2 US Astronauts Conduct Unplanned, Rapidly Executed Contingency Space Walk on Space Station

Astronaut Jack Fischer waves while attached to the Destiny laboratory during a spacewalk on May 23, 2017 to replace a failed data relay box and install a pair wireless antennas. Credit: NASA

In the space of just 3 days, a pair of NASA astronauts conducted an unplanned and rapidly executed contingency space walk on the exterior of the space station on Tuesday, May 23 in order to replace a critical computer unit that failed over the weekend.

The spacewalk was conducted by Expedition 51 Commander Peggy Whitson – NASA’s most experienced astronaut – and Flight Engineer Jack Fischer aboard the International Space Station (ISS).

This marked the 10th spacewalk for Whitson – who already has the most cumulative spacewalk time by a female and the most time in space by a NASA astronaut. This was Fischer’s second spacewalk.

Furthermore Whitson now moves into third place all-time for cumulative spacewalking time totaling 60 hours, 21 minutes. Only Russia’s Anatoly Solovyev and NASA’s Michael Lopez-Alegria have more spacewalking time to their credit.

Peggy Whitson @AstroPeggy is 3rd place all-time for cumulative spacewalk time with 10 spacewalks totaling 60 hours, 21 minutes. Credit: NASA

NASA managers ordered the spacewalk over the weekend when a computer unit known as multiplexer-demultiplexer-1 (MDM-1) unexpectedly failed Saturday morning, May 20 at 1:13 p.m. Central time.

The cause of the MDM failure is not known, says NASA. Multiple attempts by NASA flight controllers to restore power to the MDM-1 relay box were not successful.

The US dynamic duo successfully changed out the MDM computer relay box with a spare unit on board the station. They also installed a pair of antennas on the station on the U.S. Destiny Laboratory module to enhance wireless communication for future spacewalks.

The MDM functions as a data relay box and is located on the S0 truss on the exterior of the US segment of the ISS, thereby necessitating a spacewalk by astronaut crew members.

After NASA engineers thoroughly assessed the situation and reviewed spacewalk procedures on Sunday, May 21, they gave the go ahead for Whitson and Fischer to carry out the hurriedly arranged extravehicular activity (EVA) spacewalk on Tuesday.

Meanwhile, Whitson worked on Sunday to prepare the spare data relay box and test its components to ensure it was ready for Tuesdays swap out of the failed unit.

“The relay box, known as a multiplexer-demultiplexer (MDM), is one of two units that regulate the operation of radiators, solar arrays and cooling loops.” says NASA.

“Because each MDM is capable of performing the critical station functions, the crew on the station was never in danger and station operations have not been affected.”

The two MDM’s housed in the truss are fully redundant systems.

“The other MDM in the truss is functioning perfectly, providing uninterrupted telemetry routing to the station’s systems.”

The spacewalk began Tuesday morning, May 23 at 7:20 a.m. EDT when the two NASA astronauts switched their spacesuits to battery power.

While Whitson focused on the MDM swap, Fischer worked on the antenna installation.

The unplanned spacewalk marks the second this month by Whitson and Fischer. The first was on May 12 and the 200th overall. The Destiny module antenna installation was deferred from the May 12 spacewalk.

Astronaut Peggy Whitson is pictured May 12, 2017, during the 200th spacewalk at the International Space Station. Credit: NASA

The relatively short EVA lasted a total of two hours and 46 minutes. It concluded at 10:06 a.m. EDT.

Overall this was the 201st spacewalk in support of the space station assembly, maintenance and upgrade. Spacewalkers have now spent a total of 1,250 hours and 41 minutes working outside the orbiting lab complex since its inception.

Spacewalk 201 was also the sixth spacewalk conducted from the Quest airlock in 2017 aboard the ISS.

