PARSECS
From The Space Library
PARSECS (Program For Astronomical Research and Scientific Experiments Concerning Space) was first proposed in early 1958. Spokesmen were Henry K. Hebeler and Richard S. White. In April 1960 Wellwood E. Beall presented the advanced concepts for PARSECS to the Society Of Automotive Engineers. The planetary vehicle would use a low thrust nuclear powered propulsion system, at the end of a boom, thus utilizing distance for radioactive shielding.
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Mission I—Satellite Observatory
Mission I in Project Parsecs is the manned Earth Satellite Observatory. In some missions there were both unmanned and manned versions. However, this program was intended to stay in advance of early 1960s activities such as Explorer, Pioneer, Discoverer, Tiros, Transit or the NASA unmanned Orbiting Satellite Observatory. The research objectives for Mission I are:
- a) Better view of the cosmos in the visible spectrum via unobscured telescopic observations.
- b) Ability to see in invisible radiation bands with spectroscopic techniques.
- c) Advanced geophysical research by means of orbital data plus direct observations of earth.
- d) Weather observation and control, the latter with experimental giant sun-reflectors.
- e) Communication facility to further world-wide radio-TV.
- f) Research station, utilizing the ready-made space tools of vacuum and cryogenic temperatures.
The space vehicle concept for Mission I is based on a general-purpose nuclear-powered capsule fitted with appropriate instrumentation.
Mission II—Moon Colony
Mission II creates the Moon Colony. The exact order in which these missions will occur would be subject to a great many future vicissitudes and developments, both technical and organizational. The entire program ould have to keep up to date with rapidly developing propulsion, reentry and other technological advances. A Parsecs study from that time indicated that the Moon Colony could actually precede the Satellite Observatory. In that event the detailed objectives for Mission I would be subject to change and, probably, reduction. On the moon almost all the functions of the Satellite Observatory can be performed under more favorable conditions. The mass and size of the moon offer stability and permanence unattainable in any artificial satellite. The primary objectives of the Moon Colony were:
- a) A more stable base for astronomical full-spectrum instrumentation. Conservatively, telescopic efficiency will increase by a factor of ten. The 200-inch Palomar mirror would be equal to 2,000 inches on the moon.
- b) Exploration of the lunar surface whose ageless, untouched details may reveal the "life story" of the solar system.
- c) Experiment station for research in advanced space technology under ideal low-gravity conditions.
- d) Headquarters for International Selenophysical Year activities which, like the earthly IGY, would fill the gaps in present lunar knowledge. A Moon Colony was included in the initial formulation of the Parsecs project in 1958. Shortly thereafter Boeing engaged in a definitive study of a Lunar Observatory, under Government auspices.
Mission III—Counter-Moon
After the Moon Colony, it becomes desirable to establish a cooperative system to make solar observations which are of primary importance in understanding the phenomena of earth itself. The Counter-Moon vehicle is perhaps one of the most effective means of measuring the magnetohydro dynamics (high - temperature magnetic "flows") of the solar corona. If the sun is viewed simultaneously from the moon and from a position directly opposite the moon and at the same distance from the earth, there is, in effect, a stereo optical view of the sun and its coronal manifestations. The primary objectives of the Counter-Moon were the development of :
- a) Stereoscopy of solar phenomena applied to telescopic, photographic, spectroscopic and other instrumentation.
- b) Loran-type deep space navigation aid with a base leg of 480,000 miles. This would furnish long-range astro-navigational guidance for later spaceships to interplanetary distances.
- c) Full-spectrum interferometric astronomy to catalog the sun's thermonuclear reactions throughout its great temperature range.
In the general-purpose space capsule outfitted for Counter-Moon service, the power source would be an array of solar cells. Four ion rocket motors would provide stabilization and enough total thrust for its distant orbit maintenance. Two similar vehicles were planned for seleno-Trojan positions 60° behind Luna in its orbit, and 60° ahead. As with the Trojan asteroids , in Jupiter's orbit, these positions would be "stable" so that the seleno-Trojan vehicles would be at the "neutral" point of earth, moon and solar gravitational forces, and would remain there indefinitely.
