COMMITTEE MEETING

 

        Members of the Committee are respectfully reminded that there will be a meeting of the Committee at Phil Berry’s house starting at 1930 on the new date of Thursday 8th of October 2009.

        As always, any member of the Society is welcome to come along but please give a Phil a ring before turning up.

 

MEETINGS

 

SEPTEMBER MEETING

 

        The meeting was chaired by Phil Berry who said how successful this year’s Astro-barbecue had been and gave a brief report on the various activities, and kindly thanked Michael and Claire Harte for hosting it once again.

        He also told the meeting that Ashford Astronomical Society is planning an “Astro Bash” on the 24th of October to which we are all invited.  There is a further note about this event later in this Newsletter.

        Phil mentioned the Society’s under used 4-inch refractor telescope.  This is an excellent telescope and any member particularly without a telescope and wanting to become familiar with the night sky is welcome to borrow it at any time for any for as long as they find it useful.  Now is a good time as autumn is again with us together with those long, hopefully clear evenings.

        Phil then introduced Rob Cray, who is a founder member of our Society and was there at its inception now well over ten years ago.

 

The Apollo Missions; 13 to 17

By Rob Cray

 

        Back in March this year, Rob gave a wonderfully researched talk about the Apollo Missions from the start to Apollo 12 and including a short introduction to the launch of Apollo 13 and subsequent events.  He now returned to complete the Apollo story.

        He began this talk with some remarkable pictures only recently released by NASA of the Apollo landing sites taken by the Lunar Reconnaissance Orbiter and showing in detail for the first time, the actual landing craft and equipment at the various sites with their shadows.  These images can be seen on the NASA website at:

www.nasa.gov/mission_pages/LRO/multimedia/lroimages/apollosites.html

        The only one missing is Apollo 13 and that is where Rob began.

        The original crew consisted of Lovell, Mattingly and Haise, although Ken Mattingly was replaced at the last minute because of a contact with measles.  He never succumbed to it but the risk was too great.

        Public interest in the Lunar missions was beginning to wane and there was less TV coverage than there had been in the past.  This all changed when, during the journey to the moon Lovell reported “Houston, we have a problem”.  An oxygen tank had burst, damaging the outside of the craft and causing a life-threatening loss of power and oxygen.

        Rob gave a very interesting account of why this occurred.  To prevent hot-spots developing inside the tank, they are “stirred” occasionally.  But owing to various upgrades during development of the equipment from 28 volts to 60 volts, the Service Module’s tank’s internal thermostat had been left out and was an older original.  Unfortunately bare wires on the stirrer motor shorted during the stirring process causing the insulation to burn and heating the oxygen so that the pressure became too great to be contained and resulted in a catastrophic explosion of the tank.

        Despite not having reached the moon at this stage, rather than risk using fuel to turn the craft round and return to Earth, the safest option was to continue into free return orbit around the Moon.

        The crew were moved into the Lunar module where life support would keep them alive, although this had been designed for two people for two days.  At least this would given them time whilst alterations were made to the lithium-hydroxide scrubber that removes carbon-dioxide from the air.  This had to be modified so that the unit would fit into the Service Module for the return journey to Earth.

        Remarkably, this was successful and the crew were able to return safely to Earth although there was huge disappointment at not being able to land on the surface of the Moon and complete the mission.

        Apollo 14 successfully landed in the highlands of Fra Mauro despite a brief scare when a warning light in the abort circuit was activated by a small piece of loose solder.  To prevent the automatic landing sequence being initiated, NASA reprogrammed the computer to prevent this occurring.

        The mission went on to take soil samples and set up a solar-wind detector, a spectrometer and a laser ranging retro-reflector to enable the Moon’s distance from Earth to be measured continuously.  At present the Moon is moving away from Earth at something like three or four centimetres a year.

        Rob went on to describe the Apollo 15 Mission when the Lunar module landed 2 kilometres from Hadley Rill, a collapsed lava plume.  The lander came to rest with one leg off the surface but appeared stable.

        The astronauts had the use of a motorised module that had been carefully folded and stowed in the lander.  This enabled them to travel up to 4½ kilometres away and take core and other samples.

        One significant problem was the very fine lunar dust that got into just about everything… such as the sample containers that could not be sealed properly as a result and later became contaminated.

        The astronauts suffered magnesium deficiency.  This caused their heart-rate to increase to 86% more than it should have been.  Their medical state was being monitored back on Earth and it was suspected that Irwin was suffering a very mild heart attack.  In fact He died from a heart attack some time after the mission.

        On the Apollo 16, coloured bands were included on the legs of the astronauts’ suits so that the individuals could be identified on camera.  This time EVAs took them as far as 6 kilometres from base and they reached speeds of up to 11 mph.

