Question: The first one to reach outer space in the Man In Space Soonest program was which Captain in the United States Air Force, an American World War II pilot, an experimental physicist, and NASA test pilot?
Context: Jeffrey Kindersley Quill, (1 February 1913 – 20 February 1996) was a British test pilot who served on secondment with the Royal Air Force and Royal Naval Volunteer Reserve during the Second World War.  He was also the second man to fly the Supermarine Spitfire after Vickers Aviation's chief test pilot, Joseph "Mutt" Summers.  After succeeding Summers as Vickers' chief test pilot, Quill test-flew every mark of Spitfire.  Quill's work on the aircraft aided its development from a promising but untried prototype to become, with the Hawker Hurricane, an instrument of the Royal Air Force's victory in the Battle of Britain.  The Spitfire later played a leading role in gaining Allied air superiority over Europe.  Quill later wrote two books about the Spitfire. Eileen Marie Collins (born November 19, 1956) is a retired NASA astronaut and a retired United States Air Force colonel.  A former military instructor and test pilot, Collins was the first female pilot and first female commander of a Space Shuttle.  She was awarded several medals for her work.  Colonel Collins has logged 38 days 8 hours and 20 minutes in outer space.  Collins retired on May 1, 2006, to pursue private interests, including service as a board member of USAA. Clarence Emil "Bud" Anderson (born January 13, 1922) is a retired officer in the United States Air Force and a "triple ace" in World War II.  During the war he was the highest scoring ace in his P-51 Mustang squadron.  This was the same squadron as well known test pilot (and first pilot to break the sound barrier) and ace Chuck Yeager, and they have remained lifelong close friends.  Towards the end of Anderson's two combat tours in Europe in 1944 he was promoted to major at age 22, an extremely young age even for a highly effective officer in wartime.  After the war Anderson became a well regarded fighter test pilot, and a fighter squadron and wing commander.  He served his wing commander tour in combat in the Vietnam War.  He retired as a full colonel in 1972, after which he worked in flight test management for McDonnell Douglas.  A member of the National Aviation Hall of Fame, Col. Anderson has remained a sought after speaker at aviation and military events well into his 90's. Man In Space Soonest (MISS) was a United States Air Force (USAF) program to put a man into outer space before the Soviet Union.  The program was cancelled on August 1, 1958, and was replaced by NASA's Project Mercury.  Only two men from the program would actually reach outer space.  The first, Joseph A. Walker, did so twice in two X-15 rocket plane tests in 1963.  Another, Neil Armstrong, became a NASA astronaut in 1962 and became the first person to walk on the Moon in 1969. The Royal Australian Air Force's Aircraft Research and Development Unit (ARDU) plans, conducts and analyses the results of ground and flight tests of existing and new Air Force aircraft.  ARDU consists of four flights located at RAAF Bases Edinburgh, Amberley, Richmond and Williamtown, staffed by qualified test pilots, flight test engineers and flight test system specialists.  Up until 2016 the Squadron also conducted flight test for the Australian Army with Army personnel also working within the unit.  The flight test crew are long course trained at test pilot schools including the United States Air Force Test Pilot School, the United States Naval Test Pilot School, the Empire Test Pilots' School, the École du personnel navigant d'essais et de réception and the National Test Pilot School. Robert Aitken "Bob" Rushworth (October 9, 1924 – March 18, 1993), (Maj Gen, USAF), was an American World War II, Korean War and Vietnam War pilot, mechanical and aeronautical engineer, and United States Air Force test pilot for the North American X-15 program. Robert Franklyn "Bob" Overmyer (July 14, 1936 – March 22, 1996), (Col, USMC), was an American test pilot, naval aviator, aeronautical engineer, physicist, United States Marine Corps officer, and USAF/NASA astronaut.  He was born in Lorain, Ohio, but considered Westlake, Ohio his hometown.  Overmyer was selected by the United States Air Force as an astronaut for its Manned Orbiting Laboratory in 1966.  Upon cancellation of this program in 1969, he became a NASA astronaut and served support crew duties for the Skylab program and Apollo-Soyuz Test Project.  In 1976, he was assigned to the Space Shuttle program, and flew as pilot on STS-5 in 1982, and as commander on STS-51-B in 1985.  He was selected as a lead investigator into the Space Shuttle "Challenger" disaster, and retired from NASA in 1986.  Ten years later, Overmyer died in Duluth, Minnesota while testing the Cirrus VK-30 composite homebuilt aircraft. Donald Kent "Deke" Slayton (March 1, 1924 – June 13, 1993), (Major, USAF) was an American World War II pilot, aeronautical engineer, test pilot who was selected as one of the original NASA Mercury Seven astronauts, and became NASA's first Chief of the Astronaut Office. Joseph Albert "Joe" Walker (February 20, 1921 – June 8, 1966) flew the world's first two spaceplane flights in 1963, thereby becoming the United States' seventh man in space.  Walker was a Captain in the United States Air Force, an American World War II pilot, an experimental physicist, a NASA test pilot, and a member of the U.S. Air Force Man In Space Soonest spaceflight program.  His two X-15 experimental rocket aircraft flights in 1963 that exceeded the Kármán line – the altitude of 100 km , generally considered to mark the threshold of outer space – qualified him as an astronaut under the rules of the U.S. Air Force and the Fédération Aéronautique Internationale (FAI). Kenneth O. "K.O." Chilstrom (born April 20, 1921) is a retired United States Air Force officer, combat veteran, test pilot, and author.  He was the first USAF pilot to fly the XP-86 Sabre, chief of fighter test at Wright Field, commandant of the U.S. Air Force Test Pilot School, and program manager for the XF-108 Rapier.  Chilstrom was a pilot in the first jet air race and delivered the first air mail by jet.  He flew over eighty combat missions in the Italian Campaign of World War II and tested over twenty foreign models of German and Japanese fighters and bombers to evaluate their strengths and weaknesses.
Answer: Joseph A. Walker