CHAPTER 10

THE NEW LOOK OF VENUS

The historic mission of Mariner II to the near-vicinity of Venus and beyond has enabled scientists to revise many of their concepts of interplanetary space and the planet Venus.

The composite picture, taken from the six experiments aboard the spacecraft and the data from the DSIF radar experiments of 1961 and 1962 revealed the following:

—Interplanetary space between the Earth and Venus, at least as it was during the four months of Mariner’s mission, had a cosmic dust density some ten-thousand times lower than the region immediately surrounding the Earth.

—During this period, the extremely tenuous, widely fluctuating solar winds streamed continually out from the Sun, at velocities ranging from 200 to 500 miles per second.

—An astronaut travelling through these regions in the last quarter of 1962 would not have been seriously affected by the cosmic and high-energy radiation from space and the Sun. He could easily have survived many times the amount of radiation detected by Mariner’s instruments.

—111

—The astronomical unit, as determined by radar, the yardstick of our solar system, stands at 92,956,200, plus or minus 300 miles.

—The mass of Venus in relation to the Earth’s is 0.81485, with an error probability of 0.015%.

—The rotation rate of Venus is quite slow and is now estimated as equal to 230 Earth days, plus or minus 40 to 50 days. The rotation might be retrograde, clockwise with respect to a Sun-facing reference, with the Sun rising in the west and setting in the east approximately one Venusian year later. The planet seems to remain nearly star-fixed rather than permanently oriented with one face to the Sun.

—Venus has no magnetic field discernible at the 21,598-mile approach of Mariner II and at that altitude there were no regions of trapped high-energy particles or radiation belts, as there are near the Earth.

—The clouds of Venus are about 15 miles thick, extending from a base 45 miles above the surface to a top altitude of about 60 miles.

—At the resolution of the Mariner II infrared radiometer, there were no apparent breaks in the cloud cover. Cloud-top temperature readings are about minus 30 degrees F near the center (along the terminator), and ranging down to minus 60 degrees to minus 70 degrees F at the limbs, showing an apparent limb-darkening effect, which would indicate a hot surface and the absence of a supercharged ionosphere.

—A spot 20 degrees F colder than the surrounding area exists along the terminator in the southern hemisphere: a high mountain could exist in this region, but such an hypothesis is purely conjectural. A bright radar reflection is also found on the Equator in the same general region. Causes of these phenomena are not established.

—At their base, the clouds are about 200 degrees F and probably are comprised of condensed hydrocarbons held in oily suspension. Below the clouds, the atmosphere must be heavily charged with carbon dioxide, may contain slight traces of oxygen, and probably has a strong concentration of nitrogen.

—112

—As determined by the microwave radiometer, Venus’ surface temperature averages approximately 800 degrees F on both light and dark sides of the planet. Some roughness is indicated and the surface reflectivity is equivalent to that of dust and sand. No water could be present at the surface but there is some possibility of small lakes of molten metal of one type or another.

—Some reddish sunlight, in the filterable infrared spectrum, may find its way through the 15-mile-thick cloud cover, but the surface is probably very bleak.

—The heavy, dense atmosphere creates a surface pressure of some twenty times that found on the Earth, or equal to about 600 inches of mercury.

The mission was completed and the spacecraft had gone into an endless orbit around the Sun. But before Mariner II lost its sing-song voice, it produced 13 million data words of computer space lyrics to accompany the music of the spheres.

APPENDIX SUBCONTRACTORS

Thirty-four subcontractors to JPL provided instruments and other hardware for Mariners I and II.