The International Space Station with its prominent solar arrays and radiators attached to the truss structure was pictured May 2010 from space shuttle Atlantis. Credit: NASA

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

Space Station Drama After Vital Micrometeorite Shielding Floats Away

This past week (on Thurs. March 30th), two crew members of Expedition 50 conducted an important spacewalk on the exterior of the International Space Station. During the seven hours in which they conducted this extravehicular activity (EVA), the astronauts reconnected cables and electrical connections on a new Pressurized Mating Adapter (PMA-3) and installed four new thermal protection shields on the Tranquility module.

These shields were required to cover the port that was left exposed when (earlier in the week) the PMA-3 was removed and installed robotically on the Harmony module. In the course of the EVA, the two astronauts – Commander Shane Kimbrough and Flight Engineer Peggy Whitson – were forced to perform an impromptu patch up job when one of the shield unexpectedly came loose.

While things flying off into space is not entirely unusual, on this occasion, there were concerns given the size and weight of the object. This shield measures about 1.5 meters by 0.6 meters (5 feet by 2 feet) and is 5 centimeters (2 inches) thick. It also weighs a little over 8 kg (18 lbs), which would make it a serious impact hazard given the relative velocity of orbital debris (28,000 km/h).

Spacewalk support personnel quickly at the Johnson Space Center, looking for a solution to the loss of thermal and micrometeoroid shield. Credit: NASA

After coming loose, the bundled-up shield quickly floated away and became visible in the distance as a white dot. In response, a team from the Mission Control Center at NASA’s Johnson Space Center began monitoring the shield as it drifted. At the same time, they began working on a contingency plan to substitute the shielding, and advised the astronauts to finish covering the port with the PMA-3 cover Whitson removed earlier that day.

The plan worked, and the cover was successfully installed, providing thermal, micrometeoroid and orbital debris protection for the port. Kimbrough and Whitson finished their EVA at 2:33 pm EDT, having successfully installed the remaining shields on the berthing mechanism port. A few hours after it came loose, Mission Control also determined that the shield posed no risk to the ISS and will eventually burn up in Earth’s atmosphere.

Before concluding their spacewalk, Kimbrough and Whitson also installed what has been nicknamed a “cummerbund” around the base of the PMA-3 adapter. This cloth shield – which also provides micrometeorite protection – is so-named because it fits around the adapter in a way that is similar to how a tuxedo’s cummerbund fits around a person’s waist.

Another highlight of this spacewalk was the fact that Peggy Whitson set two new records with this latest EVA. In addition to setting the record for the most spacewalks by a female astronaut (eight), she also set the record for most accumulated time spent spacewalking – just over 53 hours – by a female astronaut. The 57-year old astronaut now ranks fifth on the list of all-time spacewalking by any astronaut.

Astronaut Peggy Whitson signs her autograph near an Expedition 50 mission patch attached to the inside the International Space Station. Credit: NASA

On top of all that, Expedition 50 is Whitson’s third mission to the ISS, and she has spent a total of 500 days in space – also a record for any female astronaut. She arrived aboard the ISS aboard the Soyuz MS-03 – along with ESA flight engineer Thomas Pesquet and Roscosmos flight engineer Oleg Novitskiy – and is scheduled to return to Earth in June (though she may remain there until September).

The top spot for most accumulated time in spacewalking is currently held by Russian cosmonaut Anatoly Solovyev, who has participated in 16 spacewalks for a grand total of 82 hours spent in EVA. And in total, spacewalkers have now spent a total of 1,243 hours and 42 minutes performing 199 spacewalks in support of the assembly and maintenance of the ISS.

When it comes to being an astronaut, one of the most important requirements is flexibility – the ability to adapt to unexpected situations and come up with solutions on the fly. Crew 50 and Mission Control certainly demonstrated that this week, maintaining a tradition that brought the Apollo 13 astronauts safely back to Earth and has kept the ISS running for almost two decades.

Further Reading: ABCnews, NASA

Watch Live: 180th Spacewalk for the International Space Station



Broadcast live streaming video on Ustream

Cosmonauts Alexander Skvortsov and Oleg Artemyev are working outside at the International Space Station today! They will spend about 6.5 hours outside installing an antenna for data relays, relocating a cargo boom, swabbing samples from a window on the Zvezda service module and switching out science experiment gear. Watch live above.

