Language selection


Top of page

MARROW: Keeping bones healthy in space

Health science

The Canadian experiment MARROW studies how bone marrow (the spongy tissue inside bones) and the blood cells it produces change in space.


During a space mission, the hard bones lose calcium and strength, but what happens to the bone marrow has never been measured. Experiments on Earth suggest fat cells in bone marrow may increase, leaving less room for the production of red and white blood cells.

A decrease in red blood cells can produce anemia, whose symptoms include physical limitations such as weakness, persistent fatigue, and slower brain function. With fewer white blood cells, the body becomes more vulnerable to infections and more sensitive to radiation exposure.

Studying the effects of ageing and immobility in space with Tim Peake

ESA astronaut Tim Peake is taking part in the Canadian experiment MARROW that will study these effects to benefit astronauts and people on Earth who are bedridden or who have reduced mobility. (Credits: Canadian Space Agency, NASA, University of Ottawa)



MARROW aims to:

 Impacts on Earth

MARROW's findings will help ease the effects of physical inactivity on seniors, bedridden patients, and those with reduced mobility or undergoing rehabilitative treatment.

In fact, Principal Investigator Dr. Guy Trudel hopes to apply the knowledge gained in space to his work at The Ottawa Hospital, where he directs the rehabilitation of patients who have been bedridden for long periods of time, like father and entrepreneur Raymond Nicholas.

How it works

Thirteen astronauts are participating in this study.

  1. Before the astronauts leave Earth, researchers use magnetic resonance imaging (MRI) to establish the fat content in their bone marrow.
  2. The participants also give blood and breath samples before their flights to assess red and white blood cell function.
  3. On the International Space Station (ISS), astronauts repeat the same blood and breath samples.
  4. For up to a year after return, they undergo serial MRI scans. Comparing these images allows scientists to chart their recovery and track how much fat tissue has accumulated in the confined space inside the bones.
  5. A final set of blood and breath samples are tested and compared.
David Saint-Jacques collecting blood samples for Canadian study MARROW

David Saint-Jacques collecting blood samples for Canadian study MARROW. (Credit: NASA)


MARROW began collecting data in and is scheduled to complete its final tests in June 2020.

Research team

Principal investigator

Co-investigators and employees

Explore further

Date modified: