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A Robotic and Piloted Planetary Exploration Program for the Seventies and Early Nineteen Eighties (1968)

CSM-017 cut up into its part modules — Command Module (CM) and Service Module (SM) — then the previous reoriented itself with its bowl-shaped warmth protect ahead in order that it may stand up to fiery environment reentry. The SM burned up as deliberate. The CM’s warmth protect, in the meantime, reached a temperature of almost 2760 C (5000° F). Crew cabin temperature didn’t exceed 21 C (70° F). Simply eight and a half hours after liftoff, the Apollo 4 CM deployed three parachutes and lowered to a splashdown within the Pacific. 

reported that, paradoxically, on the very day of NASA’s Apollo 4 triumph, NASA Marshall House Flight Heart (MSFC) in Huntsville, Alabama, had laid off staff because of the FY 1968 funds cuts. NASA MSFC was the house of the Saturn household of rockets. 

On 12 December 1967, a bit of greater than a month after Apollo 4, President Lyndon Baines Johnson toured NASA’s Michoud Meeting Facility close to New Orleans, Louisiana, the place Saturn rockets had been assembled and examined. His go to was meant to reassure native and state officers and to lift employee morale. Whether or not he succeeded is open to interpretation. Standing earlier than {a partially} full Saturn V S-IC first stage, Johnson informed the employees

. . .that man will make house his area is inevitable. Whether or not America will lead mankind to that future doesn’t rely in your capacity, however is dependent upon our imaginative and prescient, our willingness, and our nationwide will and willpower. This nice pilgrimage of man — like all his adventures — prices cash. Christopher Columbus spent extra years looking for cash for his voyage than he spent discovering the New World. Within the trendy world, we will now not rely on Queen Isabella pawning her jewels. We now have to rely on taxes. We should have revenues that solely Congress can grant. . . So we’ll advance in house to the extent that our individuals and their representatives are ready for us to advance and are ready to pay the price of that advance. We could not all the time proceed on the tempo we need. I remorse — I deeply remorse — that there have been reductions and there can be extra. There have been interruptions. . . However I do have religion and confidence within the American individuals.

This background could assist to clarify why two engineers at Bellcomm, NASA’s Washington, DC-based advance planning contractor, responded as they did when NASA invited them in late November-early December 1967, to state their opinions on the course U.S. planetary exploration ought to take within the Seventies and early Nineteen Eighties. In a report accomplished and distributed to related NASA amenities on 26 February 1968, J. P. Downs and W. B. Thompson had been cautiously optimistic. 

Downs and Thompson defined that their report mirrored “the authors’ considering at. . . [a] explicit time” and that it was “a mirrored image of a long run standpoint.” They assumed that the deep FY 1968 funds cuts had been a short-term, momentary setback, not an indication of a long-term pattern. Actually, they anticipated an annual NASA funds of between $5 billion and $6 billion by FY 1971 or FY 1972, when, they anticipated, NASA would begin growth of a piloted planetary program.

On the identical time, the Bellcomm engineers cautioned that “[a]s extra info turns into accessible on technical particulars and sources, this system could change.” They added, nonetheless, that “the rationale expressed. . . is anticipated to stay a lot as it’s now.”

Downs and Thompson described a NASA planetary program containing 21 missions to 11 Photo voltaic System our bodies between the years 1969 and 1984. Missions would happen in three “branches.” The primary department would comprise missions to Venus and Mars that will function precursors to not less than three piloted Mars and Venus missions. Missions within the second department would discover Mercury, Jupiter, and the opposite “main planets” (Saturn, Uranus, and Neptune), a process they referred to as “the key problem to the unmanned program.” The third department would come with missions to discover two comets and two asteroids. 

Their program would start with the dual Mariner ’69 Mars flybys already on NASA’s schedule and proceed in 1970 with a Mariner Venus/Mercury twin flyby mission launched on an Atlas/Centaur rocket. The Atlas/Centaur was already in early 1968 the workhorse of the NASA robotic lunar and planetary program. 

