Crew-4 is the fourth rotational mission with SpaceX, launching four crew members, in the fourth month of the year, on a fourth flight booster – a first for Commercial Crew and a huge accomplishment for the team and industry.

While on their six-month tour of duty three NASA astronauts – Kjell Lindgren, Robert Hines, and Jessica Watkins – and ESA (European Space Agency) astronaut Samantha Cristoforetti will be conducting several science experiments, including the XROOTS study. The XROOTS plant growth system that was launched to ISS in February uses hydroponic (liquid-based) and aeroponic (air-based) techniques to grow plants without soil or other traditional growth media. Current space-based plant systems are small and use particulate media-based systems to deliver water and nutrients. These do not scale up well in space due to mass, containment, maintenance, and sanitation issues. 

Investigators plan to use video and still images to evaluate plant growth through the entire life cycle. Hydroponic and aeroponic techniques could enable production of crops on a larger scale for future space exploration. The system components developed for this investigation also could enhance cultivation of plants in terrestrial settings such as greenhouses, contributing to better food security for people on Earth.

On his previous mission, Lindgren worked on Veg-01, a system that cultivated plants using pillows, small expandable units containing growth medium and seeds. That experiment produced red romaine lettuce, and Lindgren became one of the first people to taste a plant grown in space.

Crew-4 members are not expected to eat the XROOTS plants, which will be sent back to Earth for analysis.

Image: XROOTS hardware undergoing ground-based plant tests. Credit: Sierra Space.

Dr. Anand Ramasubramanian of San Jose State University has successfully tested a tissue-on-a-chip platform that uses blood from healthy human subjects to examine the movement of red blood cells in a model of a venous valve.

This microfluidic model aims to measure the unique geometry of blood flow patterns and RBC distribution in and around venous valves. It is thought that the lateral movement of red blood cells (RBCs) is responsible for the formation and progression of blood clots, or thromboses, in venous valves, aortic aneurysms, and blood-circulating devices.

This study shows that increased feed rates contribute to an uneven distribution of RBCs and the entrapment of RBCs in the vortices.  Findings from this study provide insight into the complex interactions between fluid flow, RBC distribution, and wall shear rates in a model of blood veins, which may shed light on the pathophysiology of thrombosis and improve cell separation efficiency.
 
A high priority for NASA is to use a systems biology approach to understand the underlying mechanisms of microgravity effects on cardiovascular physiology. Recent findings raise the question of risk of thrombosis as a health concern in astronauts. Studies such as this one using ground-based analogs will generate testable hypotheses and new, high-value tools that can be translated to full-scale spaceflight investigations on the risk of thrombosis.

Image: Still image from a experimental video showing Red Blood Cell (RBC) entrapment in a microfluidics model of venous blood flow through a simulated valve. Click to play video.

This research was funded by Space Biology grant 80NSSC21K0272 to Dr. Anand Ramasubramanian at San Jose State University. This work is part of his research understanding the effects of microgravity on the risk of thrombosis. The article is available online here.