Research and testbeds

What has flown, what was cancelled, and the testbed programs the thread proposed for finding the minimum g and maximum rpm.

Key results

What has flown or been built

Facility Status Key facts
Gemini 11 tether with Agena (1966) flown First AG test, about 0.00015–0.0005 g at 0.15 rpm. Gravity gradient alone did not keep the tether taut muomega0, 2014-03-16; Aussie_Space_Nut, 2018-07-14. See Gemini 11.
Spacelab and Spacehab small centrifuges flown Partial-g research is already part of microgravity research Jim, 2015-02-20.
ISS Centrifuge Accommodation Module (CAM) cancelled, left in Japan Cancelled over cost overruns, schedule and vibration concerns RanulfC, 2015-02-19; Lampyridae, 2018-07-18. See CAM.
Mars Gravity Biosatellite cancelled (funding) Was to run 15 weeks at 0.38 g on a ~30 cm radius at 32 rpm kdhilliard, 2015-02-24.
DLR Eu:CROPIS flown Dec 2018 250 kg spinning satellite: tomatoes and Euglena, 6 months at lunar g then 6 at Mars g. Attitude control with water and magnetorquers, plus a passive water nutation damper mikelepage, 2019-01-08; LMT, 2023-11-05; LMT, 2023-11-09.
JAXA MHU / "MARS" mouse centrifuge on ISS operating 6 mice rotating plus 6 non-rotating, high rpm, about one 1-month run per year, mice climb so g varies. Supports full gestation studies Twark_Main, 2023-01-01; Paul451, 2023-01-02. The 1 g run spins at 77 rpm versus ~47 rpm for Mars g, and g varies by ~0.5 g over the cage height Paul451, 2018-07-17.
ISS Multiuse Variable-g Platform (MVP) operating Small commercial centrifuge for small experiments edzieba, 2022-09-07.
Airbus LOOP (concept) design Centrifuge deck under 4 m radius with fixed-orientation AG boxes LMT, 2023-04-19.
Vast Haven-1 building (launch slipped to 2027) Includes a lunar-g artificial-gravity demonstration while docked StraumliBlight, 2025-09-28; JulesVerneATV, 2026-02-07.

Proposed testbed ladders

  • Principle: "one mission, one step; do not multiply unknowns." A ten-step program costs no more than a single leap Paul451, 2015-03-02; Paul451, 2015-03-10.
  • Start at the extremes of the data void. Test 1/100 g and 1/10 g first, for example by spinning a whole Dragon: 2.5 rpm → 1/100 g, 8 rpm → 1/10 g Paul451, 2015-09-01. Alternatively, start at a 1 g baseline matched to Earth controls and step down mikelepage, 2015-09-01.
  • Separate spin rate from g-level. A test matrix with radius ≤20 m mikelepage, 2018-07-18; mikelepage, 2018-07-19:
  • Mars g at 4.2 rpm (20 m) vs 6.7 rpm (7.8 m) vs Earth g at 6.7 rpm (20 m);
  • Mars g at 5 rpm (14 m) vs 56% g at 5 rpm (20 m);
  • Mars g at 5.8 rpm (10.5 m) vs 75% g at 5.8 rpm (20 m).
  • Spin-rate "runs" of a baton. Paul451's plan: 1.7, 2.6 and 4.3 rpm runs of a Vast-like baton. Ramping up tests the structure; running in reverse tests ECLSS at progressively lower g, starting from hardware proven at 1 g Paul451, 2022-11-01.
  • Starship Gen1 "tumbling pigeon" floors. 3-month runs with floors at radii of 7/11/15/19 m Paul451, 2022-12-31:
  • 3 rpm → 0.07–0.19 g;
  • 4 rpm → 0.13–0.34 g;
  • 5 rpm → 0.20–0.53 g.
  • Overlapping g at different rpm separates spin effects. See Paul451 generations.
  • Small-animal concepts.
  • ISS rack with concentric mouse runs at 0, 0.1, 1/6 and 1/3 g plus spinning Earth controls mikelepage, 2015-02-16.
  • AGRARIAN satellite with 7 arms at 1/0.75/0.5/0.376/0.25/0.165 g plus a 0 g control, ~$500M A_M_Swallow, 2015-10-05.
  • A hubless mouse wheel inside an 8 m module. At 3.8 m radius: 1 g at 15.34 rpm, Mars g at 9.33, Moon g at 6.1. Controls: Mars g at 15.34 rpm needs a 1.4 m radius Solarsail, 2023-01-04.
  • A 1 m radius mouse torus at 12–30 rpm as the "only realistic near-term" station Greg Hullender, 2024-03-21.
  • Trays at several radii inside a Dragon (1.85 m) give about 10 g-levels at once A_M_Swallow, 2015-09-01.
  • Human-scale testbeds.
  • Two Dragons on an extensible pantograph node (Polaris-style): radius ~9–11 m, up to ~80% g if the IDSS vestibule is unpressurized mikelepage, 2023-12-28; mikelepage, 2023-12-30.
  • Coastal Ron's "X" testbed (NSF topic 48095).
  • Vast's 100 m spinning stick neoforce, 2023-05-11.
  • See testbed concepts.
  • Ground tests. A 10 m radius ring at 10 rpm could be tested on Earth (√2 g total) A_M_Swallow, 2015-03-12. A biosphere "step-down" experiment: start at 1 g and step down 0.9, 0.8 … until the ecosystem destabilizes mikelepage, 2015-09-04.

