Concept Breakdown

Definition

A spacewalk (Extravehicular Activity, EVA) is any activity performed by an astronaut outside a spacecraft in space. Spacewalks are essential for spacecraft maintenance, scientific experiments, and construction of space infrastructure like the International Space Station (ISS).

History

  • First spacewalk: Alexei Leonov (Soviet Union), 1965.
  • First American spacewalk: Ed White, 1965.
  • Longest spacewalk: Christina Koch & Jessica Meir, 7 hours 17 minutes, 2019.

Spacewalk Equipment

Spacesuit (Extravehicular Mobility Unit, EMU)

  • Layers: Thermal insulation, micrometeoroid protection, pressure retention.
  • Life support: Oxygen supply, CO₂ removal, temperature regulation.
  • Communications: Radio systems for contact with mission control.

Safety Systems

  • Tethers: Prevent astronauts from drifting away.
  • SAFER (Simplified Aid for EVA Rescue): Mini-jetpack for emergency return.

Tools

  • Specialized wrenches, drills, and cameras.
  • Tool carriers attached to the suit.

Spacewalk Procedures

  1. Preparation: Suit checks, pre-breathing pure oxygen to prevent decompression sickness.
  2. Airlock Egress: Transition from spacecraft to vacuum.
  3. Task Execution: Repairs, installations, experiments.
  4. Return: Re-enter airlock, suit removal, health checks.

Physical and Environmental Challenges

  • Microgravity: No up or down; movement requires careful planning.
  • Radiation: Increased exposure outside spacecraft shielding.
  • Temperature Extremes: -157°C to +121°C; suit systems regulate temperature.
  • Vacuum: No atmospheric pressure; suits must maintain astronaut pressure.
  • Space Debris: Risk of collision with micrometeoroids.

Spacewalk Diagram

Spacewalk Diagram

Surprising Facts

  1. Bacteria Can Survive Spacewalk Conditions: Certain extremophiles, like Deinococcus radiodurans, have survived direct exposure to space vacuum and radiation on the ISS exterior (Meral et al., 2020).
  2. Astronauts Grow Taller: Microgravity causes spinal elongation; astronauts can be up to 5 cm taller after a spacewalk.
  3. Spacesuit Water Leak Incident: In 2013, astronaut Luca Parmitano nearly drowned during a spacewalk due to a suit cooling system leak.

Interdisciplinary Connections

Biology

  • Astrobiology: Study of microbial survival in space informs the search for life on other planets.
  • Human Physiology: Effects of microgravity and radiation on the body.

Engineering

  • Suit Design: Materials science, robotics, thermal engineering.
  • Life Support Systems: Chemical engineering for air and water recycling.

Physics

  • Orbital Mechanics: Planning movement and tasks in microgravity.
  • Radiation Physics: Shielding and exposure calculations.

Environmental Science

  • Space Debris: Impact of human activity on near-Earth environment.

Health Implications

  • Decompression Sickness: Risk during transitions between pressure environments.
  • Radiation Exposure: Increased cancer risk; ongoing monitoring required.
  • Musculoskeletal Effects: Muscle atrophy, bone density loss, vision changes.
  • Immune System Changes: Microgravity can suppress immune responses.

Microbial Survival and Health

  • Bacteria surviving outside the ISS (e.g., Bacillus and Deinococcus) raise concerns about contamination and infection risk for astronauts. These microbes may also be harnessed for bioremediation or life support systems in future missions.

Current Event Connection

NASA Artemis Missions (2024–present):

  • Artemis astronauts will conduct lunar surface spacewalks, testing new suits and procedures for long-duration missions.
  • Recent tests focus on suit flexibility, dust resistance, and improved life support, reflecting lessons learned from ISS EVAs.

Recent Research

Meral, M. et al. (2020). “Survival of extremophilic bacteria on the exterior of the International Space Station and implications for planetary protection.” Astrobiology, 20(5), 637-648.
Link to study

Diagram: Spacesuit Layers

Spacesuit Layers

Summary Table

Aspect Detail
Definition Activity outside spacecraft
Equipment Spacesuit, tethers, tools
Health Risks Radiation, decompression, muscle loss
Microbial Survival Some bacteria survive spacewalks
Interdisciplinary Biology, engineering, physics
Current Event Artemis lunar EVAs
Recent Study Meral et al., 2020, Astrobiology

Further Reading

Key Takeaways

  • Spacewalks are critical, complex operations requiring interdisciplinary expertise.
  • Microbial survival in spacewalk conditions has implications for planetary protection and astronaut health.
  • Ongoing research and new missions continue to advance spacewalk technology and safety.