How Astronauts Travel to the ISS: Step-by-Step
This guide explains the full process of how astronauts travel to the International Space Station (ISS), from pre-launch preparations to docking and entering the station. You’ll learn the sequence of events, what the crew experiences, and the key systems involved—whether flying on a SpaceX Crew Dragon or a Russian Soyuz spacecraft.
What You’ll Need
- A certified launch vehicle and spacecraft (e.g., Crew Dragon, Soyuz)
- A space suit (e.g., SpaceX IVA suit or Russian Sokol suit)
- Mission control support (NASA, Roscosmos, or commercial provider)
- Training: 2+ years of technical, survival, and spacecraft systems training
- Medical clearance and physical fitness
- International agreements and flight assignment
Step-by-Step
- Complete training and certification. Astronauts train for years on spacecraft systems, emergency procedures, spacewalking, and Russian language (for Soyuz). They must pass simulations and final exams before being assigned to a mission.
- Undergo pre-launch medical and quarantine. About two weeks before launch, astronauts enter quarantine to prevent illness. They receive medical checkups, and their health is monitored closely.
- Travel to the launch site. For Crew Dragon, that’s Kennedy Space Center, Florida. For Soyuz, it’s Baikonur Cosmodrome, Kazakhstan. They arrive a few days before launch.
- Don the spacesuit. On launch day, astronauts put on their pressure suits, which protect them if the cabin loses pressure. The suit connects to the spacecraft’s life support and communications.
- Board the spacecraft. Astronauts are driven to the launch pad, take an elevator to the crew access arm, and climb into their seats. They strap in and run communication checks with mission control.
- Launch and ascent. The rocket lifts off. During ascent, the crew experiences up to 3-4 Gs. The spacecraft reaches orbit about 8-12 minutes after liftoff, depending on the vehicle.
- Orbit and rendezvous. Once in orbit, the spacecraft separates from the rocket. The crew monitors systems and may change out of suits. The spacecraft performs a series of engine burns to raise its orbit and align with the ISS.
- Approach and docking. The spacecraft approaches the ISS slowly. For Crew Dragon, docking is automated but monitored; for Soyuz, it’s also automated. The spacecraft aligns with a docking port and latches on. This typically takes 4 to 24 hours after launch, depending on the mission profile.
- Check for leaks and pressurize. After docking, the crew and mission control check for a tight seal. Then the pressure between the spacecraft and the station is equalized.
- Open the hatch and enter. The crew opens the hatch and floats into the ISS. They are greeted by the current expedition crew. They then complete safety briefings and start their mission.
Common Mistakes
- Misjudging orbital mechanics: Trying to ‘catch up’ to the ISS by just flying faster is wrong; you need to raise your orbit to slow down relative to the station, then lower it to speed up. This is why rendezvous uses specific burn sequences.
- Ignoring suit checks: A spacesuit that isn’t sealed properly can be fatal. Every connection and seal must be verified before launch.
- Overlooking the ‘fast-track’ vs ‘long-duration’ approach: Some missions reach the ISS in 4 orbits (~6 hours), others take 2 days. The crew must be prepared for both profiles.
Tips
- Stay hydrated and follow ‘suiting’ protocols to avoid needing a bathroom break during the long ride to the pad.
- Practice emergency procedures until they are second nature—especially for fire, depressurization, and abort scenarios.
- Learn to move in microgravity before you arrive: use handrails, push off gently, and keep your center of mass low.
Troubleshooting
- If the launch is scrubbed: Mission control will call off the launch due to weather, technical issues, or medical concerns. The crew returns to quarters and tries again on the next available window.
- If docking fails: The spacecraft automatically aborts and backs away. The crew and mission control assess the issue, then retry docking—often after a manual override.
- If the hatch won’t open: Both sides can attempt to open it. If that fails, the spacecraft may need to undock and return to Earth, or the crew may use a backup tool.
- If the spacecraft loses pressure: The crew puts on suits immediately and uses emergency oxygen. The spacecraft can return to Earth if needed.
Frequently Asked Questions
How long does it take to get to the ISS?
Typically 4 to 24 hours. The fastest crewed flight was about 3 hours, but most missions take 6 to 24 hours depending on the launch vehicle and trajectory.
Do astronauts have to know how to fly the spacecraft?
Yes, they train extensively, but the spacecraft is largely automated. They can take manual control in emergencies.
What happens if the rocket fails during launch?
Launch abort systems are in place. For Crew Dragon, the SuperDraco engines push the capsule away from the rocket. For Soyuz, the escape tower does the same. The capsule lands on parachutes.
Can astronauts sleep during the trip?
Yes, but it’s not always comfortable. They can sleep in their seats or in a sleeping bag, but the ride is short and busy.
What do astronauts wear during launch?
They wear a pressure suit that protects them if the cabin loses pressure. It also provides oxygen and communications.
How do astronauts use the toilet during the trip?
Modern spacecraft like Crew Dragon have a built-in toilet. Soyuz has a small tube system. It’s not luxurious, but it works.
Related
Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.