Robert Behnken
   HOME

TheInfoList



OR:

Robert Louis Behnken (; born July 28, 1970, in
St. Ann, Missouri St. Ann is a city in northwest St. Louis County, Missouri, United States. The population was 13,019 at the 2020 census. History The city was established in 1948 but began to develop six years before it was granted the petition of incorporation. ...
) is a
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
astronaut An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
,
engineer Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the l ...
, and former
Chief of the Astronaut Office The Chief of the Astronaut Office is the most senior leadership position for active astronauts at the NASA, National Aeronautics and Space Administration (NASA). The Chief Astronaut serves as head of the NASA Astronaut Corps and is the principal ...
. Behnken holds a
Ph.D A Doctor of Philosophy (PhD, Ph.D., or DPhil; Latin: or ') is the most common Academic degree, degree at the highest academic level awarded following a course of study. PhDs are awarded for programs across the whole breadth of academic fields ...
in
mechanical engineering Mechanical engineering is the study of physical machines that may involve force and movement. It is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, and ...
and the rank of
colonel Colonel (abbreviated as Col., Col or COL) is a senior military officer rank used in many countries. It is also used in some police forces and paramilitary organizations. In the 17th, 18th and 19th centuries, a colonel was typically in charge of ...
in the U.S. Air Force, where he served before joining NASA in 2000. He flew aboard
Space Shuttle The Space Shuttle is a retired, partially 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. Its official program na ...
missions STS-123 (2008) and
STS-130 STS-130 ( ISS assembly flight 20A) was a NASA Space Shuttle mission to the International Space Station (ISS). 's primary payloads were the ''Tranquility'' module and the ''Cupola'', a robotic control station with six windows around its sides and ...
(2010) as a mission specialist, accumulating over 708 hours in space, including 55 hours of
spacewalk 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 environmen ...
time. He is married to fellow astronaut
K. Megan McArthur Katherine Megan McArthur (born August 30, 1971) is an American oceanographer, engineer, and NASA astronaut. She has served as a Capsule Communicator (CAPCOM) for both the Space Shuttle and International Space Station (ISS). Megan McArthur has f ...
. Following retirement of the Space Shuttle, Behnken was
Chief of the Astronaut Office The Chief of the Astronaut Office is the most senior leadership position for active astronauts at the NASA, National Aeronautics and Space Administration (NASA). The Chief Astronaut serves as head of the NASA Astronaut Corps and is the principal ...
from 2012 to 2015. Assigned to the
SpaceX Space Exploration Technologies Corp. (SpaceX) is an American spacecraft manufacturer, launcher, and a satellite communications corporation headquartered in Hawthorne, California. It was founded in 2002 by Elon Musk with the stated goal of ...
Dragon Capsule American private space transportation company SpaceX has developed and produced several spacecraft named Dragon. The first family member, now referred to as Dragon 1, flew 23 cargo missions to the ISS between 2010 and 2020 before being retired. ...
in 2018 as part of NASA's
Commercial Crew Program The Commercial Crew Program (CCP) provides commercially-operated crew transportation service to and from the International Space Station (ISS) under contract to NASA, conducting crew rotations between the expeditions of the International S ...
, Behnken launched aboard the spacecraft's first crewed mission with fellow astronaut
Doug Hurley Douglas Gerald Hurley (born October 21, 1966) is an American engineer, former Marine Corps pilot and former NASA astronaut. He piloted Space Shuttle missions STS-127 (July 2009) and STS-135 (July 2011), the final flight of the Space Shuttle pro ...
on May 30, 2020, and became one of the first two astronauts launching aboard a commercial orbital spacecraft in spaceflight history. The mission,
Crew Dragon Demo-2 Crew Dragon Demo-2 (officially Crew Demo-2, SpaceX Demo-2, or Demonstration Mission-2) was the first crewed test flight of the Crew Dragon spacecraft. The spacecraft, named '' Endeavour'', launched on 30 May 2020 on a Falcon 9 booster, and ca ...
, took Behnken and Hurley to the
International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
(ISS), where they docked and stayed aboard for 62 days. Behnken completed four spacewalks with NASA Astronaut
Christopher Cassidy Christopher John "Chris" Cassidy (born January 4, 1970) is a retired NASA astronaut and United States Navy SEAL. Chris Cassidy achieved the rank of captain in the U.S. Navy. His first spaceflight was on a Space Shuttle mission in 2009. He was ...
.


