9. The longest solo spaceflight in human history, lasting for a full five days, Vostok 5 orbited the Earth between June 14 and June 19, 1963
Operating concurrently with Vostok 6, due to delays in launch preparations caused by concerns over solar flare activity and the potential effect on the spacecraft and its passenger, Vostok 5 was eventually launched on June 14, 1963. Although inadequate repairs and modifications placed the vessel into a lower orbit than originally intended, Vostok 5 successfully reached space along with its occupant: Valery Bykovsky. Originally intended to endure an eight-day stay aboard the orbiting spacecraft, continued concerns over elevated levels of solar flares resulted in Bykovsky being ordered to return to Earth after only five.
During this residency, the longest in history at the time and remaining the longest solo stay in orbit, Bykovsky conducted a series of important physical scientific experiments to test the durability of humans in space. Returning safely to Earth on June 19, Bykovsky was greeted by bemused local farmers due to delays impeding the rescue team. His findings greatly improved conditions for future cosmonauts, including the improper placement of emergency equipment, the discomfort of certain pieces of gear, and, perhaps most helpfully, that the waste collection system rendered conditions “unpleasant” for the passengers during prolonged stays.