April 25, 2025, by Brigitte Nerlich
Space, hype and science communication
I recently wrote a post with Kate Roach about some hyped-up claims regarding de-extinct dire wolves. In the middle of writing about this, another claim came along, and, again, I thought “hmmm, is that really true or is it hype?”. This time it was not about de-extinct life but about extraterrestrial life. At the same time there was also the spectacle of six women floating in space, a totally different space story that backfired badly, but I won’t go into that here. It didn’t do space communication any favours though (or feminism either).
The exoplanet and the extrapolations
Let’s stick to the claims about extraterrestrial life. What was this about? On 17 April 2025 we read or saw on the news, be it traditional or social, that astronomers, using the James Webb Space Telescope, might have detected potential biosignatures, signatures of life, in the atmosphere of an exoplanet called K2-18b, which orbits in its star’s habitable zone 124 light years away.
This news was triggered by a press release from the University of Cambridge that explained that researchers lead by Professor Nikku Madhusudhan had found ‘the strongest evidence yet’ of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS), chemicals that on Earth are only produced by living organisms, particularly marine microbes. The press release also stressed that the researchers remain cautious and are seeking additional observation time to confirm their scientific discovery.
Summarised like this, this doesn’t sound too hyperbolic, does it? So what happened? The phrase ‘strongest evidence yet’ was picked up and reproduced in many news headlines, suggesting that there is indeed ‘evidence’. Professor Madhusudhan himself amplified that claim when he said “The signal came through loud and clear”.
He also stated in a widely quoted interview with the BBC and elsewhere: “I can realistically say that we can confirm this signal within one to two years”; that the finding “inches the human race closer to proving we are not alone in the universe” and might suggest that the planet is “teeming with life”; and could “confirm that life is very common in the galaxy”. He added that: “Decades from now, we may look back at this point in time and recognise it was when the living universe came within reach” and that “This could be the tipping point, where suddenly the fundamental question of whether we’re alone in the universe is one we’re capable of answering.”
These are extraordinary claims and, as Laura Kreidberg, an astronomer at the Max Planck Institute for Astronomy in Germany, told NPR: “I think this is one of those situations where extraordinary claims require extraordinary evidence.” And: “I’m not sure we’re at the extraordinary evidence level yet.”
Media credulity
The story was however picked up quite credulously by the mainstream press. Almost every article I have seen contained the phrase ‘strongest evidence yet’; some even talked about ‘strongest proof’ or ‘compelling evidence’.
Not surprisingly, some of the tabloids had a field day, with The Mail Online announcing that “Scientists reveal what aliens could REALLY look like on K2-18b”. The Mirror headlined one article with “GAS TO BE SOMETHING OUT THERE; Space boffins say vapours detected on alien planet mean it’s ‘teeming with life’”, while the The Sun proclaimed: “ET PHONES HOME! Best-ever sign of alien life found as scientists say they are ‘99.7% sure’ & believe planet could be ‘teeming’ with ETs” and “VERY LITTLE GREEN MEN; SHOCK SPACE DISCOVERY REVEALS ‘BIO ACTIVITY’ Distant planet ‘full of life’ say scientists Clue to ‘plankton’ aliens in atmosphere”… Even The Times got carried away a bit with “Krill Baby Krill!; Gases usually made by marine microbes have been discovered on a distant planet”.*
So, in a Chinese whispers sort of way, Professor Madhusudhan’s ‘teeming with life’ speculation became a speculation about aliens. That is not surprising, but could probably have been avoided. The same goes for the repetition of ‘the strongest evidence yet’ and the 99.7% certainty claim.
Community critique
After reading a headline in The Times, Paul Mainwood posted on Bluesky: “I see that the exoplanet field took one look at the high-temperature superconductivity field, and thought: ‘We want some of that.’” This refers to hyped claims about a breakthrough in room-temperature superconductivity which swirled around in August 2023 (see my post here). Paul then added: “(To be clear, the ‘99.7% probability’ in the headline here is a) an accurate report of the claims in the paper, and b) wrong.)” Others described the press release as “misleading” and the evidence as “flimsy“.
In contrast with the mainstream news then, the astronomy and astrophysics community online was rather sceptical about the discovery from day one (see Chris Lintott, Laura Kreidberg, Astropierre, Ken Rice, Phil Plait, Ryan MacDonald, and many more)**. Even the peer-reviewed paper published in Astrophysical Journal Letters on which the press release was based was more cautious than the press release, as it pointed out “While [the presence of molecules] DMDS and DMS best explains the current observations, their combined significance…is at the lower end of robustness required for scientific evidence”. As Chris Wheeler pointedly said on Bluesky: “I guess maybe the strongest evidence yet is really really weak wouldn’t make a great headline.”***
And one needs headlines to get funding…. The Sun reported that “Prof Madhusudhan wants to get more analysis time to reach the coveted ‘five-sigma’, which means there is just a 0.00006 per cent probability the results occurred by chance. He told The Sun that the results came from eight hours of James Webb Space Telescope usage, and they needed 16 to 24 more, hopefully next year. He continued: ‘We have to formally apply for JWST time and there will be a selection process.’”
