What's happened
Researchers from the German Aerospace Center have found that Mercury’s diameter loss could be up to 14 miles (23 km), about 30% more than previously believed. BepiColombo’s approaching orbit will help confirm the extent of the planet’s contraction as the mission advances toward Mercury.
What's behind the headline?
Analysis
- The finding challenges prior estimates of Mercury’s contraction, suggesting more wrinkles may be buried under ejecta and debris, which hides true shrinkage in rough terrain.
- BepiColombo’s instruments will offer a direct test of current models, possibly revising how we understand planetary cooling in small rocky worlds.
- This development underscores the value of international collaboration in unveiling subtle planetary processes and how that can inform future missions to small bodies and Mercury-style worlds.
Implications for readers: better understanding of planetary evolution informs models for terraforming analogs and exoplanetary studies, with potential implications for how we assess geological activity on small planets.
How we got here
Mercury has been shrinking since its formation 4.5 billion years ago due to cooling of its hot iron core and mantle. A cooperative effort from multiple space agencies is tracking this contraction as BepiColombo nears Mercury to provide more precise measurements.
Our analysis
AP News reports and independent outlets summarize the same Geophysical Research Letters findings, with quotations from lead author Gaku Nishiyama of Hokkaido University. Ars Technica provides mission context on BepiColombo’s trajectory and the separation of the Mercury Transfer Module.
Go deeper
- What will BepiColombo’s data tell us about Mercury’s core?
- How might this change our view of small rocky planets?
- When can we expect updated measurements from the mission?
More on these topics
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Mariner 10 - Space probe
Mariner 10 was an American robotic space probe launched by NASA on 3 November 1973, to fly by the planets Mercury and Venus. It was the first spacecraft to perform flybys of multiple planets.
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National Aeronautics and Space Administration - Agency
The National Aeronautics and Space Administration is an independent agency of the U.S. Federal Government responsible for the civilian space program, as well as aeronautics and space research.
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BepiColombo - Plan
BepiColombo is a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter and Mio.
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Mercurio - Planet
Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets.
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Hokkaido University - National university in Sapporo, Hokkaido, Japan
Hokkaido University (北海道大学, Hokkaidō daigaku), or Hokudai (北大), is a public research university in Sapporo, Hokkaido, Japan. Founded in 1918, it is the fifth-oldest government-authorised university in Japan and one of the former Imperial Universities. The university finds its roots in Sapporo Agricultural College, which was a pioneer in the country's modern agricultural education and research, founded in 1876. The university's motto is 'Boys, Be Ambitious', which is said to be the parting words of the American dean of the Agricultural College, William S. Clark. The university has 12 undergraduate faculties and 21 postgraduate schools. The university mainly operates on two campuses: the main campus is located in downtown Sapporo, just north of Sapporo Station, and the other campus is located in Hakodate, primarily used by the Faculty of Fishery Sciences.
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Geophysical Research Letters - Peer-reviewed journal
Geophysical Research Letters is a biweekly peer-reviewed scientific journal of geoscience published by the American Geophysical Union that was established in 1974. The editor-in-chief is Harihar Rajaram.