Ionisation Blackouts- Due to the ionisation of air around the space vechile radio transmission is impossible for a period of time. On the space shuttle this is longer then on the command modules due to the longer landing time.
Heat- Due to friction in the atmosphere a large amount of heat is generated, to counter this either an ablative skin (which melts off) or insulated tiles may be used.
Stopping- To bring the space vechile to rest a method of decelleration must come under affect, this can be achieved by using parachutes, such as in the Soyuz modules, or by landing like a space shuttle (which follows a curved path to counter this)
G-Forces- G-forces must be kept to a minimum to ensure that there is no adverse effects on the space travellers.
Weather- Weather must be taken into account as space vechiles may be struck by lightning or have reduced visibility.
