Saturn Sheila’s Solar System Safari
Dr Sheila Kanani, UCL Mullard Space Science Laboratory
Dr Sheila Kanani’s flying tour of our celestial home: the Solar System. Journey into our local galactic neighbourhood, where you will encounter Planets and other astronomical bodies, exploring each one in terms of origin and formation as well as its similarities and differences to our planet. Through exciting demonstrations and vivid photographs, discover new and unexpected aspects of our Solar System.
Our solar system discoveries are a bit like old world exploration except that we no one has actually physically gone to these places.
The equipment necessary to investigate the Solar System have to be launched and Dr Kanani demonstrated a rocket launch using empty tea bags. The tea bag reached the ceiling, honest.
Below is a portrait of the Solar System (not to scale) in terms of the number sheets of toilet paper.
Above picture on the left shows volunteer one representing the Sun and the above picture on the right show volunteer two representing Mercury.
Volunteers three and four representing Venus and Earth.
Below is volunteer five representing Mars. The distance to Jupiter from the Sun is far too great to continue this demonstration in the lecture theatre.
Some moons in the Solar System are actually bigger than Mercury. We know very little about Mercury because it is so close to the Sun.
Hopefully the Colombo mission will allow us to learn more.
Venus is often termed the Earth’s twin. However it has a dense cloud of sulphuric acid so it could be described as Earth’s evil twin and breathing the atmosphere would melt our lungs.
The atmospheric pressure is over 90 times bigger than on Earth and Dr Kanani illustrated the effect by showing what happens to marshmallows when you remove the air around them. Less pressure allows them to swell up but increasing the pressure causes them to implode.
The Soviets were the first people to attempt sending probes to Venus (quite a few were unsuccessful).
Venus express is the next project to investigate Venus. It was made from spare parts from the Mars express.
The above picture shows the Earth and Moon. It is very misleading as they look to close together and the Moon looks too big.
The above picture shows the Earth and Moon from Mars.
The above picture on the left shows the Earth from Saturn and the above picture on the right is the Earth from the edge of the universe.
Artificial satellites and probes have given us a lot of information about the planets.
The above picture shows the artificial satellites orbiting Earth.
Mars has been seen to have massive volcanoes and rift Valleys. Olympus Mons is bigger than Everest.
Spirit and Opportunity rovers showed there was dried up river beds on Mars indicating what Mars may have looked like.
Curiosity is as big as a mini and its tyres leave prints on the surface of mars. These prints are Morse code for JPL.
Curiosity was lowered to the surface of Mars by cables from the sky crane system.
Sunset on Mars actually shows a blue colour (unlike Earth’s red). In both case the colour is caused by refraction in the atmosphere.
The Saturn system is being investigated by the Cassini mission.
Cassini-Huygens was launched in 1997 and entered Saturn’s orbit in 2004. It contains over eighty instruments to measure things like the dust, infrared radiation and magnetism.
The Huygens probe landed on Titan (one of Saturn’s moons) in 2005.
Saturn has a density 30% less than water so it would actually float in a bath tub of water (if you could get one big enough).
In the above picture the bottom right hand image is of Saturn side on. The black lines are the rings.
Cassini has shown that Saturn has seasons.
Titan is bigger than Mercury and has lakes, rivers and rain of methane. It is considered to be like a primordial Earth and may one day evolve into an Earth like body. The picture below contains false coloured images of Titan.
Hyperion is sponge-like and is made up of porous rock.
The large crater on Mimas is called Herschel. If the object that created it had fallen on Australia it would have destroyed it.
Enceladus is a tiny but important moon. It is covered in ice with cracks at the South Pole where liquid water is ejected.
The plume at the South Pole indicates the presence of liquid water under the crust. It is salty water and is a prime candidate for astrobiology.
The above picture on the right was taken in 2005 and shows Saturn and its rings. The E ring is mainly made up of ice and water vapour formed from the Enceladus’ plume.
The image below shows the backlit E ring, with Enceladus silhouetted against it. The moon’s south polar jets erupt brightly below it.
Jupiter new horizons enhanced colour image shows lots of different structures. The Great Red Spot, a persistent anticyclonic storm, is at the middle right of the upper right image. White atmospheric bands, termed zones, represent areas of upwelling; reddish bands, called belts, represent areas of downwelling. Any colour changes in these are called by ultra violet light from the Sun. They display high-altitude ammonia ice clouds and lower clouds of unknown composition, respectively. Energy for the movement of the clouds comes from the lower atmosphere. Water vapour is found below the ammonia cloud. Jupiter has five times more volcanic activity than the Earth. There can be 50km ejections of Lava making it a fiery Hell.