This is milestone of sorts for ISS spacewalks: it is the 180th spacewalk in support of space station construction and maintenance since December 1998, when the Russian Zarya module was mated to the US Unity node. You can read what that first spacewalk was like in an interview with astronauts Bob Cabana: What Day 1 on the International Space Station Was like for the Astronauts.

And what’s going on inside the ISS today?

If you want to know who is who during the spacewalk, Skvortsov is wearing the Russian Orlan spacesuit with red stripes, and Artemyev’s has a spacesuit with blue stripes.

UPDATE: Spacewalkers Zip Through Tasks To Fix Broken Computer

UPDATE, 11:42 a.m. EDT: Rick Mastracchio and Steve Swanson finished their spacewalk in just 1 hour and 36 minutes, nearly an hour faster than what NASA budgeted for. Early tests show the replacement computer is working well, providing backup once again for the robotics, solar arrays and other systems on station.

Can two astronauts fix a broken computer quickly on the International Space Station, preventing possible problems with the solar arrays and robotics? Watch live (above) to find out.

The NASA spacewalk involving Rick Mastracchio and Steve Swanson is scheduled to start today (April 23) at 9:20 a.m. EDT (1:20 p.m. UTC), with coverage starting around 8:30 a.m. EDT (12:30 p.m. UTC). The spacewalk is scheduled to last 2.5 hours. Bear in mind that the times could change as circumstances arise.

The computer, also called a multiplexer/demultiplexer (MDM), failed for unknown reasons a couple of weeks ago. While the primary computer is working perfectly and the crew is in no danger, things get more risky if the primary computer also breaks. That’s why NASA worked to get the spacewalkers outside as quickly as possible. You can see a full briefing of the rationale here.

As a note, all non-urgent spacewalks have been suspended because NASA is still working on addressing the recommendations given after a life-threatening water leak took place in a NASA spacesuit last summer. Urgent spacewalks can still go ahead because the agency has implemented safety measures such as snorkels and helmet absorption pads in case of another leak.

That said, in the months since NASA has traced the problem to contamination in a filter in the fan pump separator. After replacing the separator, the leaky spacesuit was used during two contingency spacewalks in December with no water problems at all.

How Did That Spacesuit Water Leak Spread? New Video Has Clues

As NASA investigates how astronaut Luca Parmitano’s spacesuit filled with water during a spacewalk two weeks ago, a new video by fellow Expedition 36 astronaut Chris Cassidy demonstrated the path the pool took inside Parmitano’s helmet.

Cassidy described the situation as leaking “cooling water” that got “somehow into his ventilation system” and spread into Parmitano’s helmet. The cause is still being investigated.

From a ventilation port at the back of the helmet, “the water bubbles started to build up behind this white plastic piece,” Cassidy said in the video, pointing at a support that was behind Parmitano’s head.

Update: There’s now part 2 of Cassidy’s description of the leak, below:


“Once the water got big enough that it went all the way around and started coming outside the edge of the white plastic, then it saturated his communication cap and the … flow brought the water all around his head. And he had water filled up in his ear hubs, and it started to creep into his eyes, and cover his nose.”

Calling it a “scary situation”, Cassidy said that if the leak had continued, “it would have been very serious.” NASA, however, aborted the spacewalk quickly after Parmitano reported the problem. Parmitano and Cassidy, who were outside together, were back in the International Space Station in minutes.

Parmitano, for his part, has repeatedly said that he is doing all right. “Guys, I am doing fine and thanks for all the support. I am really okay and ready to move on,” he said, as reported in a July 18 ESA blog post.

NASA has at least two probes going on: an engineering analysis to find the cause, and a more wide-ranging mishap investigation to look at spacewalk procedures and overall crew safety during spaceflights. The agency also sent a spacesuit repair kit on the Progress spacecraft that docked with the International Space Station on July 27.

