A team led by researchers at MIT has detected pyrene, a complex carbon-containing molecule, in a distant interstellar cloud. This finding opens new avenues for understanding the chemical origins of our solar system. Pyrene, a type of polycyclic aromatic hydrocarbon (PAH), was found in a molecular cloud similar to the one from which our solar system formed.

This marks the first time a complex form of carbon essential for life on Earth has been observed outside the solar system. Its discovery sheds light on how the compounds necessary for life could originate in space. The team detected pyrene in
a star-forming region known as the Taurus Molecular Cloud, located 430 light-years away, making it one of the closest such clouds to Earth.

This discovery also aligns with recent findings from the asteroid Ryugu, suggesting that pyrene may have played a key role in the carbon composition of the early solar system. To learn more about the significance of this discovery, EdPublica interviewed the researchers behind the study– Gabi Wenzel, Ilsa Cooke, and Brett McGuire, who shared their insights on the implications of pyrene’s presence in space and its potential impact on our understanding of star and planet formation. Brett McGuire is an assistant professor of chemistry at MIT, Ilsa Cooke is an assistant professor of chemistry at the University of British Columbia, and Gabi Wenzel is a postdoctoral researcher in McGuire’s group at MIT.

Below, the team responds to questions from EdPublica Editor Dipin Damodharan about this unexpected and exciting discovery.

‘Pyrene could be a major source of carbon in our solar system’

Q: How does the discovery of pyrene in TMC-1 enhance our understanding of the chemical inventory that contributed to the formation of our solar system?

Gabi Wenzel:

Stars much like our own sun are born from dense molecular clouds. The discovery of pyrene in a molecular cloud called TMC-1, one that might be very similar to our sun’s natal cloud and which will go on to form a star of its own, significantly enhances our understanding of the chemical inventory that contributed to the formation of our own solar system. As a polycyclic aromatic hydrocarbon (PAH), pyrene is one of the most complex organic molecules found in early molecular clouds, suggesting that the building blocks of organic matter were available in the environments where stars and their orbiting (exo)planets form.

This discovery sheds light on the chemical processes occurring in interstellar space, including gas-phase and surface reactions on dust grains, which are crucial for the evolution of organic chemistry. This further supports the notion that the primordial materials of our solar system contained a diverse range of organic compounds, providing insights into the potential for prebiotic chemistry on a young Earth and planetesimals.

Q: What specific challenges did you face in detecting pyrene, given that it is invisible to traditional radio astronomy methods, and how did the use of cyanopyrene help overcome these challenges?

Gabi Wenzel:

Pyrene, a fully symmetric PAH, does not possess a permanent electric dipole moment and hence is invisible in radio astronomical observations or rotational spectrometers in the laboratory. The CN radical is highly abundant in the cold and dark molecular cloud TMC-1, an environment that is about 10 K cold and in which you’d assume little chemistry to happen. However, earlier experimental works have shown that the CN addition (followed by hydrogen abstraction) to ringed hydrocarbon species such as benzene and toluene at low temperatures is a barrierless process.

Adding a CN (nitrile) group to a hydrocarbon will drastically increase its permanent electric dipole moment and so allow rotational transitions. Indeed, several CN-functionalized species have been detected in TMC-1 and other sources, among which the CN-substituted benzene (cyanobenzene or benzonitrile) and other smaller PAHs, with cyanopyrene being the largest molecule found via radio astronomy to date, allowing us to infer the presence of pyrene itself.

Q: Can you elaborate on what it means for our understanding of carbon sources in the solar system that pyrene is found in both TMC-1 and asteroid Ryugu?

