There are only four ‘Terrestrial Planets’ in our solar system. Mercury, Venus, Earth and Mars. This means that they are rocky planets where you can land a rover to explore unlike gaseous planets. Planets are interesting and space exploration is way more interesting. Have you ever wondered whether it is possible to land a rover on Gaseous planets like Jupiter or Saturn? Can you land on gas? Would a spacecraft go through gas and pass through a planet? Well the answer is a big ‘NO’.
Gas planets do have solid cores. But you can’t land on solid cores because the pressure is so enormous. If we were to send any probes there, they would be torn apart because of pressure, gravity and extreme winds. This is what happened to Galileo Probe in July 1995 while entering Jupiter’s atmosphere. The closest it got was to 156 Kms below the cloud layer and recorder weather data for 58 minutes. Then it stopped transmitting at 24 bar pressure. The temperature and turbulence was higher than expected. 30 minutes after entry, the parachute would have melted. After 40 minutes of free fall the aluminium components would have become liquid. After 6.5 hours, the titanium parts would have become liquid due to extreme temperature and pressure. During this whole phase, no solid surface was ever reached and the probe was completely destroyed in the gaseous or liquid layers of jupiter. Looks like no human can ever land on these planets. The more I think about this, the more amazed I am at how spectacular this thing called ‘Universe’ is. Here is an artist's impression of Galileo's probe.
What about landing on Terrestrial Planets? We all know we have the curiosity rover on Mars. Happily exploring stuff. During the 1960’s, Soviet Union sent a series of probes called ‘Venera’ to Venus. ‘Venera 4′ was the first one the enter venus’ atmosphere in 1967 and ‘Venera 7’ made a soft landing on Venus in the year 1970. As the surface conditions on Venus are extreme, the probes that landed on Venus only survived for a maximum of 23 minutes before becoming dust. The final probes lasted 2 hours. Even though Venus is called Earth’s sister planet, it has harsh conditions. The pressure is crushing, temperature is around 500 degree celsius and let’s not forget the sulphuric acid. They say that if Venus was 5 feet away from the sun, it would be cooler. Below is the surface of Venus captured by Venera.
How amazing is this? Makes you think how precious planet Earth is. And yet we humans destroy our own planet. We sure take things for granted. There is no planet like ours. Perfect distance from the sun. A little off from the sun, temperature would drop drastically and a little closer to the sun, we’d all be roasted chickens. Earth is awesome. Look at the earth from a distance and you will see that the ‘Blue Planet’ is indeed charming. Below is a picture of earth taken from Galileo Spacecraft in 1990. If there was intelligent life out there in space, life on earth could be easily detected. Our planet is unique. Save it before it’s too late. All those post apocalyptic sci-fi movies will all end up coming true otherwise.