The subcontractors were:

Aeroflex Corporation Jet vane actuators Long Island City, New York American Electronics, Inc. Transformer-rectifiers for flight Fullerton, California telecommunications Ampex Corporation Tape recorders for ground telemetry Instrumentation Division and data handling equipment Redwood City, California Applied Development Corporation Decommutators and teletype encoders Monterey Park, California for ground telemetry equipment Astrodata, Inc. Time code translators, time code Anaheim, California generators, and spacecraft signal simulators for ground telemetry equipment Barnes Engineering Company Infrared radiometers Stamford, Connecticut Planet simulator Bell Aerospace Corporation Accelerometers and associated Bell Aerosystems Division electronic modules Cleveland, Ohio Computer Control Company, Inc. Data conditioning systems Framingham, Massachusetts Conax Corporation Midcourse propulsion explosive Buffalo, New York valves Squibs Consolidated Electrodynamics Corp. Oscillographs for data reduction Pasadena, California Consolidated Systems Corporation Scientific instruments Monrovia, California Operational support equipment Dynamics Instrumentation Company Isolation amplifiers for telemetry Monterey Park, California Operational support equipment Electric Storage Battery Company Spacecraft batteries Missile Battery Division Raleigh, North Carolina Electro-Optical Systems, Inc. Spacecraft power conversion Pasadena, California equipment Fargo Rubber Corporation Midcourse propulsion fuel tank Los Angeles, California bladders Glentronics, Inc. Power supplies for data Glendora, California conditioning system Groen Associates Actuators for solar panels Sun Valley, California Houston Fearless Corporation Pin pullers Torrance, California Kearfott Division Gyroscopes General Precision, Inc. Los Angeles, California Marshall Laboratories Magnetometers and associated Torrance, California operational support equipment Matrix Research and Development Power supplies for particle flux Corporation detectors Nashua, New Hampshire Menasco Manufacturing Company Midcourse propulsion fuel tanks and Burbank, California nitrogen tanks Midwestern Instruments Oscillographs for data reduction Tulsa, Oklahoma Mincom Division Tape recorders for ground telemetry Minnesota Mining & Manufacturing and data handling equipment Los Angeles, California Motorola, Inc. Spacecraft command subsystems, Military Electronics Division transponders, and associated Scottsdale, Arizona operational support equipment Nortronics Attitude control gyro electronic, Division of Northrop Corporation autopilot electronic, and antenna Palos Verdes Estates, California servo electronic modules, long-range Earth sensors and Sun sensors Ransom Research Verification and ground command Division of Wyle Laboratories modulation equipment San Pedro, California Rantec Corporation Transponder circulators and monitors Calabasas, California Ryan Aeronautical Company Solar panel structures Aerospace Division San Diego, California Spectrolab Solar cells and their installation Division of Textron Electronics, and electrical connection on Inc. solar panels North Hollywood, California State University of Iowa Calibrated Geiger counters Iowa City, Iowa Sterer Engineering & Manufacturing Valves and regulators for midcourse Company propulsion and attitude control North Hollywood, California systems Texas Instruments, Inc. Spacecraft data encoders and Apparatus Division associated operational support Dallas, Texas equipment, ground telemetry demodulators Trans-Sonic, Inc. Transducers Burlington, Massachusetts

In addition to these subcontractors, over 1,000 other industrial firms contributed to the Mariner Project.

FOOTNOTES

[1]Throughout this book “Mariner” refers to the successful Mariner II Venus mission. Mariner I was launched earlier but was destroyed when the launch vehicle flew off course.

[2]For scientific reasons, distances from Venus are calculated from the center of the planet. Hereafter in this chapter, these distances will be reckoned from the surface.

INDEX

A ABMA, 17 Agena B, 21, 22, 40 Antennas, 66 Goldstone, description, 70, 71, 73 onboard, description, 30, 31 directional control, 30 Pioneer tracking site, 70, 71 ARPA, 17 Astronomical unit, 111 refinement, 107 Atlantic Missile Range, 2, 10, 43, 83 Atlas-Agena B, 63, 52 Atlas D, 19, 21, 36-39, 89 Attitude control Atlas D, 38 Earth acquisition, 58 loss of control and reorientation, 56, 60 Attitude control system, 31, 32

