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NASA's historic all-female spacewalk, by the numbers

Historic all-female spacewalk

Astronauts Christina Koch and Jessica Meir plan to float outside the International Space Station on Friday for a five-and-a-half-hour spacewalk — the first ever carried out by two women — to replace a faulty component in the lab's solar power system.

It will be the first all-female spacewalk in the 54 years since the late Soviet cosmonaut Alexey Leonov carried out history's first spacewalk, or EVA (extravehicular activity), in 1965. Cosmonaut Svetlana Savitskaya became the first woman to walk in space during an outing with a male cosmonaut in 1984. NASA astronaut Kathryn Sullivan followed suit later that year, joining astronaut David Leestma for a shuttle spacewalk.

Koch became the 14th woman to walk in space earlier this year and Meir will be the 15th. Other than Savitskaya, all are current or retired NASA astronauts.

Here are a few facts and figures about Friday's excursion and the astronauts taking part.

Christina Koch, 40

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NASA astronaut Christina Koch aboard the International Space Station. NASA

14th woman to walk in space

Previous spacewalks: 3

  • 03/29/19: 6 hours 45 minutes; solar array battery replacement (left inboard array); with Nick Hague
  • 10/06/19: 7 hours 1 minute; solar array battery replacement (right outboard array); with Drew Morgan
  • 10/11/19: 6hours 45 minutes; solar array battery replacement (right outboard array); with Drew Morgan


Spacewalk call sign: EV-1

Spacesuit: EMU 3008 (red stripes)

Helmetcam: No. 18

Hometown: Jacksonville, N.C.

Education: Master's degree  in electrical engineering

Hobbies: Backpacking, rock climbing, sailing

Launch (first space flight): Soyuz MS-12/58S, 3/14/19, Baikonur Cosmodrome, Kazakhstan

Landing (planned): Soyuz MS-13/59S, 02/06/20, Kazakhstan

Mission duration (planned): 328 days (female single flight world record)

Jessica Meir, Ph.D., 42

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Astronaut Jessica Meir during training at the Johnson Space Center in Houston. NASA

Will be the 15th woman to walk in space

Previous EVAs: None

Spacewalk call sign: EV-2

Spacesuit: EMU 3004 (no stripes)

Helmetcam: No. 11

Hometown: Caribou, Maine

Education: Master's degree in space studies, Ph.D. in marine biology

Hobbies: Skiing, hiking, running; private pilot

Launch (first flight): Soyuz MS-15/61S, 9/25/19, Baikonur Cosmodrome, Kazakhstan

Landing (planned): Soyuz MS-51/61S, 04/01/20, Kazakhstan

Mission duration (planned): 188 days

Friday's spacewalk will be

  • The 221st International Space Station spacewalk, or EVA
  • The 8th ISS EVA this year (7 by U.S., plus 1 Russian)
  • The 3rd EVA for the Expedition 61 crew
  • The 4th EVA for Koch
  • The 1st EVA for Meir
  • The 2nd EVA to replace a failed battery charge/discharge unit (BCDU)
  • The 168th US/ISS EVA (Russian EVAs: 53)

Total spacewalkers to date: 227 (Meir will be the 228th)

Total female spacewalkers to date: 14 (Meir will be the 15th)

Total ISS EVA time logged to date: 1,381 hours and 12 minutes, or 57.6 days

List of female spacewalkers

  1. Svetlana Savitskaya, USSR; 1984
  2. Kathryn Sullivan, U.S.; 1984
  3. Kathryn Thornton, U.S.; 1992
  4. Linda Godwin, U.S.; 1996
  5. Tammy Jernigan, U.S.; 1999
  6. Susan Helms, U.S.; 2001
  7. Peggy Whitson, U.S.; 2002
  8. H. Stefanyshyn-Piper, U.S.; 2006
  9. Sunita Williams, U.S.; 2006
  10. Nicole Stott, U.S.; 2009
  11. Tracy Caldwell Dyson, U.S.; 2010
  12. Kate Rubins, U.S.; 2016
  13. Anne McClain, U.S.; 2019
  14. Christina Koch, U.S.; 2019
  15. Jessica Meir, U.S.; 2019 (planned)
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Astronaut Christina Koch, visible near top center with a red stripe on her spacesuit, moves along the International Space Station's power truss during an Oct. 11 spacewalk to install new batteries for the lab's outboard solar arrays. NASA

Why this spacewalk is necessary

The International Space Station is powered by four huge solar array wings, two on the left side of a football field-long truss and two on the right. The lab originally was equipped with 48 nickel-hydrogen batteries in four sets of 12 (one set per solar wing) to provide uninterrupted power when the space station is in the darkness of Earth's shadow.

To control battery charging in sunlight and discharging in darkness, each solar array wing, with its 12 nickel-hydrogen batteries, was equipped with six battery charge-discharge units, two per battery.

Because batteries lose their ability to recharge over time, NASA is in the process of replacing all 48 nickel-hydrogen batteries with 24 more powerful lithium-ion power packs and circuit-completing "adapter plates" to fill in where older batteries were removed but not replaced. In the upgraded system, each lithium-ion battery is charged and discharged by a single BCDU.

In 2017, spacewalkers replaced the 12 right-side inboard solar array batteries with six lithium-ion units. Last March, the 12 left-side inboard batteries were replaced. NASA currently is working to replace the left-side outboard batteries. The final set of lithium-ion batteries will be installed in the right-side outboard arrays next year

Three of six lithium-ion batteries were installed on the left outboard array during spacewalks by Koch and Morgan on Oct. 6 and 11. Shortly thereafter, engineers discovered one of the three BCDUs in that circuit had failed, reducing the power output by up to 5 kilowatts. Work to install the three remaining batteries was put on hold pending resolution of the BCDU issue.

The failure is troubling because an identical charger failed last March after a new battery was installed for the left inboard array. Only three spares are available, and NASA engineers want to make sure a generic problem of some sort is not present before proceeding with additional battery installations.

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