If you were lost in space without a tether or any means of communication or propulsion, the situation would be extremely dangerous and life-threatening. Here's a step-by-step analysis of what could happen: 1. Isolation: You would be isolated from any immediate help, floating in the vacuum of space without the ability to return to your spacecraft. 2. Life Support: Your survival would depend on the life support system of your spacesuit. Spacesuits are equipped with a limited supply of oxygen and power, which would only last for a certain period, typically a few hours to a day. 3. Temperature Extremes: Space is an extreme environment with temperatures varying from extremely hot to extremely cold. Without proper shielding, you would be exposed to these temperature fluctuations, which could be fatal. 4. Decompression and Asphyxiation: If your spacesuit were to fail, you would face rapid decompression and asphyxiation due to the vacuum of space. 5. Radiation Exposure: Without the protection of Earth's atmosphere or a spacecraft, you would be exposed to harmful radiation from the sun and cosmic rays, which could lead to severe health issues or death. 6. Disorientation: The lack of visual cues in space can lead to spatial disorientation, making it difficult to determine up from down or which direction to move in. 7. Rescue: The chances of being rescued would depend on the proximity of other spacecraft or the ability of mission control to locate and send a rescue mission. However, given the vastness of space, this would be highly unlikely. 8. Long-Term Survival: If you were unable to return to your spacecraft, your chances of long-term survival would be virtually nonexistent. In the context of space missions, safety protocols are in place to prevent such occurrences. NASA and other space agencies use tethers and safety procedures to ensure that astronauts are not lost in space. These precautions are critical for the safety of spacewalkers. read more >>

Despite the risks, no mission has ever lost a space-walking astronaut. In the film Gravity, which opens this month, two astronauts are on a spacewalk when an accident hurtles them into the void. ... NASA requires spacewalking astronauts to use tethers (and sometimes additional anchors).read more >>