The Venus/Mercury mission, which might kind a part of each the primary and second of Downs and Thompson’s three branches, would search gaps in Venus’s cloud cowl within the hope of glimpsing its mysterious floor. As well as, because the spacecraft flew previous the planet, it will transmit radio alerts to Earth by means of the Venusian environment in an try and chart its construction.

Mariner Mars ’69 engineering mannequin. Be aware the big steerable digicam “pod” mounted under the hexagonal bus physique, the high-gain dish antenna on prime, and the 4 photo voltaic arrays. Picture credit score: NASA.
House workhorse: an Atlas-Centaur rocket launches the Surveyor 1 lunar lander on 30 Might 1966. Picture credit score: NASA.

In the course of the flyby, Venus would give the spacecraft a gravity help that would cut back by between 50% and 75% the quantity of propulsive vitality it will want to succeed in Mercury. Downs and Thompson defined that the innermost planet is, by dint of its proximity to the Solar, usually misplaced in glare when seen from Earth and therefore mysterious; orbiting near the Solar additionally implies that its orbital pace is excessive, making it troublesome for spacecraft to succeed in.

In 1971, NASA would launch on a Titan III-C rocket its first new-design Mars orbiter and floor probe. Downs and Thompson instructed that the brand new orbiter may be based mostly on the Boeing Lunar Orbiter design. The Titan III-C, a U.S. Air Pressure rocket, was meant to switch the Saturn IB-Centaur rocket previously emphasised in NASA planetary mission plans. Use of the Titan III-C within the Downs and Thompson program was a response to an announcement by NASA Administrator James Webb that the Saturn IB could be phased out to save cash. 

18 June 1965: the primary Titan III-C rocket stands on the pad at Launch Advanced 40, Cape Canaveral Air Pressure Station, Florida. Picture credit score: U.S. Air Pressure.

The 159-kilogram (350-pound) battery-powered survivable floor impactor probe would come with an environment entry shell, a parachute, a protecting affect shell carved from delicate, light-weight balsa wooden, and 13 kilos of science devices. These may embody a life detection gadget. Devices on the entry shell would  chart atmospheric construction because it plummeted towards the floor after separation from the impactor. These knowledge would allow engineers to design heavier, extra subtle Mars landers. 

NASA would launch in 1972 its first new-design Venus orbiter and atmospheric probe on a Titan III-C. Along with “a concentrated search over the whole planet for seen entry to the floor,” the orbiter would make use of an imaging radar to chart floor topography. The probe would measure the thermodynamic properties of the environment to allow design of meteorological balloon probes suited to Venusian situations.

In 1973, NASA would ramp up the tempo by launching on three Titan III-Cs a pair of Mars orbiter/impactor probe missions and a second Mariner-derived Venus/Mercury flyby spacecraft. The latter would resemble that launched in 1970 however would add a Venus survivable floor impactor probe. The prime goal of the Mars impactor probes could be to seek for life. 

The 600-pound Venus impactor probe would try and return knowledge on the planet’s harsh floor situations for not less than an hour. The dense Venusian environment would, Downs and Thompson wrote, allow a survivable touchdown with no parachute.

The next yr, NASA would launch its first flyby mission to Jupiter on a Titan III-C augmented with a Centaur higher stage. Dubbed a “galactic Jupiter probe,” it will be the primary NASA spacecraft designed for an operational lifetime of as much as 10 years. It will survey interplanetary particles and fields and help future spacecraft designers by surveying the interplanetary meteoroid setting with explicit emphasis on the Asteroid Belt between Mars and Jupiter. A Jupiter gravity-assist would make it the primary spacecraft to flee the gravitational grip of the Solar.

NASA would ramp up the planetary exploration tempo in 1975 by launching 4 rockets — most likely Titan III-Cs with Centaur higher phases. An orbiter and floor probe would go away Earth for Mars. Two orbiters with affect lander probes would launch to Venus. The house company would additionally launch a clone of the 1974 galactic Jupiter probe mission.