Education

Behnken attended
Pattonville High School Pattonville High School is a public high school located in Maryland Heights, Missouri. It is the only high school in the Pattonville School District. History Pattonville High School's first graduating class was in 1937 with 2 girls graduating. ...
in
Maryland Heights, Missouri Maryland Heights is a second-ring north suburb of St. Louis, located in St. Louis County, Missouri, United States. The population was 27,472 at the 2010 census. The city was incorporated in 1985. Edwin L. Dirck was appointed the city's first may ...
(in St. Louis County), and went on to earn
Bachelor of Science A Bachelor of Science (BS, BSc, SB, or ScB; from the Latin ') is a bachelor's degree awarded for programs that generally last three to five years. The first university to admit a student to the degree of Bachelor of Science was the University of ...
degrees in
mechanical engineering Mechanical engineering is the study of physical machines that may involve force and movement. It is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, and ...
and
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
from
Washington University in St. Louis Washington University in St. Louis (WashU or WUSTL) is a private research university with its main campus in St. Louis County, and Clayton, Missouri. Founded in 1853, the university is named after George Washington. Washington University is r ...
in 1992. He then attended the
California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...
, where he earned an MS degree in 1993 and a PhD in 1997, both in mechanical engineering. While at Caltech he shared a doctoral advisor, Christopher E. Brennen, with another future NASA astronaut, Garrett Reisman. Behnken's graduate thesis research was in the area of
nonlinear control Nonlinear control theory is the area of control theory which deals with systems that are nonlinear, time-variant, or both. Control theory is an interdisciplinary branch of engineering and mathematics that is concerned with the behavior of dyn ...
applied to stabilizing rotating stall and surge in
axial-flow compressor An axial compressor is a gas compressor that can continuously pressurize gases. It is a rotating, airfoil-based compressor in which the gas or working fluid principally flows parallel to the axis of rotation, or axially. This differs from other ...
s. The research included nonlinear analysis, real-time software implementation development, and extensive hardware construction. During his first two years of graduate study, Behnken developed and implemented real-time control algorithms and hardware for flexible robotic manipulators.


Air Force career

Before entering graduate school, Behnken was an
Air Force ROTC The Air Force Reserve Officer Training Corps (AFROTC) is one of the three primary commissioning sources for officers in the United States Air Force and United States Space Force, the other two being the United States Air Force Academy (USAFA) ...
student at Washington University in St. Louis, and after graduate school was assigned to enter
Air Force An air force – in the broadest sense – is the national military branch that primarily conducts aerial warfare. More specifically, it is the branch of a nation's armed services that is responsible for aerial warfare as distinct from an a ...
active duty at
Eglin AFB Eglin Air Force Base is a United States Air Force (USAF) base in the western Florida Panhandle, located about southwest of Valparaiso in Okaloosa County. The host unit at Eglin is the 96th Test Wing (formerly the 96th Air Base Wing). The 9 ...
,
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
. While at Eglin, he worked as a technical manager and developmental engineer for new
munition Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weapo ...
s systems. Behnken was next assigned to attend the
U.S. Air Force Test Pilot School The U.S. Air Force Test Pilot School (USAF TPS) is the Air Force's advanced flight training school that trains experimental test pilots, flight test engineers, and flight test flight officer, navigators to carry out tests and evaluations of new ...
Flight Test Engineer's course at
Edwards AFB Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, but its eastern end is in San Bernardino County and a southern arm is in Los Angeles County. The hub of the base is Ed ...
,
California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
. After graduating, he was assigned to the
F-22 The Lockheed Martin F-22 Raptor is an American single-seat, twin-engine, all-weather stealth tactical fighter aircraft developed for the United States Air Force (USAF). As the result of the USAF's Advanced Tactical Fighter (ATF) program, th ...
Combined Test Force (CTF) and remained at Edwards. While assigned to the F-22 program, Behnken was the lead flight test engineer for Raptor 4004 and a special projects test director. These responsibilities included flight test
sortie A sortie (from the French word meaning ''exit'' or from Latin root ''surgere'' meaning to "rise up") is a deployment or dispatch of one military unit, be it an aircraft, ship, or troops, from a strongpoint. The term originated in siege warfare. ...
planning, control room configuration development, and test conduct. Behnken also flew in both the
F-15 The McDonnell Douglas F-15 Eagle is an American twin-engine, all-weather tactical fighter aircraft designed by McDonnell Douglas (now part of Boeing). Following reviews of proposals, the United States Air Force selected McDonnell Douglas's ...
and
F-16 The General Dynamics F-16 Fighting Falcon is a single-engine Multirole combat aircraft, multirole fighter aircraft originally developed by General Dynamics for the United States Air Force (USAF). Designed as an air superiority day fighter, it ...
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
in support of the F-22 flight test program.


