Mars is not made of ham. But the route by which a modest planetary-science result becomes an enormous claim is well documented, and the interesting part is where along that route the exaggeration actually enters.
The intuitive answer is the newsroom — a reporter under deadline pressure inflating a finding for clicks. There is evidence that this is not the main mechanism. A study published in the BMJ in 2014 by Sumner and colleagues compared university press releases about health research with both the underlying journal articles and the resulting news coverage. It found that exaggeration in the news — advice not present in the paper, causal claims drawn from correlational findings, inference to humans from animal studies — was largely already present in the press release. When the release was accurate, the coverage was much more likely to be accurate too.
That study looked at health research specifically, and it would be overreaching to treat it as a measured result about planetary science. But the institutional incentives it describes are not unique to medicine. A press office exists to generate attention for its institution. It is staffed by people whose professional success is measured in coverage, working from a paper whose authors have every reason to want the work noticed. The hedges in an abstract are load-bearing for scientists and inconvenient for everyone downstream.
The newsroom gets blamed for the exaggeration. The evidence points further upstream, to a document written by people whose job is enthusiasm.
The embargo system compounds it. Major journals and space agencies distribute results to reporters ahead of publication under an agreement not to publish until a set time. The intent is sound: it gives journalists a chance to read the paper and call outside experts instead of racing. The side effect is that a large number of outlets publish simultaneously, working from the same press materials, often without the time to get an independent voice. What looks like many outlets confirming a finding is frequently one press release, replicated.
None of this makes science journalism untrustworthy. It makes the press release a specific document with specific properties, and reading it as one is a skill.
Three habits do most of the work.
Find the paper. Agencies and journals almost always link it, and the abstract is usually readable even when the methods are not. Compare the paper’s own description of what was found against the headline. The distance between those two sentences is the story.
Look for the qualifiers that headlines cannot carry. “Consistent with,” “may indicate,” “in a laboratory analogue,” “one candidate explanation.” A result that is interesting because it narrows a hypothesis will not survive translation into a result that announces one.
Check whether anyone unaffiliated has commented. A quote from a researcher who was not on the paper, and who is willing to say the finding is preliminary, is the single most useful thing in a science story — and its absence is informative.
The ham headline is doing the same job as the real ones, minus the plausibility. Which is the point: you can tell instantly that this one is nonsense. The hard cases are the ones where the only exaggeration is a missing “may.”