Mohawk Valley Astronomical Society

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Forgotten Planet

by Perry Pezzolanella

It can be argued that space exploration is a waste of money and can be better spent elsewhere since there are so many problems here on Earth. The truth is that even if the space program was cancelled, the extra money freed up would most likely never be used where people would want it to go. At this moment U.S. spacecraft are exploring Mercury, Mars, and Saturn with three others headed for Ceres, Jupiter, and Pluto. Missing is one planet that is probably the most vital of all in understanding our history, evolution, and fate: Venus.

Venus is the closest planet to Earth and almost as large. It has very nearly the same composition, but somewhere along the way something went way wrong and a runaway greenhouse turned Venus into a pressurized, toxic inferno. A new mission is needed to try and figure out how and why this happened and how this relates to Earth’s atmosphere and climate. At one time Venus had oceans and even though it is closer to the Sun it should not have experienced such a severe change in climate. Both Earth and Venus have the same amount of carbon dioxide. Plate tectonics, oceans, and life help remove most of the carbon dioxide from Earth’s atmosphere and lock it safely away in limestone and other rocks leaving only 0.04% in the atmosphere, just enough to keep the Earth from becoming a completely frozen planet. All of the water boiled away on Venus and without water to lubricate the crustal plates, plate tectonics seized up tight. With no water and no tectonics, the carbon dioxide that was belched out from the thousands of volcanoes built up in the atmosphere increasing the temperature further. Eventually the atmosphere became what we know it today: 96.5% carbon dioxide, atmospheric pressure 92 times Earth’s, average surface temperature of 870ºF, and a dense veil of sulfuric acid clouds. If life ever got started on Venus, it was savagely destroyed.

NASA has no plans for a Venus mission for at least a decade and, as we continue to neglect Venus, we lose vital knowledge on how climate works on an Earthlike planet. With no missions, the scientists dedicated to Venus research are forced to go where there are active missions. Support for basic research about the geology and climate of Venus has declined and fewer graduate students are pursuing Venus science. Fewer scientists mean fewer that are able to design and advocate new missions. NASA has not launched a Venus mission since Magellan in 1989. Seven new missions were proposed for development and launch in a recent round of funding requests, only to lose out to an asteroid sample return mission. With this loss there may be no new Venus data for the rest of the careers of the current scientists.

The European Space Agency’s (ESA) Venus Express has been orbiting Venus since 2006 and has made great discoveries including the confirmation that Venus once had oceans and also has lightning, but its mission is nearing an end and will probably terminate next year. Japan’s Akutsaki missed going into orbit around Venus on December 6, 2010 due to rocket trouble but a second attempt will be made on November 22, 2015. There are many good U.S. Venus missions to consider, but Venus is a tough planet to explore, and to try and understand it means landing on the surface. Technology can handle the pressure and acid, but the intense heat is the villain. This involves new technology and extensive testing of parts, electronics, and refrigeration, which makes Venus missions expensive, easily costing over $1 billion. Trying to sell a mission for approval where a lander can only last about five hours in an inferno and cost around $1 billion is a hard sell. That is probably one reason why a U.S. Venus lander mission called SAGE lost out to OSIRIS-Rex, an asteroid sample return mission.

There is still hope as the Venus Climate Mission is an option and can deliver a balloon into the atmosphere where it can study the weather, wind patterns and analyze the atmosphere, composition, and temperature for nearly a month. A camera and an infrared imager would photograph the surface far below, even at night. A mini probe would be released from the base of the balloon’s gondola which would study the atmosphere during its 45-minute free-fall to the surface. It would acquire a complete profile of the pressure, temperature, wind, and chemical composition. Two smaller drop sondes, which would be attached to the balloon’s gondola, would be released selectively so that one could study the atmosphere prior to impacting a high elevation site while the other would study the atmosphere down to a depressed elevation. Or, one of them could study how the atmosphere behaves on the dayside while the other would study the night side during its descent. Both probes would also take about 45 minutes to impact the surface due to the thick atmosphere, but they are not expected to survive impact. The orbiter that would deliver the balloon and probes would orbit Venus for at least a year and study the clouds and weather and monitor lightning. The cost of such a mission is still around $1 billion, but it has more science to offer for the money and a longer life expectancy.

Studying the planets is crucial for our survival on Earth. Martian dust storms made us aware that dust chills an atmosphere and that nuclear war could ultimately trigger an ice age on Earth, hence “Nuclear Winter” and a wake-up call to reduce the world’s nuclear arsenal. The U.S. Pioneer Venus orbiter found huge holes in Venus’ ozone layer over each pole. The Pioneer Venus multi-probes plunged into the atmosphere and found chlorine and fluorine which naturally becomes chlorofluorocarbons. The orbiter revealed how the chlorofluorocarbons easily attack and destroy ozone. This triggered a ban on the use of chlorofluorocarbons for refrigeration and aerosol sprays in order to save our own ozone layer, but not before it created a huge hole in the ozone layer over Antarctica.

The time is now for the ultimate test for humanity. Venus, the planet next door that once was so earthlike, has volcanoes that spewed so much carbon dioxide that it turned it into a lifeless inferno. We are undertaking a similar experiment on Earth with our burning of fossil fuels. Carbon dioxide is on the rise in our atmosphere. How much will it take to cross the point of no return and become another Venus? Pioneer Venus proved that the study of planets is the study of Earth and the knowledge gained can increase our understanding of Earth and teach us how to take better care of our home planet. Venus exploration will benefit all of us regardless of the price, because life is priceless, and there is only one Earth with nowhere else to go. Venus has quite a lesson to teach us, if we are willing to go and learn, and in spite of the inferno, the lessons could be chilling.