capsule comes through, even more heat is created. As the capsule slows down, the compression of the air molecules hitting the capsules surface creates a lot of heat. The surface of a capsule can get to as it descends through the Earth's atmosphere. All this heat has to be directed away. Reentry capsules are typically coated with a material that melts and then vaporizes ("ablation"). It may seem counterproductive, but the vaporization takes heat away from the capsule. This keeps the reentry heat from getting inside the capsule. Capsules see a more intense heating regime than spaceplanes and ceramics such as used on the Space Shuttle are usually less suitable, and all capsules have used ablation. In practice, capsules do create a significant and useful amount of lift. This lift is used to control the trajectory of the capsule, allowing reduced g-forces on the crew, as well as reducing the peak heat transfer into the capsule. The longer the vehicle spends at high altitude, the thinner the air is and the less heat is conducted. For example, the Apollo CM had a lift to drag ratio of about 0.35. In the absence of any lift the Apollo capsule would have been subjected to about 20g deceleration (8g for low-Earth-orbiting spacecraft), but by using lift the trajectory was kept to around 4g. Current designs Shenzhou The reentry capsule is the "middle" module of the three-part Soyuz or Shenzhou spacecraft – the orbital module is located at the front of the spacecraft, with the service or equipment module attached to the rear. A feature in the landing system allows the use of a single parachute and "braking rocket", thus the heatshield is dropped from the spacecraft similar to the landing bag deployment on the U.S. Mercury spacecraft. Like the Command Module of the Apollo spacecraft, the Shenzhou reentry capsule has no reusable capabilities; each spacecraft is flown once and then "thrown away" (usually sent to museums). Few details are known about the Shenzhou reentry capsule, except that it uses some technology from the Soyuz TM design. The new Soyuz TMA spacecraft, now used solely for International Space Station flights, had its couches modified to allow for taller crewmembers to fly, and features "glass cockpit" technology similar to that found on the Space Shuttle and newer commercial and military aircraft. Soyuz The former Soviet Union suffered two disasters, and one near-disaster, all three