Two Tims in the vacuum of space. A first for humankind. NASA astronaut Tim Kopra and first-time spacewalker Tim Peake are fixing the Space Station. But what's it like out there in the void?
The spacewalk is due to last 6hrs30min. The Tims will replace a broken ‘sequential shunt unit’ which regulates the voltage of the solar panels that power the space station.
Despite hours of training in the neutral bouyancy lab and using virtual reality headsets, Tim Peake says "I guess nothing can fully prepare you for the feeling of being outside of a spacecraft in the vacuum of space." Good luck Tim(s)!
When you are outside on a spacewalk, it is a continual series of battles with your own mind. The physical tasks are relatively simple, but the environment is stark, and cold, and merciless, and powerfully unforgiving.NASA astronaut Doug Wheelock
A Dangerous Business
Entering the vacuum of space is a dangerous business, but there are times when it is essential in order to keep the international space station safely working. Before astronauts leave the space station they must get into their space suits. The pressure inside the suits is lower than in the station itself and to prevent them getting decompression sickness, known as “the bends” (much like divers coming up the the surface too quickly). The astronauts spend a couple of hours breathing pure oxygen in order to remove the nitrogen in their blood.
Entering the void - what a sight
“As soon as you move outside of your spacecraft there is depth and dimension. It takes a few minutes to get your wits about you, because you're not used to it.”
“When you are inside your brain usually processes the view in 2-dimensions. Much like the way we look at the moon from the surface of the Earth. We know the moon is a sphere, but we really only see in in 2-dimensions.”
“In the EMU helmet, you now have a 180-degree panoramic view of the cosmos. Your brain suddenly and amazingly opens up a third dimension of depth. It's hard to describe the breathtaking beauty of our planet suspended in the blackness.”
“On top of that it is complete and utter silence. You are left alone with communication coming through your headset...and the white noise of the fan blowing air in your suit, your breathing, and your heart beating. No other sounds travels through the vacuum of space. You can feel vibration, but you can't hear sound.”
NASA astronaut Doug Wheelock
Tims in Space - but what are they doing?
The International Space Station is powered by eight solar arrays, which are each made up of 33,000 solar cells. These can rotate as the space station travels around the Earth so that they can catch the most sunlight.
Power produced by the solar panels is used to run equipment and vital life support systems on the space station and also charges batteries that power the station so there is continuous power even when the station is in shadow.
The power produced by the solar panels needs to be regulated, and each solar array has a special unit - a “sequential shunt unit” (SSU) - that regulates the power and delivers a usable 160V. One of these units failed in November last year and needs to be removed and replaced. While the station can run as normal with only seven of the eight SSUs working, if another unit failed they would have to shut down some equipment on the space station.
Replacing the failed unit is the main aim of this spacewalk, and once this task has been completed there are some additional tasks such as laying cables, fitting valve and retrieving a broken light.
ISS Spacewalk Animation
Space helmets - the ultimate bling?
As the space station orbits the Earth roughly every 90 minutes it moves in and out of daylight and so astronauts experience an orbital sunrise or sunset every 45 minutes. This means that the spacewalkers will have to work in pitch darkness or bright sunlight.
The helmets come with a visor that is cover in a thin layer of gold. This filters some of the sun’s harmful rays, as well helping to protect the astronauts from extreme temperatures and small objects.
Even if everything goes according to plan, a spacewalk requires full concentration and a lot of physical exertion. While the space suit protects you from the vacuum of space, it’s also stiff and unwieldy, making movement difficult and tiring.
“It is exhilarating, but it is also very hard physical work” says retired astronaut Leroy Chiao. “It takes strength to work against the pressure of the suit, and after 6.5 hours, you can be pretty spent”. It’s not just aching muscles and physical tiredness, but some astronauts report losing fingernails from manoeuvring in space gloves.
With such a unique view of Earth, how do they keep their minds on the task in hand? The answer to this lies partly with the amount of training and the desire to do a good job, but a lot comes down to the stark reality that any mistakes could be fatal.
“You are continually reminding yourself to stay 'in the moment'” says astronaut Doug Wheelock. “Complacency is your worst enemy. Mistakes are greeted with instantaneous peril.”
Chiao agrees “I felt a sense of extra-high awareness of everything I did outside, so as to make doubly sure not to make a mistake”.
Space Station Maintenance
The team of Tim's currently out in space have successfully removed the broken power regulator and replaced it with a new unit. This will allow the space station to run on full power, with electricity generated by all eight solar arrays.
The swap went smoothly during the first of three 31-minute periods of darkness available to the spacewalkers for completing the task. The unit had to be replaced while the station was in shadow so that they could work without without risking electrocution from the power created when the solar arrays are in sunlight.
An Early End to the Spacewalk
Astronaut Tim Kopra noticed some water in his helmet so today’s spacewalk has been terminated at 4 hours and 10 minutes. The decision to end a spacewalk early is not taken lightly because of the amount of time and preparation they take, but following the emergency situation that ESA Luca Parmitano found himself in back in July 2013, it was decided it was better to be safe than sorry.
It was during Parmitano’s first spacewalk - the first by an Italian - that water began leaking into his helmet, leading to the cancellation of the spacewalk and his return to the ISS. Today's early termination is not considered an emergency. The astronauts calmly returned to the airlock, having completed the main task of the space walk.
Although the spacewalk was terminated early after Tim Kopra reported water in his helmet, he and Tim Peake successfully completed the main task for the spacewalk, replacing the faulty voltage regulator, allowing the space station to return to full power for the first time since November 13th 2015.
Astronauts on the space station will take a sample of the water that collected in Kopra’s helmet and measure how much water had collected. The absorption pad inside his helmet will also be saved to help with the investigation.