Spacewalks are probably the most complex and demanding part of human space exploration. Astronauts have to leave the safety of their spacecraft and work in the vacuum of space.
These extravehicular activities, or EVAs, keep space stations running, make satellite repairs possible, and let crews build things that support commercial space operations.
A spacewalk—officially called an extravehicular activity (EVA)—happens when astronauts step outside their spacecraft to do work in space. They depend entirely on their suits for life support while they’re out there.
Spacewalks matter for a bunch of reasons. Astronauts handle maintenance on the International Space Station, swap out broken parts, and install new gear.
They fix satellites and other spacecraft that can’t come inside for repairs. Construction is another big reason for EVAs.
Astronauts built most of the International Space Station through spacewalks, connecting modules and putting up solar arrays. They also set up scientific instruments and run experiments that need direct exposure to space.
Primary EVA Functions:
Space agencies break down extravehicular activities by location and mission goal. Each type brings its own set of headaches and needs special preparation.
Orbital EVAs happen around spacecraft in Earth’s orbit, like the ISS. These are the most common spacewalks, with astronauts handling station maintenance, adding modules, and upgrading gear.
Microgravity lets them move big stuff pretty easily. Surface EVAs take place on planets or moons.
The Apollo lunar missions are the classic example—astronauts explored the Moon and did geology work. Future Mars missions will need a ton of surface EVA operations for building habitats and running science experiments.
Deep space EVAs show up on missions that go beyond Earth’s orbit. These are tougher because of higher radiation and the sheer distance from Earth.
Astronauts have to make more decisions on their own. Contingency EVAs are for emergencies.
When something threatens the crew or the mission, astronauts need to get outside fast, often with little warning.
The first spacewalk happened on March 18, 1965. Soviet cosmonaut Alexei Leonov spent 12 minutes outside his Voskhod 2 spacecraft.
He showed the world that humans could survive and work in space while tethered to their vehicle. Just three months later, Ed White became the first American to spacewalk during Gemini 4.
He spent 23 minutes outside, using a handheld maneuvering unit to get around. Those early EVAs helped develop the skills needed for later Moon missions.
The Apollo program pushed spacewalks even further. Neil Armstrong and Buzz Aldrin did the first lunar surface EVA in 1969, spending more than two hours exploring.
Later Apollo missions stretched surface operations to days at a time. Space station programs changed everything again.
Soviet cosmonauts racked up hundreds of hours on Salyut and Mir stations. American astronauts started doing lots of EVAs with the Space Shuttle, fixing satellites and servicing the Hubble Space Telescope.
Some spacewalks really changed what humans could do in space. They proved we could pull off complex jobs way beyond Earth’s surface.
In 1984, Space Shuttle Discovery astronauts pulled off the first satellite repair. They captured and fixed the Solar Maximum Mission satellite.
That showed astronauts could service spacecraft in orbit and extend their lives. Hubble Space Telescope servicing missions took EVAs to another level.
From 1993 to 2009, astronauts did five missions to replace instruments and upgrade systems, keeping Hubble running well past its original life.
Putting together the International Space Station took over 160 spacewalks and more than 1,000 EVA hours. Astronauts from different countries teamed up to build the biggest thing humans have ever assembled in space.
The longest single spacewalk? Susan Helms and James Voss went for 8 hours and 56 minutes in 2001 while assembling the ISS. That was a serious test of human endurance.
Now, private companies are getting in on the act. They’re planning EVAs for space tourism and manufacturing.
These missions could take spacewalks beyond science and maintenance, opening up new business possibilities.
Spacewalk prep takes a ton of planning that starts months before astronauts ever leave their spacecraft. Mission Control puts together detailed timelines, and ground teams work closely with the crew to meet strict safety standards.
Planning for spacewalks kicks off six months to a year before launch. NASA teams come up with task lists based on what needs doing—maybe installing gear or moving antennas.
Ground control teams look at all kinds of factors. They figure out how long jobs will take, check if both crew members need to team up or can split, and look at where everything happens on the station.
