Carthage College — Modal Propellant Gauging (MPG)¶
Lead PI: Kevin M. Crosby, Physics, Carthage College (Kenosha, WI)
13-year FO arc (2014–2027) · 9 FO projects · Active IM-3 development
Last updated: Session 73, 2026-04-07
TL;DR¶
A small liberal arts college has quietly run NASA's primary low-gravity propellant gauging research program for over a decade. Modal Propellant Gauging (MPG) — non-invasive tank vibration analysis to measure liquid mass in microgravity — is now under development for Intuitive Machines' 3rd lunar mission (IM-3 NOVA-C lander). The program has an Airbus commercialization partnership, a 2025 TechLeap Prize, and explicit Orion/SLS and Gateway architecture targeting. Longest continuous research arc in the FO portfolio.
FO Projects — Complete Arc¶
| Project | Title | Period | TRL | Notes |
|---|---|---|---|---|
| 94131 | Modal Analysis Phase I | 2014–2015 | 4→5 | Parabolic flights; "Advanced To" outcome; T0147/T0160/T0191 follow-on |
| 91347 | Modal Propellant Gauging Testing | 2015–2017 | 5→5 | Continuation of Phase I; Acta Astronautica 2019 paper |
| 89417 | Modal Analysis Phase II | 2016–2018 | 4→6 | Co-I Rudy Werlink (NASA KSC); sloshing propellant assessment |
| 106702 | Magneto-Active Slosh Control (MAPMD) | 2019–2021 | 4→6 | Free-floating magnetic diaphragm suppresses slosh; co-I Gangadharan (Embry-Riddle) |
| 106670 | Propellant Mass Gauging in Gateway Vehicles | 2019–2023 | 5→6 | Gateway architecture explicit target; new SDM + PSM extensions; co-I Eric Hurlbert (JSC) |
| 106707 | Modal Analysis Phase III | 2020–2022 | 5→6 | Orion/SLS architecture explicit target; OMS tank focus |
| 106631 | Non-invasive Propellant Detection Transfer | 2021–2025 | 4→6 | Piezoelectric sensors on tank exterior; 3167 views; Eric Hurlbert co-I |
| 106620 | Propellant Gauging During On-Orbit Refueling & Transfer | 2020–2025 | 6→7 | On-orbit refueling application; MPG for propellant transfer scenarios; co-I Werlink (KSC) + Hurlbert (JSC); 1893 views |
| 184147 | MUTT: Microgravity Ullage Trapping Technology | 2025–2027 | TBD | 9th project — acoustic ullage bubble control for propellant transfer venting; co-I Alvaro Romero-Calvo (Georgia Tech) |
9 FO projects across 13 years (2014–2027). Longest continuous single-technology FO research arc. (Session 20: discovered 9th project [184147] MUTT — extends arc to 2027)
Technology¶
Core technique — Modal Propellant Gauging (MPG):
Attach piezoelectric transducers to the outside of a propellant tank. Apply acoustic excitation. Measure modal response (resonant frequencies). The resonant frequencies shift with liquid fill level — high resolution without any sensors inside the tank. Works in both settled (accelerating) and unsettled (sloshing) conditions.
Why this matters: Standard gauging methods (pressure/temperature equations of state, capacitance probes, RF gauging) all require settled propellant or internal sensors. MPG works passively, non-invasively, with COTS piezo hardware — compelling for spacecraft where internal tank access is impossible or undesirable.