NASA career

Selected as an astronaut candidate by NASA in July 2000, Behnken reported for training in August 2000. Following the completion of 18 months of training and evaluation, he was assigned technical duties in the Astronaut Office Shuttle Operations Branch 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 National Aeronautics and Space Administration's (NASA) ten field centers. Since December 1968 ...
, Florida. In September 2006, Behnken served as an
aquanaut An aquanaut is any person who remains underwater, breathing at the ambient pressure for long enough for the concentration of the inert components of the breathing gas dissolved in the body tissues to reach equilibrium, in a state known as satura ...
during the NEEMO 11 mission aboard the
Aquarius Aquarius may refer to: Astrology * Aquarius (astrology), an astrological sign * Age of Aquarius, a time period in the cycle of astrological ages Astronomy * Aquarius (constellation) * Aquarius in Chinese astronomy Arts and entertainme ...
underwater laboratory, living and working underwater for seven days.


STS-123

Behnken was a crew member of the STS-123 mission that delivered the
Japanese Experiment Module Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...
and the
Special Purpose Dexterous Manipulator Dextre, also known as the Special Purpose Dexterous Manipulator (SPDM), is a two armed robot, or telemanipulator, which is part of the Mobile Servicing System on the International Space Station (ISS), and does repairs that would otherwise r ...
to the
International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
in March 2008. Behnken took part in three
spacewalks Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmental support. EVA inc ...
during the mission.


STS-130

Behnken flew to space for the second time as a Mission Specialist on
STS-130 STS-130 ( ISS assembly flight 20A) was a NASA Space Shuttle mission to the International Space Station (ISS). 's primary payloads were the ''Tranquility'' module and the ''Cupola'', a robotic control station with six windows around its sides and ...
, which launched at 04:14 EST (09:14 UTC) February 8, 2010. This mission delivered the ''
Tranquility Tranquillity (also spelled tranquility) is the quality or state of being tranquil; that is, calm, serene, and worry-free. The word tranquillity appears in numerous texts ranging from the religious writings of Buddhism, where the term ''passaddhi'' ...
'' module and Cupola to the International Space Station. Behnken again took part in three spacewalks during this mission.


Chief of the Astronaut Office

In July 2012, Behnken was named
Chief of the Astronaut Office The Chief of the Astronaut Office is the most senior leadership position for active astronauts at the NASA, National Aeronautics and Space Administration (NASA). The Chief Astronaut serves as head of the NASA Astronaut Corps and is the principal ...
, succeeding
Peggy Whitson Peggy Annette Whitson (born February 9, 1960) is an American biochemistry researcher, retired NASA astronaut, and former NASA Chief Astronaut. Whitson has a total of 665 days in space, more than any other woman or American. Her first space mi ...
. He held the job until July 2015, when he was succeeded by Chris Cassidy, after being selected as one of four astronauts training to fly spacecraft contracted under NASA's
Commercial Crew Program The Commercial Crew Program (CCP) provides commercially-operated crew transportation service to and from the International Space Station (ISS) under contract to NASA, conducting crew rotations between the expeditions of the International S ...
.


