Interview
Sara Seager: Search for Planets and Life Outside Our Solar System | Lex Fridman Podcast #116
- Seeger anticipates that humanity will likely determine whether planets capable of supporting life are common within the next two decades by detecting specific biosignature gases in exoplanet atmospheres, though she notes that definitive 100% confirmation of extraterrestrial life will likely require future generations.
- Her professional outlook for the next 20 years involves focusing on the detection of detectable gases produced by life and their atmospheric interactions, with her probability estimates for success ranging from 1% on her worst days to 80% on her best.
- The "Starshade" project is expected to transition from a theoretical concept to a serious engineering endeavor involving a 30-meter diameter screen with razor-thin petals to block starlight 10 billion times fainter than the star, utilizing formation flying at tens of thousands of kilometers away from a telescope.
- Engineering hurdles for the Starshade, such as sensing position via beacon lasers and solving diffraction math to prevent light ripples, are viewed as solvable, with a full-scale facility test planned prior to launch, while the initiative is estimated as a billion-dollar endeavor.
- Seeger predicts that the "Starshot" initiative, backed by the Breakthrough Foundation, will shift interstellar travel timelines from tens of thousands of years to approximately 20 years by accelerating thousands of "star chips" with a few-meter solar sails using gigawatt-power laser banks.
- Starshot spacecraft are designed to zoom past the nearest star system without slowing down, utilizing solar sails made from materials resistant to laser vaporization, with 19 specific engineering challenges identified regarding airspace, sail materials, and laser power.
- Future missions, including those utilizing the Sun as a gravitational lens, are expected to take 25 years to reach targets but could eventually provide surface resolution of 10 to 100 pixels, while near-term prospects for detecting water and life signs are stronger for Earth-cousins orbiting red dwarf stars.
- Seeger projects that one in five sun-like stars may host a true Earth-like planet, while red dwarf stars offer more accessible targets for finding water vapor and potential biosignatures compared to the fainter, less massive Earth-twins.
- The existence of "rogue planets" potentially equal in number to stars is expected, having been ejected from systems, alongside "mini-Neptunes" which may be water worlds composed of more than half water by mass.
- She anticipates that oxygen serves as a major indicator of life detectable by distant civilizations, while liquid water remains essential for molecular reactions, with water vapor in atmospheres implying the presence of surface liquid reservoirs.
- Seeger expresses a hope that life is super abundant and that every nearby star hosts a living planet, while maintaining the intuition that intelligent life is likely rare and located far away due to the difficulties of its evolution.
- A risk is identified where human destruction of the biosphere might be undetectable to extraterrestrial observers, making humanity's impact on planetary detectability potentially negligible from a distance.
- Commercial value in space exploration is expected to follow initial pure exploratory research, with Mars exploration predicted to yield interesting scientific findings before becoming commercially viable, and multi-generational ships viewed as the only feasible conventional method for deep space travel.
- The "Smallest Lights in the Universe" concept is framed as a metaphor for the search for Earth-like planets and a source of hope, while the possibility of "printing" life forms is considered potentially easier than transporting humans across the galaxy.