They make sure all the tools fit in the airlock. Crew experience matters too—rookies get different jobs than veterans.
The team sorts tasks by priority. High-priority stuff goes first, and “get-ahead” items get added if there’s extra time.
Some jobs have tight deadlines. If you cut power to a device, you might have only minutes to finish before things get damaged.
That kind of timing adds pressure before the walk even starts.
Mission Control lays out hour-by-hour schedules for each spacewalk. These show exactly when astronauts should finish each job outside.
Astronauts spend almost a full day prepping before the walk. They stay in an airlock for 24 hours to get used to different air pressure.
Controllers have to plan around spacesuit limits—oxygen, battery life, and even how tired the crew gets. Teams talk in real time to decide if extra tasks can be squeezed in.
Draft timelines get tested and tweaked a lot. Astronauts train on these schedules, and teams update them based on how practice runs go.
Sometimes changes happen right up to the last minute. Ground teams choreograph every move, picking which handholds to grab and how to shuffle tools around the station.
Astronauts and ground teams work together for months before the spacewalk. They practice tasks in underwater pools and use special simulators.
Mission Control gives step-by-step instructions over the radio during the walk. Astronauts on the ground at NASA Johnson Space Center guide the crew outside.
Before each walk, astronauts spend hours getting their suits and tools ready. They do safety checks over and over, with ground support watching closely.
Teams run tests to make sure everything works before the mission. This helps catch problems that could pop up in space.
The teamwork doesn’t stop when the walk starts. Ground controllers keep an eye on suit systems and help solve problems right away.
They track air supply and work time to keep everyone safe. Both the ground and the crew can suggest changes to the timeline during the mission.
This flexibility lets them finish more tasks if conditions are right.
Astronauts spend months training for EVAs. They use underwater pools that simulate weightlessness and virtual reality systems that mimic space.
These methods help astronauts master tricky tasks and learn safety routines before ever stepping outside.
NASA’s Neutral Buoyancy Laboratory in Houston is the main place astronauts train for spacewalks. The pool holds 6.2 million gallons of water and has full-size models of spacecraft and station parts.
Astronauts put on full suits and practice underwater for hours, working through the exact tasks they’ll do on their missions.
Training Duration: 6-10 hours underwater for every 1 hour of planned spacewalk time
Scuba divers stay close to help astronauts move around and keep things safe. The pool lets astronauts get used to moving in three dimensions, since you can’t walk or balance like normal.
Astronauts practice tool handling, setting up equipment, and emergency procedures. These sessions build muscle memory and confidence—absolutely essential once they’re in space.
Modern training uses advanced virtual reality too. VR lets astronauts practice without the hassle or time limits of pool sessions.
Virtual reality can simulate lighting, equipment setups, and emergencies astronauts might run into. The system gives instant feedback on technique and timing.
Key VR Training Benefits:
NASA mixes VR with partial gravity simulators like POGO and ARGOS. These help astronauts get the hang of EVA movement.
VR also lets mission planners try out procedures before they commit to pool time, which makes the whole process more efficient.
Safety training is all about life support, emergency routines, and backup systems. Astronauts learn to watch their suit systems constantly while working outside.
Critical Safety Elements:
Emergency drills take up a big part of the training. Astronauts practice what to do if there’s a suit leak, lost tools, or radio trouble.
They also learn how to help a struggling crew member during EVA. Gloves get tested in vacuum chambers to make sure astronauts can actually move their fingers and stay protected.
Astronauts run through emergency return routines and learn to spot early warning signs of trouble. Training focuses on making good decisions under pressure and staying aware of their surroundings.
Safety steps become second nature thanks to all the repetition.
Spacesuits are basically wearable spacecraft. The Extravehicular Mobility Unit gives astronauts life support, keeps pressure steady, and shields them from space hazards with a bunch of carefully designed parts.
Today’s spacesuits have two main systems working together to protect astronauts. The pressure garment is the part shaped like a human body that keeps astronauts safe and lets them move during spacewalks.
