29 January 1926: At McCook Field, near Dayton, Ohio, First Lieutenant John Arthur Macready, Air Service, United States Army, took off in an experimental airplane, the Engineering Division XCO-5. Macready was attempting to exceed the existing Fédération Aéronautique Internationale world altitude record of 12,066 meters (39,587 feet), which had been set by Jean Callizo at Villacoublay, France, 21 October 1924.¹
The official observers of the National Aeronautic Association were Orville Wright (co-inventor with his brother Wilbur, of the airplane); George B. Smith of Dayton; and Levitt Luzurne Custer (inventor of the statoscope, the original barometric altimeter).
The Dayton Daily News reported:
Every part of the plane functioned perfectly. . . with the exception of the supercharging apparatus. The plane climbed to 25,000 feet in less than 45 minutes. The remainder of the flight was a fight against the dropping pressure in the motor.
In taking off, the altitude plane required approximately 50 feet and immediately began a steep ascent. Throughout the test the several hundred people who had congregated to see the flight start could find the plane by a long line of white vapor, which trailed in the wake of the ship in the rare atmosphere.
On other tests the plane has shown sea level pressure at approximately 32,000 feet. The super-charger showed a steadily declining pressure after 25,000 feet, indicating its lack of sufficient capacity for the motor. . .#0000ff;">
—Dayton Daily News, Vol. XL, No. 162, January 29, 1926, Page 1, Column 7, and Page 2, Column 2
Lieutenant Macready reported, “My watch stopped at 30,000 feet and I believe it was frozen, because just before landing it started again.” He observed a temperature of -62 °C. (-79.6 °F.) at 34,600 feet (10,546 meters), which he said then increased to -56 °C. (-68.8 °F.) at 36,000 feet (10,973 meters).
When the airplane was inspected after landing at McCook Field, it was found that a crack had developed in the supercharger intercooler, allowing the supercharged air to escape. This resulted in a significant loss of power, and prevented Macready from passing Callizo’s record.
Lieutenant Macready reported that the Fédération Aéronautique Internationale altimeter (one of two altimeters in the airplane’s cockpit) had indicated that he had reached a maximum of 36,200 feet (11,034 meters). When the sealed barograph was sent to the Bureau of Standards in Washington, D.C., for calibration, it indicated a peak altitude of 38,704 feet (11,797 meters). This was 269 meters (883 feet) lower than the existing world record, but it did establish a new United States national altitude record.
The XCO-5 was a prototype two-place, single-engine, two-bay biplane, a reconnaissance and observation variant of the TP-1 fighter. It was built by the Engineering Division at McCook Field. The airplane carried project number P305 painted on its rudder.
The XCO-5’s wings were built specifically for flight at very high altitude, using an airfoil (Joukowsky StAe-27A) designed by Professor Nikolay Yegorovich Zhukovsky (Николай Егорович Жуковский), head of the Central AeroHydroDynamics Institute (TsAGI) at Kachino, Russia. The two-bay biplane wings had a significant vertical gap and longitudinal stagger. The lifting surface was 600 square feet (55.742 square meters). The upper wing had dihedral while the lower wing did not.
The XCO-5 was 25 feet, 1 inch long (7.645 meters) with a wingspan of 36 feet (10.973 meters) and height of 10 feet (3.048 meters). The empty weight was 2,748 pounds (1,246 kilograms) and the gross weight was 4,363 pounds (1,979 kilograms).
The XCO-5 was powered by a water-cooled, 1,649.34-cubic-inch-displacement (27.028 liter) Liberty 12 single overhead cam (SOHC) 45° V-12 engine. It produced 408 horsepower at 1,800 r.p.m. The L-12 is a right-hand tractor, direct-drive engine. As installed on A.S. 23-1204, the engine turned a specially-designed, two-bladed, ground-adjustable, forged aluminum propeller with a diameter of 10 feet, 6 inches (3.200 meters). The Liberty 12 was 67.375 inches (1.711 meters) long, 27.0 inches (0.686 meters) wide, and 41.5 inches (1.054 meters) high. It weighed 844 pounds (383 kilograms).
