Walking above the air: The awe-inspiring history of spacewalks

The launch of SpaceX's Polaris Dawn mission will mark the beginning of what could be another historic moment in commercial spaceflight: the first spacewalk by a private citizen.

Billionaire Jared Isaacman, who has funded much of the mission, is aiming to become the first non-professional astronaut to complete a private spacewalk by stepping outside SpaceX's Dragon capsule.

The mission is aiming to reach an altitude of around 870 miles (1,400km), which would make it the highest crewed spaceflight since the Apollo missions more than 50 years ago.

Isaacman will perform his two-hour spacewalk at a lower orbit altitude of around 434 miles (700km), and will be accompanied by SpaceX engineer Sarah Gillis. The pair will be wearing SpaceX spacesuits equipped with helmet displays and helmet-mounted cameras.

But unlike other modern spacecraft, the Crew Dragon lacks an airlock, so the entire capsule will need to be depressurised before they exit, which when combined with the use of the new spacesuits increases the risk involved to all onboard.

If all goes to plan, the spacewalk will join a long list of iconic and memorable moments when astronauts have braved the outside of their spaceships with little more than a few layers of fabric between them and the expanse of space.

From a being stuck in an airlock to nearly drowning inside their own spacesuit, there has been no shortage of drama during the long history of extravehicular activities (EVAs), as spacewalks are formally known. Here are some of the most notable to have taken place since the Soviet cosmonaut Alexei Leonov became the first human to "walk" in space almost 60 years ago.

The first spacewalk

At the height of the Space Race during the Cold War, the Soviet Union had already beaten the United States to a number of key milestones. The USSR had put the first satellite into orbit with Sputnik 1, the first mammal into orbit and then in 1961, the first human.

On 18 March 1965, the USSR achieved another space first – sending the first human outside of a spacecraft to "walk" in space. Exiting the Voskhod 2 through an inflatable airlock deployed outside the spacecraft's hatch, cosmonaut Alexei Leonov spent 12 minutes outside, attached via an umbilical cord.

But this first ever extravehicular activity didn't go completely to plan. The spacesuit Leonov was wearing became rigid when pressurised in the near vacuum of space, making it difficult for him to move or take pictures. The cord connecting him to the Voskhod 2 also became twisted, sending him into a tumble that made it difficult to renter the airlock.

Even when he did, he became stuck and was unable to close the hatch behind him. To get inside, Leonov had to open the valves on the spacesuit to reduce the pressure so he could move enough to squeeze inside and shut the hatch.

So exhausting had the escapade been that when his spacesuit was examined back on Earth, it contained several litres of his sweat.

The first American spacewalk

Nasa Astronaut Ed White became the first American to perform a spacewalk in June 1965 (Credit: Nasa)Nasa

Astronaut Ed White became the first American to perform a spacewalk in June 1965 (Credit: Nasa)

It would take more than two months before the first American would step outside the relative safety of their spacecraft into the vastness of space. On 3 June 1965, Ed White opened the hatch of the Gemini 4 spacecraft as it made its third orbit around the Earth.

Using a hand-held oxygen-jet gun, he manoeuvred himself out of the capsule just as the spacecraft was passing over Hawaii. He spent 23 minutes outside, at the end of an eight metre (26ft) long tether.

At first, he manoeuvred himself back and forth to the spacecraft three times using the jet gun, but it ran out of fuel after three minutes, so White was forced to move around by tugging on the tether.

White would tragically die just under two years later with two other astronauts in a fire that swept through the Apollo 1 spacecraft during a test on the launchpad.

The first space 'selfie'

Edwin "Buzz" Aldrin might be better known for another walk he took as the second human to set foot on another world during the Apollo 11 mission to the Moon. But he is also responsible for what is possibly the first "selfie" taken during a spacewalk.

During the four-day Gemini XII mission in November 1966, he performed a number of spacewalks to photograph stars, test equipment and perform experiments. Before launching, Aldrin became the first astronaut to use neutral buoyancy training in a swimming pool to prepare for these spacewalks.

It was this preparation, he later claimed, that helped him overcome many of the manoeuvring problems that had been encountered during previous spacewalks. In total he clocked up five hours 48 minutes of spacewalking, a record at the time.

It was just before the end of his first spacewalk on the second day of the mission that Aldrin mounted a camera on the edge of the hatch into the Gemini spacecraft and pointed it towards himself.

The resulting "selfie" shows one of his eyes and forehead illuminated inside his helmet, with the blue curve of the Earth over his shoulder.

Untethered and alone

Astronauts had been bravely stepping outside their spacecraft for nearly 20 years by the time Bruce McCandless II performed his pioneering spacewalk in 1984. In the past, astronauts and cosmonauts had remained attached to their spacecraft by tether to keep them from floating off into the vastness of space.

The difference with McCandless was that he would be doing it untethered. Anyone who's seen the 2013 film Gravity, starring Sandra Bullock, will understand just how terrifying a prospect this is.