Here’s what the pressure garment includes:
The life support system sits on the back like a backpack. It controls oxygen, gets rid of carbon dioxide, and regulates temperature.
Water cooling tubes run through the suit to stop astronauts from overheating. Pressurized gloves are a pain—honestly, they feel like stiff balloons and take serious hand strength to use.
Even simple jobs get tough when your gloves feel like oversized garden gloves. The helmet gives a clear view and protects the head from bumps.
Built-in radios keep astronauts in touch with Mission Control and the crew inside.
The Extravehicular Mobility Unit (EMU) acts like a tiny spacecraft meant for spacewalks. NASA came up with this system so astronauts can survive outside the International Space Station without needing anything from inside.
The EMU keeps its internal pressure at 4.3 pounds per square inch. Since that’s lower than the station’s pressure, astronauts have to go through pre-breathing routines to avoid decompression sickness.
Pure oxygen fills the suit.
Key EMU capabilities include:
The Primary Life Support System backpack weighs about 180 pounds on Earth, but in space, you don’t feel that weight. Engineers built in multiple redundant systems so astronauts stay safe if something major fails during a spacewalk.
They added emergency features like the Simplified Aid for EVA Rescue system. This little jetpack can literally bring astronauts back if they get separated from the station.
Getting the spacesuit fit right matters for both safety and actually moving around up there. Astronauts and spacesuit techs work together to tweak suit parts for each person’s measurements and whatever the mission calls for.
Suiting up takes about 15 minutes once everything’s laid out. But, honestly, the whole prep routine takes several hours before anyone even thinks about leaving the airlock.
Pre-spacewalk spacesuit procedures involve:
Astronauts check for leaks to make sure pressure holds across the entire suit. If they find a leak, they have to fix it or swap out parts before anyone gets the green light for a spacewalk.
Adjusting the fit focuses on making sure joints move well and there aren’t painful pressure spots. If a suit fits badly, it can cause injuries or just make it impossible to get the job done.
Mission Control keeps an eye on all the spacesuit systems during fitting. Ground teams double-check that every part meets safety standards before giving the go-ahead for a spacewalk.
The airlock acts as the gateway between the pressurized station and the emptiness of space. Astronauts have to follow exact breathing routines and pressure changes to avoid dangerous medical issues during their spacewalks.
Astronauts start breathing pure oxygen about two hours before they leave the airlock. This step flushes nitrogen out of their blood to stop decompression sickness—nobody wants “the bends” out there.
The nitrogen purge means astronauts breathe 100% oxygen while already suited up inside the airlock. They do some light exercises during this to help get rid of nitrogen faster.
Crews usually hang out in the equipment lock for a few hours during this phase. They use that time to eat, drink, and review their procedures one last time.
Medical monitoring goes on the whole time. Ground teams keep tabs on each astronaut’s vitals to make sure the nitrogen’s really gone before anyone steps outside.
Sometimes, pre-breathing takes longer than two hours if the pressure difference between the airlock and main habitat is bigger than usual. Airlocks on the station run at lower pressures than the living quarters.
Controllers follow strict steps to lower airlock pressure safely. They slowly drop the pressure from the station’s normal atmosphere down to a full vacuum.
Pressure reduction happens in carefully timed stages, usually taking about 30 minutes. This slow approach stops sudden expansion that could hurt astronauts or damage their suits.
Astronauts double-check their gear during depressurization—spacesuit systems, tools, and comms with Mission Control. They make sure every connection and tether is good before hitting vacuum.
The airlock’s outer hatch stays closed until the pressure inside matches space. Automated systems track pressure and block the hatch from opening too soon with several safety interlocks.
Final verification means running one last round of comms checks with the station and Mission Control. Only when everything checks out do astronauts get the OK to open the hatch and start the spacewalk.
Spacewalk safety relies on strict rules to protect astronauts from vacuum, equipment breakdowns, and comms issues. Mission control keeps an eye on every EVA using backup systems and emergency plans.
The vacuum of space is instantly dangerous for astronauts. If a suit gets punctured, decompression can knock someone out in just 15 seconds.
