Question 1: Define nuclear fission and explain how it releases energy.

Answer: Nuclear fission is a process in which a heavy nucleus splits into smaller nuclei, releasing a large amount of energy, usually accompanied by neutrons. This energy results from the conversion of mass into energy according to Einstein's equation.

Question 2: Describe the role of a moderator in a nuclear fission reactor.

Answer: A moderator slows down fast neutrons produced during fission to increase the likelihood of further fission reactions, maintaining a controlled chain reaction.

Question 1: Calculate the energy released when 1 gram of Uranium-235 undergoes fission. (Given: 1 atom of U-235 releases approximately 200 MeV of energy; Avogadro's number = 6.022×10^23).

Answer: Energy = (Number of atoms in 1 g of U-235) × 200 MeV. Number of atoms = (1 g / 235 g/mol) × 6.022×10^23. Convert MeV to joules for the final answer.

Question 2: If a space reactor releases 1 gigawatt of power continuously, how much energy in joules does it produce in 24 hours?

Answer: Energy = Power × Time = 1×10^9 W × 24 hours × 3600 seconds/hour = 8.64×10^13 joules.

Question 1: Identify three safety precautions that must be considered when designing a space nuclear reactor.

Answer: Precautions include shielding to prevent radiation exposure, fail-safe shutdown systems to control chain reactions, and robust containment to prevent radioactive leaks.

Question 2: Explain why nuclear fission is considered a suitable energy source for long-duration space missions.

Answer: Nuclear fission provides a high energy density, produces large amounts of power continuously, and can operate reliably for long periods without refueling, making it ideal for space missions.

Question 1: A space nuclear reactor's output drops from 1 GW to 0.5 GW over a period of 6 months. List possible reasons for this decrease and suggest methods to monitor and maintain reactor performance.

Answer: Possible reasons include fuel depletion, buildup of fission products that absorb neutrons, or technical malfunctions. Monitoring methods involve regular radiation and temperature measurements, neutron flux analysis, and inspection protocols. Maintenance may require fuel replacement, system recalibration, or component repairs to ensure consistent power output.

Question 1: Discuss the advantages and disadvantages of using nuclear fission reactors in space exploration. Include safety, efficiency, and environmental considerations.

Answer: Advantages include high energy output, long operational lifespan, and compact size suitable for space. Disadvantages involve radiation hazards, radioactive waste management, risk of accidents, and high costs. Safety measures and containment are critical to mitigate environmental and health risks in space.

Question 1: Explain how nuclear fission reactors can enable deep-space exploration missions that are beyond the reach of solar power. Provide specific examples of current or planned missions.

Answer: Nuclear fission reactors provide a reliable and long-lasting power source unaffected by distance or sunlight, enabling missions to distant planets or asteroids. Examples include NASA's Kilopower project and future plans for nuclear-powered spacecraft to explore outer planets and interstellar space.