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A Robot 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 Carrier Module (SM) — then the previous reoriented itself with its bowl-shaped warmth protect ahead in order that it would face up to the fiery environment reentry. The SM burned up as deliberate. The CM’s warmth protect, in the meantime, reached a temperature of just about 2760 C (5000° F). Workforce cabin temperature didn’t exceed 21 C (70° F). Simply 8 and a part hours after liftoff, the Apollo 4 CM deployed 3 parachutes and reduced to a splashdown within the Pacific. 

reported that, sarcastically, at the very day of NASA’s Apollo 4 triumph, NASA Marshall Area Flight Middle (MSFC) in Huntsville, Alabama, had laid off employees because of the FY 1968 funds cuts. NASA MSFC used to be the house of the Saturn circle of relatives of rockets. 

On 12 December 1967, a bit greater than a month after Apollo 4, President Lyndon Baines Johnson toured the NASA Michoud Meeting Facility close to New Orleans, Louisiana, an MSFC satellite tv for pc web site the place Saturn rockets have been examined. His consult with used to be intended to reassure native and state officers and to lift employee morale. Whether or not he succeeded is open to interpretation. Status sooner than a partly entire Saturn V S-IC first degree, Johnson informed the employees

. . .that guy will make area his area is inevitable. Whether or not The united states will lead mankind to that future does now not rely on your talent, however relies on our imaginative and prescient, our willingness, and our nationwide will and resolution. This nice pilgrimage of guy — like several his adventures — prices cash. Christopher Columbus spent extra years looking for cash for his voyage than he spent finding the New Global. Within the trendy international, we will be able to not rely on Queen Isabella pawning her jewels. We need to rely on taxes. We should have revenues that best Congress can grant. . . So we can advance in area to the level that our other people and their representatives are ready for us to advance and are ready to pay the price of that advance. We won’t all the time continue on the tempo we want. I remorseful about — I deeply remorseful about — that there were discounts and there shall be extra. There were interruptions. . . However I do have religion and self belief within the American other people.

This background might assist to give an explanation for why two engineers at Bellcomm, NASA’s Washington, DC-based advance making plans contractor, answered as they did when NASA invited them in overdue November-early December 1967, to state their critiques at the direction U.S. planetary exploration must take within the Seventies and early Nineteen Eighties. In a record finished and disbursed to related NASA amenities on 26 February 1968, J. P. Downs and W. B. Thompson have been cautiously constructive. 

Downs and Thompson defined that their record mirrored “the authors’ pondering at. . . [a] specific time” and that it used to be “a mirrored image of a long run viewpoint.” They assumed that the deep FY 1968 funds cuts have been a non permanent, brief setback, now not an indication of a long-term development. In truth, they expected an annual NASA funds of between $5 billion and $6 billion through FY 1971 or FY 1972, when, they anticipated, NASA would get started construction of a piloted planetary program.

On the similar time, the Bellcomm engineers cautioned that “[a]s additional info turns into to be had on technical main points and assets, this system might exchange.” They added, on the other hand, that “the explanation expressed. . . is anticipated to stay a lot as it’s now.”

Downs and Thompson described a NASA planetary program containing 21 missions to 11 Sun Device our bodies between the years 1969 and 1984. Missions would happen in 3 “branches.” The primary department would contain missions to Venus and Mars that may function precursors to a minimum of 3 piloted Mars and Venus missions. The second one would discover Mercury, Jupiter, and the opposite “main planets” (Saturn, Uranus, and Neptune), a role they known as “the most important problem to the unmanned program.” The 3rd department would discover two comets and two asteroids. 

Their program would start with the dual Mariner ’69 Mars flybys already on NASA’s agenda and proceed in 1970 with a Mariner Venus/Mercury twin flyby venture introduced on an Atlas/Centaur rocket. The Atlas/Centaur used to be already in early 1968 the workhorse of the NASA robot lunar and planetary program. 

The Venus/Mercury venture, which might shape a part of each the primary and 2nd of Downs and Thompson’s branches, would search gaps in Venus’s cloud duvet within the hope of glimpsing its mysterious floor. As well as, because the spacecraft flew previous the planet, it might transmit radio indicators to Earth during the Venusian environment in an try to chart its construction.

