The Lab in Space: Life Detection Experiments Quiz

If a sample is provided with nutrients containing radioactive Carbon-14, and if microbes are present to consume those nutrients, then they will release radioactive CO2 or methane as waste. If this gas is detected by a sensor, then it provides evidence of active metabolism.

If a non-living geological process releases a gas that we usually associate with life, and if our experiment incorrectly identifies that gas as proof of biology, then the result is a false positive.

If scientists need to prove a result is biological, then they must show it does not happen in a dead sample. If the signal vanishes when the sample is heated to kill all life, then the test has a valid negative control.

If abiotic chemistry produces equal amounts of left-handed and right-handed amino acids, and if Earth-based life almost exclusively uses left-handed amino acids, then finding a "chiral imbalance" in a sample suggests a biological origin.

If an experiment is to function on a moon or planet, then it must be shielded from heat and radiation. If the experiment involves liquids, then the design must account for how low pressure or microgravity affects the behavior of those fluids.

If we need to identify specific chemical structures, then we must separate a mixture into individual components and weigh the resulting fragments. If a GCMS performs both separation and mass measurement, then it is the most effective tool for organic identification.

If gases like Oxygen and Methane are present together, they will naturally react to form CO2 and water. If they both exist in high amounts, then an active source (like life) must be pumping them in faster than they can react.

If an organism is no longer active but left behind unique fossils or chemical traces, then those are still considered biosignatures. Therefore, scientists look for both past and present life.

If biological molecules like DNA or proteins are stained with specific dyes, or if they naturally glow under UV light, then a fluorescence microscope can highlight those structures against an otherwise dark soil background.

If life is active, it will change its environment by "breathing" (gas change), generating body heat (thermodynamics), and "eating" (nutrient uptake). If these changes are measured, they provide evidence for metabolism.

If Earth bacteria are introduced to a sample, then the experiment will detect Earth life instead of alien life. If the sample is processed in a sealed, sterile environment, then the risk of "forward contamination" is minimized.

If plants on Earth absorb visible light for energy but reflect near-infrared light to stay cool, then a sharp jump in brightness at the 700 nm wavelength (the Red Edge) serves as a global-scale biosignature.

If an experiment is performed at the location where the sample was found rather than bringing the sample back to Earth, then the scientific term for this is in-situ.

If all life we know uses ATP to store and transfer energy within cells, and if there are no known abiotic ways to create high concentrations of ATP, then its presence is a very strong indicator of biological activity.

If methane can be produced by rocks reacting with water or by volcanic heat, then methane alone is not proof of life. If we see methane, then we must look for other clues to decide if it is biological or geological.

If the intensity of starlight decreases as the square of the distance (1/d^2), then at large distances there may be too little energy for plant-like life to function. Therefore, the experiment's sensitivity must account for distance from the star.

If we send a robot to a new world, we must not bring Earth germs with us. If we successfully keep Earth life off our spacecraft, then we have prevented forward contamination.

If a space probe has limited weight and power, and if we need to run complex chemistry tests on soil or water, then using microscopic channels to move and mix tiny droplets of liquid (microfluidics) is the most efficient design.

If life leaves a physical shape or structure behind, such as a shell, a cell wall, or a layered rock pattern from bacteria, then these are morphological signatures of life's existence.

If non-living chemistry creates simple molecules, and if life requires complex instructions and machines, then life will build long, repeating chains (polymers) that don't occur naturally in sterile environments.