Extensions developed during 10-year arc: - Spectral Density Method (SDM): Uses power spectral density instead of instantaneous modal frequencies; more reliable during high-rate tank drains under acceleration - Point Sensor Method (PSM): Single-sensor variant for mass measurement under varying pressures - MAPMD (Magneto-Active PMD): Free-floating magnetic diaphragm positioned by field gradients to suppress slosh and improve gauging resolution
Downstream Impact¶
IM-3 Lunar Mission (Active — Highest Confidence)¶
- MPG technology installed on Intuitive Machines' NOVA-C lander test articles
- Planned for IM-3 (IM's 3rd CLPS lunar mission)
- Direct lineage: 11-year FO program → lunar surface deployment
- Source: Parabolic Arc (2022), Carthage College press release
Airbus Partnership (Commercialization)¶
- Airbus identified as commercialization partner
- Technology being evaluated for in-orbit refueling and propellant transfer applications
- Source: Carthage College press materials, Parabolic Arc 2022
TechLeap Prize 2025 ($500K)¶
- Awarded for Microgravity Ullage Trapping — an extension of MPG for unsettled propellant states
- Continues the FO-to-TechLeap pipeline established by several other FO alumni
Orion/SLS Architecture (Phase III, 2020–2022)¶
- Phase III description: "addresses immediate needs in the Orion/SLS Exploration Mission architecture"
- Focused specifically on OMS (Orbital Maneuvering System) tank: NASA JSC OMS tank test data reduction contract ($20K, 2023–2024)
- Co-I Eric Hurlbert (JSC propulsion systems) is the bridge from FO research to mission requirement
Gateway Architecture (Phase IV, 2019–2023)¶
- Explicitly targets "Gateway architecture vehicles" for lunar orbit fuel depot scenarios
- SDM/PSM extensions developed specifically for Gateway propellant scenarios
Publication¶
- Acta Astronautica (2019): "Modal Propellant Gauging: High-resolution and non-invasive gauging of both settled and unsettled liquids in reduced gravity" — DOI 10.1016/j.actaastro.2019.01.050
Lemelson-MIT Student Prize (2020)¶
- Awarded to Carthage student research team — national recognition for innovation
Key Personnel¶
| Name | Role | Organization |
|---|---|---|
| Kevin M. Crosby | PI (all 7 projects) | Carthage College, Physics |
| Rudy J. Werlink | Co-I (Phases II–IV) | NASA KSC Structures Lab |
| Eric A. Hurlbert | Co-I (Gateway + latest FO) | NASA JSC, Propulsion/Power/Thermal |
| Brant Carlson | Co-I (Phase II) | Carthage College |
| Sathya Gangadharan | Co-I (MAPMD) | Embry-Riddle Aeronautical University |
| Pedro Llanos | Co-I (MAPMD) | Carthage College |
Key connection: Eric Hurlbert is NASA JSC's principal propellant systems expert and co-chair of the Propulsion Subgroup for the Human Exploration Framework Team. His involvement from Phase IV onward connects the research directly to Artemis mission propulsion requirements.
Timeline¶
| Year | Event |
|---|---|
| 2014 | FO Phase I awarded; first parabolic flights |
| 2015–2017 | Phase testing; "Advanced To" outcome recorded |
| 2016–2018 | Phase II: sloshing propellant, Blue Origin New Shepard |
| 2019 | Acta Astronautica paper published |
| 2019–2023 | Gateway targeting; SDM/PSM extensions developed |
| 2020 | Lemelson-MIT Student Prize |
| 2020–2022 | Phase III: Orion/SLS OMS tank |
| 2021–2025 | Phase IV: piezo sensors, Eric Hurlbert co-I |
| 2022 | Commercialization with Airbus + Intuitive Machines announced |
| 2023 | OMS tank test data reduction contract ($20K, NASA JSC) |
| 2025 | TechLeap Prize ($500K); IM-3 development ongoing |
TRL gap: FO program topped out at TRL 6 (Phase IV). IM-3 deployment would validate TRL 7+ on actual lunar lander.
Funding Tracked¶
| Source | Amount | Note |
|---|---|---|
| FO program (7 grants) | ~$2.2M est. | Based on typical FO grant sizes; not directly in USASpending |
| NASA JSC OMS contract | $20K | USASpending 80NSSC23PC036 (2023–2024) |
| NASA sabbatical support | $200K | Prof. Crosby at NASA (travel/housing contracts) |
| TechLeap Prize 2025 | $500K | Microgravity Ullage Trapping |
| Total tracked | ~$2.9M | Predominantly FO grants |
Assessment¶
Outcome category: Active Mission Infusion Path (IM-3) + Commercial (Airbus)
Confidence: High for IM-3 development; medium for Orion/Gateway flight (no confirmed contract)
Archetype fit: "Small Lab, Big Impact" — 10-year systematic research program at a liberal arts college; Crosby has turned FO into a continuous R&D pipeline rather than one-off experiments
Why this works:
- Single technology, incrementally improved across 7 projects
- Early JSC co-investigator involvement (Hurlbert) created mission architecture alignment before TRL was high enough for mission selection
- Liberal arts college model allows undergraduate researchers to make genuine contributions to flight hardware
- Tech is low-cost (COTS piezo hardware) and easily integrated → attractive for IM commercial landers
Open questions: - ~~Will IM-3 actually fly the MPG system, or is it still at test article stage?~~ Partially resolved Session 38: see below. - What is the Gateway/Orion MPG status after Gateway cancellation (Mar 2026)? - Has Airbus moved beyond evaluation to purchase agreements?
