Laser Retroreflector Array (LRA)

Peregrine Mission Three · manifested · NASA payload

A passive optical marker: eight small quartz corner-cube prisms in a dome-shaped aluminum frame, 'cookie-sized'. Laser altimeters on orbiters or approaching landers can range to it, so it marks the lander's position for decades and helps orbiters fix their own orbits. It needs no power. Astrobotic will mount it on top of the lander. The same kind of array flew on Peregrine Mission One, which did not land, and Peregrine Mission Two carries another to the same region.

PI: Xiaoli Sun (NASA Goddard), PI of the LRA project and of the Peregrine Mission One LRA; deputy PI Daniel Cremons. NASA's June 2026 release names no PI for these units.
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's matching for the four late-2028 landings lists it with no data gap ('navigation aid'). NASA flies the LRA on all four landings to build a network of location markers, which fits #0101 (surface positioning) and #1101 (precision landing) in general. Goddard's team says the arrays can guide later landers to the same spot. Peregrine Mission Two and Three both aim near the Gruithuisen Domes, so this array would sit near Peregrine Mission Two's. Two markers close together add less to a global network than two far apart, but the first to land could, in principle, guide the second; no source says that is planned (the study's reading). The site is on the near side, not in a South Pole exploration zone, so its value is to the network rather than to a Moon Base site. A late-2028 landing falls in Phase 1 ('Now through 2028'), the study's reading.)
Route onto CLPS	other NASA; No payload call. The LRA is a CLPS-program payload that goes on most CLPS landers. NASA's Moon Base Program named the same three 'flight-proven' payloads (SCALPSS, LRA, LETS) for each of four late-2028 landings, awarded on 30 June 2026; Astrobotic won two, $297.9 million for both. Voyager, which bought Astrobotic, ties its 'approximately $298 million' award, NASA's figure for both Peregrine deliveries, to CS-8, but its July release names only Peregrine-2; its September page names both missions as two Moon Base task orders. That Peregrine Mission Three is a CS-8 order is the study's reading, from the matching amount.; 2026-06-30
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 2026-06-30 (named for the four late-2028 landings); launch 2028 (Astrobotic); no earlier than Q4 2028 (SCALPSS team poster); landing late 2028 (NASA, target)
On the Moon	not yet flown
FO	none

Flights before the Moon

• earlier lunar mission: SpaceIL's Beresheet lander (the same Goddard design, metal-coated), 2019-02-21 (launch). The first flight of the design. 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"
— NTRS 20205001993

• earlier lunar mission: ISRO's Chandrayaan-3 Vikram lander (a NASA retroreflector), 2023-08-23 (landing). The design on the surface, working: LRO's laser altimeter ranges to it, in 32% of tries by day and 9% by night by December 2025.

"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

"32% daytime and 9% nighttime for CH3"
— hou.usra.edu: 1707.pdf

• Earth orbit or deep space: Astrobotic's Peregrine Mission One (its NASA LRA, on the lander deck): the same lander type, aimed at Sinus Viscositatis near the Gruithuisen Domes, 2024-01-08 (launch); did not land. Nothing measurable: the LRA is passive and works only on the surface, and Peregrine did not land. It did carry an LRA through integration on a Peregrine deck and launch.

"It will be mounted on Astrobotic’s Peregrine lander deck"
— TO2-AB Science Payloads - NASA Science

"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

"Destination: Sinus Viscositatis (Bay of Stickiness) located near the Gruithuisen Domes"
— The Linear Energy Transfer Spectrometer (LETS) Payload on NASA's CLPS TO2 Peregrine-1 (M. Ecord,…, JSC, July 2023

• earlier lunar mission: JAXA's SLIM lander (a NASA retroreflector), 2024-01-19 (landing). A NASA retroreflector on the surface. LRO ranged to it, but rarely, because SLIM rests in an off-nominal attitude.

"including one on JAXA’s (Japan Aerospace Exploration Agency) SLIM lander"
— 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"
— hou.usra.edu: 1707.pdf

• earlier lunar mission: Intuitive Machines' IM-1 and IM-2 (Nova-C), 2024-02-22 and 2025-03-06 (landings). The design on commercial landers. Both landers came to rest tilted or on their sides. LRO had no returns from the IM-1 array by late 2025; the team blames the off-nominal landing and the array's place on a solar panel. No ranging to the IM-2 array is reported in these sources.

"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

"NASA’s Laser Retroreflector Array, a passive instrument meant to provide a reference point on the lunar surface"
— NASA Receives Some Data Before Intuitive Machines Ends Lunar Mission - NASA, IM-2

Heritage hardware

• design heritage and batch build: Eight 1.27 cm corner cubes in a 5 cm aluminum dome, about 20 g, built for decades on the surface and radiation-tested to 19 Mrad; the metal-coated version was space-qualified at Goddard in 2018. Goddard had optically tested 13 units by 2021; which unit flies here is not stated. The design is too small to range to from Earth, so it depends on lunar orbiters or landers with a lidar.

