Plans For Exploring The Planets

Press, Volume CVI, Issue 31341, 11 April 1967, Page 10

Plans For Exploring The Planets

Next month an American spacecraft to be known as Mariner V will be fired toward the planet Venus and will be followed a few weeks later by Mariner VI. These new spacecraft will continue the scientific investigation of Venus which began with the historic mission of Mariner II almost five years ago. Mariner II quashed any notions that Venus may abound with life by reporting a surface temperature four times that of boiling water. The new Mariner spacecraft have been designed to seek information on many questions left unanswered by Mariner 11, and subsequent Soviet Venus probes. Opportunities for "launching space vehicles to other planets occur at intervals which always exceed one year. The “launch-windows," as they are termed, recur at 19-month intervals for launchings to Venus and every 26 months in the case of Mars. The length of the launch-window depends on the power of the launching rocket and the weight of payload, but six weeks is a typical figure. Probably Mariner V will not be launched earlier than May 7 and Mariner VI should be on its way by the end of June There is also the interesting possibility that one or two Soviet space vehicles will be fired towards Venus in this coming period. The last time this happened was when Zond II travelled to Mars with Mariner IV; but unfortunately the Soviet craft died on the journey and left Mariner IV to win all the glory with its famous radio-pictures which exploded the myth of the Martian canals. Long-term Programme

The forthcoming Mariner missions to Venus are part of America’s long-term programme for exploring the solar system. Senior officials of the National Aeronautics and Space Administration consider that this programme will lead to manned missions flying past Mars and Venus eight to ten years from now. By that time a dozen or more unmanned Mariner, Voyager and smaller vehicles will have paved the way and, what is probably more important, the sun will be quiet Bursts of harmful proton radiation are relatively weak and infrequent in the quiet years between peaks of solar activity which occur every 11 years.

The manned Mars-Venus flight will take nearly two years for the round trip and calm weather in space will be essential. By the mid 1970’5, however, the solar activity warning system will be fully developed and it should become possible to radio a warning if a storm develops. The space travellers will then be able to shield themselves from the worst of the radiation. Time-table For 10 Years The time-table for the next decade of planetary exploration is something like this: 1968:, The first of five Sunblazer spaceprobes will be sent into an orbit taking it over one third of the way to the sun. Later Sunblazers will be fired at the rate of two a year and will travel almost half way to the sun. 1969: Two more Mariners will be sent to Marff, followed by another two in 1971. 1972: The first advanced planetary probe will be sent to fly-by Jupiter, and another two Mariners will be sent to Venus, mainly to probe its atmosphere. 1973. The first Voyager spacecraft will be sent to orbit Mars and soft-land a capsule on the Martian surface. 1975: Voyagers will travel to Mars, more Mariners will go to Venus and another advanced planetary probe will be sent to Jupiter. In addition there could be the manned flight already mentioned. 1977: Voyager spacecraft will visit Venus and a probe may be dispatched to visit Jupiter, Saturn, Uranus and Neptune. Beyond 1977 the emphasis

should begin to swing heavily toward the manned exploration of the planets and satellites of the solar system, including landings on some of the more hospitable bodies. Role of Voyagers In the 1973-77 period the new Voyager class of spacecraft will play a principal role. Although the Voyagers were first suggested as long ago as 1960, it is only last January that they were awarded a major Budget allocation of 67 million dollars to allow their construction to proceed. According to Edgar M. Cort wright, a N.A.SA. administrator for space science who last month addressed the annual symposium in memory of the rocket pioneer, Robert Goddard, “in many ways Voyager constitutes the most important undertaking in space exploration since Apollo was begun in 1961.” And the Space Science Board of the U.S. National Academy of Sciences has recommended "... planetary exploration as the most rewarding scientific objective for the 1970-85 period.” The Voyagers will be launched in pairs by a single Saturn V rocket. It so happens that two 20-ton Voyagers utilise the full payload capability of the Saturn V rocket and the use of dual craft greatly increases the chance of a successful mission. If both Voyagers survive the rigours of the journey to the target planet they provide increased orbital coverage besides the chance to ex-

plore two areas of the planet’s surface.

Each landing capsule will weigh about two and a half tons. It will be shaped like a very flat cone, almost saucerlike, and will be twenty feet in diameter to gain the greatest possible braking effect in the thin Martian atmosphere. It is ironical to think that the Martians, if any, may be the first dwellers of our solar system to have tangible evidence of a “flying saucer” arrival from space. At 15,000 feet altitude a rocket will fire to slow the capsule to a soft landing. During the landing phase the capsule will transmit atmospheric data and TV pictures of the Martian surface back to the orbiting mother-vehicle which will relay them back to earth across 50 million miles br more of interplanetary space. After landing, the capsule will set itself up as a laboratory for performing experiments, some to eheck for the existence of Martian lifeforms, and will take a series of TV pictures of the cratered Martian landscape. The next stage in the exploration of Mars will be the manned fly-by missions during which a seven-ton capsule may be sent ahead to land on Mars and take colour, pictures and samples of surface material. These would be automatically stowed in a threestage rocket which will meet the manned vehicle as it passes overhead. Further plans are still too vague but one thing is sure: the sky is no longer the limit.