Definition

Extravehicular Activity (EVA) refers to any activity performed by an astronaut outside a spacecraft beyond the Earth’s atmosphere. EVAs are commonly called “spacewalks.”

History of EVA

Early Milestones

  • First EVA: Alexei Leonov (Soviet Union), March 18, 1965, during Voskhod 2 mission. Duration: ~12 minutes.
  • First American EVA: Edward H. White II, Gemini IV mission, June 3, 1965. Duration: ~23 minutes.
  • Apollo Program: Introduced lunar EVAs (moonwalks) starting with Apollo 11 (Neil Armstrong, Buzz Aldrin, July 1969).

Key Developments

  • Skylab (1973-1974): Introduced longer-duration EVAs for repairs and solar observations.
  • Space Shuttle Era (1981-2011): Enabled complex EVAs for satellite deployment, repairs, and International Space Station (ISS) assembly.
  • ISS Era (2000–present): Regular EVAs for maintenance, upgrades, and scientific experiments.

Key Experiments Conducted During EVA

Material Exposure

  • MISSE (Materials International Space Station Experiment): Exposed materials to space environment to study degradation, crucial for future spacecraft design.

Biological Studies

  • BioSuit Testing: Evaluated advanced spacesuit prototypes to improve mobility and reduce health risks.
  • Microbial Sampling: Astronauts collected samples from ISS exterior to study microbial survival in space.

Technology Demonstrations

  • Robotic Tool Use: Tested remote-controlled tools for satellite servicing.
  • 3D Printing: Recent EVAs tested 3D-printed tools for repairs.

Scientific Payloads

  • AMS-02 (Alpha Magnetic Spectrometer): Installed and maintained by astronauts during EVAs to study cosmic rays and search for dark matter.

Modern Applications of EVA

Spacecraft Maintenance

  • ISS Upkeep: Replacing solar arrays, repairing cooling systems, and upgrading scientific instruments.
  • Satellite Servicing: Hubble Space Telescope repairs (notably in 1993, 1997, 1999, 2002, 2009).

Lunar and Martian Exploration

  • Artemis Program: Planned lunar EVAs for geology, resource extraction, and technology testing.
  • Mars Simulation: Analog missions on Earth (e.g., HI-SEAS, NEEMO) simulate EVAs for future Mars exploration.

Commercial Spaceflight

  • Private Missions: Companies like SpaceX and Axiom Space plan commercial EVAs for research and tourism.

Training and Education

  • Neutral Buoyancy Lab: Astronauts train underwater to simulate microgravity EVAs.

Global Impact

International Collaboration

  • ISS Partnership: U.S., Russia, Europe, Japan, and Canada collaborate on EVA protocols and missions.
  • Technology Sharing: EVA research benefits global aerospace industries (e.g., advanced robotics, materials science).

Earth Applications

  • Medical Devices: EVA suit technology influences development of prosthetics and emergency medical gear.
  • Remote Operations: Techniques from EVA inform remote surgery and hazardous environment work on Earth.

Inspiration and Outreach

  • Public Engagement: Spacewalks broadcast globally inspire STEM education and international cooperation.

Famous Scientist Highlight: Dr. Kathryn D. Sullivan

  • First American woman to walk in space (1984, STS-41-G).
  • Instrumental in Hubble Space Telescope deployment and repair EVAs.
  • Advocated for EVA safety protocols and suit improvements.

Health Implications of EVA

Physiological Challenges

  • Decompression Sickness: Risk due to pressure changes between spacecraft and suit.
  • Musculoskeletal Strain: EVA tasks require significant physical effort; risk of fatigue and injury.
  • Radiation Exposure: Increased risk during EVAs, especially outside Earth’s magnetosphere.

Psychological Considerations

  • Isolation and Stress: EVAs can be mentally taxing due to isolation, high stakes, and complex tasks.

Recent Research

  • 2021 Study (NASA Human Research Program): “Spaceflight-Associated Neuro-ocular Syndrome” (SANS) found that EVAs may exacerbate changes in astronauts’ eyes due to fluid shifts in microgravity (NASA HRP, 2021).
  • Suit Design Innovations: Ongoing research into suit ergonomics to reduce injury and improve astronaut health during EVAs.

Recent Advances and News

  • 2022: ESA astronaut Samantha Cristoforetti performed the first European EVA from the ISS, demonstrating new suit interfaces and tool designs (ESA News, 2022).
  • 2023: NASA’s xEMU suit prototype tested for Artemis lunar missions, featuring improved mobility and dust protection.

Relation to Exoplanet Discovery

  • EVA experiments on ISS and Hubble maintenance have enabled advanced astronomical observations, including exoplanet studies.
  • The first exoplanet discovery in 1992 expanded the scope of EVA-supported research, as space telescopes maintained by EVAs now routinely study exoplanet atmospheres and habitability.

Summary

Extravehicular Activity is a cornerstone of human space exploration, enabling spacecraft maintenance, scientific discovery, and technological advancement. Its history spans from the first spacewalks in the 1960s to modern lunar and commercial missions. Key experiments during EVAs have advanced materials science, biology, and robotics, with significant health implications for astronauts. The global impact of EVA includes international collaboration, technological spin-offs, and public inspiration. Ongoing research continues to improve EVA safety and effectiveness, supporting humanity’s push into deeper space and the study of distant worlds.