Mission IV—Interplanetary Probes
Before going beyond the moon, man will need much trail-blazing service from unmanned robot vehicles. The type of robot vehicle to be designed depends on the existence of manned geoorbital facilities or "spaceports" for assembling new vehicles. The NASA Mars and Venus probes would be earth-launched ballistic vehicles with no return capability. The Parsecs Martian Explorer represented a much more sophisticated concept. It was a self-propelled, self-guided circum-Martian vehicle that would make a round trip back to earth. The objectives of Mission IV were:
- a) Physical-data acquisition from planets, Venus as well as Mars, including magnetic field, gravity force, local "Van Allen" belts and such.
- b) Study of radiation-intensity distribution versus solar distance which would pinpoint the temperature ranges later spacemen would meet upon landing.
- c) Study of spacial-matter distribution versus solar distance to complete the space-plasma (rarefied ionized gas) picture now only known in cislunar regions.
- d) Planetary surface-data acquisition via TV or radar.
The Martian Explorer vehicle would be adaptable for all the terrestrial planets (Mercury, Venus and Mars).
Mission V—Close Solar Orbit
Because the sun was the most important subject of solar system research, it deserved separate consideration. Certainly a close solar orbit involves many radically different problems and solutions than do planetary probes. A set of objectives for solar research in Mission V of Parsecs can be broadly stated as follows:
- a ) Collection of direct and meaningful data on the nuclear-physics of the sun's thermo-nuclear phenomena.
- b ) Collection of astrophysical data.
- c ) Collection of cosmological data.
The instrument package of a solar probe would be designed to make a series of passes in a heliocentric orbit with a perihelion on the order of 10,000,000 miles—closer than the planet Mercury ever comes to the sun. The main problems were the thermo-dynamic properties of the various "sensors" that would be included in the probe. These sensors would have differing physical properties so that some would be overheated while others were still operating. Some means for "shading" the sensors selectively from the intense radiation of the sun would have to be devised.
Mission VI—Trojan-Point Observatories
Astronauts can travel in open space and precede the ability to make difficult planetary landings. The geo-Trojan points give a unique opportunity to set up a deep space laboratory and observatory at the same radial distance from the sun as the earth, and not too far away from an earthly base. In addition, these positions, 60° ahead of and behind the earth in its orbital path, are expected to be stable, that is, relatively unaffected by perturbations from other bodies. The objectives of the Trojan-Point Observatories are:
- a) A very long base leg for full-spectrum interferometric astronomy to fill out previous probe data.
- b) Long base leg for space-navigation aids with the added factor of human intelligence to increase performance, especially in emergency decisions that robots cannot handle.
- c ) Simultaneous view of solar phenomena by men in both stations who can compare data directly via radio conversation thus accelerating the research pace.
- d ) Communication links for general space exploration as spaceships range further away into cis-planetary regions.
Mission VII—Out-of-Ecliptic Orbit
Our entire solar system, with the exception of a few stray comets and maverick meteors, lies in a flattish plane. All planets, moons, asteroids, plus most comets and meteors, spin within this narrow disk shaped slice of space. Mercury, Pluto and a few other eccentric bodies dip only a few degrees up or down from this level of the whirling solar system. The great majority of bodies obediently stay almost precisely in the restricted general plane. What lies above and below the ecliptic herd? That is the riddle this mission would seek to solve, out in trans-solar-space.
This, then, is an opportunity to conduct meaningful deep-space or "outer space" operations without the additional complexities of orbital maneuvers near the planets and without the necessity of making landings. There is some evidence that the true void that we think of in connection with space does not exist in the vicinity of the earth. It was not known if the solar corona finally fades to "nothingness" or duplicates the interstellar degree of vacuum in the vicinity of earth, Mars, the asteroids, or Jupiter. However, it is probable that the solar corona, like the ecliptic, is also a thin disk-shaped structure not exceeding 20, 000,000 miles in thickness on either side of the earth. Therefore, by the simple maneuver of establishing a heliocentric orbit at the same radius as the earth's orbit (93,000,000 miles) but inclined to the ecliptic plane by more than 10 degrees, a ship can actually leave the milieu of the sun and test a sample of "alien" space. In so doing, it would accomplish the following objectives:
- a) Enter into the true void of outer space where no bodies other than a rare comet or meteor exist.