The yr 1976 would see NASA’s first mission to a comet. After launch on an Atlas/Centaur, a Mariner-derived spacecraft would race previous Comet d’Arrest. Downs and Thompson defined that the small dimension of the comet nucleus and the fast pace of the flyby would require NASA to develop a complicated new monitoring system for its comet spacecraft cameras.

In 1977, the primary Mariner-derived “Grand Tour” spacecraft would depart Earth on a Titan III-C/Centaur. A collection of gravity-assist flybys would pace it throughout the outer Photo voltaic System, enabling it to discover all 4 planets past the Asteroid Belt within the house of a decade. That very same yr, NASA would launch on two Titan III-C/Centaur rockets a Mars orbiter with an impactor and a Venus orbiter with a pair of impactors. The Venus impactors may be focused to land on high-elevation floor options; these may, Downs and Thompson instructed, have cooler temperatures than decrease elevations, and thus be extra prone to help life.

The yr 1978 would see launch of NASA’s first asteroid mission (a flyby of asteroid Icarus utilizing a Mariner-derived spacecraft launched on a Atlas/Centaur) and the second “Grand Tour” mission (a clone of the 1977 mission). It will additionally see an vital shift within the character of the U.S. planetary program as astronauts joined the motion. 

Thompson was a veteran of the NASA OMSF Planetary JAG piloted flyby research. The NASA funds appeared unlikely to stretch far sufficient to help growth in time to hold out the Planetary JAG’s 1975 piloted Mars flyby mission, so the Bellcomm engineers opted as an alternative to reap the benefits of a chance to launch a piloted Venus/Mars/Venus flyby mission in late 1978. 

The piloted flyby spacecraft and its Earth-orbit departure booster stack could be assembled in Earth orbit utilizing parts launched on two-stage Saturn V rockets. After leaving Earth orbit and discarding its boosters, it will comply with a free-return heliocentric path that will finish at Earth. Solely minor course corrections could be required after Earth-orbit departure.

In 1979, the crew of the piloted flyby spacecraft would deploy automated meteorological balloons and impactor probes as they handed Venus for the primary time and automatic pattern returners as they handed Mars. The balloons would drift the Venusian environment for a protracted interval. They might search proof of life in cool environment layers. 

Astronauts would study in a sealed lab the Mars filth and air the pattern returners launched to the flyby spacecraft to find out whether or not they may very well be safely returned to laboratories on Earth. The next yr (1980) would see the mission perform its second Venus flyby — a clone of the primary — adopted a number of months later by a direct Earth-atmosphere reentry.

The years 1979 and 1980 would additionally see the final two Mariner-derived comet/asteroid flyby missions on the Downs and Thompson schedule. The primary, the final mission launched on an Atlas/Centaur, would go to asteroid Eros, whereas the second, launched on a Titan III-C/Centaur, would race previous Comet Encke.

A second piloted flyby mission would depart Earth in 1981. Throughout its Venus flybys in that yr and in 1983 it will deploy a pair of balloon-borne “a number of thousand pound” Buoyant Venus Stations of a sort proposed by the Martin Firm in 1967, in addition to an unspecified variety of long-duration Venus landers. All would search for life. The Mars flyby in 1982 would see extra floor pattern assortment and observations tailor-made towards choosing websites for eventual piloted Mars landings.

Downs and Thompson anticipated that their 1984 piloted planetary mission, the final on their schedule, would most likely take the type of a Venus orbiter. A piloted Venus mission would, they wrote, “serve to tempo the event of a excessive vitality house storable propulsion system.” After proving that it may gradual the piloted Venus spacecraft in order that Venus’s gravity may seize it into orbit and speed up it out of Venus orbit again towards Earth, the compact, highly effective, long-lived rocket stage would propel piloted Mars orbiter and touchdown missions and enhance out of Earth orbit massive new-design robotic outer planet and “deep house” spacecraft.

