Deep Space Pioneers

Where were you on the 2^nd March 1972 (some refs state 3^rd of March) – the day Pioneer 10 (AKA Pioneer F) was launched into space on its epic journey to Jupiter and its search for alien life? 

Thirty-seven years – is a lifetime away.  Imagine the crudity of the ‘ancient technology’!  Big – clunky – cutting edge in the broadest sense of the word!  Then consider the mathematical beauty of the successes achieved – and how it was so painstakingly accomplished.  As has been said many times – today, we have more computing power in a home PC than was available to such complex cosmic endeavours. 

Launched atop an Atlas/Centaur/TE364-4 three-stage launch vehicle; Pioneer 10 carried only eleven instruments – as follows:  1. Plasma Analyzer (P/L) 2. Charged Particle Instrument 3. Cosmic Ray Telescope 4. Geiger Tube Telescope 5. Trapped Radiation Detector (P/L) 6. Meteoroid Detector (ENC) (F) 7. Asteroid-Meteoroid Experiment (ENC)(F) 8. Ultraviolet Photometer 9. Imaging Photopolarimeter (ENC) (P/L) 10.  Infrared Radiometer (F) and 11. A Helium Vector Magnetometer. 

This very limited and specific collection of instruments sent back more useful information in its working lifetime than could of ever been hoped for; leading the way for all future deep space exploration.

For the record – the third stage booster was required to gain a speed of 51,810 kph to enable the unit to complete its flight to Jupiter.  At the time, this made Pioneer 10 the fastest man-made body to leave Earth – at a speed that would take it past the Moon in just eleven hours; traversing 80 million kilometres of space and crossing the orbit of Mars in only twelve weeks.  

Measuring just 2.9 metres in length, and 2.7 metres at its widest point, Pioneer 10 weighed in at just 258 kgs.  Electrical power was supplied by four radioisotope thermoelectric generators (RTGs), each providing just 155 watts of power at launch – decaying to 140w in transit to Jupiter.  The spacecraft required just 100w to power all systems. 

An RTG is a nuclear electrical generator that draws its power from the process of radioactive decay!  Heat released by the decay process is converted into electricity via the Seebeck effect (an explanation of which would take us down the murky road to the magic world of semiconductors).  Put simply, an RTG is a form of battery; a power source long associated with space probes, satellites and even terrestrial unmanned scientific facilities.  The most obvious drawback to their use is the requirement to safely contain the radioisotopes long after the useful ‘battery life’ has been expended.

By July 15^th 1972, Pioneer 10 entered the Asteroid Belt – an area 280 million kms wide and 80 million kms thick – located approximately between the orbits of Mars and Jupiter.  The thinly spaced objects within the Asteroid Belt travel at speeds estimated to be 20 km/sec and the objects within, vary in size from mere dust particles to rocks the size of the state of Queensland!  Whilst other spacecraft have since negotiated this area of space, at the time scientist were unsure if Pioneer 10 would be able to safely navigate its way across this possibly terminal minefield.

By the 4^th of December, 1973, Pioneer 10 made its first fly-by of the gas giant, Jupiter, achieving a dream first approved in February 1969.  The earliest mission objectives had been outlined as follows: explore the interplanetary medium beyond the orbit of Mars – investigate the environment within the Asteroid Belt and assess the belt’s potential hazards to future outer planet missions – explore the locality around Jupiter – and make a close approach Jupiter to gather information on the possible effects of Jovian radiation on spacecraft instrumentation.

In just twenty-one months the textbook mission had been completed beyond all expectations – but the story continued for the tiny probe well beyond this point as for many years a weak signal continued to be traced by the Deep Space Network.  Right up to 1997 and onward, the probe was employed to train flight controllers on how to obtain radio signals from space!  The final successful telemetry – the technology that allows remote measurement and reporting – from Pioneer 10, was on April 27^th 2002.

Amazingly, on the 23^rd of January 2003, what is recognised as the very last extremely weak signal was received from the still operating probe.  At that time Pioneer 10 was estimated to be 12 billion kilometres from Earth (80 au).  A further contact effort was made on February 7^th 2003 – but this attempt was unsuccessful. 

On March 4th, 2006 – the last time the probe’s antenna would be acceptably aligned with Earth – yet one last attempt at contact was made.  No response from Pioneer 10 was forthcoming.  It is thought that sheer distance and lack of power were the reasons for the eventual loss of contact, rather than the destruction of the probe.  It should also be noted that the probe must first be contacted by NASA before it will respond and send back data.

When its last position was recorded, Pioneer 10 was headed in the general direction of Aldebaran, in the constellation of Taurus.  At an estimated speed of 2.6 au per year – assuming Aldebaran has relative zero speed – Pioneer 10 should reach this distant destination in approximately 2 million years.

Pioneer 10 and its twin, Pioneer 11 (AKA Pioneer G), may yet possibly achieve one last duty if they are ever intercepted by ‘alien life’.  Both vehicles carry the famous gold anodized aluminum plaques - suitably shielded from erosion and cosmic dust - which depict the human race in all its naked glory.  Further information – should the extraterrestrials be adventurous or interested enough – and have technology well in advance of that presented to them in the shape of the defunct Pioneer probes – provides the exact location of our ‘Blue Island’ world.

Refs:

Encyclopedia, W. T. F. (2010). Radioisotope thermoelectric generator. Retrieved January 1, 2011, from Wikipedia: http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator.

Encyclopedia, W. T. F. (2010). Thermoelectric effect. Retrieved January 1, 2011, from Wikipedia: http://en.wikipedia.org/wiki/Seebeck_effect#Seebeck_effect.

Hamilton, C. J. (N/A). Pioneer 10 & 11. Retrieved December 31, 2010, from NASA Houston TX 77058: http://www.solarviews.com/eng/pn10-11.htm.

Lakdawalla, E. (2006). The final attempt to contact pioneer. Retrieved January 3, 2011, from The Planatary Society: http://www.planetary.org/blog/article/00000477/.

NASA. (2010, April 1). Pioneer 10 & 11. Retrieved December 31, 2010, from NASA  Science Missions: http://science.nasa.gov/missions/pioneer-10-11/.

Stenger, R. (2002, December 1). A distant pioneer whispers to earth. Retrieved January 3, 2011, from CNN - Science and Space: http://edition.cnn.com/2002/TECH/space/12/18/pioneer.contact/index.html.

Today, S. (2003). The pioneers are way out there after 30 years. Retrieved December 31, 2010, from Space Today Online: http://www.spacetoday.org/SolSys/ThePioneers.html.

Ward, M. (2001, April 30). Distant probe phones home. Retrieved January 1, 2011, from BBC News: http://news.bbc.co.uk/2/hi/science/nature/1305068.stm.