Fortunately for McCandless, he carried on his back a new nitrogen-propelled device that could be controlled using joysticks. The Manned Manoeuvring Unit (MMU) had 24 nitrogen thrusters that allowed him to remain stable and move around in space.

During the STS-41-B Space Shuttle Mission on 7 February 1984, McCandless flew 91m (300ft) from the shuttle while testing the MMU for the first time. The picture above shows him at his maximum distance from the Space Shuttle Challenger, a lonely figure in the black of space and the curve of the Earth beneath him.

"It may have been one small step for Neil, but it's a heck of a big leap for me," McCandless said at the time, referring to the words spoken by Neil Armstrong as he took his first steps on the Moon in 1969.

Space salvage with a sting

Following McCandless's success with the MMU, Nasa then put the backpack to work. In November 1984, astronauts Dale Gardner and Joseph Allen were dispatched from the Space Shuttle Discovery in a mission to retrieve a pair of faulty satellites from orbit for the first time. It would be the first time a salvage mission had been performed in space.

With the MMU on his back, Allen left the relative safety of the shuttle's remote manipulator arm to cross the 11m (35ft) gap to the Palapa B-2 communications satellite. It had been deployed alongside the Westar VI communications satellite in an earlier shuttle mission that same year, but both had failed to reach the correct orbit.

Allen and Gardner's job was to "sting" the slowly spinning satellites through the motor nozzle with a docking device they carried with them. Allen would go first, inserting the specially constructed Apogee Kick Motor Capture Device into the Palapa B-2 satellite's motor. He then used his MMU jets to slow the rotation of the satellite. Mission specialist Anna Fisher would then help to manoeuvrer the failed satellite into Discovery's cargo bay.

Nasa Dale Gardner and his colleagues spent three days in orbit recovering two satellites (Credit: Nasa)Nasa

Dale Gardner and his colleagues spent three days in orbit recovering two satellites (Credit: Nasa)

Next up was Gardner and the Westar VI, which would undergo the same procedure. Once the two stricken satellites were safely nestled in the space shuttle's cargo bay, Gardner took a moment to pose for a cheeky photograph holding a "for sale" sign.

It was in reference to the scrap-yard salvage nature of the mission. Both satellites would go on to be resold by their insurance companies and would eventually be refurbished and relaunched in April 1990.

The highest repairman in the world

In the three years after it was launched into orbit in 1990, the Hubble Space Telescope was becoming a joke. Despite costing more than $1.5bn (around £1bn at the time), it had been beaming back blurry images to Earth due to a minute flaw in its main mirror.

In December 1993, a team of astronauts onboard Space Shuttle mission STS-61 were dispatched to carry out urgent repairs on the telescope. It would be one of the most challenging and complex missions ever attempted.

During five back-to-back spacewalks, two teams of astronauts spent a total of 35 hours and 28 minutes conducting the first ever in orbit service of a space telescope. The remote manipulator arm of the Space Shuttle Endeavour was used to position the 13m-long (43ft) Hubble above the shuttle's payload bay.

This allowed the astronauts to conduct vital hardware repairs and upgrades, including new solar arrays, gryroscopes and fuse plugs. Mission specialist Kathryn Thornton set a record with the longest time spent spacewalking by a US woman during the repair mission, clocking up a total of 21 hours and 10 minutes outside of the spacecraft. Mission specialist Tom Akers also set an EVA record, with 29 hours and 39 minutes of spacewalking.

The walk of friendship

With the dissolution of the Soviet Union in December 1991 and the end of the Cold War, the years that followed saw growing cooperation in space between Russia and the US.

From 1994 to 1998, the US Space Shuttle made 10 visits to Russia's Mir space station. During that time, seven American astronauts lived and worked on board Mir, accumulating nearly 1,000 days in orbit alongside their cosmonaut colleagues. The fourth American to live on Mir was medical doctor and astronaut Jerry Linenger in 1997.

His time on Mir was stressful. He and five other crew onboard faced what is probably the most serious fire to have occurred in space after a blaze broke out in the oxygen generating system. Although it lasted only a few minutes, the fire filled the space station with smoke and cut off access to one of the two Soyuz escape vehicles.

Later, a Russian Progress M-34 resupply ship also collided with the space station during a docking attempt, puncturing Mir's hull and causing the first decompression on board an orbiting spacecraft. They also faced the failure of several vital pieces of equipment during the mission.

But before all this drama, Linenger performed the first spacewalk by a US astronaut while wearing a Russian spacesuit. The five-hour EVA on 29 April 1997 saw Linenger joined by Mir-23 commander Vasily Tsibliyev as they installed scientific instruments to the outside of the space station.

Constructing a new space station

In 1998, work began on what may be a contender for the most expensive structure ever built by humans – the International Space Station. Astronauts onboard the space shuttle Endeavour would undertake a 12-day mission to connect the first two modules of what would eventually provide a permanent human residence in space.