SpX-DM2

In August 2018, Behnken was assigned to the first test flight
SpX-DM2 Crew Dragon Demo-2 (officially Crew Demo-2, SpaceX Demo-2, or Demonstration Mission-2) was the first crewed test flight of the Crew Dragon spacecraft. The spacecraft, named '' Endeavour'', launched on 30 May 2020 on a Falcon 9 booster, and carr ...
of the SpaceX
Crew Dragon Dragon 2 is a class of partially reusable spacecraft developed and manufactured by American aerospace manufacturer SpaceX, primarily for flights to the International Space Station (ISS). SpaceX has also launched private missions such as Ins ...
. Behnken and fellow crewmember
Douglas Hurley Douglas Gerald Hurley (born October 21, 1966) is an American engineer, former Marine Corps pilot and former NASA astronaut. He piloted Space Shuttle missions STS-127 (July 2009) and STS-135 (July 2011), the final flight of the Space Shuttle pro ...
were humorously compared in news and social media to the fictional brothers
Bob and Doug McKenzie Bob and Doug McKenzie are a pair of fictional Canadian brothers who hosted "Great White North", a Sketch comedy, sketch which was introduced on ''Second City Television, SCTV'' for the show's third season when it moved to CBC Television in 1980 ...
because of their friendship when they participated in the first commercial astronaut launch on SpaceX
Crew Dragon Demo-2 Crew Dragon Demo-2 (officially Crew Demo-2, SpaceX Demo-2, or Demonstration Mission-2) was the first crewed test flight of the Crew Dragon spacecraft. The spacecraft, named '' Endeavour'', launched on 30 May 2020 on a Falcon 9 booster, and ca ...
. It successfully launched on May 30, 2020. The spacecraft successfully docked with the
International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
on May 31, 2020. Behnken and
Doug Hurley Douglas Gerald Hurley (born October 21, 1966) is an American engineer, former Marine Corps pilot and former NASA astronaut. He piloted Space Shuttle missions STS-127 (July 2009) and STS-135 (July 2011), the final flight of the Space Shuttle pro ...
joined the ISS
Expedition 63 Expedition 63 was the 63rd long duration mission to the International Space Station, which began on 17 April 2020 with the undocking of the Soyuz MS-15 spacecraft and continued until the undocking of the Soyuz MS-16 spacecraft on 21 October 20 ...
crew, which consists of NASA astronaut Chris Cassidy and Russian cosmonauts
Ivan Vagner Ivan Viktorovich Vagner (born 10 July 1985) is a Russian engineer and cosmonaut who was selected in October 2010. He graduated from the Baltic State Technical University in 2008, before working as an engineer for RKK Energia. He began his first ...
and
Anatoli Ivanishin Anatoli Alekseyevich Ivanishin (russian: link=no, Анатолий Алексеевич Иванишин; born 15 January 1969) is a former Russian cosmonaut. His first visit to space was to the International Space Station on board the Soyuz TM ...
. They returned to Earth in the same capsule on August 2, 2020. Alongside, his seat of the
SpaceX Space Exploration Technologies Corp. (SpaceX) is an American spacecraft manufacturer, launcher, and a satellite communications corporation headquartered in Hawthorne, California. It was founded in 2002 by Elon Musk with the stated goal of ...
Crew Dragon Dragon 2 is a class of partially reusable spacecraft developed and manufactured by American aerospace manufacturer SpaceX, primarily for flights to the International Space Station (ISS). SpaceX has also launched private missions such as Ins ...
Endeavour will again be used by his wife,
K. Megan McArthur Katherine Megan McArthur (born August 30, 1971) is an American oceanographer, engineer, and NASA astronaut. She has served as a Capsule Communicator (CAPCOM) for both the Space Shuttle and International Space Station (ISS). Megan McArthur has f ...
in
SpaceX Crew-2 SpaceX Crew-2 was the second operational flight of a Crew Dragon spacecraft, and the third overall crewed orbital flight of the Commercial Crew Program. The mission was launched on 23 April 2021 at 09:49:02 UTC, and docked to the Internationa ...
mission which is the second flight of Endeavor capsule.


Personal life

Behnken is married to fellow astronaut
K. Megan McArthur Katherine Megan McArthur (born August 30, 1971) is an American oceanographer, engineer, and NASA astronaut. She has served as a Capsule Communicator (CAPCOM) for both the Space Shuttle and International Space Station (ISS). Megan McArthur has f ...
and they have one son. Behnken holds an
amateur radio license Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communic ...
with the
call sign In broadcasting and radio communications, a call sign (also known as a call name or call letters—and historically as a call signal—or abbreviated as a call) is a unique identifier for a transmitter station. A call sign can be formally assigne ...
KE5GGX. His wife flew on the
Crew-2 SpaceX Crew-2 was the second operational flight of a Crew Dragon spacecraft, and the third overall crewed orbital flight of the Commercial Crew Program. The mission was launched on 23 April 2021 at 09:49:02 UTC, and docked to the Internationa ...
mission, using the same Dragon capsule and the same seat that Behnken himself used during the
Demo-2 Crew Dragon Demo-2 (officially Crew Demo-2, SpaceX Demo-2, or Demonstration Mission-2) was the first crewed test flight of the Crew Dragon spacecraft. The spacecraft, named '' Endeavour'', launched on 30 May 2020 on a Falcon 9 booster, and carr ...
mission. She returned from the
International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
on November 8, 2021.


