Svetoblok M: the left unit was ground control, the right unit was in orbit.

Svetoblok was the first airtight, sterile growth chamber for spaceflight, and its experiments helped us understand that plants can develop flowers in space. This chamber was compact, with a small removable cylinder that could be returned to Earth independently from the chamber. To return the plants to Earth, cosmonauts simply held the removable cylinder in their laps on the trip down! Svetoblok was first flown in 1982, and was used on both the Salyut and the Mir space stations.

Svetoblok’s sterile environment was believed to be a big reason for its success. In 1982 cosmonauts successfully grew the first flowers in space from Arabidopsis, a tiny mustard species used commonly in research. Although these flowers bloomed and began to develop fruit the male and female organs degenerated, so no viable seeds were produced. These plants developed abundant branches, though the leaves were smaller than ground controls and the “leaf and shoot tissues had a finer structure and looked like aquatic plant shoots”. Although all of the buds, flowers, and fruits were sterile, some plants were returned to Earth and did eventually produce mature seeds. Other Svetoblok experiments were conducted with Arabidopsis and wheat, with similar results: flowers without viable seeds. Scientists concluded that low light and lack of gas flow were probably responsible for the plants’ inability to reproduce.

The success of flowering in Svetoblok demonstrated that the seed-to-seed life cycle should be possible in microgravity, given the right environmental conditions. Svetoblok was one of the key growth chambers that laid the groundwork for plant reproduction in space.

Chamber Components:

Hardware on the Svetoblok