Geosynchronous Drift: Krafft Ehricke's Destination Mankind Apollo Mission (1972)
14 April 2017 David S. F. PortreeApollo 17 launch, 7 December 1972. Image credit: NASA
In May 1972, Krafft Ehricke, Executive Advisor in the Space Division of North American Rockwell Corporation, proposed that the last piloted lunar landing mission, Apollo 17, scheduled for the end of 1972, be postponed until the U.S. Bicentennial in July 1976 and dispatched to a new destination: a geosynchronous orbit (GSO) 22,300 miles above the Earth. An object in a GSO requires one day to complete one revolution of the Earth. Since Earth revolves in one day, an object in equatorial GSO appears to hang over one spot on the equator.
"The mission into geosynchronous orbit," Ehricke declared, would provide "additional return on America's investment in Apollo" by dramatizing "the usefulness of manned orbital activities." He added that his proposal, which he dubbed Destination Mankind, "would inspire many, as did the lunar missions before it, but in a different, perhaps more direct manner, because of its greater relevance to some of the most pressing problems of our time."
Ehricke's Destination Mankind mission reflected a significant shift in the public perception of spaceflight - one which had gained momentum throughout the 1960s. As the Soviet Union decreased its level of piloted space activity - it flew one piloted mission in 1964, one in 1965, none in 1966, and suffered the loss of astronaut Vladimir Komarov at the conclusion of the Soyuz 1 mission in 1967 - many came to question the desirability of the race to the moon.
On 7 March 1970, President Richard Nixon articulated this shift in his "Statement About the Future of the United States Space Program." Nixon said that he believed that the U.S. space program should be devoted to exploration, the pursuit of scientific knowledge, and, crucially, "practical application - turning the lessons we learned in space to the early benefit of life on Earth." The 37th President declared that results of space research should be "used to the maximum advantage of the human community." He listed among the practical applications of spaceflight "surveying crops, locating mineral deposits, and measuring water resources." "The very act of reaching into space can help man improve the quality of life on Earth," Nixon added.
Many in the aerospace community found Nixon's statement and subsequent policies to be unfathomable. Apollo engineers and managers - including NASA Administrator Thomas Paine - had expected to be rewarded for reaching the moon by being given new bold objectives - a permanent space station with a reusable logistics vehicle, a moon base, a piloted Mars mission, or perhaps all three. Instead, NASA funding took repeated hits. Instead of building Mars ships, many of the 440,000 contractor and NASA employees across the United States whose labors had made Apollo a success faced layoffs.
Apollo 17 had not always been the planned last lunar mission; when Nixon took office in January 1969, many expected that advanced Apollo missions would fly as part of the Apollo Applications Program (AAP) well into the 1970s. AAP was meant to include at least two Earth-orbital "workshops" - precursors to a permanent space station - as well as lunar surface missions lasting up to two weeks. By the end of 1970, it was clear that AAP would most likely comprise a single orbital workshop. The workshop flew with the designation Skylab 1 in May 1973. Launched on the last Saturn V rocket to fly, Skylab 1 hosted three three-man crews in 1973-1974.
Ehricke described a representative 12-day Destination Mankind mission. Reaching GSO would require about as much propulsive energy as reaching lunar orbit, he noted. The three-stage Destination Mankind Apollo Saturn V rocket would lift off from Launch Complex 39 at Kennedy Space Center, Florida, at about 8:30 p.m. local time. Following first and second stage operation, the S-IVB third stage would fire briefly to place itself, the Apollo Command and Service Module (CSM), and a Payload Module (PM) into 100-nautical-mile parking orbit. Ehricke did not describe the PM design.
One orbital revolution (about 90 minutes) later, the S-IVB would ignite again to perform Transynchronous Injection (TSI). After S-IVB shutdown, the astronauts would separate their CSM and turn it 180° to dock with the PM, which would be attached to the top of the S-IVB in place of the Apollo Lunar Module (LM). They would then extract the PM, maneuver away from the S-IVB, and settle in for the 5.2-hour coast to GSO. Deep Space Climate Observatory (DSCOVR) image of Africa, the Middle East, India, Europe, and adjacent seas and oceans. Cairo, close to the northern limit of the Destination Mankind Afro-Eurasian Station, is located near the center of the image. DSCOVR images Earth every two hours from Sun-Earth L1, not from geosynchronous orbit. Image credit: NASA
The Destination Mankind CSM would ignite its Service Propulsion System (SPS) main engine to enter a GSO at 31° east longitude. This would place it over the equatorial nation of Uganda - if the CSM entered an equatorial GSO. The mission's GSO would, however, be inclined 28.5° relative to Earth's equator, so the CSM would oscillate between 28.5° south latitude (over South Africa's east coast) and 28.5° north latitude (southwest of Cairo) and back every 24 hours. The CSM would reach its southern limit at 10 a.m. local time and its northern limit at 10 p.m. local time. This 57°-long stretch of the 31° east longitude line would, Ehricke explained, constitute Destination Mankind's "Afro-Eurasian Station."
