Establishing a New Habitability Metric for Future Astrobiology Surveys

An illustration of the variations among the more than 5,000 known exoplanets discovered since the 1990s. Could their stars' metallicity play a role in making them habitable to life? Credit: NASA/JPL-Caltech
An illustration of the variations among the more than 5,000 known exoplanets discovered since the 1990s. Could their stars' metallicity play a role in making them habitable to life? Credit: NASA/JPL-Caltech

The search for exoplanets has grown immensely in recent decades thanks to next-generation observatories and instruments. The current census is 5,766 confirmed exoplanets in 4,310 systems, with thousands more awaiting confirmation. With so many planets available for study, exoplanet studies and astrobiology are transitioning from the discovery process to characterization. Essentially, this means that astronomers are reaching the point where they can directly image exoplanets and determine the chemical composition of their atmospheres.

As always, the ultimate goal is to find terrestrial (rocky) exoplanets that are “habitable,” meaning they could support life. However, our notions of habitability have been primarily focused on comparisons to modern-day Earth (i.e., “Earth-like“), which has come to be challenged in recent years. In a recent study, a team of astrobiologists considered how Earth has changed over time, giving rise to different biosignatures. Their findings could inform future exoplanet searches using next-generation telescopes like the Habitable Worlds Observatory (HWO), destined for space by the 2040s.

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Earth-like exoplanets might be in short supply for the Habitable Worlds Observatory

Credit: NASA

How common are Earth-like exoplanets—also called exo-Earths—and which exoplanetary systems should we target to find them? This is what a recently submitted study hopes to address as a team of researchers investigated potential targets for the planned Habitable Worlds Observatory (HWO), which was recommended during the Decadal Survey on Astronomy and Astrophysics 2020 (Astro2020) and is slated to launch in the 2040s. Most notably, HWO will use the direct imaging method to identify exo-Earths, and this study holds the potential to create a more scientifically cost-effective approach for identifying and studying exoplanets.

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How to SUPPPPRESS Light From a Star That Is Ten Billion Times Brighter Than Its Habitable Exoplanet

This artist’s concept features one of multiple initial possible design options for NASA’s Habitable Worlds Observatory. Credits: NASA’s Goddard Space Flight Center Conceptual Image Lab

Searching for Earth 2.0 has been an obsession of almost all exoplanet hunters since the discipline’s dawn a few decades ago. Since then, they’ve had plenty of technological breakthroughs help them in their quest, but so far, none of them have been capable of providing the clear-cut image needed to prove the existence of an exo-Earth. However, some of those technologies are undoubtedly getting closer, and one of the most interesting is utilizing a system called a multi-grated vector vortex coronagraph (mgVVC). Researchers funded by ESA think it may hold the optical properties to enable space-based telescopes like the Habitable Worlds Observatory (HWO) to finally capture the holy grail of exoplanet hunting – and it may be ready for prime time as early as next year.

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Research Work Begins on the Habitable Worlds Observatory

This artist’s concept features one of multiple initial possible design options for NASA’s Habitable Worlds Observatory. Credits: NASA’s Goddard Space Flight Center Conceptual Image Lab

NASA are planning on building a telescope to hunt for habitable worlds. The imaginatively named ‘Habitable Worlds Observatory’ is at least a decade away but NASA have started to develop the underlying technology needed. The contracts have been awarded to three companies to research the next-generation optics, mission designs and telescope features at a cost of $17.5 million. Work should begin late summer 2024.

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Suppressing Starlight: How to Find Other Earths

One underappreciated aspect of the current flood of exoplanet discoveries is the technical marvels that enable it. Scientists and engineers must capture and detect minute signals from stars and planets light years away. With the technologies of even a few decades ago, that would have been impossible – now it seems commonplace. However, there are still some technical hurdles to overcome before finding the “holy grail” of exoplanet hunting – an Earth analog. To help that discussion, a team of researchers led by Bertrand Mennesson at NASA’s Jet Propulsion Laboratory has released a paper detailing the current experimental and theoretical work around one of the most critical technical aspects of researching exoplanet atmospheres – starshades.

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Could Alien Solar Panels Be Technosignatures?

This image shows the Westlands Solar Park in the San Joaquin Valley. Could massive solar farms create a distinct technosignature? Image Credit: Westlands Solar Park

If alien technological civilizations exist, they almost certainly use solar energy. Along with wind, it’s the cleanest, most accessible form of energy, at least here on Earth. Driven by technological advances and mass production, solar energy on Earth is expanding rapidly.

It seems likely that ETIs (Extraterrestrial Intelligence) using widespread solar energy on their planet could make their presence known to us.

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The Habitable Worlds Observatory Could See Lunar and Solar ‘Exo-Eclipses’

Exo-moon
An artist's conception of an exoplanet with a large orbiting exomoon. Credit: University of Columbia/Helena Valenzuela Widerström

A future space observatory could use exo-eclipses to tease out exomoon populations.

If you’re like us, you’re still coming down from the celestial euphoria that was last month’s total solar eclipse. The spectacle of the Moon blocking out the Sun has also provided astronomers with unique scientific opportunities in the past, from the discovery of helium to proof for general relativity. Now, eclipses in remote exoplanetary systems could aid in the hunt for elusive exomoons.

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Astronomers Identify 164 Promising Targets for the Habitable Worlds Observatory

Planning large astronomical missions is a long process. In some cases, such as the now functional James Webb Space Telescope, it can literally take decades. Part of that learning process is understanding what the mission will be designed to look for. Coming up with a list of what it should look for is a process, and on larger missions, teams of scientists work together to determine what they think will be best for the mission. In that vein, a team of researchers from UC Berkeley and UC Riverside have released a paper describing a database of exoplanets that could be worth the time of NASA’s new planned habitable planet survey, the Habitable Worlds Observatory HWO.

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When did the First Continents Appear in the Universe?

Continents might be necessary for life, especially complex life. This image shows super-continent Pangaea during the Permian period (300 - 250 million years ago). Credit: NAU Geology/Ron Blakey

On Earth, continents are likely necessary to support life. Continents ‘float’ on top of the Earth’s viscous mantle, and heat from the planet’s core keeps the mantle from solidifying and locking the continents into place.

The core is hot because of the presence of radioactive elements that came from neutron star collisions. It should be possible to calculate when the first continents formed in the Universe.

So that’s what one researcher did.

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How Can We Bring Down the Costs of Large Space Telescopes?

Our space telescopes are becoming more and more powerful. But they're also enormously expensive. Can we bring the cost down? Image Credit: STScI/NASA/ESA/CSA

We’re all basking in the success of the James Webb Space Telescope. It’s fulfilling its promise as our most powerful telescope, making all kinds of discoveries that we’ve been anticipating and hoping for. But the JWST’s story is one of broken budgets, repeated requests for more time and money, and near-cancellations.

Can we make space telescopes less expensive?

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