Faster Better And Cheaper

The trouble with space exploration is that we always want to launch more probes with ever more complex instruments. But as the budgets available are very limited, tough choices have to be made on what missions should be on top of the wish-list and what missions, however interesting, need to be forsaken to free money for the selected few. Then, at the level of individual projects, more cost-related decisions must be made Can we afford the scientifically most capable design, or do we have to go...

Communication

Space probes are not alone in the Universe. They are part of a society of engineers and scientists without whom the machine's life is meaningless. Interplanetary space probes need to be able to talk to us, to tell us how they are and send us the streams of data from their scientific instruments. Likewise, people in the mission's control room need to talk to the spacecraft to make it change its orbit, to switch on a certain instrument and point it at an interesting object or to help the probe to...

Thermal control

Most equipment on board a spacecraft operates best at temperatures between -5 and +40 degrees Celsius (20 and 120 degrees Fahrenheit). However, in Earth orbit the part of the spacecraft in full sunlight can reach temperatures around 120 degrees Celsius (250 degrees Fahrenheit), while the shadow side may get as cold as -160 degrees Celsius (-260 degrees Fahrenheit). The temperatures can even soar to much higher levels if the probe gets closer to the Sun, for instance if it flies to Mercury. In...

Attitude control

A spacecraft needs to control its own attitude while flying through space. This is necessary to point the scientific instruments to the target, the solar arrays to the Sun, the antennas to the Earth, and to keep the heat-dissipating radiators in the shadow. Moreover, before firing a rocket thruster to do orbit maneuvers, the nozzle has to be pointed in the right direction. There are two main ways to control the attitude of a space probe. The simplest is to make the spacecraft spin. Like a...

Mechanisms

The mechanisms on a spacecraft have the same function as the joints in our bodies they are used to rotate, deploy, eject, open and close things. Designers always attempt to keep the number of mechanisms in a spacecraft as low as possible, because they have a relatively high chance of failure and usually a breakdown is critical to the mission. For instance, if a mechanism that has to release a folded solar array does not work, the spacecraft will not be able to generate enough electricity or...

Beyond The Solar System

Pioneers 10 and 11, and the two Voyager spacecraft, are currently our most distant space probes. Voyager 1 has recendy even reached the zone where the solar winds hits the interstellar gas, 14 billion kilometers (8.7 billion miles) from Earth. However, although these four probes sent us valuable data about the Solar System's far frontier, they have not been specifically designed to explore the area they are now flying through. Scientists would like to make detailed measurements of the...

The outer giants uranus and neptune

Voyager l's planetary explorations ended at Saturn, and it is now on its way out of the Solar System. However, Voyager 2 was directed onward. Using the gravitational fields of each of the planets it visited, it traveled from Jupiter to Saturn and on to Uranus and Neptune. The alignment of all these planets had to be just right to make this game of interplanetary billiards possible - a condition that is very rare. In 1986, just over four years after its Saturn flyby, Voyager 2 arrived at Uranus....

Humans Versus Robots

During the Moon Race of the 1960s, astronauts and cosmonauts captured the hearts of the public much more than any robotic spacecraft ever could, and proved to be far more flexible in adapting mission operations and handling emergency situations. Even in comparison with today's advanced robotic Marsrovers, the Apollo lunar astronauts were much more efficient in collecting surface samples and covered far more terrain in less time. The two NASA rovers that were landed on Mars in January 2004 have...

Michel van Pelt

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The Kidnap of Luna

As we are curious about how a modern interplanetary spacecraft works, in our imagination we have put one on an operating table and investigated it inside and out. However, in a Spaceflight magazine article called Those magnificent spooks and their spying machines, author Dwayne A. Day describes how the CIA once did such a thing for real In 1959 the Cold War was running hot in space. The Soviets were launching a series of ever-larger satellites on their big launchers, and the USA was scrambling...