Space Systems
for Benefits
on Earth

OSTP Sustainability of Microgravity R&D Request for Information Response Summary

Question 1:

“What should be the United States' vision for the future of microgravity research?”

Short answer to question 1:

We believe the United States’ vision for the future of microgravity research should be to maintain the continuity of current research in low Earth orbit (LEO) while expanding research, exploration and commercial development utilizing all LEO and cislunar space resources for the betterment and expanded opportunities for all on Earth.

Detailed answer to question 1:

In order to meet this vision, future research platforms, need to be expanded to include longer duration experiments with pristine microgravity not interrupted or jolted by visiting spacecraft docking or system vibration and noise. Samples from the microgravity experiments need to be evaluated near real time and not have to wait weeks or months for down mass transportation to a terrestrial laboratory. Living arrangements need to accommodate expert researchers and technicians and must provide for their health and comfort for both short and long durations. On demand communication to experts and loved ones on Earth must be available for crew wellbeing but also to transfer work to Earth facilities. Sustainable logistics from and back to Earth and eventually from cislunar resources need to be reliable and affordable. Human-machine interfaces need to be built in to transfer work from expert researchers to automated production with mostly maintenance and upgrade technicians on board when required.

Question 2:

“What should be the long-term microgravity research goals for U.S. presence in LEO?”

Short answer to question 2:

Certainly, LEO microgravity research will be required for the foreseeable future due to the close proximity, lower transportation costs and manageable radiation hazards inside the Van Allen belts. Our long-term goals in LEO should be the preparation and support for the broader cislunar research, exploration and commercial development vision discussed previously. In addition, the U.S. should support the rule of law, traffic control, debris mitigation, communication, transportation, power and logistics for LEO commercial development

Microgravity and Artificial Gravity Human Health and Wellbeing:

A critical goal that can and should be accomplished in LEO is a clear understanding of human health and wellbeing in microgravity and partial to full Earth artificial gravity We have good data from the MIR space station and especially from the ISS on the effects of microgravity but almost no knowledge of the effects of partial gravity or the human tolerance for gravity gradients and rotation rates in spinning artificial gravity platforms. This knowledge is required for the design of future cislunar platforms, lunar bases, Mars missions, etc. The current estimate for the maximum rotation rate humans can tolerate due to the Coriolis effect and gravity gradient is 4 revolutions per minute (rpm). To achieve full Earth gravity at 4-rpm requires a spin radius of 55-meters. Of course, the 4-rpm limit is an estimate and could vary widely for a diverse human population and crews may be able to be conditioned for higher spin rates. The gravity gradient for a six-foot-tall standing person rotating at 4-rpm in a 55-meter spin radius platform is 9.81 to 9.48-m/s2 or a 3.3% change. We need to understand these effects much better and can do it in an experimental spinning space station before committing to the design of large LEO, cislunar or exploration systems. A full circular hoop configuration makes sense for the future, especially if it is made in space using lunar and perhaps near-Earth asteroid materials, but the gravity level, spin rate and spin diameter effects need to be well understood before proceeding with such a huge investment. Pristine microgravity compartments with low impact docking ports and low vibration systems are required for microgravity research and made in microgravity production. Artificial gravity habitats provide crew health and comfort as well as workstations to manage the microgravity activities, control experiments and analytical laboratory instruments that cannot function in microgravity. This allows researchers to tend their microgravity experiments and retrieve samples for immediate comparison to artificial gravity control samples using standard terrestrial laboratory instruments such as gene sequencers, mass spectrometers, etc.

Made in Microgravity Human Organ Tissues

LEO is perhaps the best location for research, development and then production of human organ tissues for eventual use in human transplants. Early experiments indicate that growing human organ tissues in microgravity enables the growth of isotropic three-dimensional (3D) tissue structure that lay flat when attempted in Earth gravity. This improves diffusion, fluid flow and growth rate. The microgravity organoid function continues to improve over time possibly due to better fluid flow through the more 3D structure. Tissues can be grown from disassociated organ tissues or human skin derived stem cells. Since the cells have the genetic instructions in their DNA, it is possible that the microgravity grown isotropic tissues will differentiate and form a vascular system and sinew sufficient for transplant. Liver, retinas and other organs have potential and could make significant impact on human health on Earth as transplant tissues or treatments. Liver tissues are particularly interesting due to the dire need and the natural ability of livers to regenerate to full size with only a one third adult liver mass transplant tissue. LEO is a great location due to the lower up and down mass transportation costs, low latency for automated system telemetry and manageable space radiation due to the Van Allen belts. With some Government stimulus, made in LEO human organ tissues could transition nicely to commercial operations.

Question 3:

“What are the top critical research, development, or operational needs required to ensure a smooth transition between the International Space Station and future commercial LEO microgravity platforms and realize the ideal future of microgravity research?”

Answer to question 3:

Time is running out to develop and deploy the next LEO research platforms before the ISS is retired. Perhaps a number of simple, optionally inhabited platforms make sense. The B-21 bomber is being designed to be optionally piloted and serves as a model for an optionally inhabited LEO research platform. A gap in LEO R&D waiting for an exquisite new platform would be terrible. Do not let perfect be the enemy of on time and good enough.

Question 4”

“What would be the most effective role of the U.S. government to ensure sustained LEO microgravity R&D following the retirement of the ISS?”

Short answer to question 4:

The U.S. government most effective roles to ensure sustained LEO microgravity R&D are:

• Enforce the rule of law with international partners

• Manage orbital traffic control

• Establish and enforce debris mitigation treaties and methods

• Manage and ensure available and open communication

• Establish and enforce cyber security treaties and methods

• Improve safety and reliability through expert objective accident prevention and investigations

In addition, the US government should promote commercial research and made in LEO economy via:

• Promote affordable space transportation as an anchor customer

• Promote electric and thermal power and other logistics as an initial provider and later as an anchor customer

• Stimulate promising LEO commercial research and development through seedlings and other grants and by providing an anchor customer

Question 5:

“Should the U.S. government continue to sponsor a national lab in LEO after ISS transition? If so, what would be the best model(s) for a LEO national lab?”

Answer to question 5:

Possibly. A cislunar national lab and lunar national labs makes sense. LEO R&D can likely be transferred to commercial outfits. A possible exception is the Microgravity with artificial gravity research platform.