The Bellcomm engineers’ report landed on desks throughout NASA in late February. Their timing may have been higher — barely a month forward of its distribution North Vietnam attacked South Vietnam on the eve of Tet, the Chinese language New Yr, resulting in enormously expanded U.S. involvement within the Vietnam Battle. The Tet Offensive created new strain on the Federal purse, serving to to make sure (amongst different issues) that NASA’s funds slide would proceed in FY 1969 and past.  

Regardless of the conflict and different nationwide challenges, within the interval lined by the Downs and Thompson plan NASA managed to fly a dozen planetary missions, of which 11 reached their targets. Largely, these had been justified by way of heading off new Soviet house victories and offering an avenue for the event of recent know-how with protection implications. 

All of the flown missions had been directed towards main planets; none would go to asteroids or comets and (after all) none would come with astronauts. Italicized preliminary dates given under are launch years.

  • 1969: The Mariner ’69 Mars flyby spacecraft had been designated Mariner 6 and Mariner 7 after launch; they left Earth atop Atlas/Centaur rockets.
  • 1971: The Mariner ’71 Mars orbiter spacecraft had been designated Mariner 8 and Mariner 9 after launch; Mariner 8’s Atlas/Centaur rocket malfunctioned however Mariner 9, the primary planetary orbiter, was a terrific success, mapping all of Mars till late 1972.
  • 1972: Pioneer 10, launched on an Atlas/Centaur rocket with a solid-propellant kick stage, grew to become the primary spacecraft to traverse the Asteroid Belt;  in 1973, it grew to become the primary spacecraft to fly previous Jupiter. The gravity-assist kick it acquired made it the primary spacecraft positioned on a path to flee the Photo voltaic System.
  • 1973: Pioneer 11 adopted Pioneer 10 by means of the Asteroid Belt to Jupiter; in 1979 it grew to become the primary spacecraft to fly previous Saturn.
  • 1973: Mariner 10 left Earth on an Atlas/Centaur rocket and flew previous Venus in early 1974; later that yr it grew to become the primary spacecraft to fly previous Mercury. It flew previous Mercury twice extra in 1974-1975.
  • 1975: Viking 1 and Viking 2, every of which comprised a lander and a Mariner-derived orbiter, launched atop Titan III-E rockets, arriving in Mars orbit in June 1976 and August 1976, respectively. Viking 1, which touched down on 20 July 1976, was the primary profitable Mars lander; Viking 2 landed efficiently on 3 September 1976. Their life detection experiments yielded equivocal outcomes.
  • 1977: The Mariner Jupiter-Saturn ’77 spacecraft had been renamed Voyager 1 and Voyager 2. They left Earth atop Titan III-E rockets. Voyager 1 flew previous Jupiter in 1979 and Saturn in 1980; Voyager 2 flew previous Jupiter in 1979, Saturn in 1981, Uranus in 1986, and Neptune in 1989.
  • 1978: Pioneer Venus Orbiter and Pioneer Venus Multiprobe (PVM) launched atop Atlas/Centaur rockets. Although not designed to outlive touchdown, one PVM small probe continued to function after hanging the floor, turning into the primary (up to now solely) profitable U.S. Venus lander.
The Pioneer Venus Multiprobe bus (decrease proper) is proven deploying three small probes (middle) and one massive probe (higher left). In actuality the big probe was deployed on 16 November 1978 and the small probes had been deployed on 20 November 1978. The bus and probes entered the Venusian environment on 9 December 1978. Picture credit score: NASA.

Of their report, Downs and Thompson anticipated that NASA could be given the go-ahead to begin a brand new piloted planetary program in FY 1971 or  FY 1972, and after a vogue they had been appropriate. In January 1972, President Richard Nixon referred to as on Congress to fund the winged Earth-orbital House Shuttle. 