- b) Probe the depth and content of the solar corona and sample the next order of interstellar "emptiness" where loose ions and dust-motes are perhaps yards apart.
- c) Get a polar view of the sun and solar system as if "looking down" on its flat panoramic sweep, much as if we could slip out of our galactic plane and see the Milky Way broadwise the way we view Andromeda.
Mission VIII— Planetary Exploration
Finally, at its end phase, Parsecs came to manned Planetary Exploration. This is as far as the studies were carried. Interplanetary exploration will certainly challenge all our skills for many years to come. There were four broad objectives, which are:
- a) Planetary physical data acquisition greatly enlarging that gathered previously by robot probes. Cosmological research superior to that done by limited instrumentation abilities.
- b) Study of natural resources on planets by direct exploration in an expanding circle around the expedition camp.
- c) Colonization, the culminating phase when earthmen can stay in permanent "cities" and become "citizens of two worlds".
One single basic vehicle concept was adaptable to the requirements of Missions VI, VII, and VIII. In addition, the space capsule around which these adaptations would be configured could be an off-shoot of the Satellite Observatory and Counter-Moon vehicles. Because it was too early to start definitive engineering and cost estimating for these missions the vehicle concepts were flexible and subject to change as more space flight techniques were learned in the interim.
General-Purpose Space Capsule
The following "ground rules" were established for the general purpose space capsule:
- a) The vehicle was to be spherical and would be assembled at some suitable satellite "shop" in a geocentric orbit. A vehicle wholly assembled in zero-g space would not have to be designed for a short burst of high acceleration such as needed for earth launch. For interplanetary work, where the vehicle was to be propelled a long distance, weight optimization (the least weight necessary) would remain the most critical design-nut to crack until the advent of some radically different means of propulsion.
- b) The space-launch vehicle would use a low-thrust nuclear-powered propulsion system. A plasma jet system, reactor, and liquid-hydrogen tanks at the extremity of a boom to minimize radiation shielding.
- c) There would be no planned ship rotation to induce artificial gravity. This caused arrangements tending toward elongated, disk-shaped or toroidal volumes which cut down interior room as compared to designs resembling spheres. Ship "gravity", though convenient, is not necessarily vital to health. One way an astronaut might schedule his exercise and simultaneously avoid long- term exposure to weightlessness would be simply to learn how to walk around the inside of this 40-foot diameter vehicle as in a squirrel cage. This would create his own "gravity" via centrifugal force. At a brisk walk of 4 miles an hour, for instance, he would be pulling 1/20 of an earth gravity. At a trot he could approach half a gravity for considerable periods of time, depending on his wind. Of course, a companion would have to go the other way, or the lone exerciser would have to do an equal number of turns in both directions himself, in order not to "turn" the vehicle into a different attitude than when he began.
- d) There would be provision for dual reliability (backup "redundant" devices) in encapsulation. All interplanetary missions would involve years of continuous service. The shortest Martian round trip by minimum energy orbits , would take 2.5 years. Permanent Trojan - Point stations involve indefinite operation.
The construction of the space capsule in orbit is ideal for a minimum-weight/maximum-payload vehicle for deep space or interplanetary missions. Materials could be transported to orbit in small handy packages, and building of the structure would be facilitated by the zero-g condition. With proper planning and rehearsal, the crew of space steeplejacks would be able to complete one of the basic pressure vessels, from which they can then operate further, in about 6 months. Until then, they could work inside a plastic balloon without the hindrance of space suits. The life of such a balloon is, of course, a matter of considerable uncertainty, depending on micrometeorite penetration or abrasion. As a safeguard and warning system, a double wall would contain a gaseous-chemical indicator making a chromatic change in the presence of some constituent of the interior atmosphere. Thus meteoroid penetrations or other leaks would mix escaping air with the color changing gas in the wall "sleeve" and warn the crew of repairs needed.
Image at centre right shows Henry "Bud" Hebeler and Richard "Dick" White with the model of the Mission 3 Counter Moon. Hebeler and White designed the Mission 3 and Mission 4 vehicles (and possibly others) as early as August 1958. Wellwood Beall of Boeing presented the PARSECS project to audiences at conferences using these images until at least late 1960. Bottom left is an image of their model for the Mission 4 Interplanetary Probe.