The July 16 spacewalk ended after just 1 hour, 32 minutes. All of the tasks for the planned 6.5-hour outing, which included preparing data cables and power for a forthcoming Russian module, are not urgent and can be done any time, NASA said. Further American spacewalks are suspended for the time being.

Opening Sequence of Today’s ISS Spacewalk Highlight Video Will Knock Your Space Socks Off

Want a “you are there” view of today’s EVA that took place outside the International Space Station? Take a look at this great video of astronaut Chris Cassidy getting a ride on the station’s Canadarm-2 to make repairs and prepare for a new Russian laboratory. There are several great “over the shoulder” views during this short highlight video.

During their 6-hour and 7-minute spacewalk, Cassidy of NASA and Luca Parmitano of the European Space Agency worked on replacing a failed communications receiver, relocating grapple bars for future spacewalks and stringing cables for the when the Russian laboratory module arrives later this year.

The Ku-band communications receiver replaces one that failed last December. There was already a redundant backup system now in use, and this new one will become the backup.

The new Russian lab, called Nauka, will replace the Pirs airlock. It is scheduled to launch on a Proton rocket booster late this year, although the flight could be delayed a bit until early next year as because of assembly delays in Russia.

This spacewalk was the first of two in as many weeks for the duo. They will again venture outside the Quest airlock on July 16 for more upgrades and repairs. This was Parmitano’s first spacewalk, and he has now become the first Italian astronaut to walk in space. Old pro Cassidy has now been on five spacewalks, and this was the 170th spacewalk in support of space station assembly and maintenance.

ISS Spacewalk Prepares for New Russian Laboratory

On Monday, two Russian cosmonauts conducted a 6-hour, 34-minute spacewalk to prepare for a new Russian module that will be launched later this year. Expedition 36 Flight Engineers Fyodor Yurchikhin and Alexander Misurkin also work on the first module ever launched for the ISS – the Zarya module which has been in space since 1998 – replacing an aging control panels located on the exterior.

The new lab will be a combination research facility, airlock and docking port, and is planned to launch late this year on a Proton rocket.

Watch video highlights of the EVA below:

This was the second of up to six Russian spacewalks planned for this year to prepare for the lab. Two U.S. spacewalks by NASA’s Chris Cassidy and Luca Parmitano of the European Space Agency are scheduled in July.

While Yurchikhin and Misurkin worked outside the ISS, the crew inside the ISS were separated and isolated from each other. Cassidy and station commander Pavel Vinogradov were sequestered in their Soyuz TMA-08M spacecraft that is attached to the Poisk module on the Russian segment due to the closure of hatches to the other passageways on the Russian side of the station which would have made the Soyuz inaccessible if there was an emergency. Parmitano and US astronaut Karen Nyberg were inside the U.S. segment of the station, and were free to move around since entry to their Soyuz vehicle (TMA-09M) was not blocked by hatch closures, since it is docked to the Rassvet module that is attached to the Zarya module.

NASA said the spacewalk was the 169th in support of space station assembly and maintenance, the sixth for Yurchikhin and the first for Misurkin.

More Incredible Images from the Space Station ‘Emergency’ EVA

The image above could go down as an iconic shot of space exploration. Taken during the ’emergency’ spacewalk last Saturday to fix the leaking ammonia coolant in the pump and flow control system for the International Space Station’s power-supplying solar arrays, visible is astronaut Tom Marshburn taking a look at planet Earth. He shared the picture today on Twitter, saying, “Leaving is bittersweet. It’s been an unbelievable ride. Can’t wait to see what’s next!”

Marshburn is scheduled to return back to Earth later today along with ISS commander Chris Hadfield and cosmonaut Roman Romanenko.

Below are more great shots from Saturday’s EVA that were just released by NASA today. See here for earlier images of the spacewalk from Chris Hadfield via Twitter.

