At the start of the game
Q (Astronomy and Physics): A mission to an extrasolar planet would be so cool! Why haven’t we done this in real life?
A: We can’t get there fast enough. Our planet orbits Epsilon Eridani, which is about 10.5 light years from here. If we were to travel at the speed of the Voyager probes -- 17km per second -- it would still take about 180,000 years to reach that star system. The closest known exoplanet orbits Alpha Centauri at a distance of 4.36 light years. At the speed of the Voyager probes, that’s still 77,000 years.
Also, communications would be a big problem. Radio communications are limited at the speed of light, so a round-trip message to Epsilon Eridani would take 21 years and a round-trip message to Alpha Centauri would take 8.7 years.
After most of the class has seen blog post 1, an introduction to exobiology
Q (Biology): What are the essential characteristics of life that we might expect to see if we were to find creatures on another planet?
A: The ability to harness energy (could be through photosynthesis, chemical reactions, or something else), the ability to grow, and the ability to reproduce.
Follow-up Q (Biology): Where do species on Earth get their energy? Are there species on Earth that violate the energy patterns that we typically see?
A: Plants get their energy from the sun and animals get their energy by eating plants or other animals. But even on Earth, creatures can get energy from a variety of different sources. For instance, there are extremophiles (organisms that live in extreme conditions) that get their energy directly from inorganic mineral compounds.
Q (Biology): In one of your first missions, the team biologist Jane Eastwood explains you that it would be incorrect to refer to any of the species that you see on Epsilon Eridani e as “plants” and encourages you to instead use a term that she makes up -- “photobionts”. They look like plants, so why isn’t it scientifically correct to call them plants?
A: Species in the plant kingdom on Earth are all related to a common evolutionary ancestor. Since the species on Epsilon Eridani e have evolved independently, they don’t share any of the ancestors of the plant kingdom.
Q (Biology): Almost none of the species on Epsilon Eridani e are green in color. Why is this surprising and what might be your hypothesis about how species get energy for life?
A: On Earth, chlorophyll a is one of the principle molecules used for photosynthesis. It reflects a green color, giving plants their characteristic green look. Since we don’t see green on Epsilon Eridani e, we can hypothesize that the species get their energy from somewhere else -- it could be a different molecule that they use for photosynthesis, or it might be that they get their energy from some other source entirely.
After most of the class has seen blog post 2, visual techniques for biological classification
Q (Biology): What might a microscope be able to tell us about life on another planet?
A: It will help us determine if the life has a cellular structure and possibly if different cells within an organism are specialized.
Q (Biology): In the absence of sophisticated scientific tools and using only simple visual observations, is there much that we can learn about a species?
A: Tons! With careful observation, we can learn where a species gets its nutrients, how it reproduces, how its appearance changes as it ages, whether it has any predators, and much more. After all, there was a time before scientists had DNA sequencers and spectrometers and they still managed to learn a great deal about life on Earth.
After most of the class has seen blog post 3, species variation
Q (Biology): It appears that there may be two different variants of bristletongues on the island -- on variant with long necks and one with short necks. Why might each variant be better-suited to a particular ecological niche?
A: A long-necked species may have an easier time getting nutrients from high places, whereas a short-necked species might be less vulnerable to attack and better able to get nutrients from low places.
Q (Biology): What role does geographic isolation play in allowing a species to split into two variants?
A: Different geographic locations may have different evolutionary pressures that cause a species to evolve in different ways. For instance, as discussed in Jane’s blog post, Darwin theorized that when finches were introduced to a new island of the Galapagos, there were several plants with large seeds that weren’t being consumed by any species. Finches with larger beaks that were big and strong enough to eat these big seeds had an evolutionary advantage that allowed them to fill an otherwise unoccupied niche on the island.
After most of the class has seen blog post 4, an convergent evolution
Q (Biology): If the species on Epsilon Eridani e evolved independently from species on Earth, then why do some of the photobionts look so similar to Earth plants?
A: The evolutionary pressures on Epsilon Eridani e are similar to those on Earth. Species need to harness energy, replicate, conserve resources, and defend against predators. The result is that species on both planets may evolve similar structures. This is known as convergent evolution.
Q (Biology): If we observe thorns on an Earth plant or an alien photobiont, can we make any assumptions about the evolutionary pressures that may have driven the evolutionary process to result in that feature?
A: Thorns might mean that the plant or photobiont had predators. The thorns could have evolved as a defense mechanism. There are also other possible explanations -- features that look like thorns may help collect moisture from the air, allow for more efficient gas exchange by increasing surface area, or provide some other benefit.
Discussion topics for any time
Q (Astronomy): If you look closely at your night photos, you may recognize some familiar constellations that look almost identical to the constellations that you would see here on earth. That may seem surprising since the planet that you’re exploring orbits a star -- Epsilon Eridani -- that is nearly 10.5 light years (100 trillion kilometers) away. Why would the night sky look so similar to ours?
A: 10.5 light years may seem like a huge distance -- and it is -- but relative to the size of the milky way galaxy, it’s hardly any distance at all. The Milky Way is more than 100,000 light years across. By comparison, the closest star to Earth -- Proxima Centauri -- is 4.2 light years away. If you were to travel 10.5 light years, only a few stars would appear to noticeably change their position.