Mariner Mars ’69 engineering fashion. Notice the massive steerable digital camera “pod” fixed beneath the hexagonal bus frame, the high-gain dish antenna on best, and the 4 sun arrays. Symbol credit score: NASA.
Area workhorse: an Atlas-Centaur rocket launches the Surveyor 1 lunar lander on 30 Would possibly 1966. Symbol credit score: NASA.

Throughout the flyby, Venus would give the spacecraft a gravity help that would scale back through between about 50% and 75% the volume of propulsive power wanted to succeed in Mercury. Downs and Thompson defined that the innermost planet is, through dint of its proximity to the Solar, incessantly misplaced in glare when considered from Earth and therefore mysterious; orbiting with reference to the Solar additionally signifies that its orbital velocity is excessive, making it tricky for spacecraft to succeed in.

In 1971, NASA would release on a Titan III-C rocket its first new-design Mars orbiter and floor probe. Downs and Thompson recommended that the brand new orbiter may well be in keeping with the Boeing Lunar Orbiter design. The Titan III-C, a U.S. Air Power rocket, used to be intended to exchange the Saturn IB-Centaur rocket previously emphasised in NASA planetary venture plans. Use of the Titan III-C used to be a reaction to a remark through NASA Administrator James Webb that the Saturn IB can be phased out to save cash. 

18 June 1965: the primary Titan III-C rocket stands at the pad at Release Advanced 40, Cape Canaveral Air Power Station, Florida. Symbol credit score: U.S. Air Power.

The 159-kilogram (350-pound) battery-powered survivable floor impactor probe would come with an environment access shell, a parachute, a protecting affect shell carved from comfortable, light-weight balsa wooden, and 13 kilos of science tools. Those may come with a lifestyles detection tool. Tools at the access shell would  chart atmospheric construction because it plummeted towards the outside after separation from the impactor. Those knowledge can be implemented to permit engineers to design heavier, extra refined Mars landers. 

NASA would release in 1972 its first new-design Venus orbiter and atmospheric probe on a Titan III-C. Along with “a concentrated seek over all the planet for visual get admission to to the outside,” the orbiter would make use of an imaging radar to chart floor topography. The probe would measure the thermodynamic homes of the ambience to permit design of meteorological balloon probes suited for Venusian stipulations.

In 1973, NASA would ramp up the tempo through launching on 3 Titan III-Cs a couple of Mars orbiter/impactor probe missions and a 2nd Mariner-derived Venus/Mercury flyby spacecraft. The latter would resemble that introduced in 1970 however would upload a Venus survivable floor impactor probe. The high purpose of the Mars probes can be to seek for lifestyles. 

The 600-pound Venus impactor probe would try to go back knowledge on this planet’s harsh floor stipulations for no less than an hour. The dense Venusian environment would, Downs and Thompson wrote, permit a survivable touchdown with out a parachute.

The next yr, NASA would release its first flyby venture to Jupiter on a Titan III-C augmented with a Centaur higher degree. Dubbed a “galactic Jupiter probe,” it will be the first NASA spacecraft designed for an operational life of as much as 10 years. It will survey interplanetary debris and fields and help long run spacecraft designers through surveying the interplanetary meteoroid atmosphere with specific emphasis at 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 through launching 4 rockets — most definitely Titan III-Cs with Centaur higher levels. An orbiter and floor probe would depart Earth for Mars. Two orbiters with affect lander probes would release to Venus. The gap company would additionally release a clone of the 1974 galactic Jupiter probe venture.

The yr 1976 would see NASA’s first venture to a comet. After release on an Atlas/Centaur, a Mariner-derived spacecraft would race previous Comet d’Arrest. Downs and Thompson urged that the small measurement of the comet nucleus and the fast velocity of the comet flyby will require NASA to increase an advanced new monitoring device for its comet spacecraft cameras.

In 1977, the primary Mariner-derived “Grand Excursion” spacecraft would go away Earth on a Titan III-C/Centaur. A sequence of gravity-assist flybys would velocity it around the outer Sun Device, enabling it to discover all 4 planets past the Asteroid Belt within the area of a decade. That very same yr, NASA would release on two Titan III-C/Centaur rockets a Mars orbiter with an impactor and a Venus orbiter with a couple of impactors. The Venus impactors may well be centered to land on high-elevation floor options; those may, Downs and Thompson recommended, have cooler temperatures than decrease elevations, and thus be much more likely to fortify lifestyles.

