Keeping fit in space a real workout for NASA human research teams
British astronaut Tim Peake will be joining the runners of the 2016 London Marathon from 250 miles (402 kilometers) above his fellow contestants on the International Space Station (ISS). Peake trained for the marathon for months on Earth as he also prepared for ISS Expeditions 46/47, and he has continued to train in space since his arrival at the ISS on Dec. 15 of last year.
Peake’s effort throws a spotlight on physical fitness in space and presents a perfect moment for a closer look at current space fitness equipment as well as other exercise devices under development for use aboard NASA’s Orion spacecraft and future deep space missions.
Space Marathon Essential — The Glenn Harness
Peake’s upcoming run on the space station’s T2 treadmill would not be possible without a special restraining device called the Glenn Harness, which holds the runner onto the treadmill. It is so-named because it was developed at NASA’s Glenn Research Center in Cleveland, Ohio.
“It’s based on a backpack-like design that we developed in collaboration with the Cleveland Clinic, Zin Technologies, and Terrazign, Inc., a ‘technical soft goods’ manufacturer in Portland, Oregon,” Project Manager Gail Perusek told Spaceflight Insider.
Perusek manages Advanced Exercise Concepts project within NASA’s Human Research Program.
“It has more aggressive padding than the previous versions,” Perusek said, “It’s more ergonomic and has a stiff outer shell to distribute the loads so the astronauts experience fewer hot spots and pressure points.”
The newer harness was transitioned into operation in 2011. Each crew member gets a harness made specifically for them. They come in small, medium, large, and extra large—like shirt sizes.
“We did an add-on study to the initial experiment to work the shoulder straps better for female crew members,” Perusek said. “Crew members get fitted up at the Johnson Space Center (JSC) training lab with a crew trainer unit there. They can get on the treadmill and see how it feels.”
A number of these harnesses were lost in the explosion of an Orbital ATK Antares rocket and the Orb-3 Cygnus spacecraft that it carried in October 2014 as well as the explosion of a SpaceX Falcon 9 rocket, which caused the loss of the CRS-7 Dragon in June 2015. Other harnesses were produced to replace those that were lost.
“One of the crew members recommended we incorporate a biocidal fabric, like the Under Armour athletic wear,” Perusek said. “So we incorporated a biocidal fabric on the inside surfaces of the harness because they never get washed. They wear them for the whole expedition. And the ones we’ve gotten back that have been worn have been fresh as a daisy. So it really works well.”
3-station Space Gym
In addition to running on the T2 treadmill with the aid of the Glenn Harness, ISS astronauts also workout on a mechanical bicycle called the Cycle Ergometer with Vibration Isolation System (CEVIS), and a machine that simulates the experience of weight-lifting, called the Advanced Resistive Exercise Device (ARED). Astronauts on the ISS typically workout on some combination of these three machines for about two hours a day, six days a week, in order to maintain their strength and limit the muscle atrophy and bone loss that occurs during long-duration missions on orbit.
Peake’s running of the London Marathon in orbit, however, will serve as a different test of both himself and the equipment. His run will take up to four hours or so to complete. In preparing for his marathon run, Peake has said that the Glenn Harness starts to become uncomfortable after about 45 minutes or so.
“The new harness is a great improvement over the previous model,” Perusek said, “but it is a very challenging loading condition because ideally the crew member would replace their full body weight through the harness. It clips into the treadmill via bungees at the hips. So for a 200-pound (90-kilogram) person, that’s 100 pounds (45 kilograms) at each hip. So imagine carrying a backpack with 200 pounds (90 kilograms) in it, and trying to run with that. Over time, it’s a tough go.”
The T2 treadmill and Glenn harness, the CEVIS bicycle, and the ARED weight-lifting machine require a lot of room on the ISS to operate. ARED in particular, with its bars and foot-pads and the vacuum air cylinders that provide the “weight-lifting” resistance for the astronauts, requires a major portion of the spatial volume in the station’s Node 3, Tranquility, for the astronauts to exercise with it. Having the luxury of that much roomy space will not be available to astronauts aboard the agency’s new Orion spacecraft or other future deep space vehicles.
