1. Definition

Spacewalk (Extravehicular Activity, EVA):
An activity where an astronaut leaves a spacecraft to perform work in outer space. Spacewalks can be conducted outside orbiting vehicles, on the Moon, or on other celestial bodies.

2. History of Spacewalks

2.1. Early Milestones

  • First Spacewalk:
    • Date: March 18, 1965
    • Astronaut: Alexei Leonov (Soviet Union, Voskhod 2)
    • Duration: 12 minutes
    • Challenges: Suit overinflation, difficulty re-entering the airlock
  • First American Spacewalk:
    • Date: June 3, 1965
    • Astronaut: Ed White (Gemini 4)
    • Duration: 23 minutes
    • Used a hand-held maneuvering unit

2.2. Moonwalks

  • Apollo Missions:
    • First Moonwalk: July 20, 1969 (Neil Armstrong, Buzz Aldrin)
    • Activities: Sample collection, experiments, setting up equipment

2.3. Shuttle and ISS Era

  • Space Shuttle (1981ā€“2011):
    • Enabled complex construction and repair missions
    • Notable: Repair of Hubble Space Telescope (1993, 1999, 2002, 2009)
  • International Space Station (ISS, 2000ā€“present):
    • Over 250 spacewalks
    • Tasks: Assembly, maintenance, upgrades

3. Key Experiments and Achievements

3.1. Construction & Maintenance

  • ISS Assembly:
    • Spacewalks essential for connecting modules, installing solar arrays, and external repairs
  • Hubble Space Telescope Servicing:
    • Upgrades and repairs extended the telescopeā€™s lifespan and scientific output

3.2. Scientific Experiments

  • Exposure Experiments:
    • Materials exposed to space to study degradation (e.g., MISSEā€”Materials International Space Station Experiment)
  • Biological Studies:
    • Microbial survival on surfaces
    • Plant growth in microgravity (e.g., Veggie experiment)

3.3. Technological Demonstrations

  • Robotic Assistance:
    • Use of Canadarm2 and Dextre for assisting astronauts
    • Testing of new spacesuit designs (e.g., NASAā€™s xEMU suit)

3.4. Emergency Procedures

  • Ammonia Leak Repairs:
    • Multiple spacewalks to address coolant system leaks on the ISS

4. Modern Applications

4.1. Spacecraft and Station Maintenance

  • Regular Upkeep:
    • Replacing batteries, installing new instruments, fixing leaks
  • Upgrades:
    • Installing new solar panels (ISS Roll-Out Solar Arrays, 2021ā€“2023)

4.2. Scientific Research

  • Astrobiology:
    • Collecting cosmic dust and micrometeoroid samples
  • Earth Observation:
    • Installing and maintaining Earth-facing instruments for climate and environmental monitoring

4.3. Preparation for Deep Space Missions

  • Testing Technologies:
    • EVA techniques for Moon/Mars exploration
    • Evaluating suit performance in extreme environments

4.4. Commercial and International Collaboration

  • Private Sector Involvement:
    • Spacewalks by commercial astronauts (e.g., Axiom Space, 2023)
  • International Partnerships:
    • ESA, JAXA, Roscosmos astronauts participating in joint missions

5. Case Studies

5.1. Case Study: Hubble Space Telescope Servicing Mission 4 (2009)

  • Objective:
    • Extend Hubbleā€™s operational life
  • Spacewalks:
    • 5 EVAs over 13 days
  • Tasks:
    • Replaced gyroscopes, batteries, and scientific instruments
    • Installed new camera (Wide Field Camera 3)
  • Challenges:
    • Stuck bolts, delicate electronics, limited time
  • Outcome:
    • Hubble remains operational, producing high-impact scientific data

5.2. Case Study: ISS Roll-Out Solar Array Installation (2021ā€“2023)

  • Objective:
    • Upgrade ISS power system with new roll-out solar arrays (iROSA)
  • Spacewalks:
    • Multiple EVAs by NASA and ESA astronauts
  • Tasks:
    • Transporting, positioning, and deploying new arrays
    • Integrating with existing power systems
  • Challenges:
    • Working with large, flexible structures
    • Coordination with robotic arms
  • Outcome:
    • Increased power generation, supporting future research and commercial activities

6. Recent Research and News

  • Reference:
    • ā€œNASA Astronauts Complete Spacewalk to Install Roll-Out Solar Array on ISSā€ (NASA, June 2023)
      NASA News Release
  • Key Finding:
    • New solar arrays increase ISS power capacity, enabling more experiments and commercial modules

7. Most Surprising Aspect

Surprising Fact:

  • Spacewalks are not just for repairs or constructionā€”recent studies have shown that microorganisms from Earth can survive extended exposure on the exterior of the ISS, raising questions about planetary protection and the possibility of life transfer between planets (panspermia).
  • Example:
    • Study published in 2020 by Yamagishi et al. in Frontiers in Microbiology found that Deinococcus bacteria survived for up to three years on the ISS exterior.

8. Summary

  • Spacewalks (EVAs) are critical for the assembly, maintenance, and advancement of space missions.
  • Since 1965, spacewalks have evolved from brief excursions to complex, multi-hour operations involving international crews and advanced robotics.
  • Key experiments include material exposure, biological studies, and technological demonstrations, all contributing to safer and more effective future missions.
  • Modern applications focus on maintaining the ISS, supporting scientific research, and preparing for deep space exploration.
  • Case studies like the Hubble servicing missions and ISS solar array upgrades highlight the complexity and importance of spacewalks.
  • Recent research reveals that spacewalks also contribute to our understanding of lifeā€™s resilience in space.
  • The most surprising aspect is the survival of Earth microbes in space, impacting planetary protection protocols.
  • Ongoing advancements in EVA technology and procedures are paving the way for future Moon and Mars exploration.

Did you know?
The largest living structure on Earth is the Great Barrier Reef, and itā€™s visible from space!