Ilsa Cooke:

TMC-1 is a famous example of a cold molecular cloud, one of the earliest stages of star and planet formation, while asteroids like Ryugu represent snapshots of later stages in the formation of solar systems. Asteroids are formed from material in the solar nebula that was inherited from the molecular cloud stage. Our radio observations of TMC-1 let us observe pyrene early on and possibly under conditions where it is first forming. Isotope signatures of the pyrene in Ryugu suggest it was formed in a cold interstellar cloud. From these two unique sets of measurements, we can start to unravel the inheritance of pyrene, and PAHs more generally, from their birth in interstellar space and their journey to new planets. If PAHs can survive all the way from the molecular cloud stage, they may provide planets with an important source of organic carbon.

Q: What are the different formation routes of PAHs that your research suggests, and how do these differ from previous hypotheses about PAH formation in space?

Ilsa Cooke:

Our results, combined with those of Zeichner et al., who measured pyrene in Ryugu, suggest that pyrene may form at low temperatures by “bottom-up” routes in molecular clouds. Previously, PAHs were most commonly associated with formation in high-temperature (ca. 1000 K) environments in the envelopes of dying stars. These stars are thought to eject their PAHs, along with other carbon-rich molecules, into the diffuse interstellar medium.

However, the diffuse medium is a tenuous, harsh environment permeated by ultraviolet photons, and most astrochemists think that small PAHs would not survive their journey through the diffuse medium into dense molecular clouds. So we are still left with a puzzle: does that pyrene that we observe in TMC-1 form there, or was it formed somewhere else but it was able to survive its journey more efficiently than previously thought? If the pyrene is indeed formed within TMC-1, we do not yet know the chemical mechanism. Many possibilities exist, so close collaborations between laboratory astrochemists and observers will be critical to answer this question.

Q: What are your plans for investigating larger PAH molecules in TMC-1, and what specific hypotheses are you looking to test with these investigations?

Brett McGuire:

We have a number of other targets lined up – again focusing on PAH structures that should show this special stability demonstrated by pyrene. They present the same experimental challenges, including needing to devise appropriate synthetic routes in the laboratory before collecting their spectra. The major question is just how complex the PAH inventory actually gets at this earliest stage of star formation.

Prior to our work in TMC-1, nearly everything we knew about PAHs came from infrared observations of bulk properties in much warmer and more energetic regions, where PAHs are thought to be much larger. Does the population in TMC-1 look the same as in these regions? Is it at an earlier stage of chemical evolution? And how does this distribution compare to what we see in our own Solar System?

Q: How do your findings about pyrene and PAHs in interstellar clouds influence our broader understanding of organic chemistry in the universe, particularly in relation to the origins of life?

Brett McGuire:

Life as we know it depends on carbon – it is the backbone upon which all our molecular structures are constructed. Yet, the Earth overall is somewhat depleted in carbon relative to what we’d naively expect, and we still don’t fully understand where the carbon we do have came from originally. PAHs in general seem to be a massive reservoir of reactive carbon, and what we are now seeing is that that reservoir is already present at the earliest stages of star-formation. Combined with the evidence from Ryugu, we’re now also seeing indications that the inventory of PAHs, and thus this reservoir of carbon, may actually survive from this dark molecular cloud phase through the formation of a star to be eventually incorporated into the planetary system itself.

Last year on June 5th, NASA astronauts Sunita Williams and Barry Wilmore were on a flight testing mission to dock a Boeing Starliner spaceraft to the International Space Station (ISS). Set to return just eight-days later, their mission met with an ill-fated death. A few thrusters failed, in addition to a helium leak onboard, rendered the Boeing Starliner spacecraft too unsafe for NASA’s liking. The agency’s stubborn refusal to let their astronauts be under harm’s way, meant the Starliner returned to earth later in September without its crew.

In the months passing since then, Williams and Wilmore never left the public gaze. Media headlines and TV news anchors have taken to report the event as a major predicament. This is despite the fact, that the astronauts were neither stranded, nor left alone. Williams and Wilmore weigh in on the issue recently during a live interaction with the media.

“Butch (Barry Wilmore) and I knew this was a test flight,” Sunita Williams said to CBS News. “We knew that we would probably find some things (wrong with Starliner) and we found some stuff, and so that was not a surprise.”

