Infinite Mysteries of Venus

Infinite Mysteries of Venus

The absence of water on Venus may delay the colonization of that planet a few centuries at most. It would be necessary to import the water in the form of an ice asteroid several miles across from Saturn or beyond. Perhaps it could be smashed into the planet in such a way as to speed up the spin, power up the magnetic field, and set up some protective Van Allen belts. Then the blue-green algae (a special strain tailored in genetics laboratories and resistant to sulfuric acid) would get their chance.

New space probes are already being built to investigate the old and new mysteries of Venus. Every year and a half, Venus and Earth swing around into some relative positions, opening up a launch window of several weeks’ duration, permitting a three month voyage from one planet to the other. Given enough energy, we could launch to Venus at nearly any time, but this cycle is only concerned with the most economical opportunities.

The next Venus window will open near the end of 1976. Recent Soviet statements indicate they are still studying results of their last missions and will not have new vehicles ready until min-1978. Despite traditional heavy curtains of secrecy about future space plans, the future goals of Russian astronomers can be approximated from public statements during the last mission.

With orbiting probes essentially blinded by the clouds, and landing probes facing a quick death, Soviet Scientists have picked a third environment for exploration: the atmosphere. In cooperation with French scientists, they are building inflatable aerostats (balloon platforms designed to send to send back data via orbiting relay satellites over a period of days or weeks).

Venus as seen by Mariner. Global radar view of Venus (without the clouds) from the Magellan imaging between 1990 and 1994. Image in the public domain

The latest Venus probe data has pinpointed the most productive levels for exploration. Initially, the balloon (called Eos) would carry its 50 pound instrument package through the clouds at an altitude of 30 miles, where the temperatures and pressures are close to those of Earth’s surface. Batteries could provide power for a week; longer missions use solar cells (although corrosion a problem) or nuclear power.

Once the more hospitable regions of the atmosphere had been charted, the probe could release most of its buoyant gas (probably hydrogen as there would be no danger of fire in an atmosphere devoid of free oxygen), and descend to more interesting realms. Passing quickly through the region of the sulphuric acid rains, the probe would reach an area about 20 miles high, where temperatures had climbed to 300 degrees Fahrenheit and pressures were 10 times those of Earth. Survival at this level would be short, and the orbiting radio relay would be visible only for a few hours every other day.

The primary mission of this suicide altitude would be to photograph a panorama of the surface and of the under-side of the cloud layers in the near-infrared and visible wavelengths. Areas, miles on a side, would be visible during the probe’s slow drift.

One sought-after datum would be the frequency of small craters. Volcanos, vents and faults would be prime targets of discovery. Evidence of liquid flow (whether lava or water) would be sought, and actual pool of liquid metals or hydrocarbons might be seen. Most important on a planet like Venus, the probe could detect features that are completely unexpected.

Although there is no indication that the Soviets are working on it (and there are definitely no American plans for attempting it), one more instrument would certainly produce the most haunting perceptual input from space since the first photographs from other worlds began coming back a few decades ago. The instrument in question would be a simple microphone, tuned to subsonic and ultrasonic wavelengths beyond the range of the human ear.

What does Venus sound like? The density of the atmospheric ocean would provide acoustic conduction more akin to that of Earth’s deep seas than air. Would we hear the shriek of winds, the groan of strained rocks, or the roar of volcanos? Would we hear thunder or the bubbling of escaping gases in a liquid metal pool? Would we hear only the patter of sulphuric acid rain on the roof of the gondola carrying the microphone? Whatever sounds did come back to Earth would be powerful stimuli to Earthbound imaginations, as they complete the perceptual pattern of what it would be like to really be on another world.

Besides listening to the atmosphere a crucial requirement for future surface exploration would be to listen to the land. The use of a seismometer to detect internal earthquakes could tell an incredible amount about actual Venusian tectonics. A network of two or three active seismic stations would be more valuable. However, the Soviets haven’t yet landed a seismometer on any celestial object, and it could be 20 years before one is in service on Venus.

A family of six American space probes would be launched toward Venus in the window after next, which will be open during the summer of 1978. These Pioneer-class spacecraft will make investigations of the planet’s interior and of its atmosphere; there are no current American plans for surface exploration.

One probe, Pioneer 12, will go into a polar orbit around Venus late in 1978. It will dip to within 120 miles of the surface, searching for gravitational irregularities which can tell geologists about the internal layering of the planet and about its external shape and mass distribution.

Pioneer 13 is a quintuple spacecraft. When it arrives at Venus five days after Pioneer 12, it will already have broken up into five separate parts. The mother ship (called the bus) will have ejected three small and one large entry probes, targeted for widely scattered points across the face of the planet.

As they plunge into the atmosphere, the probes will measure pressure, temperature, deceleration, cloud extent, altitude and density, and the heat exchange between the sun and Venus. One probe will also carry a mass spectrometer and a gas chromatograph to provide details about the atmospheric components. The bus will also have a mass spectrometer for measuring the upper atmosphere before it burns up (it has no heat shield).

The three small probes will fall straight down to the surface, returning data to Earth until impact. The large probe will have a parachute to give it more time for making its detailed readings. Survival after landing is not planned, but it could occur as a bonus. The large probe in particular could make further readings on the composition of particles kicked up from the surface by its impact.

Later Venus probes in the Mariner series (perhaps a Mariner 13 could be scheduled early in the 1980s) might make radar maps on the surface. In the bistatic mode, a large parabolic antenna on the spacecraft could pick up echoes from radar beams transmitted from powerful stations on Earth. New types of radar could operate directly from the spacecraft, given a high power source.

There are two possible approaches to the problem of long term survival on the surface. Specialized equipment, capable of surviving for days exposed directly to 900 degrees Fahrenheit, could be designed. Alternately, refrigeration would have to be provided, requiring extremely advanced nuclear power supplies or contamination of surroundings by evaporative water – a short term solution in any case.

Balloon-borne probes promise profitable and productive halfway house, since they could float high enough to provide Earthlike environments. Complex robot laboratories controlled by computers and advised by scientists on Earth could analyze samples brought up from the Venusian surface.

Transportation between the ground and the aerostatic balloon might be relatively easy. The lander, designed to survive a quick dash to the surface, could inflate a hydrogen balloon and automatically load the sample canister into a small gondola. Rendezvous and docking between the propeller-driven mother craft and the sample balloon provides some intriguing engineering problems, but the results could well be worth it – especially if the rock samples came from the ocean basins which once may have cradled life.

The blank face of veiled Venus belies a planet of infinite mysteries. The answers to many of these puzzles may be crucially important to questions of life on Earth. Venus is neither simple nor boring. Like every other world which men have explored, it is full of unexpected wonders. The age of the interplanetary surprise is far from over; Venus will astound us again and again.

(James Oberg, Astronomy magazine, August 1976)