Session 38 Update: IM-3 Timeline + Gateway Impact¶
IM-3 Mission Status (as of Apr 2026)¶
- IM-3 "Trinity" launch expected 2H 2026 (Reiner Gamma region)
- Payloads: Lunar Vertex (LVx) magnetic field investigation, CADRE rovers (JPL), Khon-1 relay satellite (IM Lunar Data Network), + commercial payloads
- MPG status: Carthage College confirms MPG technology installed on IM NOVA-C test articles and development with Intuitive Machines is ongoing. NASA's FO "Transitions" page lists Carthage/MPG as an active commercial transition. However, it is not confirmed whether MPG will fly as an operational system on IM-3 specifically vs. a later IM mission. The technology may be in development for IM's propellant management system across the Nova-C fleet rather than a specific single-mission payload.
- Confidence: Medium — strong institutional relationship confirmed, but no public manifest listing MPG as an IM-3 payload.
Gateway Cancellation Impact¶
NASA suspended Gateway indefinitely in March 2026. Two of Crosby's FO projects explicitly targeted Gateway architecture: - 106670 — Propellant Mass Gauging in Gateway Vehicles (2019–2023, completed) - 106620 — Propellant Gauging During On-Orbit Refueling (2020–2025, active)
Impact assessment: Moderate. The Gateway research is already completed (TRL 6 achieved). The underlying MPG technology is mission-agnostic — it works on any liquid propellant tank. The on-orbit refueling application [106620] has increasing relevance as NASA pivots to lunar surface base (propellant depot concepts remain active). Airbus commercialization and IM lander integration are unaffected. The loss is primarily the high-profile demonstration venue, not the technology's viability.
Crosby Profile Update¶
Kevin Crosby continues as Physics chair at Carthage College. The 9th FO project 184147 (MUTT — Microgravity Ullage Trapping, 2025–2027) extends the arc through 2027 with a new co-I: Alvaro Romero-Calvo (Georgia Tech), who is an emerging leader in capillary fluid dynamics for space applications.
Session 38 · 2026-04-07
Session 50 Update: TechLeap Hardware Deadline + IM-3 Manifest Check¶
TechLeap Prize — Hardware Delivery Deadline April 1, 2026¶
The $500K TechLeap Prize (awarded October 2025) requires Crosby's team to deliver hardware for testing by April 1, 2026. Five Carthage students were selected for the project: Juliana Alvarez '27, Owen Bonnett '28, Semaje Farmer '26, Skylar Farr '26, and Braedon Larsen '27. The payload is based on a solution Crosby and co-I Álvaro Romero-Calvo (Georgia Tech) devised to win NASA's Tank Venting Challenge — using carefully controlled acoustic fields to manipulate and concentrate pressurant gas bubbles, enabling efficient venting without significant propellant loss.
The April 1, 2026 deadline has now passed. Whether the hardware was delivered on time is not yet confirmed. If successful, the TechLeap flight test would be Carthage's 10th FO-connected flight campaign.
IM-3 Manifest Status¶
IM-3 "Trinity" is now targeting 2H 2026 (slipped from earlier estimates). Wikipedia's payload manifest as of early 2026 lists: - Lunar Vertex (LVx) — APL magnetometer + SwRI plasma spectrometer + Lunar Outpost rover - CADRE rovers (JPL) - ESA MoonLIGHT Pointing Actuator (MPAc) - KASI Lunar Space Environment Monitor (LUSEM) - AstroForge Vestri - ALEPH-1 (Australian plant growth experiment, added Dec 2025) - Possible data-relay satellite (Khon-1)
MPG is NOT listed in the IM-3 payload manifest. This confirms the Session 38 assessment: Carthage/Intuitive Machines collaboration is real (test article installation confirmed), but MPG may be targeting a later IM mission rather than IM-3 specifically. The technology's path is through IM's Nova-C fleet propellant management system, not as a standalone science payload.
Confidence adjustment: IM-3 deployment downgraded from "medium" to low. Overall IM partnership remains medium-high — the institutional relationship and test articles are confirmed, but the specific mission timeline is uncertain.
Open Questions Updated¶
- ~~TechLeap hardware delivery April 1, 2026~~ — deadline passed; delivery status unknown
- Which IM mission will first fly MPG operationally?
- Has Airbus moved beyond evaluation? (No new information found)
- What is Romero-Calvo's role expanding beyond MUTT to the broader MPG program?