Musk made a statement there that sparked controversy. “They were left up there for political reasons.”

This is not to say the situation the duo found themselves in is unprecedented; for it is indeed unprecedented. When NASA had Boeing Starliner‘s software reconfigured and return to earth in one shape. NASA had the benefit of doubt, given their original assessment was made with the best possible evidence available at the time; and not to compromise upon crew safety. As of latest plans, Williams and Wilmore will return to earth by late-March 2025 at the earliest.

But the rhetoric has reinforced calls to put together a “rescue mission.” SpaceX CEO Elon Musk, who advises incumbent US President Donald Trump, claimed at a Fox News interview that his proposal to bring the astronauts back in September was rejected by the previous administration led by President Joe Biden. Musk made a statement there that sparked controversy. “They were left up there for political reasons.”

Narratives draw ire from the space community

Musk’s comments drew ire from other veteran astronauts. Andreas Mogensen, a former ISS commander during Expedition 70, reacted to Musk’s comment on X to say, “What a lie. And from someone who complains about lack of honesty from the mainstream media.” Musk responded in kind soon there after, aggressively standing his ground. However, the astronauts themselves found the claims unsubstantiated.

According to WCVB Boston, Barry Wilmore himself said, “I have not heard that … I’m not sure that could be the case based on what I know. We came up here with a plan to return, and the plan changed.” NASA themselves had issued a clarification in the aftermath of Musk’s own comments, claiming it had never received a direct proposal from SpaceX for any mission. Nor did they warrant such a “rescue mission”, as now President Trump has called on for.

Political considerations are not a factor in changing the timelines in the ISS expeditions. “The White House was very good about letting us make safety decisions and leaving that to the experts at NASA,” Bloomberg reported Pam Melroy, an ex-NASA administrator involved in the mission, as having said.

Long-exposure photograph taken on July 3, 2024, of the Boeing Starliner docked to the ISS, with the earth in the background | Credit: Matthew Dominick/NASA

“Help us change the rhetoric …”

Risks and derailed plans are part and parcel of space travel, and something space agencies draw backup plans for. Much of the public angst and concern for the astronauts is the loneliness arising from prolonged isolation in space, and fears of mishap with the ISS.

“That is what the human space flight program is; it prepares for any and all contingencies that we can conceive of, and we prepare for those,” Newsweek reports Sunita Williams as having said. Health professionals on ground have helped monitor and manage their physical and psychological fitness. Inadvertently, they contribute to research studying the human body’s ability to adapt in the micro-gravity conditions; as well as psychological resilience and the astronauts’ ability to handle stress. But this is nothing astronauts cannot handle. In fact, Williams compared her situation with that of a tourist. “I call it a little vacation from earth.”

“So if you’ll help us change the rhetoric, help us change the narrative…let’s change it to ‘prepared and committed’ rather than what you’ve been hearing,” WCVB Boston reported Williams as having said.

They have had astronauts from the Crew 8 expedition give them company during the arrival in June, assisting them with their microgravity-based scientific experiments. In September, they were joined by a new party of astronauts of the Crew 9 mission – Roscosmos’ Alexander Gubnov, and NASA’s Nick Hague – replacing the astronauts from Crew 8.

In addition to extra clothing and stockpile of food, NASA had left two extra seats were left empty for Williams and Wilmore to return along with Gubnov and Hague on their return later this March or April, when astronauts from upcoming Crew 10 dock later this month. Given there is a spacecraft docked to the ISS at all time, they have all what it takes to evacuate during an emergency.

“So if you’ll help us change the rhetoric, help us change the narrative…let’s change it to ‘prepared and committed’ rather than what you’ve been hearing,” WCVB Boston reported Williams as having said.

On March 2, NASA confirmed the first ever successful soft-landing attempt by a private company. Firefly Aerospace’s lunar lander, the Blue Ghost Mission 1 (named after a rare species of fireflies thought native to the United States), touched down at precisely 2.04 p.m. IST, near Mons Latrielle at Mare Crisium on the moon’s near side. Firefly Aerospace issued a press release shortly thereafter.