Also installed on A.S. 23-1204 was an experimental supercharger. FLIGHT explained:
Since the Liberty engine, which delivers 400 h.p. at sea level, has an output of but 50 h.p. at 35,000 feet unsupercharged, a supercharger is a prime requisite of altitude work. The General Electric Form F, 20,000-ft. side type supercharger used in previous tests, with certain modifications, has been installed. The supercharger is an air compressor which keeps the air pressure in the carburettor at sea level pressure at heights where, owing to the natural decrease in the air pressure, the horsepower gradually falls away but to a fraction of its original output. In former supercharger installations, much difficulty was experienced with pre-ignition of the engine. This often became so pronounced that the plane had to be brought to earth. It was suspected that a richer mixture with the supercharger at altitude was necessary. This was found to be true but the principal difficulty was the overheating of the mixture due to the heat generated in the supercharger itself. Due to the increase in temperature created by the compression in the supercharger, it was necessary to interpose an intercooler between the supercharger outlet and the carburettor in order to obtain satisfactory engine performance. The intercooler, in the form of a honeycomb radiator, was placed on the side of the aeroplane. It was also found that the poor conductivity of the air at high altitudes, additional radiating surface for engine cooling was required. This, with the correction of mixture, put an end to pre-ignition.
—FLIGHT, The Aircraft Engineer & Airships, No. 893. (No. 5, Vol. XVIII.), 4 February 1926, Page 69, Column 1
The XCO-5 has a maximum of 129 miles per hour (208 kilometers per hour) at Sea Level, and a cruise speed of 117 miles per hour (188 kilometers per hour).
¹ FAI Record File Number 8384, Gourdou-Leseurre GL.40, 300 c.v. Hispano Suiza
See also: John Arthur Macready (14 October 1887–15 September 1979) [TDiA No. 1,500]
27 January 1967: During a “plugs out” test of the Apollo 1 Command Module, two weeks ahead of the scheduled launch of the Apollo/Saturn 1B AS-204—the first manned Apollo Program space flight—a fire broke out in the pressurized pure oxygen environment of the capsule and rapidly involved the entire interior.
The pressure rapidly built to 29 pounds per square inch (200 kPa) and 17 seconds later, at 23:31:19.4 UTC, the capsule ruptured.
The three astronauts, Lieutenant Colonel Virgil I. Grissom, United States Air Force, Lieutenant Colonel Edward H. White II, United States Air Force, and Lieutenant Commander Roger B. Chaffee, United States Navy, were killed.
AD ASTRA PER ASPERA
NASA has a detailed summary of the accident and investigation at:
27 January 1957: The last North American Aviation F-51D Mustang fighters in operational service with the United States Air Force were retired from the 167th Fighter Bomber Squadron, West Virginia Air National Guard. The squadron was based at Shepherd Field, Martinsburg, West Virginia (now known as Eastern West Virginia Regional Airport, MRB).
The United Press news service reported:
Aviation Era Ends With Last Official Flight of P51 Mustang
DAYTON, Ohio (UP)— An era in aviation has ended with the last official flight Sunday of a P51 Mustang fighter, pride of American’s [sic] World War II air arsenal.
The flight made by a former Canadian Royal Air Force ace, Major James L. Miller in a P51D, also marked the end of propeller-driven fighter planes in the U.S. Air Force.
Miller took off from nearby Wright Field at 1:30 p.m. Sunday and landed at Patterson Field several miles away 45 minutes later.
Henceforth, the Air Force will use nothing but jet-powered fighters.
The ravages of age prevented a battle-worn Mustang from taking part in decommissioning ceremonies at Wright-Patterson Air Force Base, so a substitute flight had to be arranged.
The Mustang grounded at Cheyenne, Wyo., for repairs, could not take off as scheduled Friday because of bad weather.
The flight to Kansas City on Saturday and to Wright-Patterson on Sunday, had been scheduled for Lt. Col. Joseph T. Crane, commanding officer of the 167th Fighter-Interceptor Squadron [sic] of the West Virginia National Guard.
A quick switch in plans followed, and the Air Force requisitioned the only other P51 available from an airport at Charleston, W. Va. The plane had been earmarked for a city park there.#0000ff;">
44-72948 had just completed repairs at Cheyenne, Wyoming, and was returned to Charleston by the 167th’s commanding officer, Lieutenant Colonel Joseph T. Crane, Jr.
44-72948 (North American Aviation serial number 122-39407) had been delivered to the U.S. Army Air Corps at Mitchel Field, Long Island, New York, in February 1945, but with the war drawing to a close in Europe, the Mustang never flew in combat. According to contemporary newspaper reports, during its career -948 was assigned to sixteen different Air Corps/Air Force units. It underwent nine engine changes and flew a total of 1,555 hours during nearly 12 years of service.
