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Neutron Spectrometer System (NSS)

Peregrine Mission One · failed to land · NASA payload

A neutron spectrometer with two helium-3 gas proportional counters, one wrapped in cadmium. Cosmic rays knock neutrons out of the regolith; hydrogen slows them down. By counting thermal and epithermal neutrons, NSS estimates hydrogen (a sign of water) down to about 1 m, and the bulk composition of the soil. On Peregrine it was also to watch for hydrogen from the lander's own exhaust over a lunar day.

PI: Richard Elphic (NASA Ames)
Built by: NASA Ames Research Center; the Resource Prospector version was built with Lockheed Martin's Advanced Technology Center; Johns Hopkins APL supports modeling (NASA center)
Technology science instrument (neutron spectrometer)
Moon Base need DN-007 L, DN-013 L, DN-010 L (The study's reading, and partial. NASA does not tie the Peregrine NSS to a data gap. NSS measures hydrogen to about 1 m depth (the subject of DN-007 L and DN-013 L) and bulk composition (DN-010 L), but those gaps ask for South Pole measurements, and Peregrine aimed at a mid-latitude mare site. The NSS line (Resource Prospector, VIPER, MoonRanger) was built for polar prospecting.)
Route onto CLPS NPLP; NASA-Provided Lunar Payloads: SMD's request to NASA centers, selected 21 February 2019. NSS was an instrument of Resource Prospector, cancelled in 2018; SMD then kept the RP instruments in development so they could compete for flights. Manifested on Astrobotic's first delivery (TO2-AB) and listed in January 2020; kept on Peregrine in April 2023.; 2019-02-21
Timeline first funding not in public sources (developed under AES for Resource Prospector, which began in FY2014); first flight test not in public sources; selected 2019-02-21 (NPLP); on the Peregrine manifest by January 2020; launch 2024-01-08; landing not in public sources
On the Moon partly operated
FO none

Flights before the Moon

None found in the public sources.

Heritage hardware

  • design heritage (Lunar Prospector neutron spectrometer): NSS uses the same detection method as the Lunar Prospector neutron spectrometer (1998): two helium-3 counters, one covered in cadmium. That instrument was built by another team; it is design heritage, not an earlier flight of NSS.

"As with the highly successful Lunar Prospector Neutron Spectrometer, the RP NSS detects both thermal and epithermal neutrons by using two helium-3 gas proportional counters, one covered by cadmium and the other uncovered."
— NTRS 20170010372, abstract, 2017

  • design heritage (Resource Prospector ground and field tests): Ground and field tests only before Peregrine. In October 2014 NSS rode on the KREX-2 rover in the Mojave Desert (with NIRVSS) in a lunar polar rover analog, using a neutron source to stand in for cosmic rays. At least three NSS flight units were planned for the Moon: Peregrine, MoonRanger and VIPER.

"and the neutron spectrometer system (NSS) to gauge volumetric hydration and elemental composition variations within the top 30 cm"
— NTRS 20160000570, MVP field test, 16-24 Oct 2014

"at least three flight units of the Neutron Spectrometer System (NSS) will be sent to the lunar surface"
— NTRS 20230003089, poster, 2023

Funding before the lunar flight

  • Resource Prospector, under HEOMD's Advanced Exploration Systems (TechPort 34970, now listed under ESDMD), where NSS was developed. (NASA HEOMD AES (Resource Prospector); about 2013-2018): amount not in public sources

"NSS and NIRVSS instruments were developed under HEOMD Advanced Exploration Systems."
— NTRS 20160000570, acknowledgments (LEAG 2015 abstract)

  • The CLPS payload: SMD's NASA-Provided Lunar Payloads (NPLP) (SMD NPLP; from 2019): amount not in public sources

"NASA Payloads: CLPS Astrobotic Peregrine Mission-1 NASA-Provided Lunar Payloads"
— NASA press kit, Commercial Lunar Payload Services Initiative: Astrobotic's Peregrine Mission One…

  • Johns Hopkins APL task order for NSS modeling support (80MSFC20F0179, via NASA Marshall, July 2020 to Sept 2027, obligation to date shown). It serves all NSS units (Peregrine, VIPER, MoonRanger); most of it falls after Peregrine, and the sources do not split it by unit. (NASA contract (ARDES II task order); 2020-2027): $636,828