The ISS of 2024 boasts 16 modules and is the same length as a football field. But in 1998, astronauts James Newman and Jerry Ross had to perform three long spacewalks as they used the shuttle's robotic arm to capture the Zarya control module and connect it to the 12.8-tonne Unity module.

The process wasn't without its hitches though. As the two astronauts connected cabling and handrails, nudged stuck antennas and removed restraining pins, the pair lost several construction items that drifted off into space to join a growing amount of "space junk" that now poses a threat to satellites and spacecraft.

By 13 December 1998, however, their work was done and Endeavour disengaged from the fledgling ISS, leaving the space station free to fly.

Two years later, the ISS would become permanently occupied, enabling a constant human presence in orbit ever since.

A spacewalking record

An eight-hour working day feels like a long time even with your feet planted firmly on solid Earth. So how must US astronaut Susan Helms have felt after performing the longest ever spacewalk in history in March 2001, spending eight hours and 56 minutes outside the ISS.

She and her fellow astronaut James Voss had been tasked with installing hardware to the outside of a laboratory module on the ISS, when they made their epic spacewalk. Their record still stands today.

Under the space shuttle

The flight of space shuttle Discovery on mission STS-114 in July 2005 was the first launch of the space shuttle since the tragic loss of the shuttle Columbia in 2003, where all seven on board were killed as it disintegrated on re-entry.

Nasa had spent nearly three years trying to improve the safety of the shuttle and had particularly focused on the craft's protective tiles that were intended to keep it safe from the extreme temperatures generated while re-entering the atmosphere.

The launch of Discovery was a tense one. The first attempt was scrapped after a fuel sensor failed during the countdown. When it finally did leave the launchpad, imagery showed a piece of foam being shed from the external fuel tank as well as smaller pieces of tile, raising concerns the heat shield of the shuttle may have been damaged.

Upon arrival at the ISS, astronaut Stephen Robinson was sent out to assess the situation, inching his way along the grey, thermal-protection tiles. Using his fingers, he pulled two protruding gap-fillers out from between two of the heat-shield tiles. It was the first repair of a spacecraft while in orbit before it was due to return to Earth.

The work paid off – the shuttle landed safely at Edwards Airforce Base in California on 9 August 2005.

A near drowning in space

It was supposed to be a routine EVA. Six hours outside the International Space Station preparing cables for the arrival of a new Russian research module.

But as Italian astronaut Luca Parmitano worked on the task, he noticed something that would mark the start of one of the most serious mishaps in spacewalking history – water was pooling at the back of his helmet.

It was about 44 minutes into the EVA on 16 July 2013 when Parmitano calmly reported feeling "a lot of water on the back of my head". Unable to identify the source, he continued working on his cable routing task. On the off chance it was coming from a drink bag within his suit, he drank it dry.

But the water continued to increase in quantity, intruding into his communications cap. Just over an hour into the spacewalk, Mission Control decided to terminate the spacewalk, ordering Parmitano and fellow spacewalker astronaut Chris Cassidy to return to the airlock.

But as Parmitano moved, the water shifted, obscuring his vision and forcing him to ask Cassidy for help finding his way back to the airlock. Cassidy, tethered to another part of the space station, had to take a different path back.

In the near-zero gravity environment of orbit, the blob of water on the back of Parmitano's head had shifted as he turned towards the airlock. Now it covered his eyes, ears and nose.

With the water interrupting his communications systems and blocking his ears, he struggled to alert Cassidy and Mission Control to his growing distress.

"At a certain level of subconciousness, I was afraid," he later told the BBC World Service. "We are trained to control that fear or use that fear and divert it somewhere else. Instead of focusing on the problem – which was I'm isolated, I can't see, I can't hear, they cannot hear me and I may drown with the next gulp of air – I started to think of solutions."

With blurred vision, and plunged suddenly into darkness as the space station moved behind the Earth, Parmitano felt his way gingerly back to the airlock with the help of his safety tether.

Once inside the airlock, Parmitano faced an agonising five-minute wait for Cassidy to arrive. It would take 10 minutes to lock the hatch and a further 13 minutes before the airlock could be repressurised and Parmitano's helmet could be removed.

It was found that an estimated 1.5 litres (2.6 pints) of water had filled his helmet while he was inside it.

"For a couple of minutes there, or maybe more than a couple of minutes, I experienced what it is like to be a goldfish inside a fish-bowl from the point of view of the goldfish," Parmitano would later say, in a surprisingly light-hearted reflection on the incident.

An investigation would later identify a blockage in Parmitano's fan pump separator led to water spilling from the cooling loop into the ventilation loop and then into the helmet.

Engineers would later add an absorption pad to the helmets of spacesuits and a snorkel to help astronauts deal with a water leak should one appear.

As Nasa now looks to the next stage of space exploration with its Artemis programme, the lessons learned by Parmitano and the brave spacewalkers that came before and after him will help to inform their decisions.

-BBC