Why so little has been done

  • NASA's "local minimum" Paul451, 2025-09-19:
  • ISS management sells micro-g, so centrifuges are seen as a vibration threat and cost more.
  • No funded AG teams means no graduate students, so "no demand".
  • JAXA wanted AG from the start and was held back by NASA; ESA is in between Paul451, 2018-07-28.
  • NASA's Human Research Roadmap had only a partial-g bed-rest task, and it was closed. The NASA-led international AG research roadmap is in npj Microgravity 2017 LMT, 2018-07-28.
  • The best political path may be to get JAXA (plus ESA) to build a small Japanese-owned, human-tended AG animal facility Paul451, 2018-08-02.
  • Animals first. Early human data would come from a handful of "right stuff" subjects, so results would be unreliable. Big animal samples and multiple species are faster Paul451, 2024-04-03.

Open questions

  • Which single experiment would most reduce design uncertainty: a multi-month human stay at 3–6 rpm, or multi-generation mammal studies at 0.38 g?
  • Will commercial testbeds (Vast, Gravitics) publish their data?

Sources

Forum posts

  • muomega0, 2014-03-16 (reply #171): Gemini 11: 0.00015 g; gravity gradient insufficient. Post.
  • mikelepage, 2015-02-16 (reply #278): Rack-mounted mouse runs at several g. Post.
  • RanulfC, 2015-02-19 (reply #298): CAM cancelled: cost, vibration. Post.
  • Jim, 2015-02-20 (reply #313, 1 like): Small centrifuges flew on Spacelab & Spacehab. Post.
  • kdhilliard, 2015-02-24 (reply #392): Carroll 2010 AG research facility; Sorensen JANNAF 2005. Post.
  • kdhilliard, 2015-02-24 (reply #395, 1 like): Mars Gravity Biosatellite. Post.
  • RonM, 2015-02-28 (reply #452): NASA 2002 AG status & options. Post.
  • Paul451, 2015-03-02 (reply #468): One mission, one step; roadmap. Post.
  • Paul451, 2015-03-10 (reply #497): Ten-step program ≤ single leap. Post.
  • A_M_Swallow, 2015-03-12 (reply #518): Ground test 10 m ring 10 rpm. Post.
  • Paul451, 2015-09-01 (reply #579): Test 1/100 and 1/10 g first by spinning Dragon. Post.
  • mikelepage, 2015-09-01 (reply #581): Start at 1 g baseline then step down. Post.
  • A_M_Swallow, 2015-09-01 (reply #583): Multi-g trays in Dragon. Post.
  • mikelepage, 2015-09-04 (reply #620): Biosphere step-down plan. Post.
  • savuporo, 2015-09-30 (reply #657): AOSAT-1. Post.
  • A_M_Swallow, 2015-10-05 (reply #667): AGRARIAN satellite. Post.
  • Aussie_Space_Nut, 2018-07-14 (reply #922): Gemini 11 ~0.0005 g at 0.15 rpm. Post.
  • Paul451, 2018-07-17 (reply #968): MARS centrifuge rpm; g varies over cage. Post.
  • mikelepage, 2018-07-18 (reply #982, 1 like): Test matrix separating spin rate from g-level. Post.
  • Lampyridae, 2018-07-18 (reply #983): CAM left in Japan partly for vibration. Post.
  • mikelepage, 2018-07-19 (reply #986, 1 like): Matrix details. Post.