Juno was launched in 2011 and is expected to reach Jupiter by 2015 and do 33 orbits. It contains three aluminium lego astronauts.
Uranus had been knocked so that it is tilted 90 degrees to the Sun. Because of this its poles experience 42 years of darkness. However the equator is warmer and we don’t know why.
Neptune is believed to have liquid nitrogen in its atmosphere. Dr Kanani demonstrated the effect of liquid nitrogen.
Inflate a balloon and place it in a Dewar containing liquid nitrogen. The balloon deflates because the air is contracting as it cools.
Neptune has a rocky core with an 8000 km atmosphere containing some nitrogen and ammonia (-280 degrees Celsius), There is a great dark spot and a small dark spot. The great dark spot is an anticyclonic storm and the small dark spot is a cyclonic storm. The Scooter is another storm, a white cloud group farther south than the Great Dark Spot. Its nickname is due to the fact that when first detected in the months before the 1989 Voyager 2 encounter it moved faster than the Great Dark Spot (around 200km per hour).
Pluto is now classed as a dwarf planet.
New Horizons was launched in 2006 to investigate the Pluto-Charon system. It is expected to arrive in 2015.
Our Solar System also contains comets.
A comet is an icy small Solar System body (SSSB) that, when close enough to the Sun melts, displays a visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a dust and ion tail.
Deep impact mission was designed to study the interior composition of comet 9P/Tempel.
Making a comet.
Ingredients include carbonates (sodium carbonate), water, ethanol (vodka), ammonia (nail varnish remover), organic compounds (Lea and Perrins sauce), silicates (sand) and solid carbon dioxide (-80 degrees Celsius).
Comets are very similar to the early years of the Earth.
A comet hitting the Earth is believed to have killed off the dinosaurs but a comet hitting the Earth may have turned it from a barren wasteland to a living planet. The crashing of the comet released water and organic compounds to enliven it.
The above pictures show a coronal mass ejection of plasma in 2012. The Earth’s magnetic field protects us from it.
In the late 1990s the first sighting of an exo-planet was seen in Vega. In 2005 accreted matter was seen around a star.
The Kepler mission has found 300 stars with planets and over 700 exo-planets.
Gliese 581g is an unconfirmed extrasolar planet claimed to orbit the red dwarf star Gliese 581, 22 light-years from Earth in the constellation of Libra. It is the sixth planet purportedly discovered orbiting the star. The discovery was announced by the Lick-Carnegie Exoplanet Survey in late September 2010, after a decade of observation. However, the ESO/HARPS survey team was not able to confirm that the planet exists.
Gliese 581 g has attracted attention because it is near the middle of the habitable zone of its parent star. That means it could sustain liquid water on its surface and could potentially host life similar to that on Earth. (The planet is expected to have temperatures around −37 to −12 °C, however).
The smallest exo-planet seen so far is three times the size of the Earth and is 36 light years away.
Kepler-22b is an exo-planet 5871 light years away from us and it is ten times bigger than the Earth and three times bigger than Neptune.
The above picture of the Eagle returning was taken by Michael Collins (command module pilot of Apollo 11). He joked that he was the only person of Earth who wasn’t in it.
Could tardigrades be the origin of all life on Earth?
Is the future nuclear?
Prof. Jim Smith, University of Portsmouth Involved in environmental science and modelling pollution.
Nuclear power is seen by some as providing a secure source of energy with low greenhouse-gas emissions, while others see it as dangerous, polluting and expensive. Based on his extensive experience of working on the aftermath of the Chernobyl accident, Prof. Jim Smith discussed the health and environmental risks of radioactivity, along with how the media have influenced our perceptions of these risks. With the UK planning to build new nuclear power stations to replace its current ageing reactors, join the debate with some hard facts.
What went wrong?
· Windscale fire, UK, 1957
· Kyshtym accident, Russia, 1957 (place of manufacture of cold war weapons)
· Three Mile Island, US, 1979 (civilian power station, partial meltdown but no radioactivity escaped)
· Chernobyl accident, Ukraine, 1986
· Fukushima, Japan, 2011
The Chernobyl accident involved an explosion of super-heated steam where a 2000 tonne concrete lid was blown off.