The airplane in the photographs below, North American Aviation F-51D-30-NA 44-74936, was was flown from Charleston to Wright-Patterson Air Force Base, Dayton, Ohio, by Major James Miller. It was transferred to the United States Air Force Museum (renamed National Museum of the United States Air Force in 2004) where it is on display. The fighter is painted with the markings of another Mustang, P-51D-15-NA, 44-15174, Shimmy IV, of the 325th Fighter Group, Fifteenth Air Force, which served in North Africa and Italy during World War II.
On 2 June 1944, the actual Shimmy IV, flown by Colonel Chester L. Sluder, commanding officer of the 325th Fighter Group, led the fighter escorts for the first Fifteenth Air Force “shuttle bombing” mission to attack a railroad mashaling yard at Deprecan, Hungary, before flying on to land at Piriatyn, Ukraine. The name “Shimmy” was from the name of Colonel Sluder’s daughter, Shari, and the nickname of his wife, “Zimmy,” formerly Miss Louise Zimmerman.
On 9 December 1944, 44-15174 was flown by Lieutenant Norval W. Weers, 318th Fighter Squadron, when it ran low on fuel because of adverse weather. Weers crash-landed south of the Neusiedler See, Austria. He was captured and held as a prisoner of war at Stalag Luft I.
The P-51D was the predominant version of the North American Aviation single-place, single-engine, fighter, The P-51D was 32 feet, 3.5 inches (9.843 meters) long, with a wingspan of 37 feet (11.278 meters). It was 13 feet, 4.5 inches (4.077 meters) high. The fighter had an empty weight of 7,635 pounds (3,463 kilograms) and a maximum takeoff weight of 12,100 pounds (5,489 kilograms).
Like the P-51B and C variants, the P-51D was powered by a right-hand tractor, liquid-cooled, supercharged, 1,649-cubic-inch-displacement (27.04-liter) Packard V-1650-3 or -7 Merlin single overhead cam (SOHC) 60° V-12 engine which produced 1,380 horsepower at Sea Level, turning 3,000 r.p.m at 60 inches of manifold pressure (V-1650-3) or 1,490 horsepower at Sea Level, turning 3,000 r.p.m. at 61 inches of manifold pressure (V-1650-7). (Military Power rating, 15 minute limit.) These engines were versions of the Rolls-Royce Merlin 63 and 66, built under license by the Packard Motor Car Company of Detroit, Michigan. The engine drove a four-bladed Hamilton Standard Hydromatic constant-speed propeller with a diameter of 11 feet, 2 inches (3.404 meters) through a 0.479:1 gear reduction.
The P-51D with a V-1650-7 Merlin had maximum speed at Sea Level of 323 miles per hour (520 kilometers per hour) at the Normal Power setting of 2,700 r.p.m. and 46 inches of manifold pressure, and 375 miles per hour (604 kilometers per hour) at War Emergency Power, 3,000 r.p.m with 67 inches of manifold pressure (5 minute limit). At altitude, using the Military Power setting of 3,000 r.p.m. and 61 inches of manifold pressure (15 minute limit), it had a maximum speed of 439 miles per hour (707 kilometers per hour) at 28,000 feet (8,534 meters). With War Emergency Power the P-51D could reach 442 miles per hour (711 kilometers per hour) at 26,000 feet (7,925 meters).
The P-51D could climb to 20,000 feet (6,096 meters) in 6.4 minutes, and to its service ceiling, 41,600 feet (12,680 meters), in 28 minutes. The airplane’s absolute ceiling was 42,400 feet (12,924 meters).
With 180 gallons (681 liters) internal fuel, the maximum range of the P-51D was 1,108 miles (1,783 kilometers).
The P-51D was armed with six Browning AN-M2 .50-caliber machine guns, with three mounted in each wing. 400 rounds of ammunition were provided for the inner pair of guns, and 270 rounds for each of the outer two pairs of guns, for a total of 1,880 rounds. This was armor piercing, incendiary and tracer ammunition. The fighter could also carry a 1,000 pound (453.6 kilogram) bomb under each wing, in place of drop tanks, or up to ten rockets.
North American Aviation, Inc., produced a total of total of 8,156 P-51D Mustangs at Inglewood, California and Dallas, Texas. Another 200 were built by the Commonwealth Aircraft Corporation in Australia.
