The International Space Station Refrigerator/Freezer Rack and Artificial Gravity for Initial Mars Missions: A Cautionary Tale

Chip Shepherd Jacobs Engineering

Technology Transfer & Commercialization Section August 8, 2014

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Personal Introduction • Worked for various companies around the NASA

Johnson Space Center since 1987. • Joined Technology Transfer Office (TTO) in Dec ‘09.

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Commander, Crew 61 Mars Desert Research Station

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Summary

• Artificial Gravity System proposed in Mars Direct architectures may be susceptible to elimination in similar manner as RFR. – NASA and ESA were developing

refrigerated/frozen foods and a fleet of Refrigerator/Freezer Racks (RFR’s) for the International Space Station (ISS) in 1999-2003.

– RFR’s cancelled by ISS Program Management (PO) during budget crisis in 2002; never restored.

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Caveats

• The author’s opinion only, and does not officially represent NASA, Jacobs, JSC Tech Transfer Office, Mars Society, any other organization, nor reality. Yet.

• These views only apply to initial missions to Mars.

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Outline

• The ISS RFR • The ISS Program Office Change Request that

cancelled them • Reasons Why • The Mars Direct Artificial Gravity System (AGS) • Similarities in the Situations • Conclusions & Recommendations

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The ISS Refrigerator/Freezer Rack • “Provide thermally conditioned volume for food

to be maintained in and carried to and from the International Space Station (ISS).”

• ESA contribution to ISS per Columbus Module Barter Agreement. Contractor: Astrium/Germany

• Original QTY: 10 RFR’s – 3 per re-supply mission, entire racks exchanged by crew.

• Final Delivery: A single Qualification Model (QM) and no flight models.

• 4 volumes, each programmable to be refrigerator or freezer; thermo-electric.

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RFR System Overview

Drawer

Lower Cold Volumes (CV)

Vacuum Insulation Panel (VIP)

Upper Cold Volumes (CV) Electrical Subsystem (ESS)

Liquid Management System (LMS)

ThermoElectric Cooling

Units (CU)

ISPR (reinforced)

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RFR QM – laying on its back

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RFR QM with drawers in a cargo volume

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ISSPO Change Request – RFR Cancellation

• ISS CR 6451A, “Deletion of RFR Rack Structures Development and Support Activities”

• Submitted March ‘02. Approved July ‘02. • “Due to budgetary constraints, the Program

has decided to indefinitely postpone the introduction of refrigerated/frozen food on the International Space Station.”

• 2002 savings: $2.5M; overall savings $14M

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Reasons Why • ISS was accumulating experience that food system was

fine without an RFR. (“If RFR’s are required, why aren’t we having real bad problems right now?”)

• Rationale for having RFR was physical health enhancement, mental health support, and productivity increase. NO ONE would say RFR’s were REQUIRED to complete the ISS Construction or carry on additional increments (i.e., couldn’t name one mission that would have to be cancelled if RFR’s weren’t there)

• Main RFR champion was Psych Support. Medical, Crew, Food Office wanted RFR, too, but were unwilling to say they would refuse to support any particular mission if RFR was not present.

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More Reasons Why • Adding RFR to ISS program was an UNKNOWN RISK. Current

missions w/o RFR working fine, why add the risk? • ISS PO Question: “If RFR breaks down on Day 1, do I have to

cancel or cut short the mission?” – “Yes.”: RFR is now on very high risk list, 2nd only to loss of

crew/vehicle. Unacceptable situation. ISS PO will issue action to put solution in place.

– But the answer was “No, we have a solution in place.” The non-RFR supply would be large enough to cover the contingency.

– ISS PO Reply: “In that case, let’s just go with that non-RFR supply.”

• Many other areas would gain resources from RFR loss: Racks become available for payloads; crew time; training; power; up/down mass. Most important to ISSPO: Budget.

• Conclusion: RFR was NOT REQUIRED, added RISK, and required RESOURCES that ISS PO needed to re-allocate.

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Mars Direct Artificial Gravity System

• “In Mars Direct, the final stage of the rocket is attached to the crew module by a long tether. When the stage runs out of fuel, the tether is unwound, creating a two-body system with a center of mass somewhere along the tether. The system is then rotated around this center of mass, with the burnt-out rocket stage acting as the counter-balance to the crew module.” – http://chapters.marssociety.org/toronto/Education/MarsDirect.shtml

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http://www.nasa.gov/pdf/376589main_04%20-%20Mars%20Direct%20Power%20Point-7-30-09.pdf 15

Similarities in the Situations • ISS is accumulating experience that 6+ month missions

can be successful w/o AGS. (i.e., crew is impacted, but not extensively permanently)

• Rationale for AGS is physical health enhancement and productivity increase. NO ONE appears to be willing to say AGS is absolutely REQUIRED to complete a mission to Mars (i.e., a mission to Mars is a non-starter if AGS is not part of it)

• Main AGS proponent appears to be AGS Specialists. Teams that would benefit from AGS (Medical, Crew, Ops, Geo Science) appear to be unwilling to say they would veto any Mars mission scenario if AGS is not present.