Destination Mankind mission objectives would fall into three general areas: science, technology, and public relations. Science objectives would draw upon an Apollo Geosynchronous Scientific Experiment Package (AGSEP) carried in the PM. The crew might assess the astronomical value of a GSO observatory, perform high-energy particle experiments, and observe and image the Earth. At the Afro-Eurasian Station, the astronauts could view Africa, Europe, the Middle East, Central Asia, and India. Earth imaging and observation might be conducted in collaboration with observers at "ground truth" sites on land and on ships at sea.
Ehricke emphasized the technology objectives of his Destination Mankind mission. He was particularly enamored of a solar illumination experiment that would see a circular reflector assembled by spacewalking astronauts. The experiment would provide reference data for design and operation of future space-based reflectors, he explained. He calculated that a 100-meter reflector in GSO could light Earth's surface one-tenth as brightly as a full moon in a selected area. This level of illumination, though "subvisual," would be useful for night meteorology and surveillance of border and coastal areas, Ehricke wrote.
The astronauts would also erect "Manstar," a 500-to-700-foot-diameter reflective balloon visible over a wide area of Earth's surface as a modestly bright star. Ehricke called Manstar "a visible manifestation for all mankind of the potential value of space."
Ehricke called public relations "Public Exposure." Destination Mankind astronauts would become television stars. They would describe their Earth observations - "especially aspects useful and of interest to regional populations" - via TV broadcasts from GSO. Their spacewalks would also make for good TV fare, Ehricke judged. Apollo 17 Command Module Pilot Ronald Evans retrieves film and data cassettes from the Scientific Instrument Module Bay built into the side of the Apollo 17 CSM America. Evans' 17 December 1972 spacewalk was the last performed beyond low-Earth orbit. Ehricke's Destination Mankind mission would have included several spacewalks in GSO, where none has yet occurred. Image credit: NASADSCOVR image of North America, South America, and Central America with adjacent oceans and seas. New Orleans, near the northern limit of the Destination Mankind Panamerican-Pacific Station, is located near the center of the image. Image credit: NASA
The Destination Mankind CSM and PM would remain at the Afro-Eurasian Station for an unspecified period (perhaps two days), then the astronauts would fire the CSM's SPS to climb to a slightly higher orbit and begin a two-day "drift" westward across the Atlantic to their Panamerican-Pacific Station. Upon reaching their new station, located at 90° west longitude, the crew would fire the SPS to lower their orbit and halt their drift.
The CSM and PM would oscillate between 28.5° south (over the Pacific off northern Chile) and 28.5° north (over the Gulf of Mexico south of New Orleans), again reaching the southern limit at 10 a.m. local time and the northern limit at 10 p.m. local time. Equatorial crossing would occur above the Galapagos Islands. The astronauts would spend their time much as they did at the Afro-Eurasian Station, then would fire the SPS again to drift westward across the Pacific.DSCOVR image of Australia, east Asia, east Africa, the Middle East, India, and adjacent bodies of water. The Destination Mankind Australo-Asian Station's southern limit would occur over the Indian Ocean off the coast of Perth, Australia, in the lower half of the image, just right of center. Image credit: NASA
The last stop on the Destination Mankind crew's world tour would be the 98° east longitude line, which Ehricke dubbed the Australo-Asian Station. They would reach the north point in their south-north oscillation over southern China and the south point over the east Indian Ocean west of Perth. Near the end of their stay at the Australo-Asian Station, they would discard the PM.
The Destination Mankind crew would return to Earth from the Australo-Asian Station. Using the SPS, they would perform a Trans-Earth Injection burn as their CSM crossed the equator near Sumatra moving north at 4 p.m. local time. Fall to Earth would last 5.2 hours, and splashdown would occur in the Pacific west of Hawaii at just after 6 a.m. local time. Sources
"Destination Mankind: Proposal for a Saturn V - Apollo Mission into Geosynchronous Orbit," K. Ehricke, North American Rockwell, 10 May 1972
The American Presidency Project, "Statement About the Future of the United States Space Program," Richard Nixon, 7 March 1970 - http://www.presidency.ucsb.edu/ws/index.php?pid=2903&st=Future+of+the+United+States+Space+Program&st1=
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