        The last human lunar landing was on Apollo 17 when a trained geologist was included in the crew to provide immediate human decision-making observations of the rocks and soil.

        This time they travelled as far as 8 kilometres, visiting the Taurus Littrow valley, taking samples of soil and rocks.

        When back in the spacecraft, the astronauts described the smell from the dust as being a cross between gunpowder and charcoal.

        The remaining Apollo missions were cancelled due to budget cuts and it remains undecided when there will be any further manned landings.

        One final word from Rob related again to Apollo 13.  He said that because of the emergency, the nuclear power source for the lunar lander had to be present during the return instead of being left on the moon.  Now It is somewhere beneath the middle of the Pacific Ocean.

        Together with the new information Rob had uncovered during his research and the clear pictures from his DLP projector, this was a very informative and enjoyable presentation.

 

 

OCTOBER MEETING

 

        Wednesday 21st October 2009 -.“Astro-archaeology in the British Isles”; A talk by Bob Seaney, a well known member of the Society who has given a number of talks in the past.  Bob has been doing his own research for some time and reveals what he has discovered.

        Meetings begin at 1930 although members are invited to arrive anytime after 1900 as this is a good time to exchange ideas and discuss problems and relax before the talk.

        The venue as always is in the Upper Room of the Methodist Church at the east end of Wadhurst Lower High Street, opposite the entrance to Uplands College.  (For those with SatNav – the post code is TN5  6AT)

 

 

FUTURE MEETINGS

 

 

        Wednesday 18th November 2009 - Just recently there have been quite a few notes in the Newsletter referring to Iridium Flares.  At the November meeting, Phil Berry, a member of the Committee will be giving a talk about the “Iridium Flares”; what are they, how do they come to be there with a few notes on their appearance.

 

        Wednesday 16th December 2009Paul Treadaway is giving another of his talks.

        Being the month of Christmas, there will also be the usual mince pies to go with our coffee.

 

 

OTHER NEWS AND INFORMATION

 

ASHFORD ASTRONOMICAL SOCIETY “ASTRO-BASH”

 

        A recently formed Astronomical Society, Ashford AS, is holding an event on Saturday the 24th of October called “The Astro Bash 2009 Star Party”.  Their Society meets at Woodchurch, about 5 miles south-west of Ashford where the skies are pretty free from light pollution.

        The event runs from 1400 to 2100 at the Woodchurch Community Centre in Lower Road and will include talks during the afternoon with other astronomy related activities for all ages.

        There will also be computerised projectors and a planetarium.

        During daylight hours a live image of the Sun, seen via a specially modified solar telescope will be projected on a large screen and during the evening there will be a telescope available on site to observe the night sky.

        Everyone is invited and there is more information available on their website at:

www.ashfordastro.org.uk

        They do seem to be a very lively new society and are fellow members of SAGAS.

 

SOME FILTERS USED IN AMATEUR ASTRONOMY

 

        Just the name, “Filters” suggests something is being removed and in the case of optical filters for astronomy, that is exactly what they are used for.  Perhaps one has a monochrome good quality CCD camera; this can be used to make colour images of, for instance the Orion Nebula.  The red filter removes all but the red part of the image and so on with green and blue filters.  In this way high definition monochrome cameras can be used where all the detectors in the CCD’s matrix are used to produce one image.  Several exposures are made in each of the three primary colours and then combined to produce the final high definition result in colour.  This is a very common use of filters.

        The moon is very bright when looking at it with the naked eye through a telescope, particularly at low magnification.  Here there are several neutral density filters to pick from that remove some of the unwanted light.  Two polarizing filters can be combined to produce a continuously variable neutral density variable filter by rotating one relative to the other.

        We’ll look at solar filters later.

        Photographic style colour filters can often be used to advantage and are made to fit the various sizes of telescope eyepieces.  The cloud structures on the planets Jupiter and Saturn can be enhanced using a yellow/green filter; this will also increase the contrast of the Red Spot on Jupiter.  An orange or light-red filter can help to reveal features on Mars, including the polar cap.  These are just a couple of examples of plain colour-filters.

        Other filters reduce the light from certain street lights that cause light pollution.  Modern street lights produce very narrow bands of monochrome light for economic reasons.  Fortunately these narrow bands can be removed fairly easily using narrow band filters.  Sodium lamps excite gasses that emit light centred on 589 nanometres; that’s in the yellow band.  Mercury lamps produce a number of lines throughout the spectrum, particularly below 450 nanometres and above 550 nanometres.  These light pollution filters cost from less than £20.