25 January 1946:¹ Near Pinecastle Army Airfield in central Florida, Bell Aircraft Corporation Senior Experimental Test Pilot Jack Woolams made the first unpowered glide flight of the XS-1 supersonic research rocketplane, 46-062.
46-062 was the first of three XS-1 rocketplanes built by Bell for the U.S. Army Air Corps and the National Advisory Committee for Aeronautics (NACA) to explore flight at speeds at and beyond Mach 1, the speed of sound. The airplane had been rolled out of Bell’s plant at Buffalo, New York, on 27 December 1945. The rocket engine, which was being developed by Reaction Motors, Inc., at Franklin Lakes, New Jersey, was not ready, so the experimental aircraft was carrying ballast in its place for the initial flight tests.
The XS-1 was to be air-dropped from altitude by a modified heavy bomber so that its fuel could be used for acceleration to high speeds at altitude, rather than expended climbing from the surface. Bell manufactured B-29B Superfortresses at its Atlanta, Georgia, plant and was therefore very familiar with its capabilities. A B-29, 45-21800, was selected as the drop ship and modified to carry the rocketplane in its bomb bay.
Pinecastle Army Airfield was chosen as the site of the first flight tests because it had a 10,000 foot (3,048 meter) runway and was fairly remote. There was an adjacent bombing range and the base was a proving ground for such aircraft as the Consolidated B-32 Dominator. (Today, Pinecastle A.A.F. is known as Orlando International Airport, MCO.)
The B-29 carrying the XS-1 took off from Pinecastle at 11:15 a.m., and began its climb to altitude. Woolams was in the forward crew compartment. As the bomber reached approximately 10,000 feet (3,048 meters), he entered the bomb bay and climbed down into the cockpit of the research aircraft. At the drop altitude, the B-29 was flying at 180 miles per hour (290 kilometers per hour) with the inboard propellers feathered and flaps lowered to 20°.
The XS-1 dropped away smoothly. Woolams flew the rocketplane to a maximum 275 miles per hour (443 kilometers per hour), indicated air speed, during this first glide test. He described the rocketplane as, “solid as a rock, experiencing absolutely no vibration or noise. At the same time, it felt as light as a feather during maneuvers due to the lightness, effectiveness and nice balance between the controls.” Woolams described the visibility from the cockpit as “not good, but adequate.”
The duration of the first glide flight was about ten minutes. Woolams misjudged his approach to Pinecastle and landed slightly short of the runway, on the grass shoulder, but the XS-1 was not damaged.
The conclusion of Woolams’ flight report is highly complementary of the experimental airplane:
#000000; font-family: courier new, courier;">11. Of all the airplanes the writer has flown, only the XP-77 and the Heinkel 162 compare with the XS-1 for maneuverability, control relationship, response to control movements, and lightness of control forces. Although these impressions were rather hastily gained during a flight which lasted only 10 minutes, it is the writer’s opinion that due to these factors and adding to them the security which the pilot feels due to the ruggedness, noiselessness, and smoothness of response of this airplane, it is the most delightful to fly of them all.
#0000ff;">#000000;">—PILOT’S REPORT, Flight #1, by Jack Woolams
Jack Woolams made ten glide flights with 46-062, evaluating its handling characteristics and stability. The aircraft was returned to Bell to have the rocket engine installed, and it was then sent to Muroc Army Airfield in the high desert of southern California for powered flight tests. (Muroc A.A.F. was renamed Edwards Air Force Base in 1949.)
Bell XS-1 46-062 was later named Glamorous Glennis by its military test pilot, Captain Charles E. Yeager, U.S. Army Air Corps. On 14 October 1947, Chuck Yeager flew it to Mach 1.06 at 13,115 meters (43,030 feet). Today the experimental aircraft is on display at the Smithsonian Institution National Air and Space Museum.
The Bell XS-1, later re-designated X-1, was the first of a series of rocket-powered research airplanes which included the Douglas D-558-II Skyrocket, the Bell X-2, and the North American Aviation X-15, which were flown by the U.S. Air Force, U.S. Navy, NACA and its successor, NASA, at Edwards Air Force Base to explore supersonic and hypersonic flight and at altitudes to and beyond the limits of Earth’s atmosphere.