The soft-landing comes after another US-based private company, Intuitive Machines, attempted one a year ago. On that occasion however, the lander, known as Odyssey, bounced off hard on the lunar surface at touchdown, following a steep descent. It rested titled with a stray lunar rock to offer a shoulder. In contrast, Blue Ghost which stuck both an upright landing, and its payloads intact.

The landing was the culmination of a 45 day trip that began early this year. On January 15, Blue Ghost blasted to space aboard a SpaceX’s Falcon 9 Block 5 from NASA’s Kennedy Space Centre, Florida. Sharing space during the launch was yet another commercial lunar lander, the Hakuto-R Mission 2  – built and operated by the Japanese space technology company, ispace. However, Hakuto-R has a projected landing date on the moon sometime in April, owing to a different arrival approach.

Firefly had released pictures of the lunar terrain, the Blue Ghost‘s photographed from its landing site. One of them shows a rugged gray dusty terrain, with a portion of the lander’s chassis in view in the foreground. Whereas a second one showed a desolate terrain with the earth reflecting sunlight above the horizon. Blue Ghost‘s shadow looms in the foreground in the image.

This site located close to Mons Latrielle, is what scientists think is an ancient basin formed upon a rogue asteroid impact eons ago. More than 500 km wide, Mare Crisium, as the basin is known by, is believed to have been flooded by lava in volcanic eruptions dating to some 4 billion years ago.

The SpaceX Falcon 9 rocket that carried Firefly Aerospace’s lunar lander, Blue Ghost Mission 1, is seen stationed here at NASA’s Kennedy Space Center, Florida | Credit: NASA

Laying groundwork for NASA’s Artemis

“Firefly is literally and figuratively over the Moon,” Jason Kim, CEO of Firefly Aerospace, said shortly after the landing, in a press release.  “Our Blue Ghost lunar lander now has a permanent home on the lunar surface with 10 NASA payloads and a plaque with every Firefly employee’s name. This bold, unstoppable team has proven we’re well equipped to deliver reliable, affordable access to the Moon, and we won’t stop there. With annual lunar missions, Firefly is paving the way for a lasting lunar presence that will help unlock access to the rest of the solar system for our nations, our partners, and the world.”

In 2023, Firefly Aerospace ferried the instruments as part of a $93.3 million contract signed with NASA as part of the Commercial Lunar Payload Services (CLPS) program. The CLPS program is Nasa’s attempt at driving private participation on future lunar missions. But the payloads help set stage for NASA’s Artemis program, which would mark their first attempt since the Apollo program, to land astronauts on the lunar surface.

Some of the payloads reflect the new engineering demands for such long-term lunar missions. To streamline tracking lander and rovers on the moon, NASA supplied the Lunar GNSS Receiver Experiment (LuGRE). It is a GNSS receiver to help earth-orbiting satellite constellations, including GPS and the Galileo, track the lunar lander with high accuracy in real-time. Another one is the Regolith Adherence Characterization (RAC) that investigates possible soil degradation left behind in the wake of a typical lunar mission soft-landing.

Other payloads were designed to explore various science objectives. Research institutes and universities across the United States contributed to a variety of instruments. They included laser retro reflectors to measure distances, an x-ray imaging device to study how the solar wind affects space weather on earth; a probe which can inject itself into the moon’s sub-surface to measure heat dissipation.

In a press release applauding Blue Ghost’s successful soft-landing attempt, NASA’s acting administrator, Janet Petro, said, “This incredible achievement demonstrates how Nasa and American companies are leading the way in space exploration for the benefit of all … We have already learned many lessons – and the technological and science demonstrations onboard Firefly’s Blue Ghost Mission 1 will improve our ability to not only discover more science, but to ensure the safety of our spacecraft instruments for future human exploration – both in the short term and long term.”