Particle physics experiments

University of Michigan experiments en route to the International Space Station

ANN ARBOR – Research from the University of Michigan soared into space early this morning and is heading to the International Space Station.

A pair of experiments designed to study the impact of gravity on bone density left Earth aboard a Northrop Grumman Corp rocket. Antares from the Wallops Island, Virginia launch pad.

The mechanical engineers designed the experiments, which aim to understand the differences in bone density loss on Earth and in space.

The National Science Foundation funded the study, which is also sponsored by the ISS National Laboratory, in partnership with Space Tango.

UM Associate Professor of Mechanical Engineering Allen Liu and members of his research team shared how their work can help better understand osteoporosis and how astronauts can be safer during Q&A following published by the university:

What is the connection between bone density, osteoporosis and gravity that makes this space research relevant to everyday people?

Allen Liu: Osteoporosis weakens and brittle bones as individuals age, causing fractures even with mild strains and falls. There are an estimated 10 million cases in the United States and an additional 43 million with signs of low bone density.

A weightless environment, or microgravity, can cause physiological changes in bones and presents a unique research environment without the typical mechanical stresses of gravity. It also rapidly changes the way cells grow and function without the use of drugs or genetic engineering.

A cell’s stiffness can tell us its biological age, predict how it may decline in function, or its susceptibility to chronic disease over time. We’re testing the hypothesis that when cells don’t repel gravity, this reduction in stiffness makes them susceptible to the same kind of changes we see in osteoporosis. But we also think we can prevent these health effects by mechanically compressing cells in a way that mimics gravity.

How are you going to look at the rigidity of cells in space? What can this tell you about astronauts?

Nadab Wubshet, PhD student in mechanical engineering: We hypothesize that the absence of gravity can induce cell softening, which could be the cause of the bone loss observed in astronauts after long stays on the ISS. Astronauts do resistance exercises on board to create the compression effect that is absent without gravity.

To test cell stiffness on the ISS, we use an automated microfluidic device that uses fluids to trap individual cells and slowly increase pressure on each cell to induce strain. Fluorescent markers allow you to see its shape at each level of pressure. Our device is also integrated into a system that takes snapshots and videos that allow us to collect data to measure cell stiffness.

How could this benefit human health?

Wubshet: If our hypothesis proves correct, our results will provide excellent insight into how changes in physical forces like gravity affect the mechanical characteristics of bone cells and bone formation. A better understanding of the impact of native forces such as gravity on bone formation could provide insights into better diagnoses and treatments for people struggling with bone decay.

But applications in space are also important, especially given the growing interest in space exploration that could have astronauts in microgravity for longer periods of time. We hope to develop solutions to maintain the bone density of these astronauts.

In the second experiment, you try to reduce the deterioration of bone cells. What do you hope to learn?

Grace Cai, PhD student in applied physics: The cells we call “bone cells” are osteoblasts, which deposit minerals and proteins to build bone when and where it’s needed most. In our study, we investigate how microgravity affects osteoblast activity.

Cells in microgravity experience low cell tension, and we can increase cell tension by applying mechanical compression. By placing spherical clusters of human osteoblast cells in weightlessness and applying compression, we can test whether this promotes the development and maintenance of bone cells, while preventing bone loss.

How will the samples be returned to Earth and how do you see their analysis benefiting future astronauts?

Cai: While the first experiment will be processed at the ISS, samples from this second experiment will be returned to Earth by SpaceX CRS-26 in January for analysis. Our findings here should shed light on whether spacesuits and compression garments could prevent bone loss and improve bone health in astronauts exposed to microgravity conditions. These types of technologies could help protect crews traveling to and from the ISS, as well as to other destinations.

In addition to informing osteoporosis research on Earth, we anticipate that our findings will likely be relevant to other age-related diseases and cancers. Cell mechanics and the architectures that cells build, which are of fundamental importance to our own study, are also important in these areas.

What are the most interesting things you have learned as a mechanical engineer planning experiments for space?

Liu: One of the challenges of working in a microgravity environment is that everything is weightless, so handling fluids becomes extremely difficult. Everything must be closed and our cells must be kept in a bag rather than on a Petri dish. And because space is limited on the ISS, each experiment is packaged in a small CubeLab container, approximately 6.3″ high, 8.2″ long, and 12.3″ wide.

As a researcher, I think we are used to uncertainties, but this is very different. A lot can go wrong with an experiment on Earth, and it’s even harder to pull off the experiment in space. We hope the experiments go smoothly, and I’m just glad we made the flight!

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