But is that a potentially valid reason for hype, or as Peter Cole called it in a blog post “biosignature hype”? Press releases err generally on the side of hype rather than caution, even when the researchers themselves are well aware of both. Professor Madhusudhan told National Geographic that “We need to recognize both: the achievement and the caution.” However, in interviews he mostly focused on the “transformational achievement”.
The ethics of science communication by press release
We have seen in this short description of the K2-18b communication that there was a gap between cautious scientific findings and more dramatic public messaging and that there was an escalation of claims as they moved from research papers to press releasees to mainstream media. This all begs the question asked by Chris Lintott: “At some point we need to have a discussion about the ethics of participation in press releases as scientists.” (more here) And there are other worries.
As Peter Cole said after the press release and the media uptake: “This episode worries me greatly. This is a time of increasing hostility towards science and this sort of thing can only make matters worse. Scientists need to be much more careful in communicating the uncertainties in their results.”
Nathalie Cabrol, director of the Carl Sagan Center at the Seti Institute, expressed her concerns in a Guardian article: “While the paper repeatedly stresses the preliminary nature of the findings and the need for further data, public statements by the lead author have at times conveyed a stronger sense of confidence than the published evidence supports. When this happens, we miss the critically important opportunity to understand that science progresses carefully, incrementally, and with eyes wide open to its strengths and limitations.”
Recommendations for responsible science communication
Responsible language use has been a long-standing issue in science communication, including reflections on metaphor, hype and hyperbole. As Christoph Kueffer and Brendan Larson pointed out a decade ago: using “hyperbole to report on an issue that is actually quite nuanced can lead to confusion and may hinder the responsible and effective use of scientific evidence in decision making and the media”.
While the press release and media coverage of the K2-18b findings demonstrate the pitfalls of overclaiming scientific significance, there are also excellent models of responsible science communication in the space sciences and I have blogged on some of them. Here I’ll just mention two:
Take the Cassini mission to Saturn (1997-2017), for example. Throughout its 20-year journey, the Cassini team consistently communicated findings with appropriate enthusiasm while maintaining scientific integrity. When Cassini discovered water plumes on Enceladus, NASA presented this as a thrilling but preliminary finding, carefully explaining what was and wasn’t known. As more data accumulated, the team updated the public, always distinguishing between confirmed observations and theoretical implications.
Similarly, the New Horizons mission to Pluto practiced careful expectation management. Before its 2015 flyby, the team was transparent about what they hoped to see while acknowledging the high degree of uncertainty. When stunning images and data arrived, scientists openly discussed their surprise at many features, demonstrating how scientific discovery actually works—through observation, question-formulation, and further investigation.
After discussing this with Claude, we came up with a few recommendations for responsible science communication (and you can recognise Claude at work here, as it likes bullet points and lists!):
- Clarity about certainty levels: Using consistent language to distinguish between speculation, preliminary findings, and confirmed results.
- Transparency about process: Explaining how verification works and what further evidence would be needed.
- Embracing wonder without overclaiming: Communicating genuine excitement about exploration without exaggerating significance.
- Collaborative communication: Scientists working closely with communication specialists before speaking with media.
The responsibility falls not only on individual scientists but also on institutions, funders, journalists, and editors. In a media environment that rewards sensationalism, we need structural changes that incentivise accuracy alongside interest. (The defunding of NASA and US science in general deals a heavy blow to all this of course!)
Great (space) science communication doesn’t require hyperbole. The universe is fascinating enough on its own terms. When scientists respect public intelligence by communicating honestly about what they know, what they suspect, and what remains mysterious, they build sustainable trust in science—something far more valuable than a momentary headline.
Notes:
*Some of the headlines recorded on the news database Nexis are more lurid than the ones you’ll find online!
** Some experts were highly sceptical. Dr Jake Taylord, an astrophysicist at the University of Oxford, wrote on Bluesky: “I wrote a research note about the recent publication of the MIRI/LRS spectrum of K2-18b. The authors had claimed the detection of potential signs of life. I find the data to be consistent with a flat line ”
** As the great science writer Tim Radford once pointed out to me, after confessing to using some lurid metaphors (‘magic table cloth’) when first reporting on stem cell research: “You don’t grab headlines by describing embryo stem cell research as an expensive laboratory-based technology of unproven merit guaranteed to lead to many years of frustration punctuated by small flashes of enlightenment.” I had just written this when I came across this paragraph in an article by Chris Lintott on the whole affair: “I’m reminded of the late, great Tim Radford’s rule that science journalists should, ‘if an issue is tangled like a plate of spaghetti…regard [the] story as just one strand of spaghetti, carefully drawn from the whole. Ideally with the oil, garlic and tomato sauce adhering to it’. It should be the responsibilty of the press release to point to the existence of the whole plate of pasta, not only present a single delicious piece ready for consumption, even if that’s uncomfortable for the institution or scientist involved…in the journey toward understanding how unusual we are in the Universe there will be many false steps and confusing results, and we need to be able to communicate this mess as we go.”
Image: Pixabay
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