Micrometeorite impacts are a constant threat to both suits and gear. These tiny bits zip around at up to 17,500 mph and can punch right through protective layers.
Thermal extremes swing from -250°F in the shade to +250°F in sunlight. If a suit’s thermal controls fail, astronauts could freeze or overheat.
Skipping the right pre-breathing steps risks decompression sickness. Researchers came up with specific oxygen routines to clear nitrogen before spacewalks.
Equipment failures could leave astronauts stranded outside. Broken tools, snapped tethers, or propulsion glitches demand a quick response.
Every EVA pairs up at least two astronauts as safety buddies. This system makes sure they always have eyes on each other and can help out if something goes sideways.
Primary comms channels link astronauts straight to mission control on several radio frequencies. If one system fails, backups kick in automatically.
Astronauts talk constantly, giving status updates every few minutes. Mission control tracks their positions, suit pressures, and oxygen levels in real time.
Tether systems keep astronauts physically tied to the station or each other. Backup tethers add another layer of protection against drifting off into space.
Buddies check each other’s gear before, during, and after every EVA. They confirm suit seals, battery power, and that all tools are secure.
Mission control sets up detailed emergency response plans for every possible EVA problem. These plans cover suit issues, medical crises, and broken equipment.
Rapid return protocols let astronauts end spacewalks in minutes if needed. Emergency airlock steps can repressurize the crew faster than the normal process.
Astronauts spend a lot of time training for emergency suit repairs using patches and backup life support. These skills matter when something important fails outside.
Medical emergencies have their own set of procedures, like CPR adapted for microgravity and suit removal for unconscious crew members. Mission control works with ground medical teams to guide astronauts through these situations.
Backup power systems come online if a suit battery dies. Emergency oxygen gives astronauts extra time to get back inside safely.
Mission control stays in constant touch with astronauts during every spacewalk step. NASA ground teams watch vital signs and offer real-time advice through tricky procedures.
Mission control tracks tons of data streams during each EVA. Ground controllers keep an eye on oxygen, suit pressure, and carbon dioxide scrubbing nonstop.
The comms loop between space and ground stays open the whole time. Controllers watch heart rates and breathing to spot stress. Suit sensors report temperature to help avoid overheating in the sun.
NASA flight directors work alongside specialized EVA officers who focus just on spacewalks. These folks track tool inventories, timelines, and where each astronaut is in relation to the station.
Ground teams use several camera feeds to watch the work area. External station cameras give different views so controllers can spot trouble before astronauts run into it.
Mission control follows set steps if something goes wrong during a spacewalk. Controllers can change up procedures on the fly if the situation shifts. Emergency aborts get top priority on the comms.
Technical problems trigger fast talks between flight directors and engineers. Ground experts dig into telemetry data to figure out what’s broken and come up with fixes while astronauts wait safely.
If comms drop, backup systems switch on automatically. Mission control flips between radio frequencies as needed. If all else fails, astronauts use written procedures on their tablets.
NASA keeps contingency plans for all kinds of emergencies, like sudden suit leaks or injuries. Ground controllers can walk astronauts through emergency airlock steps remotely.
Astronauts learn specialized skills for working outside the station. Moving around and handling tools in space feels nothing like it does on Earth, and losing a tool isn’t just annoying—it can be dangerous.
Space station assembly means astronauts have to get around huge structures without gravity’s help. They mostly use their hands to grab handholds and pull themselves along mapped-out paths.
Microgravity changes how astronauts move. They can’t walk or use their legs to get around. Instead, they pull themselves from one place to another using handrails.
Body positioning matters a lot for tricky tasks. Astronauts often lock their feet into portable restraints or workstations so they can use both hands and stay steady.
The robotic arm offers another way to move. Astronauts can ride at the end of the arm to reach distant spots, with someone inside the station controlling their position.
Momentum management is a constant concern. Even a small push can send someone floating away. Astronauts learn to move carefully and keep a grip on the station.
Pressurized gloves are a pain for fine work during spacewalks. They feel like stiff balloons, so finger dexterity takes a big hit compared to bare hands.
