Tracy Caldwell Dyson (born Tracy Ellen Caldwell; August 14, 1969) is an American
chemist
A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...
and
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
astronaut
An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a List of human spaceflight programs, human spaceflight program to serve as a commander or crew member of a spa ...
. She was a mission specialist on
Space Shuttle
The Space Shuttle is a retired, partially reusable launch system, reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. ...
''Endeavour'' flight
STS-118
STS-118 was a Space Shuttle mission to the International Space Station (ISS) flown by the orbiter ''Space Shuttle Endeavour, Endeavour''. STS-118 lifted off on August 8, 2007, from Kennedy Space Center Launch Complex 39, launch pad 39A at Kennedy ...
in August 2007 and has participated in two long-duration missions to the
International Space Station
The International Space Station (ISS) is a large space station that was Assembly of the International Space Station, assembled and is maintained in low Earth orbit by a collaboration of five space agencies and their contractors: NASA (United ...
,
Expedition 23 and
24 from April to September 2010 and
Expedition 70 and
71 from March to September 2024. She has completed four spacewalks, logging nearly 24 hours of
extravehicular activity
Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable atmosphere of Earth, Earthlike atmosphere, the astronaut is completely reliant on a space suit for environme ...
.
Early life and education
Caldwell Dyson was born in
Arcadia, California
Arcadia is a city in Los Angeles County, California, United States, located about northeast of downtown Los Angeles in the San Gabriel Valley and at the base of the San Gabriel Mountains. It contains a series of adjacent parks consisting of t ...
.
She is the younger of two girls. In the early 1980s, she and her family moved to
Beaumont, California
Beaumont is a city in Riverside County, California, United States, located at the summit of the San Gorgonio Pass, between the San Bernardino Mountains and Mount San Gorgonio to the north, and the San Jacinto Mountains to the south. Around 18 ...
, where her father worked as an electrician and where she attended junior high school and high school. Her recreational interests included running, weight training, hiking, softball, basketball, and auto repair and maintenance.
She attended
California State University, Fullerton
California State University, Fullerton (CSUF or Cal State Fullerton) is a public research university in Fullerton, California, United States. With a total enrollment of more than 41,000, it has the largest student body of the California State ...
, where she competed on the
CSUF Titans' track and field team as a sprinter and long jumper.
As an undergraduate researcher at California State University, Fullerton, she designed, constructed and implemented electronics and hardware associated with a laser-ionization,
time-of-flight mass spectrometer
Time-of-flight mass spectrometry (TOFMS) is a method of mass spectrometry in which an ion's mass-to-charge ratio is determined by a time of flight measurement. Ions are accelerated by an electric field of known strength. This acceleration result ...
for studying atmospherically relevant
gas-phase chemistry.
She also worked as a lab assistant in the university's research and instructional safety office, where she performed environmental monitoring of laboratories using hazardous chemicals and radioactive materials and calibrated survey instruments and helped process chemical and radioactive waste. During college and after it, she also worked as an electrician and inside wireman for her father's electrical contracting company, where she performed commercial and light industrial construction.
At the
University of California, Davis
The University of California, Davis (UC Davis, UCD, or Davis) is a Public university, public Land-grant university, land-grant research university in Davis, California, United States. It is the northernmost of the ten campuses of the University ...
, Caldwell Dyson taught general chemistry laboratory and began her graduate research. Her dissertation work focused on investigating molecular-level
surface reactivity and kinetics of metal surfaces using
electron spectroscopy
Electron spectroscopy refers to a group formed by techniques based on the analysis of the energies of emitted electrons such as Photoelectric effect, photoelectrons and Auger electrons. This group includes X-ray photoelectron spectroscopy (XPS), wh ...
,
laser desorption, and
Fourier transform
In mathematics, the Fourier transform (FT) is an integral transform that takes a function as input then outputs another function that describes the extent to which various frequencies are present in the original function. The output of the tr ...
mass spectrometry techniques.
She also designed and built peripheral components for a variable temperature, ultra-high vacuum
scanning tunneling microscopy
A scanning tunneling microscope (STM) is a type of scanning probe microscope used for imaging surfaces at the atomic level. Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer, then at IBM Zürich, the Nobel Prize in ...
system.