        Fortunately, between 450 and 550 nanometres lie the emission lines of Oxygen 3 which are the lines emitted by planetary and emission nebulae and so OIII filters are made especially for enhancing the contrast of such objects as the Veil, Ring, Dumbbell, Crescent and Orion nebulae.  These filters are a little more expensive and start at around £40 each.  Better quality ones can cost well over £100 but can be well worth it.

        Hydrogen Beta filters only pass light around the hydrogen emission lines at above 650 nanometres and allow us to see better such objects as the Horse Head nebula in Orion and the California nebula.

        Contrast when observing such objects as Mercury or Venus in daylight can be greatly improved by using polarizing or Ultraviolet filters to darken the blue of the background sky and improve the contrast.

        Observing the Sun is safest by projecting the image from the eyepiece on to a white card or sheet in a darkened room, but if it is necessary to see the Sun directly then Baarder Solar filter which comes in sheets costing about £18, can be used.  The filter must cover the whole of the object lens or main aperture to the telescope.  Care is needed to make sure no direct sunlight can reach the eye as this can spell instant retinal damage.  The gold coloured filter reveals the surface of the Sun without colour bias.  Sunspots (when they return) are seen well using this method particularly when monitoring their progress.

        To see prominences and the texture of the Sun’s surface particularly in the interesting areas near any sunspots can only be seen by using a special Hydrogen-alpha filter.  These are very expensive and consist usually of two parts.  The front aperture contains an energy rejection filter for infra-red and ultraviolet.  Immediately behind this is a thing called an Etalon narrow band filter which blocks all but the hydrogen-alpha band which is slightly tuneable.  At the eyepiece end of the telescope is the rear blocking filter that attenuates the brightness and ensures that only the hydrogen-alpha line is seen.

        More information about astronomical filters can be found at:

http://astrosurf.com/buil/filters/curves.htm#Custom%20Scientific

and links from:

http://www.sas.org.au/filters.htm

and many other sites by going through Google.

 

Geoff Rathbone

 

 

SKY NOTES FOR OCTOBER

 

Planets

 

Mercury makes its best morning appearance of 2009 during October. The planet should be a relatively easy object at magnitude -1 from the beginning until almost the middle of the month. It reaches its greatest western elongation on the 6th rising nearly two hours before the Sun.

 

Venus at magnitude -3.8 is a brilliant morning object rising two hours before the Sun. As it moves back towards conjunction its apparent size decreases whilst its phase increases. On the morning of the 13th the planet passes half a degree south of the much fainter Saturn.

 

Mars is slowly brightening (at magnitude +0.6) and has become an evening object, but only just. By the middle of the month it rises a little before midnight (BST). At the very end of the month (and through part of November) it passes in front of the cluster M44 (known as the Praesepe) in Cancer. The position of Mars in the middle of the month is shown by the cross in the diagram below. By the end of the year it will have made it’s way eastwards as far as Leo.

Jupiter at magnitude -2.6 in Capricornus is still the most conspicuous object in the evening sky looking south west.  If you do need a pointer, use the stars in the corners of the square of Pegasus as shown below.  Jupiter is decreasing both in apparent size and in brightness and will set before midnight by the end of the month.

Saturn is a morning object at magnitude +1.1 but will be difficult to find in twilight skies. The closeness of Venus on the 13th may make location easier.

 

Lunar Occultations

        As usual in the table I’ve only included events for stars down to around magnitude 7.5 that occur before midnight. DD = disappearance at the dark limb and RD = reappearance at the dark limb. Times in the first half of the table are BST.

 

Oct.

Time

Star

Mag.

Ph

PA °

2nd

22.39

SAO 128215

7.2

DD

353

3rd

20.56

SAO 109091

7.0

DD

77

6th

19.13

SAO 93062

5.7

RD

296

7th

22.43

SAO 76215

5.4

RD

229

7th

23.31

GSC0180001260

5.9

RD

299

24th

20.43

SAO 187961

7.8

DD

88

Times below are GMT

25th

21.17

SAO 188998

7.8

DD

104

26th

21.21

SAO 164013

5.9

DD

10

27th

23.00

SAO 164639

5.6

DD

94

28th

17.45

SAO 146062

5.9

DD

7

30th

17.56

SAO 128454

7.3

DD

20

 

Daylight Occultation of Antares

        On October 21st there is a daylight occultation of Antares, the brightest star in Scorpio. This will be a challenging event with the sky light and the Moon, at three days old, low in the sky. Below are the details with times in BST. RB = reappearance at the bright limb.

 

Oct.

Time

Star

Mag.