Session 50 · 2026-04-07
Cross-references: fo-portfolio-tracker.md, archetypes.md, topics/gateway-cancellation-impact.md
Session 73 Update: Two New Publications + NS-35 Flight + MPG→MUTT Pivot¶
New Publications (2024–2025)¶
Two Acta Astronautica papers published since Session 50:
-
"Liquid mass gauging during propellant transfer in microgravity" — Acta Astronautica, Vol. 220, July 2024 (online April 20, 2024). Authors: Crosby, Hurlbert, Werlink. Flight-tested on Blue Origin New Shepard; validated computational models during simulated in-space propellant transfers. Funded by NASA FO #80NSSC22K0580.
-
"Acoustic detection of the liquid–vapor interface in settled propellant tanks" — Acta Astronautica, 2025. Authors: Crosby, Wheeler, Steineke, Graves, Hurlbert. Vibration-based broad-band acoustic excitation via patch sensors on tank wall. Average 0.7% full-tank volume error. Same FO grant (#80NSSC22K0580).
The 0.7% accuracy is significant — most competing methods (PVT, capacitance) are 5–10% in unsettled propellant scenarios. This positions MPG as the highest-precision non-invasive gauging approach demonstrated in microgravity.
NS-35 Final Flight (September 18, 2025)¶
Carthage flew 2 payloads on Blue Origin NS-35 — the final flight of the RSS H.G. Wells capsule: - PROTO (Propellant Refueling and On-orbit Transfer Operations) — measuring propellant during tank drain/fill - MUD (Microgravity Ullage Detection) — non-invasive liquid-vapor interface location
Students on-site: Teagan Steineke '26, Owen Bonnett '28, Juliana Alvarez '26.
Significance: NS-35 was the last New Shepard payload flight for that capsule. Carthage has been a continuous Blue Origin customer for years — this flight platform chapter may be closing. Future flights would need to use the successor capsule or shift entirely to parabolic/orbital platforms.
Additional Awards (2024)¶
| Award | Amount | Description |
|---|---|---|
| Orr Reynolds Distinguished Service Award | — | American Society of Gravitation and Space Research (2024) |
| Hedberg Distinguished Professor of Entrepreneurial Studies | — | Named chair (2024) |
| NASA Tank Venting Challenge — 1st Place | $30K | "Who Let the Gas Out?" — won against all entrants (2024) |
| NASA SMD Bridge Seed Program | $295.7K | "Bubble Trapping and Ullage Formation in Microgravity" (2024–2026) |
The SMD Bridge Seed grant ($295.7K) is the science underpinning MUTT — a separate NASA directorate (SMD, not STMD) funding the fundamental physics that MUTT will apply in engineering tests. Total tracked funding revised to ~$3.2M (adding $295.7K SMD + $30K venting challenge to prior $2.9M).
Technology Pivot: MPG → MUTT (Gauging → Control)¶
The most important structural development: Crosby's team is expanding from gauging (measuring what's in the tank) to control (manipulating ullage gas during propellant transfer). MUTT uses phased-array ultrasonic fields to acoustically generate and direct a secondary ullage bubble to the vent port — enabling propellant venting without losing liquid.
This is not just an extension of MPG — it's a new capability that addresses the propellant transfer problem rather than just the measurement problem. The 2025 Acta Astronautica paper on acoustic liquid-vapor interface detection is the science bridge between the two.
MUTT timeline: TechPort 184147 runs Jun 2025 – Jun 2027. Hardware delivery deadline for TechLeap was April 1, 2026 (status unknown — deadline just passed). Co-I: Alvaro Romero-Calvo (Georgia Tech Low Gravity Lab).
IM-3 Status — Still H2 2026, Still No MPG Confirmation¶
IM-3 targeting H2 2026 with 12 orbital passes before landing (improved from IM-2's 3). Payload manifest includes Lunar Vertex, CADRE, MoonLIGHT, LUSEM, Vestri (AstroForge), ALEPH-1. MPG is still not listed in the public manifest. IM partnership confidence remains medium — institutional relationship confirmed via test articles, but specific mission timeline uncertain.
Airbus Partnership — No Update¶
No new information on the Airbus ZeroE Program evaluation. The one-year study may have concluded without public announcement. Watch item.
Open Questions Updated¶
- TechLeap MUTT hardware delivery (April 1, 2026 deadline) — was it delivered on time?
- Which IM mission will first fly MPG operationally?
- Is the Airbus evaluation still active or concluded?
- What platform replaces New Shepard for Carthage microgravity access?
- Will any of the 10 TechLeap winners (including MUTT) get Momentus Vigoride hosting? See topics/momentus-orbital-testbed.md.
Session 73 · 2026-04-07