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LCRT — Lunar Crater Radio Telescope

Created: 2026-04-07 (session 77)

Summary

LCRT is JPL's concept for a radio telescope deployed inside a large natural lunar crater on the Moon's far side. Science target: the Cosmic Dark Ages (z~15–300, ~13.5–13.8 Gyr ago), the epoch between the CMB and the first stars — observationally inaccessible from Earth because the Earth's ionosphere absorbs wavelengths >10m (below ~30 MHz). No existing instrument has made measurements in this era.

The R&D arc follows a clean three-step path: NIAC Phase I → NIAC Phase II → APRA. All three projects are JPL-led with the same core team.

Full R&D Lineage

Phase I: NIAC [106029] (2020–2021, TRL 1→2)

  • PI: Saptarshi Bandyopadhyay (JPL)
  • Co-Is: McGarey (JPL), Lazio (JPL, ngVLA chief scientist), Rafizadeh (JPL), Goldsmith (JPL radio astronomy)
  • Period: 2020-05-27 – 2021-03-12 (≈10 months)
  • Outcomes: Closed_Out + Advanced To [Phase II] (2021-05-01)
  • What was done: Explored fundamental physics and cosmology (Dark Ages science case); generated technical requirements for separating the 21-cm Dark Ages signal from galactic foreground (5 orders of magnitude stronger); identified suitable lunar craters by shielding geometry; defined frequency range (4.7–47 MHz, 6–64m wavelengths).
  • Library items: 2 images (file IDs 376565, 376564)

Phase II: NIAC [106036] (2021–2023, TRL 2→3)

  • PI: Saptarshi Bandyopadhyay (JPL)
  • Co-Is added: Delapierre (structures/deployment), Goel (RF characterization — later becomes APRA PI), Arya (JPL origami structures), Chahat (JPL RF), Lazio, Goldsmith, Rafizadeh
  • Period: 2021-05-28 – 2023-05-26 (2 years)
  • Outcomes: Advanced From Phase I
  • TX mismatch: ML predicts TX15.1.4 (Aeroacoustics) vs human TX08.2 (Observatories). Documented as Issue 24 in field-completeness.md.
  • What was done: (From Phase II description) Explored physics + cosmology further, generated technical requirements, selected crater candidates, designed RF characterization experiments, developed foreground removal pipeline concepts, sub-scale reflector prototype (1m mesh on wire frame).
  • Library items (5):
  • 2022 NIAC Symposium Poster [PDF] (file ID 387305) — saved as assets/lcrt-niac-2022-symposium-poster.pdf
  • 2021 NIAC Symposium Poster [PDF] (file ID 387304)
  • LCRT Image (file ID 387306)
  • Paper: Survey of Mission Concepts for Exploring the Dark Ages Universe (AERO 2025)
  • 2022 NIAC Symposium Presentations (livestream link)

APRA follow-on: [157542] (2023–2026, TRL 2→4)

  • PI: Ashish Goel (JPL) — promoted from Co-I in NIAC Phase II
  • Co-Is include: Bandyopadhyay (JPL, original PI), Arya (JPL origami), Goldsmith (JPL radio astronomy), Lazio (ngVLA chief scientist), Tang (JPL RF)
  • Period: 2023-10-01 – 2026-09-30
  • TX mismatch: TechPort assigned TX08.2 (Observatories); ML predicts TX05.2.6 (Innovative Antennas) — session 76 assessment: "ML is arguably more accurate" since this project is specifically about RF antenna characterization, not general observatory science.
  • What is being done (4 tasks per session 76):
  • RF simulations (crater geometry + regolith dielectric properties)
  • Sub-scale prototype measurements
  • Foreground removal pipeline development
  • Calibration beacon satellite trajectory design
  • Description notes: "ongoing NIAC Phase II effort" — confirms APRA is the direct follow-on
  • Views: 866 (as of Aug 2025 snapshot)

System Concept

From the 2022 NIAC Symposium poster (saved):

Science band

6–64m wavelengths (4.7–47 MHz) — the Cosmic Dark Ages 21-cm signal redshifted down to these frequencies. Earth's ionosphere blocks everything below ~30 MHz. The Moon's far side provides dual shielding: ionosphere avoidance AND Earth radio-frequency interference (RFI) shielding.

Architecture

  • 350m diameter deployable wire-mesh reflector
  • Suspended central receiver/feed over the reflector
  • Deployed inside a ~1.3km diameter natural lunar crater (crater rim as structural anchor)
  • Crater selection criteria: >1.3km diameter, smooth interior, far side only, suitable geometry for wire tension

Deployment sequence (6 steps from poster)

  1. Land robotic lander in crater
  2. Fire anchors to crater rim
  3. Tension lift wires (raise feed to focal point)
  4. Deploy feed
  5. Deploy reflector mesh (unfurl/extend from lander)
  6. Calibrate LCRT (via calibration beacon satellite in lunar orbit)

Key technical challenges

  • Galactic foreground: 5 orders of magnitude stronger than Dark Ages signal. Foreground removal requires spatial structure + spectral shape + polarization separation.
  • Regolith dielectric: Must characterize how the crater floor affects the electromagnetic boundary conditions (APRA task 1).
  • No robotic deployment system exists at 350m scale. The 1m sub-scale prototype from Phase II is the largest hardware demonstrated. Gap between TRL 3 and a flight-ready system is enormous.
  • Crater selection: Must find a crater of the right size and geometry on the far side. Bandyopadhyay et al. have identified candidate craters but far-side access requires a relay satellite.

Personnel Structure

Name Role Programs
Saptarshi Bandyopadhyay PI NIAC I+II, Co-I APRA Robotics/swarm; origami deployment
Ashish Goel Co-I NIAC II, PI APRA RF characterization
Manan Arya Co-I NIAC II + APRA JPL origami/deployable structures
T. Joseph Lazio Co-I all three JPL radio astronomer, ngVLA chief scientist
Paul Goldsmith Co-I all three JPL radio astronomy
N. Chahat Co-I NIAC II JPL RF antennas
Melanie Delapierre Co-I NIAC II JPL deployable structures

Key connectivity: Lazio appears on all three grants as the astronomy bridge — the ngVLA chief scientist is personally committed to this concept across 6+ years.

Competitive landscape (from NIAC Phase II poster)

Other low-frequency lunar/space radio concepts mentioned: - FARSIDE (NASA/JPL concept) - VLFA, ROLSS, DALI, FARVIEW — various NASA far-side radio concepts - Lunar EM-L2 Satellite constellation - LORAE, DARE, ALFA, FIRST, OLFAR — European and smaller concepts

LCRT's differentiator: using existing natural topology (crater) rather than flat deployment, enabling a much larger aperture than a mission-deployed structure.

Assessment

Concept maturation path: NIAC Phase I (TRL 1→2) → Phase II (TRL 2→3, 2 years) → APRA (TRL 2→4, 3 years) = 6 years of funded R&D to reach RF characterization and sub-scale prototype. This is appropriate for a concept this speculative.

Mission horizon: 2030s at the absolute earliest for a small precursor, realistically 2040s+ for a science-capable deployment. The core bottleneck is not RF technology (which is mature) but deployment robotics at 350m scale in a lunar crater. The APRA work is proving the RF physics; the deployment engineering challenge is orders of magnitude harder.

TechPort visibility: LCRT is the only TechPort entry in Dark Ages/21-cm cosmology. There are no competing NASA R&D grants in this space. The entire US government investment in this science target is captured in these three projects.

Confidence: suggestive — based on project metadata and poster content; no detailed technical documents reviewed.