Ph

PA °

21st

15.54

Antares

1.1

DD

116

21st

17.10

Antares

1.1

RB

253

 

 

Phases of the Moon for October

 

Full

Last ¼

New

First ¼

4th

11th

18th

26th

 

ISS

        Sadly there are no evening passes of the ISS this month, they all occur in the early hours of the morning. Details of all passes can be found at www.heavens-above.com

 

Iridium Flares

        The flares that I’ve listed are magnitude -3 or brighter. There are many more that are fainter, occur at lower altitudes and also after midnight. If you wish to see a complete list, go to www.heavens-above.com   Times are BST in the first part of the table.

 

Oct.

Time

Mag

Alt°

Az.

1st

19.42

-3

59

SE

2nd

19.36

-3

57

SE

8th

19.09

-8

55

SSE

16th

18.15

-5

11

W

19th

18.21

-5

45

S

24th

18.00

-7

39

SSW

Times below are GMT

29th

18.09

-8

49

S

30th

18.02

-7

50

NNE

31st

17.56

-5

45

S

 

Meteors - the Orionids

        The Orionid meteor shower, which is associated with Halley’s comet, is active from October 16th to the 27th with maximum occurring on the 20th. The ZHR at the time of maximum is expected to be around 30 this year with many bright meteors leaving ionised trains. The position of the radiant is shown below in the diagram.

 

Advance warning for November

        Mars passes in front of M44

        Rosetta space craft passes Earth on its last flyby before rendezvousing with a comet in 2014

Leonid meteor shower - 15th to 20th

 

Don’t forget that clocks go back one hour at 02.00 on Sunday October 25th.

 

Brian Mills

 

 

NASA’S SPACE PLACE

 

Spitzer, the Sequel

The Spitzer Space Telescope is getting a second chance at life.

 

        The liquid helium “lifeblood” that flows through the telescope has finally run out, bringing Spitzer’s primary mission to an end. But a new phase of this infrared telescope’s exploration of the universe is just beginning.

        Even without liquid helium, which cooled the telescope to about 2 degrees above absolute zero (-271°C), Spitzer will continue to do important research—some of which couldn’t easily be done during its primary mission. For example, scientists will use Spitzer’s “second life” to explore the rate of expansion of the universe, study variable stars, and search for near-Earth asteroids that could pose a threat to our planet.

        “We always knew that a ‘warm phase’ of the mission was a possibility, but it became ever more exciting scientifically as we started to plan for it seriously,” says JPL’s Michael Werner, Project Scientist for Spitzer. “Spitzer is just going on and on like the Energizer bunny.”

        Launched in August 2003 as the last of NASA’s four Great Observatories, Spitzer specializes in observing infrared light, which is invisible to normal, optical telescopes.

        That gives Spitzer the power to see relatively dark, cool objects such as planet-forming discs or nearby asteroids. These objects are too cold to emit light at visible wavelengths, but they’re still warm enough to emit infrared light.

        In fact, all warm objects “glow” with infrared light—even telescopes. That’s why Spitzer had to be cooled with liquid helium to such a low temperature. Otherwise, it would be blinded by its own infrared glow.

        As the helium expires, Spitzer will warm to about 30 degrees above absolute zero (–243°C). At that temperature, the telescope will begin emitting long-wavelength infrared light, but two of its short-wavelength sensors will still work perfectly.

        And with more telescope time available for the remaining sensors, mission managers can more easily schedule new research proposals designed for those sensors. For example, scientists have recently realized how to use infrared observations to improve our measurements of the rate of expansion of the universe. And interest in tracking near-Earth objects has grown in recent years—a task for which Spitzer is well suited.

        “Science has progressed, and people always have new ideas,” Werner says. In its second life, Spitzer will help turn those ideas into new discoveries.

        For kids, The Space Place Web site has a fun typing game using Spitzer and infrared astronomy words. Check it out at:

spaceplace.nasa.gov/en/kids/spitzer/signs.

 

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

 

 

CONTACTS

 

Chairman     John Vale-Taylor

                                                      pjvalet1@tiscali.co.uk

 

Treasurer            Mike Wyles                          01892 542863

                                                      mike31@madasafish.com

 

Editor            Geoff Rathbone                         01959 524727

                                                      geoff@rathbone007.fsnet.co.uk

 

Events                  Phil Berry                             01892 783544

                                                      phil.berry@tiscali.co.uk

 

Director of Observations       Brian Mills    01732 832691

                                                      Brian@wkrcc.co.uk

 

Wadhurst Astronomical Society website:

                                                      www.wadhurst.info/was/

 

SAGAS web-site                        www.sagasonline.org.uk

 

Any material for inclusion in the November 2009 Newsletter should be with the Editor by 28th October 2009