Mississauga Centre RASC

102nd Meeting

                                                                                                 Members’ Night      

Day:                Friday March 28, 2008

Chair:             Terry Hardman

Speakers:          Peter Waterman

                           Bob McCall 

                           Randy Attwood 

                           Roy Swanson 

Apollo Lunar Surface Experiment Package (ALSEP)

Peter Waterman came from England in 1965 and went to work for Bendix to co-ordinate the engineering and supply NASA with the end product of the surface experiment package.  It was necessary to ensure that the package was small enough to store and that astronauts could be taught to deploy the instruments in a near vacuum and temperature extremes, and that it would be supplied to NASA on time.  Of the many scientific questions to answer, the important ones were the passive seismometry, solar wind experiment, examination of the thin atmosphere, the magnetic field, heat flow and vibrations on the lunar surface. Different Apollo missions had different instruments; for example, Apollo 11 carried a passive seismic and laser reflector.  The biggest problem for the Central Station Data Subsystem which transmitted data to Earth was keeping it at the right temperature by means of thermal shielding.  Data could flow on three different frequencies to Earth using a pointing mechanism. 

Peter’s main experiment was the laser reflector whose purpose was to measure change in distance between Earth and Moon.  Three laser reflectors consisting of 100 and 300 fused silica corners reflected laser pulses of a few nano seconds duration. Three reflectors from Apollo 11, 14, 15 form an equilateral triangle on the Moon.  Objectives were i) to study physics of the Earth with crustal movements, poles, rotation,   ii) physics of the Moon regarding its motion in orbit, libration, and iii) drift of the Moon from the Earth.  One of the results showed that Hawaii is moving away from Texas. 

Peter showed images and drawing of the laser reflector with Teflon mounted rings to keep it in shadow, and a TV clip of astronauts deploying the experiments on the Moon. 

The Leap Year

Bob McCall discussed the history of the leap year.  The Earth does not go around the Sun in an integral number of days, but in about 365 ¼ days.  The Egyptian calendar was already 3,500 years old by the time of the Romans, and had a 365 day year with 12 months of 30 days and an extra 5 feast days.  Each month had 3 weeks of 10 days.  It was important to know when the inundation of the Nile occurred – at the heliacal rising of Sirius.  In 46 BCE, Julius Caesar decreed that an extra day would be added every fourth year.  However, the Julian calendar contained an error by adding too many days thus having 11 ½ minutes too many each year.  In 1582, in order to set a rule for the date of Easter, Pope Gregory dropped 10 days and introduced the century rule wherein century years were not leap unless divisible by 400. 

Bob also described the Julian date which is a calendar system using numerical days. This was devised by Joseph Scalanger in 1583, one year after the Gregorian calendar.  The Julian date begins on January 1, 4713 BCE and the day begins at noon. 

2008 General Assembly, A Visit to the Johnson Space Centre

Randy Attwood spoke about the 2008 GA and described the events.  Saturday will be  Mississauga Day. 

Recently, Randy attended the Space Exploration Educators Conference at the Johnson Space Centre in Texas.  There were ten 75 minute sessions on aspects of astronomy and  aerospace education.  The first session was given by astronaut Clay Anderson who spent 5 months in the space station.  A LEM training unit and space suits were described.  Various tours are held at the conference including one to the Neutral Buoyancy Lab where astronauts practice space walking under water and learning how to work in those conditions especially on the HST.  Mission control building used for the Apollo missions is now a heritage site.  In addition Randy showed mission control, space shuttle control facilities, vehicle mock-up training, space station trainers and Max Q a musical group made up of astronauts. 

The Sky Next Month

Roy Swanson discussed events in the sky for next month.  He spoke about the Messier objects and the history of Charles Messier as a comet hunter.  He made a list of objects some of which are star forming regions like the Orion nebula.  Roy described Mercury as a morning and evening star and mentioned the Lyrid meteor shower.  

Submitted by Chris Malicki, Secretary  Chris Malicki, Secretary                               back to Miss Centre. meeting reports page
Mississauga Centre RASC