Page 52 - Curriculum Visions Dynamic Book

To see the results from the space probes see Volumes , 5, and 8.
Manned spaceflights have told us much about how
to survive in space and how to land on a planetary object. But we would still know next to nothing
about the other planets in the solar system if manned spaceflight had been the only part of the space adventure.
Because of the enormous time involved in any journey and the difficulty of providing food, oxygen, water, and fuel, it is impossible at this time to send people to even the closest of the planets in the solar system. So, this journey of exploration has to be by unmanned space probe. Many probes have been sent to investigate other parts of the solar system, including some that have landed on other planets.
Reaching distant planets
If you want to reach a distant planet, it is not simply
a matter of launching toward the visible planet in
the sky. Every planet follows an orbit, many of which
are highly elliptical (oval). The best time to reach such planets is when they are closest to the Earth. That reduces the amount of fuel that has to be used up in getting to them.
The trajectory needed to reach the planets has to
be carefully calculated. If the launcher cannot provide enough velocity for the space probe, its speed can be increased by aiming it close to another planet. This so-called slingshot trajectory allows the probe to come within the gravitational field of a planet so that momentum can be transferred from the planet
to the probe (see page 56).
This system has been used
for long-distance probes
such as Mariner 10 to fly
past Mercury and Pioneer 11 and
Voyagers 1 and 2 to travel from
Jupiter to Saturn.
Mariner 2
Control system
solar Panels
Trusses
connecting parts of the craft
Control system
 The Mariner project was
a series of space probes sent
to Venus, Mars, and Mercury between 1962 and 1975. Later, Mariners obtained clear pictures of the Martian surface and were able to analyze the atmosphere. Mariner 10 gave the first closeup pictures of the surface of Mercury.
Mariner 5
Communications dish (antenna)
Solar panels
Communications dish (antenna)
Mariner
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