  • LMT, 2018-07-28 (reply #1042): International AG research roadmap (npj Microgravity 2017). Post.
  • Paul451, 2018-07-28 (reply #1043): JAXA & ESA fund AG; NASA's partial-g task closed. Post.
  • Paul451, 2018-08-02 (reply #1104): Convince JAXA to build small AG animal facility. Post.
  • mikelepage, 2019-01-08 (reply #1275, 1 like): Eu:CROPIS launched 3 Dec 2018. Post.
  • edzieba, 2022-09-07 (reply #1758, 2 likes): ISS MVP for small experiments. Post.
  • Paul451, 2022-11-01 (reply #2293): Baton run plan (1.7/2.6/4.3 rpm). Post.
  • Paul451, 2022-12-31 (reply #2736): Starship Gen1 floor table. Post.
  • Twark_Main, 2023-01-01 (reply #2748): ISS mouse centrifuge; results via Scholar citations. Post.
  • Paul451, 2023-01-02 (reply #2749, 1 like): MHU limits: 6 mice, 1-month runs, climbing (critique). Post. Attachments: MHU MARS.PNG.
  • Solarsail, 2023-01-04 (reply #2769, 1 like): Hubless mouse wheel inside 8 m module (SpinCalc values). Post.
  • LMT, 2023-04-19 (reply #3616): Airbus LOOP centrifuge deck. Post.
  • neoforce, 2023-05-11 (reply #3685): Vast roadmap: 100 m spinning stick. Post.
  • LMT, 2023-11-05 (reply #4276): Eu:CROPIS attitude control with water + magnetorquers. Post. Attachments: EUCROPIS attitude control hardware.png.
  • LMT, 2023-11-09 (reply #4341, 1 like): Passive water tank damper. Post. Attachments: EuCROPIS water tank.png.
  • mikelepage, 2023-12-28 (reply #4376, 1 like): Two-Dragon testbed: IDSS load limits. Post. Attachments: IDSS mated load limits.png, Dragon SpinG testbed_small.mp4, D2testbed_preview.png.
  • mikelepage, 2023-12-30 (reply #4387, 1 like): Vestibule unpressurized → up to 80% g. Post. Attachments: Bimetal_coil_reacts_to_lighter.gif, dual spiral.png, Dragon SpinG testbed_small.mp4.
  • Greg Hullender, 2024-03-21 (reply #4600): Mice-first station. Post.
  • Paul451, 2024-04-03 (reply #4631, 1 like): Animal lab first; human samples too small (1 like). Post.
  • Paul451, 2025-09-19 (reply #4990, 1 like): NASA AG research local minimum (Paul451). Post.
  • StraumliBlight, 2025-09-28 (reply #5005, 1 like): Haven-1 will perform AG tests. Post. Attachments: Lunar Artificial Gravity Demo.jpg.
  • JulesVerneATV, 2026-02-07 (reply #5040, 1 like): Haven-1 launch 2027. Post.

External references

  • Shiba, D. et al. (2017). Scientific Reports 7:10837 (JAXA MARS).
  • NASA-led international roadmap for AG research, npj Microgravity (2017), s41526-017-0034-8.
  • DLR Eu:CROPIS mission pages; Heidecker, A. et al. (2014). Attitude control system of the Eu:CROPIS mission, 65th IAC.
  • ASU AOSAT-1 CubeSat centrifuge laboratory savuporo, 2015-09-30.
  • Joe Carroll, "Design Concepts for a Manned Artificial Gravity Research Facility" (SSI 2010) kdhilliard, 2015-02-24.
  • Kirk Sorensen, JANNAF 2005 AG paper (artificial-gravity.com/JANNAF-2005-Sorensen.pdf).
  • NASA DPT/NExT (2002) "Artificial Gravity Status and Options" RonM, 2015-02-28.