"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

"including radiation testing to 19 Mrad (Si)"
— NTRS 20210010915, LPSC 2021 poster

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

"this LRA design is too small for laser ranging from the Earth"
— TO2-AB Science Payloads - NASA Science

• lander heritage (Peregrine deck mount): Peregrine Mission One carried a Goddard LRA on its deck, so the array has been integrated on this lander type before. For the two new Peregrines, Astrobotic says the array goes on top of the lander. Ranging success depends on how the array faces the sky after landing: the IM-1 array, on a solar panel of a tilted lander, has given no returns. An upright landing with a top-mounted array should suit ranging from orbit (the study's reading).

"mounted to the lander deck"
— TO2-AB Science Payloads - NASA Science

"Mounted atop the lander, NASA’s Laser Retroreflector Array (LRA) will serve as a permanent optical reference point"
— Astrobotic Awarded 2 NASA Contracts for CLPS Moon Base Missions

"Estimated cross section of each mini-LRA accounting for its mounting orientation on the lander"
— hou.usra.edu: 1707.pdf, Figure 1 caption

Funding before the lunar flight

• NASA's CLPS program, which developed the LRA design (with a NASA Postdoctoral Program fellowship for the optical tests). No amount public for the program or for one unit; no SBIR or USAspending award names a CLPS LRA unit (see open questions). (NASA CLPS; from about 2018): 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, Introduction

"LRAs are targeted for inclusion on most of the upcoming CLPS deliveries headed to the lunar surface."
— How NASA Uses Simple Technology to Track Lunar Missions - NASA

"Each delivery will carry three NASA payloads to the lunar surface:"
— NASA Awards More Moon Base Science, Previews New Opportunities - NASA

"Astrobotic is awarded $297.9 million total for two deliveries"
— NASA Awards More Moon Base Science, Previews New Opportunities - NASA

"Mounted atop the lander, NASA’s Laser Retroreflector Array (LRA) will serve as a permanent optical reference point for future missions."
— Astrobotic Awarded 2 NASA Contracts for CLPS Moon Base Missions, 30 Jun 2026

"including the CS-8 competitive procurement under the existing Commercial Lunar Payload Services (CLPS) indefinite delivery/indefinite-quantity framework"
— Voyager Awarded $298M NASA Contract Under Completed Astrobotic Acquisition

"Under this NASA award, Voyager’s Peregrine-2 is scheduled to launch in 2028"
— Voyager Awarded $298M NASA Contract Under Completed Astrobotic Acquisition, 13 Jul 2026; names only Peregrine-2

"In June 2026, NASA announced two additional Moon Base task orders that will send two Peregrine lunar landers to the Moon by the end of 2028."
— Meet Voyager’s Lunar Missions, section 'Peregrine-2 and -3'

On the Moon

Manifested on Peregrine Mission Three for late 2028, near the Gruithuisen Domes. LRAs are also manifested on several other CLPS landers, some of which may land first.

"each Peregrine will enter lunar orbit before performing an autonomous landing near the Gruithuisen Domes"
— Astrobotic Awarded 2 NASA Contracts for CLPS Moon Base Missions

FO's role

Grade: none. No FO project, flight, report or page names the LRA, retroreflectors 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 for every earlier LRA (none found) applies.

"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, Peregrine Mission One manifest

"Dr. Xiaoli Sun, also of NASA Goddard and principal investigator for the LRA project"
— How NASA Uses Simple Technology to Track Lunar Missions - NASA, Feb 2024

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

Moon Base need

"These arrays have flown on previous CLPS landers and international lunar landers and will continue to be used to build a network of permanent location markers on the Moon for future exploration."
— NASA Awards More Moon Base Science, Previews New Opportunities - NASA

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

"the reflectors could allow spacecraft to accurately range-find their way to a landing pad"
— How NASA Uses Simple Technology to Track Lunar Missions - NASA

"They will also act as beacons for lidars on future landers making return missions to the CLPS lander locations"
— NTRS 20210010915, LPSC 2021 poster, Introduction

"will deliver three NASA-sponsored payloads on Peregrine to a landing site near the Gruithuisen Domes"
— Astrobotic Awarded 2 NASA Contracts for CLPS Moon Base Missions

"Phase 1 "Now through 2028""
— Moon to Mars knowledge base: Moon Base phases

Open questions

• Which tested LRA unit flies on Peregrine Mission Three, and is it a new build: not in public sources.
• The LRA program's cost and the cost per array: not in public sources. Two Goddard-area purchases from Sellers Optical may be LRA hardware, but the records do not say: 'Hemispherical retroreflector assembly (HRA)' (80NSSC23PC022, $152,780, Aug 2023) and 'Precision optical laser retroreflector array' (80NSSC24PB542, $58,890, June 2024, performed in Greenbelt).
• Will a laser altimeter be in lunar orbit to range to it after late 2028? LRO's LOLA is 'the only lidar in lunar orbit at present'; its life is not in these sources.
• Will the Peregrine Mission Three lander use Peregrine Mission Two's array as a landing beacon, if that one lands first, or a later lander use this one? Not in public sources.
• The exact landing site: not in public sources.