Laser Retroreflector Array (LRA)

Blue Moon Pathfinder Mission 1 · manifested · NASA payload

A passive optical marker: eight small corner-cube retroreflectors on a dome-shaped aluminum mount, about 5 cm across and 20 g. Laser altimeters on orbiters, or lidars on approaching landers, can range to it, so it marks the lander's exact position for decades and helps orbiters fix their own orbits. It needs no power. On Blue Moon MK1 it would sit on the Shackleton Connecting Ridge, a potential landing and exploration region at the South Pole. It was added to this flight after SCALPSS.

PI: Xiaoli Sun (NASA Goddard), named as PI on NASA's CT-3 page.
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, and the knowledge base's own matching lists it with no data gap ('navigation aid'). A permanent marker fits #0101 (absolute surface positioning) and #1101 (precision landing close to other surface elements) in general. The Goddard team says the arrays can be beacons for lidars on later landers returning to the same spot. This unit's site matters more than most: NASA calls the Shackleton Connecting Ridge 'a strategic area of the lunar south pole', and a 2024 NASA cargo paper lists 'Connecting Ridge' among potential landing and exploration regions there. The IM-2 array reached Mons Mouton, also near the South Pole, but its lander came to rest on its side. A launch in late 2026 or early 2027 falls in Phase 1 (the study's reading).)
Route onto CLPS	other NASA; No payload call. The LRA is a CLPS-program payload that NASA puts on most CLPS landers. It was not on CT-3 at first: NASA's February 2025 IM-2 press kit gives Blue Moon MK1 one payload, and the SCALPSS team's July 2025 slides call SCALPSS 'the sole NASA payload' on the flight. NASA named both payloads on 26 May 2026, and its CT-3 page (as fetched on 4 October 2026) lists both. How and when the LRA was added is not public. CT-3 itself was signed on 24 July 2024; a July 2026 change raised its value by $122,220 and updated the delivery date and payment plan, without saying why.; between July 2025 and 2026-05-26 (first named by NASA on 26 May 2026)
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 between July 2025 and 2026-05-26 (added to CT-3; first named by NASA on 26 May 2026); launch no earlier than fall 2026 (NASA, May 2026); early 2027 at the soonest (Blue Origin's CEO, per Wikipedia); no earlier than Q1 2027 (Wikipedia); 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 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), 2024-01-08 (launch); did not land. Nothing measurable: 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"
— NASA Science, Astrobotic Peregrine Mission One Concludes - NASA

• 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 near the South Pole. 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. The team's late-2025 list of arrays LRO ranges to does not include IM-2's.

"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 corner cubes on a 5 cm aluminum hemisphere, 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 orbiters or landers with a lidar. LRO's LOLA is 'the only lidar in lunar orbit at present'.

"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

"the only lidar in lunar orbit at present"
— hou.usra.edu: 1707.pdf

• mounting (the lesson from IM-1): 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. Where the array goes on Blue Moon MK1 is not in public sources.

"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

"Blue Moon Mark 1 lander will deliver one payload to the Moon's South Pole."
— NASA press kit, Commercial Lunar Payload Services IM-2 (Intuitive Machines-2) Lunar Mission, February 2025

"SCALPSS 1.x will be the sole NASA payload onboard the Blue Origin MK1-SN101 first demo flight"
— NTRS 20250007176, page 30 (22 Jul 2025)

"and the Laser Retroreflective Array, which helps orbiting spacecraft determine a more precise location using reflected laser light"
— NASA Provides Update on Moon Base Rovers, Landers, Missions - NASA, 26 May 2026

"In addi-tion to flying two NASA science payloads, SCALPSS and a Lunar Retroreflector Array"
— Moon Base Announcement Speech – May 26, 2026 Administrator Isaacman – Remarks - NASA

"MODIFICATION 8 TO UPDATE RFTP, APPENDIX A, MILESTONE PAYMENT PLAN, DELIVERY DATE, POP AND VALUE (BY $122,220)"
— USAspending.gov, award 80JSC024F0068, transaction P00008, 2026-07-14

On the Moon

Manifested on Blue Moon Pathfinder Mission 1 (Moon Base I), landing target the Shackleton Connecting Ridge. NASA says it will let scientists 'accurately locate and track the lander'. If the lander lands upright, this would be the first working NASA mini-LRA in the South Pole region (the study's reading; IM-2's array lies on a lander on its side and has no reported returns). LRAs on other landers (IM-4, IM-5, Griffin Mission One, Blue Ghost Mission 4, the four late-2028 landings) may land first.

"allowing scientists to accurately locate and track the lander"
— Moon Base Phases - NASA

"The mission will land on the Shackleton Connecting Ridge"
— NASA Provides Update on Moon Base Rovers, Landers, Missions - NASA

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 this unit (none found) stands.

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

"Will carry Stereo Cameras and Laser Retroreflective Array."
— earlier finding of this study (not a public source)

Who built it

"PI: Dr. Xiaoli Sun, GSFC"
— CT-3 Science - NASA CLPS

"The Laser Retroreflector Array (LRA), developed at NASA's Goddard Space Flight Center, will provide a precise reference point on the lunar surface"
— 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, LRA row

"Absolute and relative positioning, navigation and timing (PNT) for crew and surface assets"
— Moon to Mars knowledge base: ESDMD #0101: Positioning, Navigation, and Timing for Lunar Surface Extreme Environments, summary

"Precision landing and hazard avoidance (PL&HA) to land crew and cargo safely close to other"
— Moon to Mars knowledge base: ESDMD #1101: Lunar Precision Landing and Hazard Avoidance for Human Exploration, summary

"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

"the Shackleton Connecting Ridge, a strategic area of the lunar south pole"
— Moon Base Announcement Speech – May 26, 2026 Administrator Isaacman – Remarks - NASA, NASA Administrator, 26 May 2026

""Connecting Ridge Extension", "Connecting Ridge""
— Moon to Mars knowledge base: Lunar Surface Cargo (ACR24 white paper), ACR24 lunar surface cargo paper, Figure 3

""potential landing and exploration regions""
— Moon to Mars knowledge base: Lunar Surface Cargo (ACR24 white paper)

"a Laser Retroreflector Array (LRA) to Mons Mouton near the Moon's South Pole"
— Commercial Lunar Payload Services - NASA, IM-2

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

Open questions

• When and how the LRA was added to CT-3, and whether the $122,220 change of July 2026 relates to it: not in public sources.
• Where the array mounts on Blue Moon MK1, and so how well LRO can range to it after landing: not in public sources.
• Which tested LRA unit flies, and is it a new build: not in public sources.
• Will a laser altimeter be in lunar orbit to range to it? LRO's LOLA is 'the only lidar in lunar orbit at present'; its remaining life is not in these sources.
• The LRA program's cost and the cost per array: not in public sources. NASA bought a 'hemispherical retroreflector assembly' (80NSSC23PC022) and a 'precision optical laser retroreflector array' (80NSSC24PB542) from Sellers Optical; the records don't say they are CLPS LRAs.