Continuing my research into which of NASA’s African American astronauts are space gardeners, I turned my attention to the second name on the (alphabetical) list: Guion Stewart Bluford Jr.

Guion (Guy) Bluford joined the astronaut class of 1978. He became the first African American in space when he launched on STS-8 in 1973. He flew on three more shuttle missions – STS-61-A, STS-39 and STS-53.

According to New Scientist, nearly every space shuttle flight through the 1980s and 1990s carried experimental plant payloads. However, as far as I can determine, three of Bluford’s four flights did not. Indeed, the primary experiments on STS-39 and STS-53 were conducted for the Department of Defense, and so are classified. It seems unlikely they involved plants.

STS 61-A Launch

However, STS-61-A was different. Space Shuttle Challenger launched on 30 October 1985 with ESA’s Spacelab, a laboratory module designed to be carried in the shuttle’s payload bay. The Spacelab D1 mission was the first with German mission management and to be controlled from the German Space Operations Centre.

STS-61-A holds the record for the largest crew to be onboard a shuttle for the entire mission – there were eight people on board. They split into two teams, each working a 12-hour shift to ensure 24-hour operations. Bluford joined NASA’s Jim Buchli and ESA’s Ernst Messerschmid on the Red team. 

Cut-out view of Spacelab in orbit. ESA developed Spacelab as a manned scientific laboratory to fly in the Space Shuttle’s cargo bay. Image credit: NASA

According to NASA’s mission press kit, there were four plant experiments onboard, all investigating how plants respond to gravity:

  • Gravi-Perception (Principal Investigator (PI): D. Volkmann, Univ. Bonn, W. Germany)
  • Geotropism (PI: J. Gross, Univ. Tubingen, W. Germany)
  • Differentiation of Plant Cells (PI: R.R. Theimer, Univ. Munich, W. Germany)
  • Statocyte Polarity and Geotropic Response (G. Perbal, Univ. Paris, France)

Spacelab’s Biorack included a centrifuge to recreate the gravitational force that plants would feel on Earth (1g), thereby allowing scientists to distinguish between the effects of microgravity and other spaceflight conditions.

ESA’s Wubbo Ockels, Payload Specialist on STS-61A, and NASA Mission Specialist Guion Bluford (right) during the Spacelab D1 mission.. Image credit: NASA/ESA/DLR.

In August 1999, NASA published a report on the microgravity experiments conducted in Spacelab. It mentions two of the plant experiments.

Perbal’s experiment showed no significant difference in the length of lentil roots grown in microgravity or 1g. While the roots grown in 1g grew “downwards”, the roots grown in microgravity grew any which way. If they were then placed into the centrifuge, they were capable of responding to the simulated gravity.

The report also mentions Volkmann’s experiment using cress roots (Lepidium sativum). It confirmed that the germination rate for cress seeds was the same in microgravity and 1g. In microgravity, the roots grew at angles of up to 60 degrees, while on Earth they mostly grew straight downwards. 

Both experiments told us more about the effects of microgravity on statoliths. Statoliths are small starch-filled packets that settle at the bottom of gravity-sensing cells. We know that plants can detect gravity using statoliths, but we also know it’s not the only way they do so, and research is ongoing. In 2017, for example, the Plant Gravity Perception experiment launched to the ISS. It used Arabidopsis mutants engineered to lack functional statoliths, so their response to gravity could be investigated.

I can’t find any images or video of Bluford with the plant experiments specifically. However, there are images of him participating in other Spacelab experiments, so I am happy to confer upon him the title of Space Gardener!

STS-61 Payload Specialist Ernst Messerschmid undergoes medical checks by NASA Mission Specialist Guy Bluford during the Spacelab D1 mission, 1985 [Image credit: NASA]

In October 2010, Ernst Messerschmid returned to Spacelab to record a video for the German Aerospace Center, which shows you exactly what the module looked like, and includes footage from the Spacelab D1 mission.



Spacelab Science Results Study
Final Report Volume III, Microgravity Science
August 1999, NASA

Header image: Official portrait of astronaut Guion S. Bluford in his launch and entry suit (LES) holding a launch and entry helmet. Dated 23 October 1992. Image credit: NASA.

Further reading

Perbal, Gérald, et al. “Graviperception of lentil seedling roots grown in space (Spacelab Dl Mission).” Physiologia plantarum 70.2 (1987): 119-126.

Volkmann, D., H. M. Behrens, and A. Sievers. “Development and gravity sensing of cress roots under microgravity.” Naturwissenschaften 73.7 (1986): 438-441