The three-person Expedition 40 crew spent its first full workday Thursday aboard the International Space Station working with a trio of botanical experiments and preparing for Sunday's departure of the SpaceX Dragon cargo craft.

Following the crew's daily planning conference with the flight control teams around the world, Commander Steve Swanson set up a test sample for the Japan Aerospace Exploration Agency's Resist Tubule experiment, which takes a look at the mechanisms for gravity resistance in plants.

Results from this study will help researchers learn more about the evolution of plants and enable efficient plant production both on Earth and in space. During a long-duration mission beyond low-Earth orbit, plants can provide future astronauts with regenerative sources of food and supplemental methods of converting carbon dioxide into oxygen.

Afterward, Swanson teamed up with Flight Engineer Oleg Artemyev to transfer research samples from some of the freezers aboard the station into the GLACIER freezer that will be returning to Earth aboard the SpaceX Dragon cargo craft.

On Sunday, Dragon is set to be detached from the Earth-facing side of the station's Harmony module and unberthed through commands sent by robotic ground controllers at mission control in Houston operating the Canadarm 2 robotic arm.

Dragon then will be maneuvered into place for its release, which is scheduled for 9:26 a.m. EDT. Dragon, which delivered about 2.5 tons of science and supplies to the station for the SpaceX-3 commercial resupply services mission when it arrived at the complex April 20, will be carrying 3,500 pounds of NASA science samples and cargo when it splashes down for recovery off the coast of California at 3:02 p.m. (12:02 p.m. PDT).

Swanson later thinned out "Outredgeous" red romaine lettuce seedlings growing in the Veggie plant facility to give the remaining plants more room to grow. Veggie is a low-cost plant growth chamber that uses a flat-panel light bank that includes red, blue and green LEDs for plant growth and crew observation. For the Veg-01 experiment, researchers are testing and validating the Veggie hardware, and the plants will be harvested and returned to Earth to determine food safety.

The commander then transferred the Micro-7 BioCell habitat to the Commercial Generic Bioprocessing Apparatus. Micro-7 takes a look at how microgravity affects the genetic expression and physical shape of non-dividing cells, which are the majority of cells that make up the human body.

After checking out a crew command control panel for Sunday's Dragon activities, Swanson fielded questions from Denver television station KMGH-TV for an in-flight interview in the station's Destiny laboratory. Swanson, who hails from Steamboat Springs, Colorado, discussed life aboard the station and his attempts to spot his hometown from space.

Swanson rounded out his day by removing the Biotube-MICRO payload from one of the station's EXPRESS racks for return aboard Dragon. This experiment investigates the potential for magnetic fields to orient plant roots as they grow in microgravity. Plants are not directly sensitive to magnetic fields, but starch grains, called amyloplasts, in plant cells respond to external magnetic fields. Results from Biotube-MICRO may lead to using high-strength magnetic fields in space as a substitute for gravitational cues for growing plants during long-duration missions.

On the Russian side of the complex, Artemyev conducted the Uragan Earth-observation experiment, which seeks to document and predict the development of natural and man-made disasters on Earth. He also participated in the Interactions experiment, which studies the impacts of personal, cultural and national differences among crew members.

Flight Engineer Alexander Skvortsov focused much of his attention on routing and connecting cables for the European Space Agency's Automated Transfer Vehicle (ATV) control panel and proximity communication equipment inside the Zvezda service module. The fifth and final ATV cargo ship, dubbed "Georges Lemaitre," is targeted to launch to the station this summer.

Meanwhile, the three flight engineers who will return the station to its full six-person crew complement are now in the homestretch leading up to their May 28 launch to the station. Reid Wiseman of NASA, Max Suraev of Roscosmos and Alexander Gerst of the European Space Agency wrapped up pre-flight activities Thursday in Star City, Russia, and flew to the Baikonur Cosmodrome in Kazakhstan where their Soyuz TMA-13M spacecraft is being prepared for launch.

Swanson, Skvortsov and Artemyev have been operating the station as a three-person crew since the departure of their Expedition 39 crewmates - Commander Koichi Wakata and Flight Engineers Rick Mastracchio and Mikhail Tyurin - on Tuesday.