An experimental cell to grow reciprocal space on protein while en route

An experimental cell to grow reciprocal space on protein while en route

Over the course of the 2018-2019 academic year, our idea of studying protein aboard a sounding rocket went from conception to competition at the annual Spaceport America Cup. Among more than 100 collegiate rocketry teams our concept won a second place in the payload category. This was only one of the project's many successes. Our work required concentrated efforts across disciplines, including undergraduate students in biology, electrical and mechanical engineering, and senior scientists in structural biology. Housing a biophysical experiment typically conducted in a lab environment the very nature of sounding rocket launches presented additional logistical challenges for our design. Protein crystals are produced passively in an incubator at tightly controlled conditions over a period of days or months - not in sixty seconds aboard a sounding rocket!

The Stanford Student Space Initiative (SSI) is Stanford’s largest project-based student group, with over 300 active members, split into six project teams: Rockets, Balloons, Satellites, Biology, Operations, and Policy. The SSI Rockets team strives to build expertise in all areas of rocketry, and competes each June in the Spaceport America Cup, held in the New Mexico desert. Teams in the intercollegiate rocketry competition launch rockets with a 4 kg payload and target altitudes of either 10,000 or 30,000 ft. Embedded in the competition is the Space Dynamics Laboratory payload challenge, which encourages participants to create rocket payloads that accomplish relevant technical functions and provide useful learning opportunities.

For the 2019 competition, the SSI Biology team suggested research on the effects of microgravity environments on protein as a potential payload objective. Our team contacted Dr. Daniel Fernandez of Stanford ChEM-H Macromolecular Structure Knowledge Center (MSKC) for a research partnership on this project. MSKC serves the Stanford research community in the study of biomolecular structure and function using the imaging facilities at nearby Stanford Synchrotron Radiation Ligthsource (SSRL) at SLAC National Accelerator Laboratory. Dr. Silvia Russi (SSRL/SLAC) completed the team.

Importantly our design had to adjust to the time and volume constraints of the SDL payload challenge and fit to a limited budget. In the lab, we sought to answer some key design questions:

  1. what protein sample would produce crystals within one minute?
  2. what container would be required to obtain and safely retrieve the crystals?, and
  3. what observations could be made on the sample on-flight?

First, with simple dialysis diffusion using inexpensive acrylic boxes and a semipermeable membrane we were able to let the protein solution progress to reach supersaturation and crystal growth within seconds.

Experimental cell
Microcrystals grown on semipermeable membrane.

Then, using student-made microfluidic syringe pumps, insulation and long-lasting cooling system, a photodiode UV spectrophotometer, and a passive gimbal stabilization system to maintain a constant gravity vector acting on the protein sample we were able to develop the experimental cell.

On rocket launch, protein and precipitant were loaded into the experimental cell and assembled into the CubeSat; afterwards, our experimental data - measurements and crystals - were brought back to the lab for analysis. The resulting protein structural changes and implications for space research are presented in full in the article:

This post was a collaboration between Autumn Luna and Daniel Fernandez.