The yr 1978 would see release of NASA’s first asteroid venture (a flyby of asteroid Icarus the usage of the Mariner-derived spacecraft introduced on a Atlas/Centaur) and the second one “Grand Excursion” venture (a clone of the 1977 venture). It will additionally see an vital shift within the personality of the U.S. planetary program as astronauts joined the motion. 

Thompson used to be a veteran of the NASA OMSF Planetary JAG piloted flyby research. The NASA funds appeared not likely to stretch a ways sufficient to fortify construction in time for the Planetary JAG’s 1975 piloted planetary venture, so the Bellcomm engineers opted as an alternative to profit from a Venus/Mars/Venus flyby alternative beginning in overdue 1978. 

The piloted flyby spacecraft and its Earth-orbit departure booster stack can be assembled in Earth orbit the usage of elements introduced on two-stage Saturn V rockets. After leaving Earth orbit and discarding its boosters, it might apply a free-return heliocentric trail that may finish at Earth. Most effective minor direction corrections can be required after Earth-orbit departure.

In 1979, the staff of the piloted flyby spacecraft would deploy automatic meteorological balloons and impactor probes as they handed Venus for the primary time and automatic pattern returners as they handed Mars. The balloons would flow the Venusian environment for an extended duration. They might search proof of lifestyles in cool environment layers. 

Astronauts would read about in a sealed lab the Mars dust and air the pattern returners introduced to the flyby spacecraft to decide whether or not they might be safely returned to laboratories on Earth. The next yr (1980) would see the venture perform its 2nd Venus flyby — a clone of the primary — adopted a couple of months later through an immediate Earth-atmosphere reentry.

The years 1979 and 1980 would additionally see the closing two Mariner-derived comet/asteroid flyby missions at the Downs and Thompson agenda. The primary, the closing venture introduced on an Atlas/Centaur, would consult with asteroid Eros, whilst the second one, introduced on a Titan III-C/Centaur, would race previous Comet Encke.

A 2nd piloted flyby venture would go away Earth in 1981. Throughout its Venus flybys in that yr and in 1983 it might deploy a couple of balloon-borne “a number of thousand pound” Buoyant Venus Stations of a kind proposed through the Martin Corporate in 1967, in addition to an unspecified collection of long-duration Venus landers. All would search for lifestyles. The Mars flyby in 1982 would see extra floor pattern assortment and observations adapted towards deciding on websites for eventual piloted Mars landings.

Downs and Thompson anticipated that their 1984 piloted planetary venture, the closing on their agenda, would most definitely take the type of a Venus orbiter. A piloted Venus venture would, they wrote, “serve to tempo the improvement of a excessive power area storable propulsion device.” After proving that it would gradual the piloted Venus spacecraft in order that Venus’s gravity may seize it into orbit and boost up it out of Venus orbit again towards Earth, the compact, robust, long-lived rocket degree would propel piloted Mars orbiter and touchdown missions and spice up out of Earth orbit massive new-design robot outer planet and “deep area” spacecraft.

The Bellcomm engineers’ record landed on desks throughout NASA in overdue February. Their timing will have been higher — slightly a month forward of its distribution North Vietnam attacked South Vietnam at the eve of Tet, the Chinese language New Yr, resulting in very much expanded U.S. involvement within the Vietnam Struggle. The Tet Offensive created new power at the Federal handbag, serving to to make sure (amongst different issues) that NASA’s funds slide would proceed in FY 1969 and past.  

Regardless of the struggle and different nationwide demanding situations, within the duration lined through the Downs and Thompson plan NASA controlled to fly a dozen planetary missions, of which 11 reached their goals. Largely, those have been justified with regards to keeping off new Soviet area victories and offering an road for the improvement of recent generation with protection implications. 

The entire flown missions have been directed towards main planets; none would consult with asteroids or comets and (after all) none would come with astronauts. Italicized preliminary dates given beneath are release years.