Astronaut Chris Cassidy during the May 11, 2013 spacewalk at the ISS. Credit: NASA
Astronaut Chris Cassidy during the May 11, 2013 spacewalk at the ISS. Credit: NASA

Expedition 35 Flight Engineers Chris Cassidy (left) and Tom Marshburn on a spacewalk on May 11 to inspect and replace a pump controller box on the International Space Station’s far port truss (P6) leaking ammonia coolant. Credit: NASA.
Expedition 35 Flight Engineers Chris Cassidy (left) and Tom Marshburn on a spacewalk on May 11 to inspect and replace a pump controller box on the International Space Station’s far port truss (P6) leaking ammonia coolant. Credit: NASA.
Astronaut Chris Cassidy takes a self-portrait during the May 11, 2013 EVA at the ISS. Credit: NASA.
Astronaut Chris Cassidy takes a self-portrait during the May 11, 2013 EVA at the ISS. Credit: NASA.
Chris Cassidy with Earth as a backdrop during the EVA on May 11, 2013. Credit: NASA.
Chris Cassidy with Earth as a backdrop during the EVA on May 11, 2013. Credit: NASA.
 Expedition 35 Flight Engineers Chris Cassidy (left) and Tom Marshburn completed a the 5-hour, 30-minute spacewalk on May 11 to inspect and replace a pump controller box on the International Space Station’s far port truss (P6) leaking ammonia coolant. Credit: NASA
Expedition 35 Flight Engineers Chris Cassidy (left) and Tom Marshburn completed a the 5-hour, 30-minute spacewalk on May 11 to inspect and replace a pump controller box on the International Space Station’s far port truss (P6) leaking ammonia coolant. Credit: NASA

Click each image for a higher-resolution version, and see more images from NASA’s 2Explore Flickr stream.

Amazing Photos from Saturday’s Emergency Spacewalk

The spacewalk outside the International Space Station was captured on film by the tweeting, Facebooking, social media maven and space station commander Chris Hadfield. “Amazing day,” he said. “EVA went off without a hitch. Great crew, phenomenal ground support and a supportive audience. Who could ask for anything more?”

How ’bout a picturesque view? We’ve got that too! See a collection of great images from the EVA, which — for the moment — appears to have been a success in fixing the leaking ammonia coolant system.

Cassidy and Marshburn work outside the ISS in the 'approaching orbital sunset, the harshest of light, a blackness like endless velvet,' said Hadfield. Credit: NASA/CSA/Chris Hadfield.
Cassidy and Marshburn work outside the ISS in the ‘approaching orbital sunset, the harshest of light, a blackness like endless velvet,’ said Hadfield. Credit: NASA/CSA/Chris Hadfield.
Chris Cassidy and Tom Marshburn turn on their helmet lights 'doing their best to light the universe on the dark side of the Earth,' said Chris Hadfield. Credit: NASA/CSA/Chris Hadfield
Chris Cassidy and Tom Marshburn turn on their helmet lights ‘doing their best to light the universe on the dark side of the Earth,’ said Chris Hadfield. Credit: NASA/CSA/Chris Hadfield
'Climbing out of the airlock, quite the commute to work!' said Chris Hadfield via Twitter.
‘Climbing out of the airlock, quite the commute to work!’ said Chris Hadfield via Twitter.
Chris Cassidy, Navy SEAL and lead spacewalker Saturday. Credit: NASA/CSA/Chris Hadfield.
Chris Cassidy, Navy SEAL and lead spacewalker Saturday. Credit: NASA/CSA/Chris Hadfield.
Dr. Tom Marshburn, well-dressed for a day's work outdoors. Credit: NASA/CSA/Chris Hadfield.
Dr. Tom Marshburn, well-dressed for a day’s work outdoors. Credit: NASA/CSA/Chris Hadfield.

Emergency Spacewalk Likely for ‘Serious’ ISS Coolant Leak

Astronauts on the International Space Station are preparing for a potential emergency spacewalk to fix an ammonia coolant leak outside the station. On Thursday, the ISS crew spotted small white flakes floating away from an area of the Station’s P6 truss structure, and noticed pressure drops in the control panel of the pump and flow control system for the power-supplying solar arrays.

