NASA's costly SOFIA telescope has reached its end. But its legacy lives on

From water on the moon to exploring the kind of comets that helped seed life on Earth.
Brad Bergan
SOFIA in a NASA plane, in flight (left), and the moon.1, 2

Sometimes you have to stop and ask yourself: is it worth it?

NASA and the German Aerospace Center did, and decided that the Stratospheric Observatory for Infrared Astronomy (SOFIA) — which is a plane-lofted telescope that has revealed some of the biggest discoveries in the history of the field — will officially shut down for keeps, according to a blog post on the U.S. agency's website.

There are reasons for this. For one, it was a very costly endeavor, and faced increased scrutiny in the last several years — namely, that despite its contributions to the field, it wasn't worth the bill, according to a Nature report.

It may be lights out for SOFIA on September 30, 2022, but its legacy will live on, and we're here for it.

NASA's SOFIA lost rank in the 2021 decadal survey

In service as an airborne observatory, SOFIA is flown up to 42,000 ft (12,800 m) — taking it to an altitude where 99.9 percent of the water vapor on Earth lies below it. This was crucial for the lofted telescope, since water vapor blocks infrared light. And, until September, it will remain the only telescope on- or off-world that can provide remote access to this aerial region, where the fingerprint of water is at an incredible low of 6.1 microns.

And, we can't deny it: in its tour of scientific study, SOFIA did a lot.

From analyzing and measuring the magnetic fields of distant galaxies to discovering water itself in sunlit regions of the moon, and even detecting the first kind of ion that came into being in the cosmos, called helium hydride. But, sadly, the cost NASA faced for operating the was upward of $85 million annually.

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That's nearly as expensive as the operational costs of the Hubble Space Telescope. SOFIA was great, but it's not that great.

This, compounded by the low scientific output until the last few years, placed it in comparably low ranking in 2021's decadal survey for the future of U.S. astronomy and astrophysics. So SOFIA will be completely closed down by September 30, 2022. Telescopes come and go — even Hubble is nearing its end — but rarely do we dive into the glorious history of such sophisticated devices, and what they contributed.

SOFIA's discovery of water on the sunny side of the moon could change everything

On October 26, 2020, NASA announced that its SOFIA telescope had discovered water on the sunward-facing surface of the moon. Specifically, the water molecules were located in and around the Clavius crater in the southern hemisphere. Their scale was tiny — at the scale of individual molecules — which is why we can't literally see them with conventional telescopes on Earth as little puddles or solid blocks of ice.

"The previously detected hydrogen on the sunlit side of the moon is associated with water molecules," said Director Paul Hertz of NASA's astrophysics division at its headquarters, in Washington. 

The detection of water on the moon was a giant landmark event not just in itself, but also because it meant NASA's forthcoming Artemis missions to return humans to the moon sometime in the next decade — now had a potential source of water (although the technologies needed to prepare it for use in fuel, or drinking water, is still in development).

We had long known that the moon had water in its coldest and darkest environments — the "permashadow" conditions within its many craters. But it's not easy to reach these regions, and even harder to work in them for prolonged periods. SOFIA's discovery meant that we might be able to access water outside of these craters.

NASA's SOFIA detected carbon in a passing icy comet

In March of 2021, it was revealed that SOFIA had detected a critical fingerprint of life on the comet Catalina — which passed by Earth at unspeakable velocities in 2016. The icy comet had come from the outer solar system, and in its majestic tail, NASA's airborne telescope spotted evidence of carbon.

This was significant because comets like Catalina may have served a crucial role in seeding the very young Earth and Mars with a key ingredient of life. "Carbon is key to learning about the origins of life," said the lead author of the paper on this discovery, Charles "Chick" Woodward, in a NASA blog post.

"We're not sure if Earth could have trapped enough carbon on its own during formation, so carbon-rich comets could have been an important source [of] delivery [for] this essential element that led to life as we know it," Woodward added.

SOFIA's legacy will live on in countless ongoing scientific endeavors

Infrared analysis of the comet by SOFIA offered data on its composition, revealing dust and gas in the process of evaporation from the comet's surface — which is how the tail is formed. And in it, carbon signatures were detected. This means that a major basic building block of life was formed in the outer regions of our solar system, when it was very young.

Eventually, a comet like this one worked its way into the early solar system, and slammed into the Earth. "All terrestrial worlds are subject to impacts by comets and other small bodies, which carry carbon and other elements," explained Woodward in his blog post statement. "We are getting closer to understanding exactly how these impacts on early planets may have catalyzed life."

But further steps in coming to grasp how such cosmic impacts helped kick-start the formation of life on Earth, in addition to the ongoing research of the water particles on the moon, and more will have to carry forward via other scientific instruments. SOFIA may have been financially underwhelming on paper — as many scientific ventures often are — but it's contributions will live on as some of the most exciting projects to understand the nature of our solar system and far beyond continue in the coming decade.

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