Awards and honors

* Outstanding
Mechanical Engineering Mechanical engineering is the study of physical machines that may involve force and movement. It is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, and ...
Senior, Washington University (1992) *
National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National I ...
Graduate Research Fellow (1993–1996) *
Air Force Research Laboratory The Air Force Research Laboratory (AFRL) is a scientific research organization operated by the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of aerospace warfighting technologies, pl ...
Munitions Directorate, Eglin AFB, Company Grade Officer of the Year (1997) * Air Force Achievement Medal (1997);
Air Force Commendation Medal The Commendation Medal is a mid-level United States military decoration presented for sustained acts of heroism or meritorious service. Each branch of the United States Armed Forces issues its own version of the Commendation Medal, with a fifth ...
(1998, 2000) * Distinguished graduate from the USAF Test Pilot School Program (1999) * Recipient of the USAF Test Pilot School Colonel Ray Jones Award as the top
Flight Test Engineer A flight test engineer (FTE) is an engineer involved in the flight testing of prototype aircraft or aircraft systems. Overview The flight test engineer generally has overall responsibility for the planning of a specific flight test phase, which i ...
/Flight Test Navigator in class 98B. * SpaceX purchased two ships for towing and supporting
autonomous spaceport drone ship An autonomous spaceport drone ship (ASDS) is an ocean-going vessel derived from a deck barge, outfitted with station-keeping engines and a large landing platform and is autonomously controlled when on station for a landing. Construction of ...
and fairing recovery operations on the east coast in May 2021. These two ships were named in honour of Behnken and his
Demo-2 Crew Dragon Demo-2 (officially Crew Demo-2, SpaceX Demo-2, or Demonstration Mission-2) was the first crewed test flight of the Crew Dragon spacecraft. The spacecraft, named '' Endeavour'', launched on 30 May 2020 on a Falcon 9 booster, and carr ...
, crewmate,
Doug Hurley Douglas Gerald Hurley (born October 21, 1966) is an American engineer, former Marine Corps pilot and former NASA astronaut. He piloted Space Shuttle missions STS-127 (July 2009) and STS-135 (July 2011), the final flight of the Space Shuttle pro ...
as ''Doug'' and ''Bob''. The earlier names of the ships were Ella G and Ingrid respectively. One of the Dragon recovery ships,
GO Searcher ''Megan'', formerly called ''GO Searcher'' is a SpaceX Dragon recovery vessel. It is one of the offshore supply ships operated by Guice Offshore. The other identical ship is '' Shannon''. History ''Megan'' is the primary recovery vessel for t ...
, was renamed after his wife as
Megan Megan is a Welsh feminine given name, originally a diminutive form of Margaret. Margaret is from the Greek μαργαρίτης (''margarítēs''), Latin ''margarīta'', "pearl". Megan is one of the most popular Welsh-language names for women in ...
in 2022.


References

''This article incorporates text in the
public domain The public domain (PD) consists of all the creative work A creative work is a manifestation of creative effort including fine artwork (sculpture, paintings, drawing, sketching, performance art), dance, writing (literature), filmmaking, ...
from the
National Aeronautics and Space Administration The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding th ...
.''


External links


NASA biography of Robert L. Behnken


* {{DEFAULTSORT:Behnken, Robert L. 1970 births Living people Aquanauts United States Air Force astronauts People from St. Louis County, Missouri Washington University physicists Physicists from Missouri Scientists from St. Louis Scientists from Missouri McKelvey School of Engineering alumni California Institute of Technology alumni U.S. Air Force Test Pilot School alumni Washington University in St. Louis alumni United States Air Force officers 21st-century American engineers Space Shuttle program astronauts Recipients of the Meritorious Service Medal (United States) SpaceX astronauts Spacewalkers