In 1997, Caldwell Dyson received the Camille and Henry Dreyfus Postdoctoral Fellowship in Environmental Science to study
atmospheric chemistry
Atmospheric chemistry is a branch of atmospheric science that studies the chemistry of the Earth's atmosphere and that of other planets. This multidisciplinary approach of research draws on environmental chemistry, physics, meteorology, comput ...
at the
University of California, Irvine
The University of California, Irvine (UCI or UC Irvine) is a Public university, public Land-grant university, land-grant research university in Irvine, California, United States. One of the ten campuses of the University of California system, U ...
.
There, she investigated reactivity and kinetics of atmospherically relevant systems using atmospheric pressure ionization mass spectrometry, Fourier transform infrared and ultraviolet absorption spectroscopies. In addition, she developed methods of chemical ionization for spectral interpretation of trace compounds. Caldwell Dyson has published and presented her work in numerous papers at technical conferences and in scientific journals.
Career
NASA

In June 1998, Caldwell Dyson was selected by
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
, and began NASA training two months later, in August 1998. Her astronaut candidate training included orientation briefings and tours, numerous scientific and technical briefings, intensive instruction in Shuttle and
International Space Station
The International Space Station (ISS) is a large space station that was Assembly of the International Space Station, assembled and is maintained in low Earth orbit by a collaboration of five space agencies and their contractors: NASA (United ...
(ISS) systems, physiological training, ground school to prepare for
T-38 T38 or T-38 may refer to:
Aviation
* Allison T38, an American turboprop aircraft engine
* Northrop T-38 Talon, an American jet trainer aircraft
* Slingsby T.38 Grasshopper, a British training glider
Other uses
* T38 (classification), a disabi ...
flight training, as well as learning water and wilderness survival techniques. Completion of this training and evaluation qualified her for flight assignment as a mission specialist.
In 1999, Caldwell Dyson was assigned to the Astronaut Office ISS Operations Branch as a Russian Crusader, participating in the testing and integration of Russian hardware and software products developed for ISS. In 2000, she was assigned prime crew support astronaut for the ISS
Expedition 5
Expedition 5 was the fifth long-duration stay on the International Space Station (ISS). The crew, consisting of three people, remained in space for 184 days, 178 of which were spent aboard the ISS. Expedition 5 was a continuation of an uninterru ...
crew, serving as their representative on technical and operational issues throughout the training and on-orbit phase of their mission. During ISS Expeditions 4 through 6, Caldwell Dyson served as an ISS spacecraft communicator (CAPCOM) inside Mission Control. In 2003, she made a transition to the Astronaut Shuttle Operations Branch and was assigned to flight software verification in the
Shuttle Avionics Integration Laboratory and worked supporting launch and landing operations at
Kennedy Space Center
The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the NASA, National Aeronautics and Space Administration's (NASA) ten NASA facilities#List of field c ...
, Florida. Caldwell Dyson also served as Lead CAPCOM for
Expedition 11.
Between her second and third flights, Caldwell Dyson continued to work inside Houston’s Mission Control Center as CAPCOM for both space shuttle and space station operations, serving as the lead CAPCOM for various ISS missions, including the lead and development of the CAPCOM cadre for
Boeing Starliner
The Boeing Starliner (or CST-100) is a spacecraft designed to transport crew to and from the International Space Station (ISS) and other low-Earth-orbit destinations. Developed by Boeing under NASA's Commercial Crew Program (CCP), it consists o ...
Mission Operations team. She was also the ground IV for US EVA 32, performed by
Scott Kelly and
Kjell Lindgren.
Caldwell Dyson initiated and led several projects to improve training and operations aboard the ISS, most notably developing the EVA Qualification training flow (EVQ) for astronaut candidates.
As Tracy Dyson, she is the host of a series on
NASA TV
NASA TV (originally NASA Select) was the television service of the NASA, National Aeronautics and Space Administration (NASA). It was broadcast by satellite television, satellite with a simulcast over the Internet. Local cable television provid ...
called ''StationLife'', which focuses on facets of life aboard the International Space Station.
On March 21, 2017, Caldwell Dyson stood behind
President Trump
Donald John Trump (born June 14, 1946) is an American politician, media personality, and businessman who is the 47th president of the United States. A member of the Republican Party, he served as the 45th president from 2017 to 2021.
...
as he signed a bill for NASA to send humans to Mars in the 2030s and receive $19.5 billion in 2018 funding. Caldwell Dyson and fellow NASA astronaut
Chris Cassidy presented Trump with an official flight jacket during the ceremony.
