WADHURST ASTRONOMICAL SOCIETY

NOVEMBER NEWSLETTER 2006

INDEX: MEETINGS, OTHER NEWS, CONTACTS

MEETINGS

OCTOBER MEETING  

Mars update

Talk given to the October meeting by Jerry Workman

This was a return visit by Jerry Workman who is the chairman the Loughton Astronomical Society in Essex.  His talk this time was to update us on recent United States Mars missions, beginning with a picture taken by an orbiting satellite of the landing sites of Vikings 1 and 2. Viking 1 was launched in August 1975, reaching Mars in June 1976.  The orbiter had shown that there was quite a bit of difference between the northern and southern hemispheres of Mars.  The northern hemisphere was much smoother.  The first landing site was chosen to be flat and fairly free of rocks and the actual site was on the western edge of Chryse Planitia in the northern equatorial region of the planet.

After a successful landing by Viking 1, the first photographs showed a few surface rocks but the colours had to be adjusted by using the sky as reference white.  The most useful pictures taken were black and white, but in colour the rocks now looked orange, although one near-by rock had some green marks on it that might have been moss but turned out to be surface minerals.

There was evidence in the thin atmosphere of very high winds and many of the rocks showed dust erosion.  There were also signs that water had once caused certain features that could have been caused a considerable time ago.

Viking 2 was launched 7 weeks after Viking 1 and also landed safely but this time the site selected was just a few metres from Mie Crater on Utopia Planitia with the aim of looking at a different kind of Mars rock where there was the possibility of observing rock that had been thrown up from beneath the surface.

Neither Viking 1 nor Viking 2 could find any evidence of life on the planet despite the suggestion of the presence of water.

Jerry went on to say that in July 1997 Mars Pathfinder landed on the surface also near Chryse Planitia.  This site is now known as the Carl Sagan Memorial Station.  The Mars rover, Sojourner, began to examine the atmosphere, soil and rocks.  Findings from the investigations showed that the planet had once been warmer and water in its liquid form had flowed beneath a thicker atmosphere, much of which had been lost to outer space.

Two rocks had been given names because of their appearance, Barnacle Bill and another called Yogi Bear, both quite close to the landing site.  Both showed evidence of wind erosion by sand blasting.  Small holes in their surfaces are thought to have been caused by gas trapped in pockets inside the rock then bursting out as erosion had taken place.  Erosion had also been caused by the incredible changes in temperature from -60 degrees Celsius to -5 degrees.  The soil was found to be rich in iron and to be very magnetic.

Next, Jerry came to the last two rovers to have landed on the surface of Mars and which are still working today although they have long passed their expected working life.  Spirit landed close to Gusev Crater in January 2004.  This crater was selected because previous satellite pictures had shown what looked like a channel leading out of the crater and could have been caused by water pouring out from the crater some time in the past.  This landing site was named Columbia Memorial Station in memory of the seven astronauts who had lost their lives in the Columbia shuttle disaster of 2003.

In a panoramic picture, a group of seven hills could be seen to the east.  Each of these hills was named after one of the seven astronauts.

Close to where Spirit landed was a shallow depression called "Sleepy Hollow" where a brush tool was used to enable rocks to be drilled and penetrated to more easily analyse the material using a spectrometer.  The rocks were found to be composed mainly of olivine, with magnetite, ferrous and pyroxene.

Spirit then moved further afield to bypass Bonneville Crater, regarded as too great a risk to enter, making for the Columbia Hills.  Jerry showed a number of slides of interesting rocks on the way, most showed signs of erosion due to sand blasting and considerable changes in temperature during the Martian day.  Some of the rocks were soft and had eroded more easily than others resulting in some very odd shaped rocks.  Some of Jerry's slides were of remarkable microphotographs showing close-up details of the rocks.

NASA decided that Spirit rover should attempt to climb 300 feet high Husband Hill by taking a zigzag path to the summit.  This was 2 kilometres from the landing site and at present Spirit rover is descending the far side of the hill, sending data via the Orbiter back to Earth.  Jerry said that the data return path at present is about forty minutes between Mars and Earth, meaning that great care is needed to direct the rover safely.

Three weeks after Spirit landed, Opportunity rover landed on the other side of the planet to look at a totally different rock formation.

Around many of the rocks were small rounded dark pebbles of higher density than in other nearby material.  Jerry thought these were released from the bigger rocks during erosion where the rest of the rock had been removed leaving the surface scattered with these 1 centimetre diameter pebbles composed of Hematite.

A day on Mars (only slightly longer than an Earth day) is called a Sol.  Both rovers were designed to last about 90 Sols but Opportunity has so far lasted over 900 Sols and has reached the rim of Victoria crater having passed the Lander's discarded heat shield and also discovering what is thought to be a meteorite from outer space.

Jerry concluded by talking about Phoenix, which is a mission, due to be launched in August 2007 and arriving at Mars on the 18th of May 2008.  Phoenix is to research the poles of Mars with the intention of looking for water trapped in the rocks or in the shadow of the rocks.

This was very a informative talk and we look forward to his return visit in April when he brings us up to date with the Mars Express Mission.

NOVEMBER MEETING

Wednesday 15th November 2006.  David Rooney, who is the Deputy Horologist at Greenwich Museum, is to give us a talk called "A Brief History of GMT". The new Time Galleries opened last February as part of the improvements to the Museum.

As usual, the meeting will be held in the Upper Room of the Methodist Church, the High Street, Wadhurst, opposite Uplands College.

The meeting commences at 1930.