Advanced Exercise Concepts
Perusek is in charge of Advanced Exercise Concepts for NASA’s Human Research Program. It is the goal of the program to develop lighter, smaller, and more versatile exercise devices for these spacecraft.
“Within the Human Research Program we are focused on the research and development, improving systems, optimizing for mass, and making steps to improve next generation equipment,” Perusek told SpaceFlight Insider. “We are benchmarking the functional capabilities of the current equipment, like ARED on ISS. Advanced Exercise Concepts, the project I manage, is taking designs through to what we’re going to need for exploration missions; for example, the Orion capsule. So we’re talking about extremely compact, lightweight, very reliable, very capable exercise countermeasure hardware.”
For the Orion spacecraft, the area that designers have allocated for an exercise device, which cannot weigh more than 23 pounds (10 kilograms), is a small area just below the inside of the spacecraft’s hatch. The area essentially is a “step” area where astronauts will place their foot to get in and out of the spacecraft.
“That small area where they step to do their ingress and egress, that is our allocation of volume for the exercise hardware,” Perusek said. “That’s about 21 inches by 13 by 7 inches deep, about the size of a large shoe box.”
Currently proposed mission plans for Orion would last between 10 to 21 days in duration—with long-term missions the spacecraft could be used on extending for far longer. The main concern for these crews is that they will still be fit and strong enough to egress the spacecraft safely. Orion will have a splashdown recovery. The goal of the onboard exercise device will be to preserve the crews’ ability to hoist themselves up and out of the spacecraft and into the water and into their life rafts in the event of an emergency. If there is an incapacitated crew member, the others must have the strength to assist them if needed. These possibilities have all been practiced at NASA’s Johnson Space Center (JSC) located in Houston, Texas.
“These are the human factors and mission tasks we have to test, and assess how difficult is this going to be,” Perusek said.
ISS missions are already long-duration, lasting six months and, on one occasion longer. A pair of ISS crew members recently completed a one-year mission on the orbiting lab. NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko successfully completed their 340-day stay on the station on March 2, 2016. With missions of this length, the concern is with bone loss, muscle atrophy, and cardiovascular issues.
“But for the 14-day Orion missions,” Perusek said, “the focus of our exercise here is preserving their functional performance for egress.”
A number of designs for the Orion exercise hardware are currently under development by teams at NASA Glenn, JSC, and related contractors with experience in the field.
The program recently completed a series of tests at JSC on four of the design concepts. One of them was a flywheel-type device that requires no power. The other three were servomotor based. Each concept centered around a T-bar interface that could provide a rowing motion, as well as other motions. They operate like a rower, but with a resistive capability to provide the crewmember with a wide range of exercise modes.
“The Human Research Program derives the exercise functional requirements from the body of research and operational evidence from the physiology community and the Astronaut Strength Conditioning and Rehabilitation (ASCR) specialists, and translate those into functional engineering requirements to build exercise hardware to meet,” Perusek explained. “For example, eccentric overloading on the return stroke so that the device does work on the muscles as they are lengthening will be more effective for muscle strength and maintaining muscle mass. So the exercise device needs to store energy, like a flywheel or through regenerative braking; for example, as opposed to operating passively like a bungee.”
The top concepts that the program is currently reviewing are servomotor-based concepts that are closed-loop controlled through a microprocessor or computer interface. The medical community likes the flexibility of a servomotor system, as it allows shaping of the load profile or the way the resistance or “weight” feels to the user. It can be programmed to feel like free weights in microgravity.
“These concepts were all run through a rigorous human-in-the-loop testing,” Perusek said. “Each device had 10 subjects exercise with it through a representative regimen of exercise on Orion. That testing was done last fall, and a selection was made of a system for further development in preparation for flight on the EM-2 mission in 2021.”
The agency chose to go forward with a concept called ROCKY, a workout-appropriate acronym which stands for Resistive Overload Combined with Kinetic Yo-Yo. It is a hybrid of two of the concepts from the recent four-concept technology down-select. Two of the teams, Zin Technologies and TDA Research of Wheat Ridge, Colorado, paired up and scored highest in the testing. ROCKY’s development will be geared toward inclusion aboard EM-2.
“We’re going to continue to keep the unpowered concepts in the hip pocket,” Perusek said.