STS-118
Caldwell Dyson was assigned to
STS-118
STS-118 was a Space Shuttle mission to the International Space Station (ISS) flown by the orbiter ''Space Shuttle Endeavour, Endeavour''. STS-118 lifted off on August 8, 2007, from Kennedy Space Center Launch Complex 39, launch pad 39A at Kennedy ...
on May 17, 2006. It was announced that she would serve as mission specialist 1 on the first flight of Space Shuttle ''Endeavour'' after the
''Columbia'' disaster.
On August 8, 2007, Caldwell Dyson lifted off for the first time 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 external spare parts platform to the International Space Station. A new system that enables docked shuttles to draw electrical power from the station to extend visits to the outpost was activated successfully. A total of four spacewalks (EVAs) were performed by three crew members. ''Endeavour'' carried some 5,000 pounds of equipment and supplies to the station and returned to Earth with some 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 of STS-118, Caldwell-Dyson celebrated her 38th birthday.
Expedition 23/24

Caldwell Dyson was assigned for her second space flight on November 21, 2008. Her second space mission consisted of a six-month trip to the
International Space Station
The International Space Station (ISS) is a large space station that was Assembly of the International Space Station, assembled and is maintained in low Earth orbit by a collaboration of five space agencies and their contractors: NASA (United ...
.
Caldwell Dyson successfully lifted off on April 2, 2010, from the
Baikonur
Baikonur ( ; ) is a city in Kazakhstan on the northern bank of the Syr Darya river. It is currently leased and administered by the Russian Federation as an enclave until 2050. It was constructed to serve the Baikonur Cosmodrome with adminis ...
spaceport on board the
Soyuz TMA-18
Soyuz TMA-18 was a 2010 Soyuz programme, Soyuz flight to the International Space Station (ISS). TMA-18 was the 105th crewed flight of a Soyuz spacecraft since the Soyuz 1, first crewed flight in 1967.
Crew
Backup crew
Launch
After a ...
as Flight Engineer 2 with Soyuz Commander
Aleksandr Skvortsov and Flight Engineer 1
Mikhail Korniyenko
Mikhail Borisovich Kornienko (Михаил Борисович Корниенко; born 15 April 1960) is a Russian cosmonaut who has undertaken multiple missions to the International Space Station (ISS).
He first served as a flight engineer duri ...
. Following a two-day rendezvous and docking maneuver with the
ISS, she joined
Expedition 23 as a flight engineer and transferred on June 2, 2010, to
Expedition 24
Expedition 24 was the 24th long-duration mission to the International Space Station (ISS). Expedition 24 initially had two planned spacewalks, one Russian and one American Extra-vehicular Activity (EVA). The U.S. EVA was re-planned and a second ...
again as a flight engineer after the departure of the
Soyuz TMA-17.
During the first half of her flight, Caldwell Dyson and the
Expedition 23 crew were joined by the
STS-131 crew from April 7 to April 17. This period was the first and only time that four women were together on board the same spacecraft: Caldwell Dyson, NASA astronauts
Stephanie Wilson
Stephanie Diana Wilson (born September 27, 1966)Laura Woodmansee, ed. ''Women Astronauts.'' (2002). Burlington, Ont.: Apogee Books. . p. 131. is an American engineer and a NASA astronaut. She flew to space onboard three Space Shuttle missions a ...
and
Dorothy Metcalf-Lindenburger, and JAXA astronaut
Naoko Yamazaki. From May 16 to May 23, the second and last Space Shuttle visiting mission for Caldwell-Dyson's flight,
STS-132
STS-132 ( ISS assembly flight ULF4) was a NASA Space Shuttle mission, during which Space Shuttle ''Atlantis'' docked with the International Space Station on May 16, 2010. STS-132 was launched from the Kennedy Space Center on May 14, 2010. The pri ...
, joined the
Expedition 23 crew for the installation of the Russian-built module
Rassvet.
The second half of Caldwell Dyson's 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. The task for this first of three contingency
EVAs was to prepare the malfunctioning coolant pump for replacement on the next spacewalks; this took place on August 11, 2010, and August 16, 2010. She performed all of this contingency EVA.
After 176 days, 1 hour, 18 minutes and 38 seconds in space, Caldwell Dyson landed in
Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...
on September 25, 2010.