The Chernobyl nuclear power plant is located next to the Pripyat River, which feeds into the Dnieper reservoir system, one of the largest surface water systems in Europe, which at the time supplied water to Kiev’s 2.4 million residents, and was still in spring flood when the accident occurred. The radioactive contamination of aquatic systems therefore became a major problem in the immediate aftermath of the accident. In the most affected areas of Ukraine, levels of radioactivity (particularly from radionuclides 131I, 137Cs and 90Sr) in drinking water caused concern during the weeks and months after the accident, though officially it was stated that all contaminants had settled to the bottom “in an insoluble phase” and would not dissolve for 800–1,000 years. Guidelines for levels of radioiodine in drinking water were temporarily raised to 3,700 Bq/L, allowing most water to be reported as safe, and a year after the accident it was announced that even the water of the Chernobyl plant’s cooling pond was within acceptable norms. Despite this, two months after the disaster the Kiev water supply was abruptly switched from the Dnieper to the Desna River. Meanwhile, massive silt traps were constructed, along with an enormous 30m-deep underground barrier to prevent groundwater from the destroyed reactor entering the Pripyat River.
The above picture shows contributions of the various isotopes to the (atmospheric) dose in the contaminated area soon after the accident. Iodine 131 has a very short half-life of about 8 days and Caesium 137 has a half-life of about 30 years.
The escaped cloud of radioactive gases rained onto the east part of Belarus and even reached North West England (including the Lake District), Scotland and Wales. Sheep restrictions in Wales were only lifted in 2012.
134 people got radiation sickness and 40 people died but now nature has overtaken the area.
Unfortunately the media just focus on individuals and worst case scenarios whereas physics facts often take a long time to appear. For instance the media gave the impression that 125,000 people died but in fact only 42 did.
Radiation and health
Radiation does have a risk but it is also used to diagnose and cure cancer.
The health of 90,000 atomic bomb survivors has been studied (msieverts, mSv) is a measure of the radiation risk. Exposure to radiation causes an increased risk of cancer. Most people won’t have a statistical risk.
People had an increased risk of thyroid cancer through eating Iodine 131 contaminated water and food because of Chernobyl but the treatment for the cancer involved Iodine 131. 0.1mSv of radiation reached the UK from Chernobyl but the average background radiation is 2.2 mSv.
50/60 people may die early from exposure to Chernobyl radiation but this is relatively small compared to thousands of early deaths from other causes.
Causes of mortality after exposure to 100 mSv of radiation (This could be the exposure from a dirty bomb)
About 20% of 16-19 year olds smoke. Half of lifetime smokers will die from a smoking related disease. 40% of the rest will develop diseases of the heart and lungs and 23% will develop cancer from natural causes .
Liquidators (Russian: ликвида́торы), or “clean-up workers”, is the generic name given in the former Soviet Union to civil and military personnel who were called upon to deal with consequences of the 1986 Chernobyl disaster on the site of the event.
The above picture on the left is about a computer game to kill mutants from the Chernobyl accident. In reality there aren’t any.
Studying aquatics in lakes has shown no effects on the insects, diversity of flora and fauna or quantity and quality of fish.
The above picture on the right shows that increasing radioactive contamination didn’t have a great effect on the quantity of invertebrates in Glubokoye lake.
The above picture shows that the effects of human activities on the ecosystem (farming, fishing, hunting etc) have a much bigger negative impact that the radiation from the nuclear accident.
The Fukushima accident only covered a fifth of the area of Chernobyl but it was just as significant.
Natural radiation in Cornwall can be higher than the radiation levels found in Fukushima.
The above picture is of Grigory Mamonin, a forester in Chernobyl. He refused to leave his home and lived to 75 even though he ate and drank contaminated food and drink. Life expectancy in men in Belarus and Ukraine in the 1990’s fell as low as sixty due to causes other than radiation such as smoking and poor diet .
Do we need to build new nuclear power stations?
We want to reduce global temperatures and our reliance on fossil fuels.
Rich people use the most energy …………. And we all want to be rich.
At the end of the lecture Professor Smith answered questions.
Something that worried me is what do we do with all the nuclear waste Professor smith replied that we do have plenty of space and materials capable of containing the radioactivity.
Somebody asked about how much nuclear fuel we have considering it is classed as a non-renewable “fuel”. Professor Smith said we have about 70 years of uranium left in current, proven resources.
Hopefully within that 70 year period we will develop new ways to get the energy we need.