Cable and hose work really tests hand strength. Astronauts’ fingers and forearms get a serious workout just plugging in cords or making connections through thick glove material.
Tool security is huge—every tool gets tethered to the suit or worksite. If something floats away, it becomes space junk.
Specialized tools help astronauts work faster and with less effort. Power tools save energy on repetitive jobs. Custom connectors and fasteners are designed to work better with pressurized gloves than regular hardware.
Ground teams plan out the exact sequence of tools and hand-offs before the spacewalk starts. This choreography helps astronauts finish their work on schedule.
The International Space Station is the main stage for today’s spacewalks. Expedition 55 really showed just how much coordination and planning goes into these high-stakes maintenance missions.
The International Space Station stands as humanity’s main orbital lab for spacewalks. Astronauts carry out extravehicular activities (EVAs) from two key airlocks.
The Quest airlock handles US spacewalks with American spacesuits. The Poisk module takes care of Russian spacewalks using Orlan suits.
Astronauts have completed 245 spacewalks since assembly began, spending a total of 1,548 hours and 26 minutes outside the station. They focus on maintenance, repairs, and installing equipment.
Mission Control builds out timelines for each spacewalk. Flight controllers weigh things like how long tasks will take, what the crew has done before, and what gear they need.
They sort out priorities based on what the station needs and what’s safest. Spacewalks can be short or really long.
Back in March 2001, astronauts spent 8 hours and 56 minutes outside—the record so far. On the other end, the shortest walk lasted just 19 minutes in June 2001.
Expedition 55’s crew trained hard for their scheduled spacewalks. Flight Engineers Ricky Arnold and Drew Feustel practiced for weeks before stepping out the airlock.
They worked through tricky procedures with pressurized gloves that made moving their fingers tough. Grabbing cables and hoses took a lot of hand strength in those stiff gloves.
Ground teams mapped out every move for the spacewalks. They even put together backup plans and “get-ahead” tasks if the crew finished early.
Ricky Arnold and his crewmate had to watch the clock, since their suits only held so much air and supplies. Mission Control kept an eye on fatigue and how much air was left during the EVA.
The whole expedition showed just how much teamwork and coordination modern spacewalks demand between space and the ground.
Astronauts follow several critical steps after spacewalks to stay safe and healthy. These include careful repressurization, medical checks, and documenting everything that happened outside.
Astronauts start by working their way back through the unpressurized bay to reach the airlock hatch. They make sure to secure all their tools and gear before entering the small chamber.
The airlock acts as the gateway between space and the pressurized station. It’s only 5.25 feet across and 6.9 feet tall, so moving around in a spacesuit takes some finesse.
Once inside, astronauts check their suits and gear for safety. They confirm all the hatches are sealed before starting to bring the airlock back up to pressure.
They keep talking to ground control and the rest of the crew during this time. Astronauts share their status and flag any problems they ran into.
The repressurization process kicks off slowly to avoid decompression sickness. The airlock pressure rises from the suit’s 29.6 kilopascals up to the station’s normal air pressure.
This step takes patience—astronauts have to wait until the pressure is fully equalized before taking off helmets or opening the inner hatch.
Once the airlock’s pressurized, astronauts get help from crewmates to take off their suits. They check the suits right away for any damage or contamination from the walk.
Equipment cleaning comes next. Astronauts wipe down their suits and tools to get rid of any coolant or gunk that shouldn’t be inside the station.
They store the suits carefully and prep them for maintenance. Each part gets checked and logged for the next time someone needs to go outside.
As soon as the suits come off, astronauts go through medical exams to check their physical condition. These health checks look for decompression sickness, fatigue, or other issues from the spacewalk.
Flight surgeons on the ground look over the medical data and give advice if anything’s off. They keep an eye on vital signs, joints, and general wellness.
Astronauts write up reports about their spacewalks, noting any weird stuff, equipment hiccups, or surprises they found out there. Team calls with ground control help capture details while everything’s still fresh.
Depending on how long or tough the spacewalk was, astronauts might need extra rest and more medical checks. Recovery routines help them get back to normal safely.