UPDATE: At a press briefing on Friday afternoon, NASA officials announced that the ISS crew will perform a spacewalk starting early Saturday to address the ammonia leak.


“Suddenly very busy!” tweeted astronaut Tom Marshburn, who along with Chris Cassidy is preparing for the contingency EVA. “Ammonia leak on the outside of station means that Cassidy and I will be doing a spacewalk tomorrow to try and repair it.”

Mission Control teams worked overnight to understand and sort through the problem and find potential fixes or work-arounds for the electricity systems. The Mission Management team met this morning to identify any issues or latent hazards of the spacewalk, and they are seeking input from all the international partners. The crew is expecting a final go or no go by later today on whether the spacewalk will take place. There will be an update on NASA TV at 20:00 UTC, 4 pm EDT.

“The whole team is ticking like clockwork, readying for tomorrow. I am so proud to be Commander of this crew. Such great, capable, fun people,” said ISS Commander Chris Hadfield via Twitter. Yesterday, he called the leak “serious” but that the situation was stable.

NASA has said that while the coolant is vital to the operation of the ISS for the electricity-supplying systems, the crew is not in any danger. The ammonia cools the 2B power channel, one of eight power channels that control the all the various power-using systems at the ISS. All the systems that use power from the 2B channel, the problem area, are being transferred throughout the day to another channel. The 2B channel will eventually shut down when the coolant is depleted, and the power is being diverted in order to keep everything up and running on the station.

Cassidy and Marshburn are now preparing for the spacewalk in the Quest airlock, arranging their spacesuits and gathering the specialized tools they will need to do the work outside the station. These two are the perfect people to conduct this spacewalk, as both are veterans of three spacewalks, two of which they performed together on the STS-127 space shuttle mission to the ISS, and they went to this exact same area on the P6 truss to replace batteries. They have also trained for this particular spacewalk already, as this spacewalk task does fall under the “Big 12” of contingency spacewalks of possible serious issues that may occur. All astronauts train for these in case an unexpected event requires a quick response.

While Cassidy and Marshburn prepare in space, Astronauts at NASA’s Johnson Space Center are using the Neutral Buoyancy lab – a 12- meter (40 ft.) deep swimming pool with mockups of the space station that simulates the zero-gravity conditions in space – going through the entire expected EVA. ESA astronaut Samantha Cristoferretti and NASA’s Terry Virts are walking through and choreographing the procedures to make sure the tasks could be done in a reasonable time as well as looking for potential hazards. They will confer with the ISS astronauts to share their experiences.

This video shows information about the potential spacewalk, as well as footage of the ammonia leak captured by the crew.

While NASA does not know for certain the exact location of the leak, they are focusing on the pump and flow control system, the suspected source. That exact same area and system was the location of a minor leak, first identified in 2007 – thought to have been caused perhaps by a micrometeorite impact — and in November 2012 two astronauts went on a spacewalk to fix the problem. They rewired some coolant lines and installed a spare radiator, and it appeared the problem had been fixed.

That first leak was not visible during the EVA, but this new leak is quite noticeable, as the crew wwas able to see the leak from inside the station.

One of the driving factors for getting the spacewalk underway as quickly as possible is that the location of the leak and the potential fix are not exactly known. The hope is that it is still leaking by the time they get out there on Saturday morning, so that they can easily identify the source of the leak. The first task will be identifying the source, then possibly replacing the current pump and flow control system with one of the spares, located handily out at the P6 truss. If that is not the source of the leak, they will look through the area to try and identify the source. NASA said the leak could potentially be located in the internal plumbing of the system, which would be harder to see immediately.

At the briefing, NASA officials said the spacewalk and ammonia leak won’t affect the scheduled departure of Hadfield, Marshburn and Russian cosmonaut Roman Romanenko, set for Monday May 13 at 7:08 p.m. EDT. Three crew members, Cassidy and Russian cosmonauts Alexander Misurkin and Pavel Vinogradov, will remain on the space station.