B Battery, 25, 27 Bumper-WAC, 18

C C-133 aircraft, 43 Centaur, 8 Central Computer and Sequencer, 28 commands, 56, 58 failure at encounter, 62 midcourse maneuver control, 59 Central Computing Facility, 81, 82 Charged particles, 13, 90 Charged particle detector, 35, 88 Computers, data processing, 84 Corporal E, 18 Cosmic dust, 13 density, 110 distribution and mass, 94, 95 measurement, 89 Cosmic dust detector, 35, 68, 87, 89 Cosmic radiation, 13, 96 Cosmic ray flux, 98

D Data conditioning system, 88 Data processing, 30, 74, 85 CCF, equipment and operation, 82, 83 launch and tracking operations, 83 telemetry data, 84 transmission time, 88 Detectors charged particle, 35 cosmic dust, 35 solar plasma, 35 DSIF, 73, 74, 75, 82, 83, 84 functions, 68 Goldstone, 1, 64, 67-79, 68, 69, 70, 71, 73, 75, 84, 107, 108, 109 Johannesburg, 64, 67, 68, 73 Mobile, 68, 73, 80 tracking during midcourse maneuver, 56 orientation, 56 Woomera, 67, 68, 71, 73, 75

E Earth sensor final orientation commands, 64 September 8, crises and recovery, 60 Echo Project, 69 Echo site functions, 71 Electronics equipment weight, 25 Explorer I, 19 Experiments, 35 Anton special purpose tube, 87 atmospheric investigation, 85 charged particle detector, 88, 96-100 density variation data, 98 radiation hazard findings, 98 cosmic dust detector data, 87-89, 94, 95 high energy radiation, 90 infrared radiometer, 87, 93 ion chamber and Geiger-Mueller tubes, 87 magnetometers, 87, 88 microwave radiometer, 87, 91-93 objectives, 13, 93 processing of data, 85 radiometers, 85, 105, 106 responsible organizations, 88 results, 110-112 solar plasma detector, 87-90 temperature investigation, 85 transmission of data, 88 weight, 25

G Geiger counter, 98 Geiger-Mueller tubes, 87, 91 George C. Marshall Space Flight Center, 13, 17 Goldstone Tracking Station, 64, 67, 69, 75, 84, 107 Echo site, 68, 69, 71, 73 Pioneer site, 56, 68, 70 Venus site, 69, 70, 108, 109 Guidance, 13

H High-energy radiation experiments, 90, 91

I Infrared radiometer experiment cloud observations, 103, 105, 106 description, 93 dimensions, 93 operating characteristics, 85, 93 Interplanetary magnetic field, 13, 99 Interplanetary space cosmic dust density, 110 distribution, 95 hazards to spacecraft, 13 Ion chamber, 98

J Johannesburg tracking station, 67, 68 equipment, 68, 73 functions, 68, 73 JPL, 2, 8, 13, 75, 76, 80, 82, 84 accomplishments, 18, 19 background, 18 DSIF control point, 67, 68 pre-Mariner spacecraft, 23 Jupiter, contrast to Venus, 101 Jupiter C, 19

L Launch Operations Center, 12, 17 Launching, 56 Atlas performance, 52, 53 Atlas-Agena B, 52 battery, 52 gyroscopes, 53 radio guidance system, 52 time limitations, 12

M Magnetometer experiment, 35, 88 data, 101, 102 description, 91 function, 91 objectives, 100 onboard location, 91 Mariner I, 43-45 Mariner R, 41 Masers, 70 Materials, thermal shielding, 33 Microwave radiometer experiment description, 91 function, 91 measurements, 103, 105 operating characteristics, 85, 92-93 Midcourse maneuver, 32, 58-59, 60, 65 Mission achievements, records, 65 Mobile tracking station, 68, 80 location, equipment and function, 73 MX-774 Project, 21

N NACA, precursor of NASA, 16 NASA, 8, 16, 17

P Parking orbit, 55 Pioneer III, 19 Pioneer IV, 19 Pioneer project, 69 Pioneer tracking site, 70, 71 Power system, 25 Private A, 18 Propellants Atlas D, 38 attitude control system, 32 spacecraft, controlled burning, 32 rocket thrust system, 32 Propulsion system, Mariner spacecraft, hydrazine propellant, 33 propellant storage, 32, 38 weight, 25