Initially proposed as a low-cost absolutely reusable House Station crew rotation and resupply car, the Shuttle grew to become as an alternative a multi-purpose spacecraft after Nixon refused to fund a House Station. It will be solely semi-reusable, which lowered its growth price however dramatically elevated its operations price. Amongst its objectives was to launch all U.S. robotic planetary spacecraft.

Downs and Thompson’s NASA funds prediction — $5-6 billion yearly by about FY 1972 — solely missed the mark. By way of shopping for energy in an inflationary time, NASA’s funds remained at about half that quantity all through the Seventies and early-to-mid Nineteen Eighties. Funding shortage adversely impacted each Shuttle growth and planetary exploration. 

Shuttle growth issues traceable to funding shortfalls, lack of profitable new Soviet planetary missions, tight planetary science budgets, and the Challenger accident (28 January 1986) got here collectively to create an 11-year hiatus in new U.S. planetary launches following the 1978 Pioneer launches. The stoppage ended ultimately with the launch of the Magellan Venus radar mapper on board the Shuttle Orbiter Atlantis on 4 Might 1989. 

By the point Magellan flew, NASA had introduced that it will stop Shuttle planetary launches after it launched the Galileo Jupiter orbiter and probe and Europe’s Ulysses photo voltaic polar orbiter in favor of resuming planetary launches on expendable rockets. Galileo launched on board the Orbiter Atlantis on 18 October 1989 and Ulysses launched on board the Orbiter Discovery on 6 October 1990. 


The primary two sentences of this submit are based mostly on the primary sentence of Charles Dickens’ 1859 novel A Story of Two Cities.

The House Program within the Submit-Apollo Interval: A Report of the President’s Science Advisory Committee, “Ready by the Joint House Panels,” The White Home, February 1967.

“Science Advisers Urge Balanced Program,” Aviation Week & House Know-how, 6 March 1967, pp. 133-137.

“Orbiters Studied for Planetary Missions,” W. J. Normyle, Aviation Week & House Know-how, 23 October 1967, pp. 30-32.

“Washington Roundup: NASA Thanks You,” Aviation Week & House Know-how, 20 November 1967, p. 25.

“Apollo 4 Closes Gaps to Lunar Mission,” W. J. Normyle, Aviation Week & House Know-how, 20 November 1967, p. 26-27.

“NASA Pushes Planetary Program,” W. J. Normyle, Aviation Week & House Know-how, 27 November 1967, pp. 16-17.

“Remarks Following an Inspection of NASA’s Michoud Meeting Facility Close to New Orleans,” President Lyndon Baines Johnson, 12 December 1967 (https://www.presidency.ucsb.edu/paperwork/remarks-following-inspection-nasas-michoud-assembly-facility-near-new-orleans — accessed 30 August 2022).

“A Possible Planetary Exploration Program Via 1980 — Case 710,” J. P. Downs and W. B. Thompson, Bellcomm, Inc., 26 February 1968.

Astronautics & Aeronautics 1967, NASA SP-4008, 1968, pp. 43-45, 246, 248, 255-256, 282-284, 295-296, 314, 320, 323-324, 333, 336-343, 352-353, 373-375.

Phases to Saturn: A Technological Historical past of the Apollo/Saturn Launch Automobiles, NASA SP-4206, Roger E. Bilstein, NASA, 1980, pp. 351-360.

Extra Info

“Important Information”: A 1963 Pitch to Broaden NASA’s Robotic Exploration Applications

NASA’s Planetary Joint Motion Group Piloted Mars Flyby Research (1966)

Missions to Comet d’Arrest & Asteroid Eros within the Seventies (1966)

“Assuming That Every thing Goes Completely Effectively within the Apollo Program. . .” (1967)

The First Voyager (1967)

Triple Flyby: Venus-Mars-Venus Piloted Missions within the Late Seventies/Early Nineteen Eighties (1967)

Issues to Do Throughout a Venus-Mars-Venus Piloted Flyby Mission (1968)



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