After Tani received his bachelor's degree from MIT, he worked at Hughes Aircraft Corporation in El Segundo, California as a design engineer in the Space and Communications group.

[1] In 1986, he returned to MIT and received his master's degree in mechanical engineering in 1988, specializing in human factors and group decision making.

In May 2002, Tani served as an aquanaut on the NEEMO 2 (NASA Extreme Environment Mission Operations) crew aboard the Aquarius underwater laboratory.

Originally scheduled to return to Earth with the crew of STS-122 in December, the mission was delayed due to engine cutoff sensor issues during countdown.

Tani left NASA in August 2012 to become the Vice President of Mission and Cargo Operations in the Advanced Programs Group of Orbital Sciences Corporation in Dulles, Virginia.

[9] Member, Japanese American Citizens League, Alpha Delta Phi fraternity, and Aircraft Owners and Pilots Association.

Tani is married to Jane Egan from Cork, Ireland, and enjoys golf, flying, running, tennis, music, and cooking.

[11] On December 19, 2007, during Tani's stay on the International Space Station as a member of Expedition 16, he was informed by the ground team that his mother had been killed when a freight train collided with her car.