  • 1969: The Mariner ’69 Mars flyby spacecraft have been designated Mariner 6 and Mariner 7 after release; they left Earth atop Atlas/Centaur rockets.
  • 1971: The Mariner ’71 Mars orbiter spacecraft have been designated Mariner 8 and Mariner 9 after release; Mariner 8’s Atlas/Centaur rocket malfunctioned however Mariner 9, the primary planetary orbiter, used to be a perfect luck, mapping all of Mars till overdue 1972.
  • 1972: Pioneer 10, introduced on an Atlas/Centaur rocket with a solid-propellant kick degree, changed into the primary spacecraft to traverse the Asteroid Belt;  in 1973, it changed into the primary spacecraft to fly previous Jupiter. The gravity-assist kick it won made it the primary spacecraft put on a trail to flee the Sun Device.
  • 1973: Pioneer 11 adopted Pioneer 10 during the Asteroid Belt to Jupiter; in 1979 it changed into 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 changed into the primary spacecraft to fly previous Mercury. It flew previous Mercury two times extra in 1974-1975.
  • 1975: Viking 1 and Viking 2, every of which comprised a lander and a Mariner-derived orbiter, introduced 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, used to be the primary a hit Mars lander; Viking 2 landed effectively on 3 September 1976. Their lifestyles detection experiments yielded equivocal effects.
  • 1977: The Mariner Jupiter-Saturn ’77 spacecraft have 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) introduced atop Atlas/Centaur rockets. Regardless that now not designed to live on touchdown, one PVM small probe endured to function after placing the outside, turning into the primary (to this point best) a hit U.S. Venus lander.
The Pioneer Venus Multiprobe bus (decrease proper) is proven deploying 3 small probes (middle) and one massive probe (higher left). In truth the massive probe used to be deployed on 16 November 1978 and the small probes have been deployed on 20 November 1978. The bus and probes entered the Venusian environment on 9 December 1978. Symbol credit score: NASA.

Of their record, Downs and Thompson expected that NASA can be given the go-ahead to begin a brand new piloted planetary program in FY 1971 or  FY 1972, and after a manner they have been right kind. In January 1972, President Richard Nixon known as on Congress to fund the winged Earth-orbital Area Go back and forth. 

At first proposed as a low cost absolutely reusable Area Station staff rotation and resupply automobile, the Go back and forth changed into as an alternative a multi-purpose spacecraft after Nixon refused to fund a Area Station. It will be best semi-reusable, which reduced its construction price however dramatically greater its operations price. Amongst its targets used to be to release all U.S. robot planetary spacecraft.

Downs and Thompson’s NASA funds prediction — $5-6 billion yearly through about FY 1972 — solely overlooked the mark. In the case of purchasing energy in an inflationary time, NASA’s funds remained at about part that quantity all over the Seventies and early-to-mid Nineteen Eighties. Investment shortage adversely impacted each Go back and forth construction and planetary exploration. 

Go back and forth construction issues traceable to investment shortfalls, loss of a hit new Soviet planetary missions, tight planetary science budgets, and the Challenger coincidence (28 January 1986) got here in combination to create an 11-year hiatus in new U.S. planetary launches following the 1978 Pioneer launches. The stoppage ended ultimately with the release of the Magellan Venus radar mapper on board the Go back and forth Orbiter Atlantis on 4 Would possibly 1989. 

By the point Magellan flew, NASA had introduced that it might stop Go back and forth planetary launches after it introduced the Galileo Jupiter orbiter and probe and Europe’s Ulysses sun polar orbiter in choose of resuming planetary launches on expendable rockets. Galileo introduced on board the Orbiter Atlantis on 18 October 1989 and Ulysses introduced on board the Orbiter Discovery on 6 October 1990. 


The primary two sentences of this publish are in keeping with the primary sentence of Charles Dickens’ 1859 novel A Story of Two Towns.

The Area Program within the Put up-Apollo Duration: A Record of the President’s Science Advisory Committee, “Ready through the Joint Area Panels,” The White Space, February 1967.

“Science Advisers Urge Balanced Program,” Aviation Week & Area Era, 6 March 1967, pp. 133-137.

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

“Washington Roundup: NASA Thank you You,” Aviation Week & Area Era, 20 November 1967, p. 25.

“Apollo 4 Closes Gaps to Lunar Challenge,” W. J. Normyle, Aviation Week & Area Era, 20 November 1967, p. 26-27.

“NASA Pushes Planetary Program,” W. J. Normyle, Aviation Week & Area Era, 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 ( — 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.

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

Extra Knowledge

“Crucial Information”: A 1963 Pitch to Amplify NASA’s Robot Exploration Methods

NASA’s Planetary Joint Motion Workforce Piloted Mars Flyby Learn about (1966)

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

“Assuming That The whole thing Is going Completely Smartly within the Apollo Program. . .” (1967)

The First Voyager (1967)

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

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

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