The X-1 has an ogive nose, similar to the shape of a .50-caliber machine gun bullet, and has straight wings and tail surfaces. It is 30 feet, 10.98 inches (9.423 meters) long with a wing span of 28.00 feet (8.534 meters) and overall height of 10 feet, 10.20 inches (3.307 meters).
46-062 was built with a thin 8% aspect ratio wing, while 46-063 had a 10% thick wing. The wings were tapered, having a root chord of 6 feet, 2.2 inches (1.885 meters) and tip chord of 3 feet, 1.1 inches (0.942 meters), resulting in a total area of 130 square feet (12.1 square meters). The wings have an angle of incidence of 2.5° with -1.0° twist and 0° dihedral. The leading edges are swept aft 5.05°.
The horizontal stabilizer has a span of 11.4 feet (3.475 meters) and an area of 26.0 square feet (2.42 square meters). 062’s stabilizer has an aspect ratio of 6%, and 063’s, 5%.
The fuselage cross section is circular. At its widest point, the diameter of the X-1 fuselage is 4 feet, 7 inches (1.397 meters).
46-062 had an empty weight is 6,784.9 pounds (3,077.6 kilograms), but loaded with propellant, oxidizer and its pilot with his equipment, the weight increased to 13,034 pounds (5,912 kilograms).
The X-1 was designed to withstand an ultimate structural load of 18g.
The X-1 was powered by a four-chamber Reaction Motors, Inc., 6000C4 (XLR11-RM-3 ) rocket engine which produced 6,000 pounds of thrust (26,689 Newtons). This engine burned a 75/25 mixture of ethyl alcohol and water with liquid oxygen. Fuel capacity is 293 gallons (1,109 liters) of water/alcohol and 311 gallons (1,177 liters) of liquid oxygen. The fuel system was pressurized by nitrogen at 1,500 pounds per square inch (103.4 Bar).
The X-1 was usually dropped from the B-29 flying at 30,000 feet (9,144 meters) and 345 miles per hour (555 kilometers per hour). It fell as much as 1,000 feet (305 meters) before beginning to climb under its own power.
The X-1’s performance was limited by its fuel capacity. Flying at 50,000 feet (15,240 meters), it could reach 916 miles per hour (1,474 kilometers per hour), but at 70,000 feet (21,336 meters) the maximum speed that could be reached was 898 miles per hour (1,445 kilometers per hour). During a maximum climb, fuel would be exhausted as the X-1 reached 74,800 feet (2,799 meters). The absolute ceiling is 87,750 feet (26,746 meters).
The X-1 had a minimum landing speed of 135 miles per hour (217 kilometers per hour) using 60% flaps.
There were 157 flights with the three X-1 rocket planes. The number one ship, 46-062, Glamorous Glennis, made 78 flights. On 26 March 1948, with Chuck Yeager again in the cockpit, it reached reached Mach 1.45 (957 miles per hour/1,540 kilometers per hour) at 71,900 feet (21,915 meters).
The third X-1, 46-064, made just one glide flight before it was destroyed 9 November 1951 in an accidental explosion.
The second X-1, 46-063, was later modified to the X-1E. It is on display at the NASA Dryden Research Center at Edwards Air Force Base. Glamorous Glennis is on display at the Smithsonian Institution National Air and Space Museum, next to Charles A. Lindbergh’s Spirit of St. Louis.
Jack Valentine Woolams was born on Valentine’s Day, 14 February 1917, at San Francisco, California. He was the second of three children of Leonard Alfred Woolams, a corporate comptroller, and Elsa Mathilda Cellarius Woolams. He grew up in San Rafael, California, and graduated from Tamalpais School in 1935.
After two years of study at The University of Chicago, in 1937 Woolams entered the Air Corps, U.S. Army, as an aviation cadet. He trained as a pilot at Kelly Field, San Antonio, Texas. On graduation, 16 June 1938, he was discharged as an aviation cadet and commissioned as a second lieutenant, Air Reserve. He was assigned to Barksdale Army Air Field, Louisiana, where he flew the Boeing P-26 and Curtiss P-36 Hawk.
On 10 February 1939, Lieutenant Woolams was one of three Air Corps officers thrown into the waters of Cross Lake, near Shreveport, Louisiana, when the boat, owned by Woolams, capsized in 4 foot (1.2 meters) waves. Woolams and Lieutenant J.E. Bowen were rescued after 4 hours in the water, but the third man, Lieutenant Wilbur D. Camp, died of exposure.
