Alien Planet starts out with an interstellar spacecraft named Von Braun , leaving Earth's orbit . Traveling at 20 % the speed of light , it reaches Darwin IV in 42 years . Upon reaching orbit , it deploys the Darwin Reconnaissance Orbiter , Which looks for potential landing sites for the probes . The first probe , Balboa , explodes along with its lifting body transport during entry , because one of its wings failed to unfold . Two backup probes , Leonardo da Vinci and Isaac Newton , successfully land on the planet , and learn much about its bizarre indigenous lifeforms , including an apparently sapient species . The robotic probes sent out to research on Darwin IV are called Horus Probes . Each Horus probe consists of an { { convert } } long inflatable , hydrogen-filled balloon , Which is covered with solar receptors , a computer ' brain ' , a ' head ' covered with sensors , and several smaller robots that can be sent to places too dangerous for the probes themselves . The probes have a limited degree of artificial intelligence , very similar to the ' processing power ' of a 4-year-old . All the real thinking is done by a supercomputer in the orbiting Von Braun . The probes are programmed with different personalities ; Ike is more cautious , while Leo is the risk-taker . The two probes are also equipped with a holographic message that will be projected to any sentient life found on Darwin . After the two probes inflate their gas-bags , they encounter a voracious Arrowtongue and watch it pursue a Gyrosprinter .

Which interstellar spacecraft reaches Darwin IV in 42 years?

Renewable Energy Resource Sunlight Sunlight can be used to heat homes. It can also be used to produce electricity. This conversion is made possible by solar cells. However, solar energy may not always be practical. Some areas are just too cloudy. Example Solar panels on the roof of this house generate enough electricity to supply a familys needs. Moving Water Falling water can have a lot of energy. Its energy can be converted into kinetic energy. This energy can turn a turbine and generate electricity. The water may fall naturally over a waterfall or flow through a dam. A drawback of dams is that they flood land upstream. They can also reduce water flow downstream. Either effect may harm ecosystems. Wind Wind is moving air. It has kinetic energy that can do work. Wind turbines change the kinetic energy of the wind to electrical energy. Only certain areas of the world get enough steady wind. Many people also think that wind turbines are noisy and not very nice to look at.

What can these forms of energy be used to produce?

Heat supplies the energy that causes motion. The deeper you go into toward the Earths core, the hotter it gets. At the core it is really hot. All that heat tries to rise toward the surface. In the Mantle, the rock is partially melted and is able to move. As it is heated, the material in the mantle moves toward the surface. As the mantle material rises, it cools. When it reaches the Earths crust, it is mostly stopped. A little of the material can break through the surface, but not all. Instead, it begins to move horizontally. The mantle material moves horizontally away from a mid-ocean ridge crest. Toward the surface, the mantle material starts to cool. As it cools it sinks back down into the mantle. These areas are where deep sea trench occur. The material sinks back down to the core. The system operates like a giant conveyor belt. The motion due to heating and cooling is called convection.
What can the motion of convection be compared to?