During this spaceflight, she completed three spacewalks, logging 22 hrs and 49 minutes of EVA work to replace a malfunctioning coolant pump.
Expedition 70/71
Caldwell Dyson returned to flight training as a backup crew member for the
Soyuz MS-24.
She backed up her NASA astronaut colleague
Loral O'Hara
Loral Ashley O'Hara (born May 3, 1983) is an American engineer and NASA astronaut.
Early life and education
Loral Ashley O'Hara was born on May 3, 1983, in Houston, Texas, to Cindy and Steve O'Hara. She grew up in Sugar Land, Texas, where she at ...
.
She was officially assigned to the
Soyuz MS-25 in 2023.
Her first attempt to launch on the Soyuz MS-25 mission on March 21, 2024 was aborted with 20 seconds left before lift-off.
[
] The scrub occurred because of a low voltage reading in the Soyuz rocket electrical system.
She launched on March 23, 2024 with
Roscosmos
The State Corporation for Space Activities "Roscosmos", commonly known simply as Roscosmos (), is a State corporation (Russia), state corporation of the Russian Federation responsible for space science, space flights, List of space agencies, c ...
cosmonaut
Oleg Novitsky and Belarusian cosmonaut
Marina Vasilevskaya.
[
] After a two-day rendezvous profile, the Soyuz crew docked with International Space Station's
Prichal
''Prichal'' (), also known as the Uzlovoy Module (UM, ) is a Russian-built component of the International Space Station (ISS). This spherical module has six docking ports (forward, aft, port, starboard, zenith, and nadir) to provide additiona ...
module on March 25, 2024. The first weeks of her mission dealt with the
SpaceX CRS-30 mission, as well as viewing the total eclipse above North America on April 8, 2024
[
] and the redocking of
SpaceX Crew-8
SpaceX Crew-8 was the eighth crewed operational NASA Commercial Crew Program, Commercial Crew flight and the 13th overall crewed orbital flight of a SpaceX Dragon 2, Crew Dragon spacecraft. The mission launched on 4 March 2024.
The Crew-8 miss ...
in early May.
Starting in mid-May, Expedition 71 crew focused themselves on the preparation for the three planned EVAs. During this period, the crew checked out EMUs, tools, and reviewed procedures. They also performed maintenance tasks around station as well as continued scientific work.
On June 6, Caldwell Dyson saw the arrival of the first crewed mission of Starliner. The Starliner crew was composed of
Barry Wilmore and
Sunita Williams
Sunita Lyn "Suni" Williams ( Pandya; born September 19, 1965) is an American astronaut and a retired U.S. Navy officer. Williams served aboard the International Space Station as a participant in Expedition 14, a flight engineer for Expedition ...
. Caldwell Dyson monitored the arrival of Starliner alongside
Matthew Dominick and helped the Starliner crew to accomplish their test flight objectives including testing the spacecraft habitability for four crew members and its capability as a safe haven in case of an emergency.
On June 24, Caldwell Dyson participated as a crew member for EVA 90 with
Michael Barratt. Unfortunately, this EVA ended early due to a water leak in the service and cooling umbilical unit on Caldwell-Dyson’s spacesuit. The leak came from the SCU when Caldwell-Dyson disconnected her SCU from her EMU after she switched to battery power. The total EVA time was only 31 minutes.
All of their EVAs were postponed to a later date after the incident, and Expedition 71 remained focused on their scientific work, cargo vehicle traffic, and maintenance tasks. More specifically, they saw the departure of
Cygnus NG-20 named after Dyson's classmate:
Patricia Hilliard Robertson on July 12th and the arrival of
Cygnus NG-21 -
Francis Scobee on August 6th.
Caldwell Dyson spent six months on the station and returned on September 23, 2024 with
Oleg Kononenko
Oleg Dmitriyevich Kononenko (; ; born 21 June 1964) is a Russian cosmonaut. He has flown to the International Space Station five times as a flight engineer for Expedition 17 aboard Soyuz TMA-12, as a flight engineer on Expedition 30 and comm ...
and
Nikolai Chub on the Soyuz MS-25 spacecraft.
