The solar system may seem a barren place when it comes to life or anything similar. Obviously we are here on our lovely planet so that statement is not true. The other planets don’t seem likely to harbour life except perhaps Mars, but the life there if there is any, is not obvious as we would have found it by now.
But, let’s not forget the satellites. There are many satellites in the solar system. Over 140 and still counting. Earth has one, Mars has two, Jupiter has 63, Saturn has 33, Uranus has 27, Neptune 13 and Pluto three. This was at last count as the satellites are being found all the time. When you think about it many satellites can be just a rock circling around its parent planet. The solar system is a busy place with an asteroid belt between Mars and Venus and the kuiper belt which is beyond Neptune. The asteroid belt contains Rocky and metal objects and the Kuiper belt contains icy bodies. There is also the Oort cloud full of comets.
It is not surprising then that there are so many moons and satellites surrounding the planets. Some of these moons and satellites are not just small chunks of rock but worlds in their own right. Titan is one of these moons and it happens to orbit Saturn. This is a good world to look for life as in many respects it resembles a frozen earth. At -179°C it is a little bit cold compared to the coolest temperature on earth which is about -89°C but as you can see it is only twice as cold so you would only need two fur coats instead of one.
The pressure on the surface of Titan is not that far away from Earth either. It is one and a half times greater than that on earth. A day would look like a dim twilight of the Earth. The actual atmosphere is made up of 95% of nitrogen and 5% methane. There are organic compounds in the atmosphere but this doesn’t mean there is life! The expression organic compounds is a very broad expression that normally means that the compounds that are found in life exist.
The methane in the atmosphere is a bit of a mystery as the sunlight breaks down the methane in the atmosphere so it must be replenished from somewhere. The source of replenishment is unknown but is thought to come from inside Titan being thrown out in what is called Cryovolcanism outbursts. Cryovolcanism is exactly the same as volcanism but instead of producing lava much colder materials are spewed out such as ice.
The surface of Titan is very similar looking to Earth but is very alien in makeup. Methane makes up a big part of this world and there are methane lakes and what looks like Methane Rivers as well. Methane rain occurs from methane clouds so if you like methane then you will be very much at home on this planet. On looking at the picture on Titan it does seem that it is full of boulders and rocks but these are lumps of ice.
There are Highland areas which are similar to Earth but not as high reaching up to only 100 to 200 m. In the lower land areas there are dunes which are made up of hydrocarbons and are very similar to the dunes found in Earth deserts.
I am not just making this up all this information comes from a recent probe that was sent to Saturn and its moons. It’s called Cassini Huygens. Cassini is the spacecraft and Huygens is the probe that actually landed on Titan. Cassini is still flying around Saturn taking lots of pictures and looking at its moons. Huygens landed on Titan on January 14, 2005 transmitting information from the planet’s surface for over three hours. The actual information recovered was only about 30 minutes as it was not expected for Huygens to last for three hours.
As the data from Huygens was sent up to Cassini for rebroadcasting to Earth at least 2 1/2 hours was lost because Cassini went beyond the horizon and wasn’t able to pick up Huygens transmissions. We know that Huygens was transmitting because telescopes on Earth picked up the background noise (the carrier wave) of its transmissions. Everything is unknown when going to different worlds and I expect that scientists on earth would have planned this mission differently if they had known that the probe would last so long. But what they did get was well worth it.
The visual picture of Titan is worth the trip in itself to me. The visual information sent back is actually only half of what was planned as somebody forgot to switch on a channel that was transmitting data back to Earth, was his name Homer? (It’s not quite as simple as that of course but in essence that is what seems to have happened). There were six other instruments that were used to gather data from Titan.
- The Huygens atmospheric structure instrument measured the physical and electrical properties of Titan’s atmosphere.
- The Doppler wind experiment which improved communication with Cassini. It also was to measure the wind speed of the atmosphere but unfortunately because a channel wasn’t switched on as mentioned earlier most of this information was lost.
- The descent imager spectral radiometer studies the radiation balance in Titan’s atmosphere.
- The gas chromatograph spectrometer was a gas chemical analyser that measured gases in Titan’s atmosphere.
- The aerosol collector and pyrolser captured particles and heated them up and then analysed the organic molecules.
- A surface science package contained lots of different instruments which for instance measured the surface, i.e. whether it was liquid or solid, an acoustic sensor that measured the rate of descent on approaching the surface and also would have measured the depth of any oceans if it had landed in methane. The speed of sound density and thermal conductivity were also measured.
All these instruments were crammed onto a probe that was made in Europe by the ESA. Lots and lots of countries were involved in the production of Huygens and Cassini and the benefits are being reaped today.
Cassini continues to fly around Saturn looking at the different types of satellite and moons and learning all the time. Huygens, because of the pressure and surface conditions of Titan, (and because the batteries ran out!) sits on Titan dormant.
These types of missions will probably be what we see in the future. Sending man into space doesn’t seem to be on the cards for an extremely long time (i.e. a couple of generations). This is a bit of a pity but the information that is sent back is a way for all of us to explore new planets and boldly look where no one has looked before.