NASA and private space companies keep rolling out new tech and automated systems to make spacewalk prep faster, safer, and more efficient. These upgrades aim to cut training time and boost safety for astronauts doing extravehicular activities (EVA).
Advanced Training Simulators are changing how astronauts get ready for spacewalks. Virtual reality systems now mimic the exact conditions astronauts face during EVAs.
These simulators even have haptic feedback so trainees can feel resistance and tool weight. NASA’s latest training centers use underwater pools with digital overlays.
Astronauts practice real mission tasks in the water while seeing digital versions of spacecraft exteriors. This setup feels much closer to the real thing than old-school methods.
Smart Spacesuit Systems are another big leap. New suits come with built-in sensors that track astronaut health and suit status in real time.
These systems alert ground teams if something’s off before it gets dangerous. The suits also have better comms—astronauts see step-by-step instructions right in their helmet displays.
That means fewer mistakes and faster, smoother procedures.
Robotic Assistants are in the works to help astronauts outside the station. These bots can carry tools, hold stuff steady, and handle routine jobs.
NASA’s tests show robots can cut spacewalk time by up to 30%. The robots link up wirelessly with ground control.
Mission specialists can take over when astronauts need a hand. This backup makes risky tasks much safer.
Automated Preparation Systems now handle lots of pre-spacewalk checks. Computers look over suit seals, tool readiness, and comms links on their own.
These systems catch mistakes humans might miss. New airlock designs even add robotic arms to help astronauts suit up.
The arms make sure everything fits and connects just right. Thanks to this, prep time drops from hours to just minutes.
Spacewalk prep takes a mix of tough physical training, strict safety protocols, and special suit routines. Astronauts spend months training to handle the weirdness of working in space and to keep everyone safe.
Astronauts train for months to build up the stamina spacewalks demand. The gloves feel like wrestling with stiff balloons, so their finger and forearm muscles get a real workout.
They practice gripping tools while wearing the bulky gloves. Handling cables and gear in space is just plain hard.
Spacewalking mostly uses arm strength, since astronauts pull themselves along handholds. They work on upper body endurance to move themselves and heavy gear for hours.
Training starts six months to a year before a real spacewalk. Flight controllers set up detailed plans based on what astronauts will do outside.
Crew members run through each step over and over in underwater pools. These sessions mimic weightlessness and let astronauts practice with the real tools.
The team keeps tweaking procedures until the day of the walk. Astronauts review tasks, talk through goals, and rehearse their moves.
Astronauts strap on a Simplified Aid for EVA Rescue system—a backup jetpack that can get them back if their tethers break. Safety tethers keep astronauts tied to the station the whole time.
These cables stop anyone from floating off into space. Mission Control watches every move and keeps up constant comms.
Ground teams track suit supplies and crew fatigue to keep things safe.
Suiting up takes hours and lots of checks. Astronauts make sure every part of their 240-pound spacesuit works.
They pre-breathe pure oxygen to clear out nitrogen and avoid decompression sickness. This step preps their bodies for the lower pressure inside the suit.
Crew members gather the tools and gear they’ll need outside. They organize everything in the airlock and do final checks before opening the hatch.
The process is a lot like scuba divers decompressing. Astronauts follow set steps to safely go from space’s vacuum back to the station’s air.
They stay in the airlock while pressure slowly returns to normal. This slow change keeps their bodies from getting hurt.
Afterward, they clean equipment and go through medical checks. Crew members report how they’re feeling and log any problems with the gear.
Astronauts have to navigate around huge structures in microgravity, which isn’t as easy as it sounds. They spend a lot of time training to get used to moving and orienting themselves when there’s no gravity.
Suit consumables, like oxygen and battery power, put a real time crunch on getting things done. Mission Control keeps a close eye on these levels, making sure astronauts stay within safe limits.
Some jobs come with strict deadlines because the equipment can’t handle temperature extremes for long. Ground teams always schedule these high-risk tasks first, so nothing important gets damaged if there’s a delay.