Lieutenant Woolams transferred from active duty to inactive reserve status in September 1939 in order to pursue his college education at The University of Chicago, where he was a member of the Alpha Delta Phi (ΑΔΦ) fraternity. While at U. of C., he played on the university’s football and baseball teams, and was a member of the dramatic society. Woolams graduated 18 July 1941 with a Bachelor of Arts (A.B.) degree in Economics.
Jack Woolams married Miss Mary Margaret Mayer at the bride’s home in Riverside, Illinois, 16 June 1941. They would have three children. Miss Mayer was also a 1941 graduate from the University of Chicago. She had been Woolams’ student in the Civilian Pilot Training Program.
Woolams became a production test pilot for the Bell Aircraft Corporation at Buffalo, New York. He tested newly-built Bell P-39 Airacobra fighters. As he became more experienced, he transitioned to experimental testing with the P-39, P-63 King Cobra, and the jet-powered P-59 Airacomet.
On 28 September 1942, Jack Woolams flew a highly-modified Bell P-39D-1-BE Airacobra, 41-38287, from March Field, near Riverside, California, to Bolling Field, Washington, D.C., non-stop. The duration of the flight was approximately 11 hours. The modifications were intended to allow P-39s to be flown across the Pacific Ocean to Hawaii and on to the Soviet Union for delivery under Lend Lease.
During the summer of 1943, Woolams flew the first Bell YP-59A Airacomet, 42-108771, to an altitude of 47,600 feet (14,508 meters) near Muroc Army Air Field in California.
On 5 January 1945, Woolams was forced to bail out of a Bell P-59A-1-BE, 44-22616. He suffered a deep laceration to his head as he left the airplane. He lost his flight boots when the parachute opened, and on landing, had to walk barefoot through knee-deep snow for several miles to reach a farm house. The deep snow prevented the company’s ambulance from getting to Woolams. Bell Aircraft president Lawrence D. Bell sent the company’s second prototype Bell Model 30 helicopter, NX41868, flown by test pilot Floyd Carlson, to transport a doctor, J.A. Marriott, M.D., to the location. Another Bell test pilot, Joe Mashman, circled overhead in a P-63 King Cobra to provide a communications link. Later in the day, an ambulance was able to get through the snow to take Woolams to a hospital.
Woolams was scheduled to make the first powered flight of the XS-1 during October 1946.
Jack Woolams was killed Friday, 30 August 1946, when his red Thompson Trophy racer, Cobra I, a modified 2,000-horsepower Bell P-39Q Airacobra, crashed into Lake Ontario at over 400 miles per hour. His body was recovered by the U.S. Coast Guard four days later.
¹ This article was originally dated 19 January 1946. There were known discrepancies as to the date of the first flight from various reliable sources. Recently discovered test flight reports, provided to TDiA by Mr. Roy T. Lindberg, Historian of the Niagara Aerospace Museum, Niagara Falls, New York, have confirmed that the date of the first flight was actually 25 January 1946. The article has been been revised accordingly, as well as to incorporate new information from these reports.
TDiA is indebted to Mr. Lindberg for providing this and other documentation.
23 January 2003: The final, very weak signal from Pioneer 10 was received on January 23, 2003 when it was 12 billion kilometers (80 Astronomical Units) from Earth.
The space probe was launched from Earth at 01:49:00 UTC, 2 March 1972, aboard an Atlas Centaur rocket.
“On January 1, 2016, Pioneer 10 was predicted to be 114.07 a.u. from the Earth (about 10 billion miles); and traveling at 12.04 km/s (26,900 mph) (relative to the Sun) and traveling outward at about 2.54 a.u. per year. Voyager 2 is projected to pass Pioneer 10 by April 2019. Sunlight takes 14.79 hours to reach Pioneer 10. The brightness of the Sun from the spacecraft is magnitude −16.6. Pioneer 10 is heading in the direction of the constellation Taurus.
“If left undisturbed, Pioneer 10 and its sister craft Pioneer 11 will join the two Voyager spacecraft and the New Horizons spacecraft in leaving the Solar System to wander the interstellar medium. The Pioneer 10 trajectory is expected to take it in the general direction of the star Aldebaran, currently located at a distance of about 68 light years. If Aldebaran had zero relative velocity, it would require more than two million years for the spacecraft to reach it.” — Wikipedia