Tracy Caldwell Dyson

Early life and education

Caldwell Dyson was born in Arcadia, California, the younger of two girls. In the early 1980s, her family moved to Beaumont, California, where her father worked as an electrician and she attended junior high and high school. Her recreational interests include running, weight training, hiking, softball, basketball, and auto repair and maintenance. At California State University, Fullerton, she competed on the track and field team as a sprinter and long jumper.

As an undergraduate researcher, she designed, constructed, and implemented electronics and hardware for a laser-ionization, time-of-flight mass spectrometer studying atmospherically relevant gas-phase chemistry. She also worked as a lab assistant in the university's research and instructional safety office, performing environmental monitoring of labs using hazardous chemicals and radioactive materials, calibrating survey instruments, and helping process chemical and radioactive waste.

During and after college, she worked as an electrician and inside wireman for her father's electrical contracting company, performing commercial and light industrial construction. At the University of California, Davis, she taught general chemistry laboratory and began graduate research, focusing on molecular-level surface reactivity and kinetics of metal surfaces using electron spectroscopy, laser desorption, and Fourier transform mass spectrometry.

She also designed and built peripheral components for a variable temperature, ultra-high vacuum scanning tunneling microscopy system. In 1997, she received the Camille and Henry Dreyfus Postdoctoral Fellowship in Environmental Science to study atmospheric chemistry at the University of California, Irvine, where she investigated reactivity and kinetics of atmospherically relevant systems using atmospheric pressure ionization mass spectrometry, Fourier transform infrared and ultraviolet absorption spectroscopies, and developed methods of chemical ionization for spectral interpretation of trace compounds.

Career

In June 1998, Caldwell Dyson was selected by NASA and began training two months later, in August 1998. Her astronaut candidate training included orientation briefings and tours, scientific and technical briefings, intensive instruction in Shuttle and International Space Station systems, physiological training, ground school for T-38 flight training, and water and wilderness survival techniques. In 1999, she was assigned to the Astronaut Office ISS Operations Branch as a Russian Crusader, participating in testing and integration of Russian hardware and software for the ISS.

In 2000, she became prime crew support astronaut for ISS Expedition 5, serving as their representative on technical and operational issues. During Expeditions 4 through 6, she served as an ISS spacecraft communicator (CAPCOM) inside Mission Control. In 2003, she transitioned to the Astronaut Shuttle Operations Branch, assigned to flight software verification in the Shuttle Avionics Integration Laboratory and supporting launch and landing operations at Kennedy Space Center.

She also served as Lead CAPCOM for Expedition 11. Between her second and third flights, she worked as CAPCOM for both space shuttle and space station operations, serving as lead CAPCOM for various ISS missions and leading development of the CAPCOM cadre for Boeing Starliner Mission Operations. She was ground IV for US EVA 32, performed by Scott Kelly and Kjell Lindgren. She initiated and led the EVA Qualification training flow for astronaut candidates.

After her third trip to space, she served as ground IV for US EVA 95, performed by Jessica Meir and Christopher Williams in March 2026, and worked as CAPCOM for Artemis II during three separate shifts. In summer 2026, she participated in the European Space Agency's CAVES training program with NASA astronaut Ben Bailey and astronauts John McFall, Ayu Yoneda, and Rosemary Coogan.

Other activities

A private pilot who can hold conversations in American Sign Language and Russian, Tracy Caldwell Dyson also fronts the astronaut band Max Q. She judged a space-themed Cupcake Wars episode in 2011 and appeared on MasterChef Junior. For the 2015 film The Martian, she advised Jessica Chastain on playing an astronaut. Her professional memberships include Sigma Xi Research Society and the American Chemical Society.

STS-118

Caldwell Dyson was assigned to STS-118 on May 17, 2006, serving as mission specialist 1 on the first flight of Space Shuttle Endeavour after the Columbia disaster. On August 8, 2007, she lifted off on the 119th Space Shuttle flight, the 22nd flight to the station, and the 20th flight for Endeavour. During the mission, she successfully added another truss segment, a new gyroscope, and an external spare parts platform to the International Space Station.

A new system enabling docked shuttles to draw electrical power from the station to extend visits was activated successfully. Four spacewalks were performed by three crew members. Endeavour carried about 5,000 pounds of equipment and supplies to the station and returned with about 4,000 pounds of hardware and no-longer-needed equipment. Traveling 5.3 million miles in space, the STS-118 mission was completed in 12 days, 17 hours, 55 minutes, and 34 seconds. On day 7 of the flight, Caldwell Dyson celebrated her 38th birthday.

Expedition 23/24

Caldwell Dyson was assigned to her second space flight on November 21, 2008, a six-month trip to the International Space Station. She lifted off on April 2, 2010, from Baikonur on Soyuz TMA-18 as Flight Engineer 2 with Commander Aleksandr Skvortsov and Flight Engineer 1 Mikhail Korniyenko. After a two-day rendezvous, she joined Expedition 23 as a flight engineer and transferred on June 2, 2010, to Expedition 24 as a flight engineer after the departure of Soyuz TMA-17.

During the first half of her flight, the Expedition 23 crew was joined by STS-131 from April 7 to April 17, marking the first and only time four women were together on the same spacecraft: Caldwell Dyson, NASA astronauts Stephanie Wilson and Dorothy Metcalf-Lindenburger, and JAXA astronaut Naoko Yamazaki. From May 16 to May 23, STS-132 joined for installation of the Russian-built module Rassvet. The second half of her mission was marked by the failure of a coolant pump at the beginning of August.

Caldwell Dyson performed her first spacewalk on August 7, 2010, with NASA astronaut Douglas Wheelock, preparing the malfunctioning coolant pump for replacement. She performed all three contingency EVAs, with the second on August 11, 2010, and the third on August 16, 2010. After 176 days, 1 hour, 18 minutes, and 38 seconds in space, she landed in Kazakhstan on September 25, 2010. During this spaceflight, she completed three spacewalks, logging 22 hours of EVA time.