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More Situational Similarities • Adding AGS to initial Mars missions presents

UNKNOWN RISK. All NASA mission experience w/o AGS works fine, and NASA has little experience in AGS at all, so why add the risk?

• Projected Mars PO Question: “If AG breaks down on Day 1, do I have to cancel or cut short the mission?” – “Yes.”: AG would now be on very high risk list, 2nd only to

loss of crew/vehicle. Unacceptable situation. PO would issue action to put solution in place.

– But the answer (see chart 15) is “No, mission continues if tether fails.”

– Which means the mission continues in microgravity – Which means….

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ALL SYSTEMS ON THE MARS HAB/TRANSIT VEHICLE WOULD BE REQUIRED TO FUNCTION/OPERATE IN

MICROGRAVITY AND PARTIAL GRAVITY.

• Adds increased complexity, cost, mass, development, and risk to almost ALL spacecraft and mission systems. – Example: ISS – very complex, expensive AS IS. Add

requirement to be operational in gravity field, too, and cost would have been prohibitive

– Example Systems unable to operate in Earth’s gravity: ISS and Shuttle Robotic Arms, ISS Thermal Systems, Toilets

• Projected ISS PO Reply: “In that case, let’s just go without that tether, and see how much easier and cheaper that makes everyone else’s systems.” 18

Budget Crisis Prediction

• Prediction: During a budget crisis, a Mars PO CR would be submitted to cut AG System – AGS support would not be strong enough to defend the

requirements against challenges – Other disciplines would report strong gains from

cancellation of AGS – Practically all spacecraft systems become cheaper to

develop – Mission and crew operations become similar to ISS

(simpler, tried-and-true) • Predicted Conclusion: AGS is NOT REQUIRED, adds

RISK, and requires RESOURCES that Mars PO would re-allocate to meet budget crisis.

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Conclusions & Recommendations • Eliminate AGS from Mars Direct initial mission

architecture – Mars Direct Plan is fundamentally strong; main components

required and defendable – AGS is not, so it negatively impacts the overall plan’s

credibility. • Move tethered AGS configuration to a subsequent Mars

exploration phase – 1st Apollo landing did not take a Lunar Rover – 1st Shuttle launched only 2 crew – 1st ISS crew did not have 6 people, and had only 2 modules – Mars Direct does not propose terraforming Mars with very

first missions

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Acknowledgements • Robert Zubrin and Richard Wagner • Larry Toups/NASA • Pasquale Di Palermo/ESA • Josef Winter & Astrium RFR Team • Mike Johansen/Jacobs • NASA JSC Technology Transfer Office • Jacobs Clear Lake Group • Skip Todd/Oceaneering • David Meadows/Oceaneering • Helen Neighbors/NASA • Samantha & Katie Shepherd

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Appx. - RFR General Description Key Requirements for RFR Design

Topic Requirement cargo volume cargo drawer stowage volume of 3 racks 65 ft³ cargo definition conditioned cargo max.: 295 kg (640 lbm) RFA weight (w/o rack and cargo) < 322 kg (710 lbm) internal temperatures Refrig.: + 0.5 °C to + 6.0 °C (+ 32.9 F to 42.8 F)

Freezer: < -22 °C (< -11.2 F) ambient temperatures on- orbit (operating/passive): 15 ... 30 °C (59 ... 86 F)

Ascent/descent: 4 ... 49°C (40 ... 120 F) allocated electr. Power 450 W (max.) max. heat dissipation 500 W from RFR sources thermal mass inputs door I/O for 60 sec up to 7 times per day and 120 sec 3 times per day.

freezing of 100 ml saline solution from ambient in 3 hrs 4 times/day cooling of 1 l water from ambient to 3°C in three hrs 3 times/day

passive periods time: 8 hours ambient temp.: increasing from 30 °C (86 F) to 49 °C (120 F) cargo temperature: < - 12 °C (10.4 F)

cooling principle thermoelectric coolers defrosting automatic lifetime 10 years operational / 15 years structural on orbit

1 year continuous on-orbit operation resupply/return cycles 25

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