Some of the research on the International Space Station focuses on meeting the needs of long-term spaceflight to destinations such as asteroids or Mars. A group of engineers at NASA's Kennedy Space Center in Florida is developing a plant habitat with a large growth chamber to learn the effects of long-duration microgravity exposure to plants in space.

Through most of Kennedy's history, the space center has focused on receiving, processing and launching vehicles developed at other centers. Design projects such as the plant habitat give people at the Florida spaceport an opportunity to further use their extensive knowledge base in preparing flight hardware.

"This is the first Kennedy-led space station payload of this magnitude," said Bryan Onate, Plant Habitat Project manager in the ISS Ground Processing and Research Directorate. "We're using in-house expertise to develop the plant habitat to go on an EXPRESS rack in the station's Destiny laboratory. It will provide a large, enclosed, environmentally-controlled chamber designed to support commercial and fundamental plant research onboard the space station."

The plant habitat is configured as a payload that will be mounted on a standard Expedite the Processing of Experiments to Space Station, or EXPRESS, rack. The multipurpose payload rack system stores and supports research and science experiments across many disciplines by providing structural interfaces, power, data, cooling, water and other needs to operate science payloads in orbit.

The compact facility is about 21 inches high, 36 inches wide and 24 inches deep and would use about 735 watts of power.

"NASA is conducting plant research aboard the space station because during future long-duration missions, life in space may depend on it," Onate said.

As NASA plans missions beyond low-Earth orbit, relying on plant growth aboard a spacecraft will play an important role.

"The ability of plants to provide high quality science within a tightly closed system, a source of food and recycle carbon dioxide into breathable oxygen may prove crucial for astronauts and add to the body of knowledge as they live in space for months at a time," he said.

Onate explained that most of the experiments conducted on the space station are developed by principal investigators from universities or other research institutions.

"The plant habitat is an effort to attract a broader audience of principle investigators that need a large growth area for a long duration," he said. "In order to expedite this capability on the space station, we have contracted with Orbital Technologies Corp. to help us design, fabricate and certify the plant habitat for flight."

Based in Madison, Wis., Orbital Technologies Corp., better known as ORBITEC, is a leading subsystems integrator and high-technology development company.

The plant habitat's design includes the ability to control temperature, humidity, carbon dioxide levels and lighting.

"Lighting is an important part of plant growth," Onate said. "We're using LEDs in this payload. Our experience shows that the LEDs work well in plant growth experiments in our labs here at Kennedy."

Within the plant habitat there is a tray called a science carrier that will hold various types of plants. The science carrier is a removable and reconfigurable tray that will provide the primary structural support and final water delivery to the root-zone for in-orbit plant growth experimentation.

The science carrier consists of a structural element, a water delivery mechanism, and a standard interface plate that will provide instrumentation support as part of the basic plant habitat capabilities. The carrier also will provide additional instrumentation interfaces for other experiment-specific measurement data required to allow investigators to extend the habitat's basic capabilities.

"Our design will allow principal investigators to modify the carriers depending on the type of plants they want to grow and the kind of experiments they have in mind," Onate said.

Plant habitat investigations can use the microgravity of space and can run 30, 60 or 90 days depending on the nature of the research.

"These trays will have a system of tubes allowing astronauts conducting the experiment to inject water and other plant nutrients into the media supporting plant growth," Onate said.

One of the next steps for the plant habitat is a preliminary design review in February. During the review, engineers will report on how the project is progressing to ensure the design meets system requirements within acceptable risk and falls within schedule and budget constraints.

"One of the design challenges we're dealing with now is the physical size and power requirements for the plant habitat," Onate said. "Weight, volume and maximizing valuable space station resources are always an important consideration for any payload designed for spaceflight."

"Launch of the Kennedy-designed plant habitat will likely go up on a SpaceX Dragon spacecraft," Onate said. "It is targeted for launch in December 2015."