FUTURE MEETINGS

Wednesday 13th December 2006.  Note that this will be second Wednesday of the month.  Phil Berry, a member of the Society is giving a talk he calls "The Trials and Tribulations of an Amateur Astronomer", which should bring to mind some interesting experiences of our own.

Since this is our last meeting before Christmas Phil's talk will be followed by mince pies and beverages!

Wednesday 17th January 2007  The talk is given by Bob Seaney, one of our Society members and the title of his talk is "The Astronomical Art of Chesley Bonestell - Destination Moon (1953) Highlights"

This will be followed by the Society's Annual General Meeting, which takes place in January for the first time.

Wednesday 21st February 2007  Ian King presents a talk he calls "The GranTeCan" which might have something to do with a trip he took recently.

Wednesday 21 March 2007  Our guest speaker will be Dr. Stephen Serjeant and his talk is called "The Big Questions in Cosmology".

Our speakers are arranged by Phil Berry, and I think you will agree, he is finding some excellent talks.  It would be also be very interesting to hear from any member who would like to give a talk.  It would not have to be for the whole meeting but very often members mention interesting experiences, which could be the basis of a talk.  The Society needs more talks that reflect the amateur's problems, and how they have been resolved, - or not resolved for that matter.  It would also help Phil if you could contact him with suggestions.

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OTHER NEWS

NOVEMBER NIGHT SKY  

Several events take place his month.  In the past few years the Leonid Meteor shower has been quite spectacular and it is thought this might be the last outburst of strong activity for the time being as the Earth passes close to the centre of the debris remaining from comet 55P/Tempel-Tuttle whose parent comet passed the Earth in 1932.  It is estimated that strong outbursts occur only every 33 years.  The peak is at 0445 on the morning of the 18th November.  The meteors are very fast, bright and often leave lingering ionisation trains.  The general shower can be observed between the 15th and 20th of November originating close to Regulus in the constellation of Leo. 

Mercury is close to the Sun at the start of the month and in fact transits the disk of the Sun viewed from the Pacific Ocean and parts of Australia on the 8th of November but we do get a chance to see Mercury just before Sun-rise when is rises at 0530 on the 25th November.  It will have a magnitude of -0.4 with a phase of 60 %.  The Sun rises at 0730 so viewing should be safe before that.  This will be about the best view we will have had this year. 

Saturn is still in a favourable position to observe, rising just before midnight at the beginning of the month and rising at about 2200 by the end of November.  It will have a magnitude of +0.4 and is about 5 degrees east of Regulus in the constellation of Leo.

Titan, Saturn's largest moon and larger than Mercury, is well worth trying to observe.  It orbits the planet every 16 days and has a magnitude of about +8.

NASA SPACE PLACE

The Planet in the Machine

By Diane K. Fisher and Tony Phillips

The story goes that a butterfly flapping its wings in Brazil can, over time, cause a tornado in Kansas. The "butterfly effect" is a common term to evoke the complexity of interdependent variables affecting weather around the globe.  It alludes to the notion that small changes in initial conditions can cause wildly varying outcomes.

Now imagine millions of butterflies flapping their wings.  And flies and crickets and birds.  Now you understand why weather is so complex.

All kidding aside, insects are not in control.  The real "butterfly effect" is driven by, for example, global winds and ocean currents, polar ice (melting and freezing), clouds and rain, and blowing desert dust.  All these things interact with one another in bewilderingly complicated ways.

And then there's the human race. If a butterfly can cause a tornado, what can humans cause with their boundlessly reckless disturbances of initial conditions?

Understanding how it all fits together is a relatively new field called Earth system science. Earth system scientists work on building and fine-tuning mathematical models (computer programs) that describe the complex inter-relationships of Earth's carbon, water, energy, and trace gases as they are exchanged between the terrestrial biosphere and the atmosphere.  Ultimately, they hope to understand Earth as an integrated system, and model changes in climate over the next 50-100 years.  The better the models, the more accurate and detailed will be the image in the crystal ball.

NASA's Earth System Science program provides real-world data for these models via a swarm of Earth-observing satellites.  The satellites, which go by names like Terra and Aqua, keep an eye on Earth's land, biosphere, atmosphere, clouds, ice, and oceans.  The data they collect are crucial to the modelling efforts.

Some models aim to predict short-term effects-in other words, weather.  They may become part of severe weather warning systems and actually save lives. Other models aim to predict long-term effects-or climate.  But, long-term predictions are much more difficult and much less likely to be believed by the general population, since only time can actually prove or disprove their validity.  After all, small errors become large errors as the model is left to run into the future.  However, as the models are further validated with near - and longer-term data, and as different models converge on a common scenario, they become more and more trustworthy to show us the future while we can still do something about it-we hope.

For a listing and more information on each of NASA's (and their partners') Earth data-gathering missions, visit science.hq.nasa.gov/missions/earth.html.  Kids can get an easy introduction to Earth system science and play Earthy word games at spaceplace.nasa.gov/en/kids/earth/wordfind .

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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CONTACTS

Chairman   Tim Bance  01732 832745 timbance@hotmail.com

Phil Berry  01892 783544 phil.berry@tiscali.co.uk

Treasurer  Mike Wyles  01892 542863 mikewyles@globalnet.co.uk

Publicity & Website  Michael Harte  01892 783292 michael@greenman.demon.co.uk

Newsletter Editor  Geoff Rathbone  01959 524727 Geoff@rathbone007.fsnet.co.uk

Any material for inclusion in the December Newsletter should be with the Editor by November 28th  2006

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