The European Space Agency has confirmed that its Venus Express probe will soon end up crashing into the planet it was sent to study.
Although Venus is located in the habitable zone of our solar system, where water could technically exist in liquid form, data from various probes has shown it to be a thoroughly disagreeable environment at present. However it has been shown that this was not always the case.
A twin planet?
Interestingly Venus is very similar to Earth. Its size and mass are almost equal, and it is composed of many of the same elements. Even its gravitational pull is similar to that of our home planet. Both the Venus Express and NASA’s Pioneer spacecraft collected data which showed that there was once liquid water on its surface, and possibly even forms of life.
The caveat is that this liquid water would have existed billions of years ago, during a time when the Sun was smaller than its current state. As the Sun grew more powerful, it began to emit more solar radiation, which given Venus’ position a third closer to the Sun than the Earth, meant that the water evaporated into its atmosphere.
The water vapor that was released set off a runaway greenhouse effect on Venus, increasing its global temperature even further. The hydrogen in the water vapor escaped from the atmosphere after being split away from the oxygen molecules by ultraviolet light from the sun, and this oxygen then combined with carbon to form the carbon dioxide atmosphere of present day Venus.
Venus Express probe: Aerobraking and space travel
This atmosphere, over 96% carbon dioxide, makes the planet even hotter than Mercury, which is closer to the Sun. The Venus Express has been testing the density of Venus’ atmosphere over the course of the last 6 months, and concluded that it is 93 times denser than Earth’s.
As its fuel began to run out, scientists attempted to “surf” the probe across the top of the dense atmosphere in order to study aerobraking, a way of slowing spaceships down using the atmosphere that they enter. If spaceships are strong enough to resist the stresses placed on them, aerobraking can save huge amounts of expensive fuel.
The final hurrah of the Venus Express could lead to major advances in space travel, with aerobraking the key to missions further into space. Data collected from the probe’s last few months could prove instrumental in the human colonization of space.
