SESSION 3

A CLOSER LOOK

FIRST ATTEMPT

• In 1962 the USSR makes a first attempt to send a probe to Mars but contact was lost when the spacecraft was 106 million kms into the journey

• It was the first of many failures and it became known as the Curse of Mars

• Russian probes were affected most of all but a number of American probes also failed to reach their destination or crashed or malfunctioned on arrival

TIME AND DISTANCE• A probe to Mars is infinitely more demanding

than putting a satellite in orbit around the Earth or even putting a lander on the Moon

• A journey to Mars takes about a year and for such a long time electronics may not survive the extreme conditions of space Communications both ways take much more time because of the huge distances

• The Russians were good engineers and had very powerful rockets but their electronics were inferior to that of the West, particularly that of the USA

RUSSIAN EFFORTS

• Two probes were launched in 1971 called Mars 2 and Mars 3

• Each carried a 3 tonne orbiter and a 1 tonne lander to parachute to the surface with rockets for final breaking

• On arrival they were designed to go into automatic landing sequence but at that time a dust storm was raging all over the planet

MARS 2 AND MARS 3

• Mars 2 became the first man made object to crash land on the surface of Mars

• Mars 3 made a successful but rather bumpy landing at 75 km/hour and started to send its first digital image. The few lines transmitted were blank and transmission ceased after 20 seconds

THE CURSE OF MARS

• The year 1973 was a bad year for the Russians. Four missions were launched: Mars 4, 5, 6 and 7. Mars 4 and 5 were orbiters and Mars 6 and 7 were landers

• Mars 4 failed to go into orbit but took a few images in passing

• Mars 5 stayed in orbit for 10 days and returned sixty images

MARS 6 AND 7

• Mars 6 lander crashed on the surface of Mars

• Mars 7 lander managed to miss its destination by 1300 kms

• Because of the huge cost involved and the minimal return for their efforts the Russians decided to cut their losses

FLYBY MISSIONS

• The USA launched the first successful flyby mission (Mariner 4) in 1964 and it reached Mars in July, 1965

• It was programmed to pass Mars at a distance of 10,000 km and take images of the surface of the Southern Highlands. The images showed a cratered landscape rather like the Moon and gave the impression that Mars was a dead planet

Image of Mariner 4

AMERICAN ATTEMPTS

• In 1973 Mariner 9 was sent into orbit around Mars. It was designed to map the whole planet over many months

• Initially frustrated by the dust storm it was able to wait and eventually obtained a series of spectacular images

• It showed a planet with much more complex landforms than anybody had expected

SURFACE OF MARS• There were spectacular volcanoes.

Olympus Mons proved to be the highest and largest volcano in the solar system and there were relatively young lava plains characterized by the near absence of craters

• Images were obtained of the polar ice caps, desert dunes, ancient river channels and landforms produced by glaciers and frost action

Image of Northern Polar Ice Sheet

Evidence of ancient stream channels

VALLES MARINERIS

• It is a spectacular canyon and was named after the Mariner 9 probe

• The discovery of channels formed by running water was a surprise and indicates that in early history Mars must have been a warmer and wetter planet with a denser atmosphere

SEASONAL COLOUR CHANGES

• Astronomers had earlier attributed these changes to seasonal variations in vegetation or soil moisture

• They turned out to be areas of dark volcanic rock covered to varying degrees by bright red dust depending on the strength and direction of seasonal wind systems

• Today Mars is a dry frozen planet with a very thin atmosphere

MARS NOMENCLATURE

• With major topographic features now much better known the nomenclature of landforms had to be revised

• A Latin terminology was proposed and accepted by the International Astronomical Union in 1973

• For the first time it became possible to compile a reasonably accurate map of the surface features of the planet

NOMENCLATURE TERMS

• Planitia – Low plain

• Mons – Mountain

• Vallis – Dry river channel

• Tholis – Small domed mountain

• Patera – Shallow volcanic crater

• Fossa – Long narrow valley

NOMENCLATURE TERMS

• Labyrinthus – Network of intersecting valleys

• Vastitas – Vast wide lowland

• Planum – Plateau or high plain

• Rupes – Scarp or cliff

• Rima – Narrow fissure

VIKING PROJECT

• Launched by NASA in 1975 it was the most expensive space project ever undertaken (US$2 billion)

• Two landers were designed to settle the question of life on Mars and also make detailed measurements of climate

• Experiments had been designed by a team of biologists led by the famous scientist Carl Sagan and also included James Lovelock

VIKING PROJECT• Two identical spacecraft consisted of a

lander and an orbiter. The latter acted as survey and relay stations and were able to assess potential landing sites for roughness before a landing was attempted

• Both landers made a successful controlled landing in 1976 and Viking 1 lasted for six years. On its first day on the surface it measured a daily temperature range from -29 to -80 degrees C

Viking spacecraft with lander enclosed in capsule

Lander during descent with retrorockets firing

THE GREAT BUG SEARCH

Five experiments were included to help detect signs of life

(1) A scanning camera to look for signs of plant or animal life. No martians or any other life were observed

(2) A gas chromatograph mass spectrometer (GCMS) to measure very small amounts of organic matter in the martian soil. No such presence was detected

OTHER EXPERIMENTS

The other three experiments were called gas exchange (GEX), labelled release (LR) and pyrolytic release (PR). The first two involved moistening and warming martian soil samples and then adding organic fertilizers. The results indicated an absence of biological processes. There appeared to be no micro-organisms present at the sample site

LIFE ELSEWHERE?

• Only two sites were sampled and life may occur elsewhere on the surface but high levels of UV radiation harmful to life make it unlikely

• If life is present, it is more likely to be found underground at depths where it is warm enough and pressures are high enough for liquid water to be present