Space Landing | Universe Today

Written by Tega Jessa

The most important part of any manned space mission is not the launch but the landing or as it is officially called the Re-entry. This is the process by which the craft returns to Earth. There are several factors that need to be taken into account so that the process occurs smoothly and safely.

First, there is attitude control. The Earth's atmosphere acts as a natural barrier reflecting the majority of meteorites, dangerous radiation and other threat that would otherwise harm the Earth's surface. So naturally it makes it difficult to enter back into the atmosphere for manned space craft. Attitude control is a combination of angle of entry and speed. If this angle is not closely adhered to, a space craft will literally bounce of the outer shell of the atmosphere. The other factor is the speed. This is often a negligible concern as the craft is already traveling at orbital speeds and will only become faster as it returns under the full influence of the earth's gravity.

The next obstacle is air resistance. Whatever does not get bounced off the outer limits of the atmosphere will get burned up by the friction created by rubbing against air particles during descent. The Apollo 11 and the other capsule missions dealt with this problem by putting ablative material on the bottom of the capsule. This works by focusing the friction on easily burning material to draw heat away from the rest of the craft. Another general solution that all space craft have in common is a blunt design. This causes a shock wave to form before the craft shielding it from the worst of the heat and friction. As the space program at NASA progressed, they abandoned ablative material as they built spacecraft that could be used more than once. The space shuttle now uses special insulation. However this has created problems in its self as aging insulation can break and at re-entry speeds pose a grave threat to the space craft.

After surviving the gruel heat of re-entry there is the final landing. In the early Apollo, Saturn, and Mercury missions, the method for safe landings was to land in the ocean, a type of landing called splash down. The capsule's descent was slowed down with aid of an parachute and when it landed it was then picked up by a helicopter to the nearest Navy ship. This method is no longer used by NASA but the Russian space program does something similar on land having their capsules land in the desert. The current method of space landing is the brilliance of the space shuttle. Upon re-entry the shuttle glides down and lads like conventional air craft the only difference is that a parachute is deployed upon landing to help it decrease its speed.

If you enjoyed this article there are several others on Universe Today you can enjoy. There is a great article about the Russian Space Program ideas to improve landings. There is also an intere3sting article about the discussion of what type of landing will be practical for the Orion spacecraft.

There are also several resources on the web. The How Stuff Works website has a great article on the Re-entry and landing process. There is also another great article on Europe planning to build a re-entry spacecraft.

You can also listen to Astronomy Cast. Episode 127 the U.S. Space shuttle has some information on space landings

Filed under: Astronomy

Tags: landings, re-entry, space craft, Space Flight