Other activities

Caldwell Dyson is a private pilot. She is conversational in
American Sign Language
American Sign Language (ASL) is a natural language that serves as the predominant sign language of Deaf communities in the United States and most of Anglophone Canadians, Anglophone Canada. ASL is a complete and organized visual language that i ...
and
Russian
Russian(s) may refer to:
*Russians (), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries
*A citizen of Russia
*Russian language, the most widely spoken of the Slavic languages
*''The Russians'', a b ...
.
She is also the lead vocalist for the all-astronaut band
Max Q.
In 2011, Caldwell Dyson served as the guest judge on a space-themed episode of the
Food Network
Food Network is an American basic cable channel owned by Television Food Network, G.P., a unit of Warner Bros. Discovery, who manages and operates it as a division of the Warner Bros. Discovery U.S. Networks Group. The channel airs both televi ...
show ''
Cupcake Wars
''Cupcake Wars'' is an American reality competition series that premiered on December 27, 2009, on cable television network Food Network. The show, which is based on creating unique and professional-style cupcakes, was hosted by Justin Willma ...
''. She appeared on Episode 3 of ''
MasterChef Junior'' Season 4.
Caldwell Dyson advised
Jessica Chastain
Jessica Michelle Chastain (born March 24, 1977) is an American actress and producer. Known for primarily starring in projects with Feminism, feminist themes, she has received List of awards and nominations received by Jessica Chastain, various ...
when the actress was preparing to appear as an astronaut and mission commander in the 2015 movie ''
The Martian.'' Chastain said she was very inspired by Caldwell Dyson.
Caldwell Dyson is a member of
Sigma Xi
Sigma Xi, The Scientific Research Honor Society () is an international non-profit honor society for scientists and engineers. Sigma Xi was founded at Cornell University by a faculty member and graduate students in 1886 and is one of the oldest ...
Research Society and the
American Chemical Society
The American Chemical Society (ACS) is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has more than 155,000 members at all ...
.
Personal life
Caldwell Dyson is married to
U.S. Naval aviator George Dyson.
She believes in
God
In monotheistic belief systems, God is usually viewed as the supreme being, creator, and principal object of faith. In polytheistic belief systems, a god is "a spirit or being believed to have created, or for controlling some part of the un ...
,
and was raised as a
Methodist
Methodism, also called the Methodist movement, is a Protestant Christianity, Christian Christian tradition, tradition whose origins, doctrine and practice derive from the life and teachings of John Wesley. George Whitefield and John's brother ...
.
Awards and honors
*
Honorary Doctorate
An honorary degree is an academic degree for which a university (or other degree-awarding institution) has waived all of the usual requirements. It is also known by the Latin phrases ''honoris causa'' ("for the sake of the honour") or '' ad hon ...
, California State University, Fullerton (CSUF) (May 2008)
*
NASA Performance Award (2002 & 2001)
* NASA Go the Extra Mile (GEM) Award (2001)
*
NASA Superior Accomplishment Award (2000)
*
NASA Group Achievement Award
The NASA Group Achievement Award (GAA) is an award given by NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the U ...
– Russian Crusader Team (2000)
* Camille and Henry Dreyfus Postdoctoral Fellowship in Environmental Science (1997)
* Outstanding Doctoral Student Award in Chemistry from the University of California, Davis (1997)
* American Vacuum Society – HWhetten Award (1996)
* American Vacuum Society Graduate Research Award (1996)
* Pro Femina Research Consortium Graduate Research Award (1996)
* Pro Femina Research Consortium Graduate Award for Scientific Travel (1996)
* University of California, Davis Graduate Research Award (1996)
* University of California, Davis Graduate Student Award for Scientific Travel (1994)
* Patricia Roberts Harris Graduate Fellowship in Chemistry (1993–1997)
* Lyle Wallace Award for Service to the Department of Chemistry, California State University Fullerton (1993)
* National Science Foundation Research Experience for Undergraduates Award (1992)
* Council of Building & Construction Trades Scholarship (1991 and 1992)
* Big West Scholar Athlete (1989–1991)
See also
*
*
References
External links
Official NASA Bio
{{DEFAULTSORT:Caldwell Dyson, Tracy
1969 births
Living people
21st-century American women
American physical chemists
American women chemists
California State University, Fullerton alumni
Crew members of the International Space Station
NASA civilian astronauts
People from Arcadia, California
People from Beaumont, California
Space Shuttle program astronauts
Spacewalkers
University of California, Davis alumni
American women astronauts