"NEUTRON SPECTROMETER SYSTEM (NSS) MODELING SUPPORT TASK ORDER UNDER AEROSPACE RESEARCH, DEVELOPMENT, AND ENGINEERING SUPPORT (ARDES) II 80MSFC20D0004."
— USAspending.gov, award 80MSFC20F0179, description; obligated 636828.0

How it got onto CLPS

"The Neutron Spectrometer System and Advanced Neutron Measurements at the Lunar Surface are neutron spectrometers that will measure hydrogen abundance."
— NASA Selects Experiments for Possible Lunar Flights in 2019 - NASA, release of 21 Feb 2019

"SMD determined to continue development of the instruments through the end of Fiscal Year 2018 and that these instruments could compete for flight on future SMD-funded missions."
— TechPort project 34970, outcomes, closeout (Resource Prospector)

"NSS is being developed at NASA Ames."
— First Commercial Moon Delivery Assignments to Advance Artemis - NASA, 22 Jan 2020, under Astrobotic Payloads

On the Moon

Peregrine could not land. NSS ran in seven sessions between 8 and 14 January 2024 and returned 12.5 hours of data from cislunar space, against a planned 2-hour checkout. The flight came during a solar particle event, so the team checked the instrument under changing proton fluxes, learned to separate the space-weather background from neutrons, and built real-time correction tools and space-weather procedures that it now uses for VIPER, MoonRanger and LUPEX. Astrobotic counts NSS among the three payloads that collected publishable scientific data. No lunar surface data.

"The Neutron Spectrometer System (NSS) on Peregrine successfully returned 12.5 hours of data from cislunar space."
— NTRS 20260003452, page 20 (LSSW 2026 slides)

"Nominal NSS checkout and background calibration activity in transit is only 2 hours."
— NTRS 20260003452, page 10

"Peregrine mission was over the course of an ongoing Solar Particle Event (SPE)"
— NTRS 20260003452, page 13

"NSS Team has implemented software tools to perform real-time corrections to NSS data, reducing uncertainty in the search for polar volatiles across multiple missions."
— NTRS 20260003452, page 19

"Two NASA payloads, Linear Energy Transfer Spectrometer (LETS) and Neutron Spectrometer System (NSS), and one commercial payload, The German Aerospace Center (DLR)'s M-42 Radiation Detector, collected publishable scientific data."
— Peregrine: Mission 1, August 2024 Post-Mission Report (Astrobotic), p. 17, (Astrobotic post-mission report, Aug 2024)

FO's role

Grade: none. No FO flight of NSS, its predecessors or its PI. FO flew a different Ames particle detector (INTREPID, TechPort 106627) under another PI: same center and topic only, which the study does not count. The study's earlier traceback grade (none found) stands.

"No FO flight of NSS or its Ames team. FO's INTREPID gamma/neutron detector (TechPort 106627, Ames, balloon) has a different PI; same center and topic only."
— earlier finding of this study (not a public source)

Who built it

"Neutron Spectrometer System (NSS) - Ames Research Center (ARC), PI: Dr. Richard Elphic"
— TO2-AB Science Payloads - NASA Science, updated manifest, 6 Apr 2023

"Authors: R. C. Elphic(ARC), E. Fritzler(ARC), J. Mobilia(LMATC), A. Kou (LMATC)"
— NTRS 20170010372, abstract, 2017 (LMATC: Lockheed Martin Advanced Technology Center)

"NEUTRON SPECTROMETER SYSTEM (NSS) MODELING SUPPORT TASK ORDER"
— USAspending.gov, award 80MSFC20F0179, description (Johns Hopkins APL)

Moon Base need

"Measure the vertical and horizontal distribution and abundance of shallow bulk water as a"
— Moon to Mars knowledge base: DN-007 L: In situ measurements of the horizontal and vertical distribution, abundance, and physical makeup of shallow bulk water ice, Description

"NSS can measure the total volume of hydrogen up to three feet below the surface"
— TO2-AB Science Payloads - NASA Science

Open questions

  • NSS's development cost (AES for Resource Prospector, then NPLP): not in public sources. No USAspending award names the NSS hardware.
  • Which NSS unit flew on Peregrine (a 2023 poster labels units ETU-3, Peregrine and MoonRanger), and how does it relate to the VIPER unit?
  • Did NSS or a prototype ever fly on an aircraft, balloon or rocket before Peregrine? Not in public sources: the papers describe ground and field tests only.
  • When was the NSS flight unit delivered to Astrobotic? Not in public sources.