R Radiation, 98-100 Ranger III, 8 Receivers, 66 Records, Mariner attitude control system, 65 measurements near Sun, 65 operation near Venus telemetry measurements, distance, 65 trajectory correction maneuver, 65 transmission, continuous performance, 65

S Sensors Earth, for attitude control, 32 Sun, for attitude control, 32 Sergeant missile, 19 Shielding, 33, 34 Solar cells, 27, 28 Solar flares, 98, 99 Solar panels description, 25 design, 27 output deterioration, 61 release, 11 support, 25 weight, 27 Solar plasma detector, 35, 88, 96, 97 description, 87, 89, 90 function, 87, 89, 90 recordings, 96, 97 Solar plasma flux correlation with geomagnetic effects, 97 Solar wind effects on cosmic-ray movements, 96 magnetic fields, 95, 96 low density and energy, 96 measurement, 89 particle concentration near Earth, 96 particle energies, 96 temperature, 96 theories, 95 velocities, 13, 95, 96, 97, 110 Space Flight Operations Center, 60 organization and operation, 75, 80, 81 Space simulator, temperature control, 41 Spacecraft, 31 attitude control system, 31 Central Computer and Sequencer, 28 components and subsystems, 27 configuration, 23 electronic equipment, 25 frame materials, 23, 25 launching, 12 power system, 25 preliminary design, 41 propulsion system, 32 shroud and adapter, 43 system tests, 41 telecommunications subsystem, 30 temperature, 33 test models, 41 testing, 23 trajectory, 11 weight, 25 Sun sensor, 32

T Telemetry continuous transmission, 65 data processing, 84 description, 30 loss of monitoring data, 62 phase-shift modulation, 30 transmission cutoff, 64 Telemetry processing station, 82, 83 Telemetry system data processing, 30 onboard, description, 30 Temperature control coatings, 34 heating problems, 62 housing structures, 35 materials, 33 problems, 33 solar panels, 35 solar radiation shielding, 35 thermal shielding, 33 Tracking Antigua, 53 Ascension, 53, 55 DSIF, 52, 66, 67, 68, 69 Earth noise, 66 Grand Bahama Island, 53 Johannesburg, 56 Pretoria, 53, 55 problems, 66 radio noise, 66 San Salvador, 53 solar noise, 66 Twin Falls Victory, 53, 55 Whiskey, 55 Woomera, 56 Trajectory, 11, 63, 64, 83

V V-2 rocket, 18 Van Allen radiation belt, 19, 97 Venus atmosphere, 3, 5, 104, 105, 112 atmospheric temperature, 85 atmospheric winds, 5 CO₂ content above clouds, 106 cloud cover, 105, 106 cloud observations, 104, 105 clouds, data, 111 compared with Earth, 5 description, 4 dielectric constant, surface material, 107 encounter, 93, 94 historical data, 2 inferior and superior conjunctions, 4 magnetic field, 98, 100, 111 comparison with geomagnetic, 100, 101 data, 100, 101, 102 strength, 100, 101, 102 mass, 109, 111 orbit, 4 radar experiments, 1961, 106, 107 radar experiments during mission, 107 reflection coefficient, 107 revolution, 4 rotation, 4, 101, 108, 111 surface, 106 brightness temperature, 103, 104 characteristics, theories, 102, 103 “greenhouse” effect, 106 measurements, 103, 104 pressure, 112 reflectivity, 111 roughness, 107, 108 temperature, 106, 111 temperature, 85, 111 topography, 5 water vapor in atmosphere, 106 Venus encounter, 63

W WAC Corporal, 18 Woomera Tracking Station, 67, 68, 75 equipment, 68, 71, 73

Transcriber’s Notes

—Retained publication information from the printed edition: this eBook is public-domain in the country of publication.

—In the text versions only, text in italics is delimited by _underscores_.

—Silently corrected a few typos.

—In the index, entry “propellant storage”, replaced one nonsensical page number (200) with a plausible conjecture (38).