Astronomy Astrobiology and the Search for Life 2 — Questions and Answers
Question 1: Panspermia is the hypothesis that:
- Life originated in deep-sea hydrothermal vents
- Life can be transported between planets via meteorites, comets, or asteroids (Correct answer)
- All planets in the habitable zone must develop life
- Bacterial spores cannot survive the vacuum of space
Correct answer: Life can be transported between planets via meteorites, comets, or asteroids
Panspermia proposes that life, or the building blocks of life, can travel through space on rocky bodies and seed new worlds, potentially explaining life's appearance on Earth.
Question 2: Which moon of Saturn has a thick nitrogen-rich atmosphere and liquid hydrocarbon lakes on its surface, making it a candidate for exotic, non-water-based life?
- Enceladus
- Titan (Correct answer)
- Rhea
- Mimas
Correct answer: Titan
Titan's surface has lakes of liquid methane and ethane, raising the possibility of life using liquid hydrocarbons as a solvent instead of water.
Question 3: The 2020 detection of phosphine in Venus's atmosphere was scientifically significant because:
- Phosphine is the primary driver of Venus's greenhouse effect
- Known abiotic processes could not fully account for the observed concentration (Correct answer)
- Phosphine had never before been detected on any planet
- Phosphine is used as evidence of volcanic activity
Correct answer: Known abiotic processes could not fully account for the observed concentration
The reported phosphine levels exceeded what known photochemical and geological processes on Venus could produce, prompting speculation about a possible biological source in the cloud layers.
Question 4: In astrobiology, 'second genesis' refers to:
- The formation of a binary star system
- Life that originated independently from Earth life through a separate origin event (Correct answer)
- The reseeding of Earth's biosphere after a mass extinction
- The reproduction cycle of extremophiles in high-radiation environments
Correct answer: Life that originated independently from Earth life through a separate origin event
A second genesis would confirm that life can arise independently more than once, showing that life's origin is not a unique cosmic accident limited to Earth.
Question 5: NASA's Perseverance rover mission to Mars is specifically designed to:
- Measure Martian atmospheric composition only
- Drill for and cache rock samples that may preserve signs of ancient microbial life (Correct answer)
- Deploy a network of seismometers across the surface
- Test nuclear propulsion technology for future crewed missions
Correct answer: Drill for and cache rock samples that may preserve signs of ancient microbial life
Perseverance is collecting and caching rock and sediment samples from Jezero Crater, a former lake bed, for eventual return to Earth for detailed analysis for biosignatures.
Question 6: What type of electromagnetic radiation poses the greatest threat to surface life by damaging DNA molecules?
- Infrared radiation
- Radio waves
- Ultraviolet radiation (Correct answer)
- Visible light
Correct answer: Ultraviolet radiation
Ultraviolet radiation, particularly UV-C and UV-B wavelengths, carries enough energy to break chemical bonds in DNA, causing mutations and cell death.
Question 7: The concept of a 'shadow biosphere' on Earth suggests the existence of:
- Life found exclusively in deep underground caves
- Organisms that may have a completely separate biochemical origin from all known life (Correct answer)
- Microbes that can only survive in the absence of sunlight
- Extremophiles living beneath Antarctic ice sheets
Correct answer: Organisms that may have a completely separate biochemical origin from all known life
A shadow biosphere would be a group of organisms that share the planet with us but arose from a different origin-of-life event, potentially using different biochemistry we might overlook.
Astronomy Astrobiology and the Search for Life 2
Panspermia is the hypothesis that: