Satgen 158 Martian Pictures By GM4IHJ 5 April 92 During 1988 several reputable publications carried Viking Mars Orbiter photographs of a curious Martian surface feature which resembled a human face. Since then others have pointed out that near the face ?, are several rock formations which resemble pyramids. It is not the intention here to join the chorus of those who see in these objects " firm evidence " of intelligent life on Mars . I merely want to point out that the Americans at JPL in California may soon be providing a way for anyone to get their own pictures of Mars, and make their own minds up about ancient life there, or , as I intend to do , just have fun getting the Mars Observer signals. These signals will be on X band around 8.42 GHz, and they will be modulated by Telemetry and Image Data at various transmission speeds. So a brief look at the signal path requirements for DIY Mars surveying may be useful :- Mars varying distance from Earth versus various Rx station Characteristics At all times Tx power 44watts Tx Dish 1.5m RxS/N +3dB RxTemp 250 kelvin Wave Length of Signal 3.6 cms RxDish Bwidth Effective Range Remarks 2m 40Hz 337 millionkms OK any time for slowest telemetry 2m 400Hz 106 millionkms not enough for 250bps when Mars near Earth 2m 4000Hz 30 millionkms Hopeless for lowest image data speed 4m 4000Hz 67 millionkms Still hopeless for image reception 8m 4000Hz 135 millionkms Maybe OK low image speed Mars near Earth 16m 8000Hz 190 millionkms Adequate Image reception Mars near Earth Note. Mars Earth Separation is 270 milkms June 93 ; 360 milkms january 94 : and reduces to 124 milkms by january 95. Summary - This experiment will start when Mars is far from Earth and during the first half of 1994 the Mars Earth separation will go through maximum, but thereafter in the second half of 1994 the Mars Earth separation will reduce rapidly . So up to mid 1994 big dishes will be essential but in late 1994 small dish users should get results. Transmissions will be broken as the Observer is eclipsed by Mars but tracking should be easy. Data and Software program P.bas mentioned in Satgen 137 refers to Mars tracking. Satgen 138 refers to Observer orbits around Mars. 73 de John GM4IHJ @ GB7SAN