These include the flywheel-based concept by Wyle Life Sciences in Houston, Texas, and a design concept from Ireland that was the winner of a competition through incentive and the Center of Excellence for Collaborative Innovation (COECI) at JSC. These concepts may be further developed for testing and possible inclusion aboard EM-3 or EM-4.
Another of the recently tested concepts is already in space, aboard ISS. The Miniature Exercise Device-2, or MED-2, was carried aboard ISS by the March 22 Cygnus re-supply vehicle launch. Med-2 was one of the servomotor concepts tested in the fall, but it followed a different developmental path to the ISS.
“It is going to the ISS as sort of a surrogate concept,” Perusek said. “Its focus was to vet the streamlined flight hardware development process that the ISS program is sponsoring, called the Class 1E. It’s being used to test out the archetype of a small device, servomotor operated, with a single cable exit to a T-bar, like a rower device. They’re looking at things like operational volume in the ISS, usability, and getting crew member feedback.”
“We’re trying to pull on everyone’s strengths,” Perusek said, “to provide the best technological solution for Orion.”
The Human Research Program and its Advanced Exercise Concepts development project must look further into the future—to Mars. One of the devices under development for human missions to Mars is HULK, the Hybrid Ultimate Lifting Kit.
“The HULK benchmarks the ARED on the ISS,” Perusek said. “ARED is a very capable machine. It can provide up to 600 pounds (270 kilograms) force on the crew members. They can do squat exercises and other exercises. The vibration isolation system isolates it from the node where it’s mounted. It weighs over 1,200 pounds (544 kilograms) on Earth. But it is about the size of a small car. The idea is to be more resource efficient. We’re not going to be able to take something of this size to Mars.”
The HULK device, in contrast, is about a tenth of the mass and a tenth of the volume as ARED, and it can actually do a greater variety of exercise motions than ARED. HULK preserves the 600 pounds (270 kilograms) force capacity. However, it can also be converted to a rower. It has the eccentric overload that the medical community likes to see. The HULK is a hybrid because it has a passive air cylinder, but it is coupled with a servomotor that kicks in the resistance on the return stroke, giving it that eccentric load. So HULK uses power from the spacecraft, but a lot less power than if it were completely servomotor based.
Perusek’s team has tested HULK on parabolic flights and did a motion-capture video for an operational volume assessment and computer modeling. These observations helped them determine what volume requirement they would need to perform certain exercises with this or similar devices in microgravity.
The motion capture videos help them quantify those volume measurements and couple them with the volume available in the spacecraft or vessel in which it will be used. HULK facilitates more than a dozen different exercise motions, the most important being squats, dead lifts, and heel raises. Those are the crucial exercises that maintain the leg muscles and preserve postural muscles.
HULK and other devices under development are designed to preserve the 600-pound (270-kilogram) resistive force level, to help maintain bone strength and muscle mass over long-duration flights. However, as the program develops the hardware, they are still learning how to optimize the equipment for how the human body performs in space.
“We’ve got a whole group looking at the biomechanics, how the body is moving, and the different forces on the body, and how that compares across different devices,” Perusek said. “We have some very sophisticated equipment. We’ve placed cameras that emit an infrared light around a subject, and the subject’s body wears reflective markers so their movement is digitized into our computer models. And then we can run computer simulations through a program that give us measures of muscle forces and bone forces so that we can understand what’s going on inside the human body computationally, and [then] make inferences on whether this design is better than that design.”
With this modeling, they can far more easily and quickly test potential design options than if they were continually cutting metal and building and fabricating new additions or improvements to different devices in order to test them.
“So we’re building a capability to really optimize these systems for maximum physiological benefit,” Perusek said. “It’s all about balancing the requirements for what we need on the medical side and what we need on the vehicle side.”
Video courtesy of NASA Johnson
Michael Cole is a life-long space flight enthusiast and author of some 36 educational books on space flight and astronomy for Enslow Publishers. He lives in Findlay, Ohio, not far from Neil Armstrong’s birthplace of Wapakoneta. His interest in space, and his background in journalism and public relations suit him for his focus on research and development activities at NASA Glenn Research Center, and its Plum Brook Station testing facility, both in northeastern Ohio. Cole reached out to SpaceFlight Insider and asked to join SFI as the first member of the organization’s “Team Glenn.”