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2.1.5Space

Risks of Manned Space Exploration

5 min read 6 parts Lesson 5 of 12

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Part 1 of 6Hazards in Space

2.1.5 Risks of Manned Space Exploration

Sending humans into space exposes them to dangers that robotic probes do not face.

Radiation
  • Outside the protection of the atmosphere and magnetic field, astronauts receive higher doses of harmful cosmic and solar radiation.
Microgravity
  • Long periods of weightlessness cause muscle loss, weaker bones and changes to the heart and eyes.
Space debris
  • Fragments of old satellites travel at several km/s, and even tiny pieces can damage a spacecraft.
Isolation
  • Confined living with a small crew far from home can create stress and psychological problems.

Part 2 of 6Launch and Return Risks

Launch and Return Risks
Launch
  • Rocket failure or explosion can happen because of the huge energy released in a short time.
Re-entry
  • Heat shield failure can be fatal as the spacecraft hits the atmosphere at high speed.
Life support
  • Failure of air, water, food or temperature systems quickly endangers the crew.
Accelerations
  • High acceleration during launch presses on the body and needs trained astronauts.
RiskPossible reduction
RadiationShielding, shorter missions
Bone lossExercise, medication
DebrisTracking, shielding

Part 3 of 6Weighing Up

1
Benefits include scientific research, technology spin-offs and inspiring the next generation.
2
Robotic probes are cheaper and carry no risk to life, but cannot adapt as well as people.
3
Costs of manned missions are billions of pounds which could be spent elsewhere.
4
Evaluating requires giving benefits and risks and reaching a justified conclusion.

Part 4 of 6Reducing the Risks

Reducing the Risks
Training
  • Astronauts train for years to handle emergencies and the stresses of launch.
Monitoring
  • Radiation doses and health are monitored, and missions are limited in length.
Design
  • Spacecraft are built with shielding, escape systems and redundant equipment.
Alternatives
  • Robotic missions are used where the risk to humans is too great or the journey too long.

Part 5 of 6Worked Example

Question

  • A space debris fragment of mass 0.010 kg moves at 7000 m/s relative to a spacecraft.
  • Calculate its kinetic energy and explain the risk.

  1. Ek = ½ m v² = 0.5 × 0.010 × 7000².
  2. 7000² = 4.9 × 10⁷, so Ek = 0.5 × 0.010 × 4.9 × 10⁷ = 2.45 × 10⁵ J.
  3. This is about 2.5 × 10⁵ J, similar to the kinetic energy of a 1200 kg car at 20 m/s, from only 10 g of material, so it can puncture a spacecraft hull.

Answer 2.5 × 10⁵ J, large enough to cause serious damage.

Part 6 of 6Exam Checklist & Tips

2.1.5 – Key Points for the Exam

  • Cosmic radiation High-energy particles from space that can damage living cells.
  • Microgravity The condition of apparent weightlessness in orbit.
  • Space debris Man-made junk orbiting the Earth.
  • Life support Systems providing air, water and temperature control.

Common Mistakes

  • Saying astronauts float because there is no gravity in orbit.
  • Ignoring the costs when evaluating benefits and risks.
  • Underestimating the risk from small fragments of debris.
  • Mixing up the risk of launch with the risk of re-entry.
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