earth stations, can range to them. Small retroreflectors also help cargo craft dock with the ISS.

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

"All 13 LRALL units tested met the design specification"
— NTRS 20210010915, LPSC 2021 poster, optical testing

"The metal-coated version of LRALL underwent space qualification and optical testing at Goddard Space Flight Center in 2018"
— NTRS 20205001993

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 (Applied Optics paper, 2020)

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

"LRALL units are manifested on upcoming CLPS missions, including Peregrine Mission 1 (Astorbotic), IM-1 (Intuitive Machines), and Masten Mission 1 (Masten Space)."
— 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

On the Moon

The LRA is passive and works only on the surface, so it had nothing to do in transit. It burned up with Peregrine on 18 January 2024.

"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

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.

"Nothing in the FO sources (a passive reflector)."
— earlier finding of this study (not a public source)

Who built it

"Laser Retroreflector Array (LRA) - Goddard Space Flight Center (GSFC), PI: Dr. Xiaoli Sun"
— TO2-AB Science Payloads - NASA Science, updated manifest, 6 Apr 2023

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

Moon Base need

"Navigation aid, not a data gap's subject."
— Moon to Mars knowledge base: Architecture data gaps: all 25, June 2026 landings table, LRA row

"optical markers such as LRAs can support precision autonomous navigation and landing regardless of lighting conditions"
— NTRS 20210010915, LPSC 2021 poster, introduction

"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. NASA bought 'hemispherical retroreflector assemblies' from Sellers Optical in 2023 (80NSSC23PC022) and a 'precision optical laser retroreflector array' in 2024 (80NSSC24PB542), but the awards do not name CLPS or a lander, so they are not counted.
  • Which of the 13 tested LRALL units flew on Peregrine? Not in public sources.
  • How did Beresheet (2019) and Chandrayaan-2's Vikram (2019) end, and did their arrays reach the surface intact? Not in these sources.