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Color-enhanced view of Mercury. Photo: NASA/JHU-APL/Carnegie

Scientists are pushing space agencies around the world to send dedicated missions to the small, relatively unexplored planet Mercury.

Why it matters: With its odd, huge core, magnetic field and unexplained chemistry, the planet is like nowhere else in the solar system.

  • "Mercury seems to be a bit of an oddball," planetary scientist Paul Byrne told Axios.

The big picture: NASA has long-dedicated many of its limited resources to studying Mars and the Moon from close range, effectively leaving planets like Mercury, Venus, Uranus and Neptune somewhat left behind.

  • NASA's MESSENGER mission, which ended in 2015, provided a wealth of data for scientists interested in Mercury, but it also left them clamoring for answers about the small planet's chemistry and composition.

What's happening: NASA is considering establishing an assessment group that will focus on bringing scientists focused on Mercury together and will help advocate for missions.

  • "This community was focused around MESSENGER for a long time and is currently self-organizing," Shoshana Weider, support scientist in NASA's Planetary Science Division, told Axios via email. "But it is important to the community, and to NASA, that we recognize ... the efforts and interests of these scientists.”
  • The European Space Agency and Japan Aerospace Exploration Agency launched the BepiColombo mission to Mercury last year. The two spacecraft in the mission should make it into orbit around the innermost planet in 2025.

Details: MESSENGER mapped Mercury's surface and also found that about 85% of the planet’s volume is taken up by a huge metal core.

  • The ratio of potassium and thorium on Mercury also suggests that the planet may have formed elsewhere in the solar system or there could be a flaw in the models used to explain planetary formation, BepiColombo scientist Johannes Benkhoff told Axios.
  • "We thought we could predict some of what Mercury would be like, and we were wrong, so we have to go back and [re-examine] some of our basic, fundamental knowledge about the solar system," planetary geologist Brett Denevi told Axios.

What's next: Some planetary scientists hope to convince NASA to send a rover or lander to Mercury in the 2030s to study the planet from its surface to get more information about the small world than an orbiter could.

  • Scientists working with NASA will soon begin a study of what would be needed for such a mission — technically and budget-wise.
The transit of Mercury

Monday's transit of Mercury gave millions of people the chance to see the smallest major planet in our solar system in much the same way that scientists spot worlds around other stars.

The big picture: Exoplanets — planets orbiting stars other than our Sun — can be detected when a star's light dips as the planet passes across the face of its star.

Details: Mercury's transits can illuminate its exosphere — the planet's extremely thin atmosphere — for telescopes.

  • "Sodium in the exosphere absorbs and re-emits a yellow-orange color from sunlight, and by measuring that absorption, we can learn about the density of gas there," NASA scientist Rosemary Killen said in a statement.
  • The Hubble Space Telescope is able to parse out some elements of exoplanetary atmospheres this way as well, by watching as the planets pass in front of their stars.
  • NASA's James Webb Space Telescope will investigate exoplanet atmospheres in even more detail after its expected launch in 2021.

ICYMI: Sorry, but transits of Mercury are relatively rare events. The next one is expected to occur in 2032.

Go deeper

Updated 43 mins ago - Science

This powerful new accelerator looks for keys to the center of atoms

Illustration: Eniola Odetunde/Axios

Nuclear physicists trying to piece together how atoms are built are about to get a powerful new tool.

Why it matters: When the Facility for Rare Isotope Beams begins experiments later this spring, physicists from around the world will use the particle accelerator to better understand the inner workings of atoms that make up all the matter that can be seen in the universe.

Updated 46 mins ago - Politics & Policy

Omicron dashboard

Illustration: Aïda Amer/Axios

  1. Health: FDA OKs antiviral drug remdesivir for non-hospitalized COVID patients — Walensky: CDC language "pivoting" on "fully vaccinated" — Pfizer and Moderna boosters overwhelmingly prevent Omicron hospitalizations, CDC finds.
  2. Vaccines: The case for Operation Warp Speed 2.0 — Teens and adults missed 37 million vaccinations during COVID — Team USA 100% vaccinated against COVID ahead of Beijing Olympics — Kids' COVID vaccination rates are particularly low in rural America — Annual COVID vaccine preferable to boosters, says Pfizer CEO.
  3. Politics: Arizona governor sues Biden administration over COVID funds tied to mandates — Biden concedes U.S. should have done more testing — Arizona says it "will not be intimidated" by Biden on anti-mask school policies.
  4. World: American Airlines flight to London forced to turn around over mask dispute — WHO: COVID health emergency could end this year — Greece imposes vaccine mandate for people 60 and older — Austria approves COVID vaccine mandate for adults — Beijing officials urge COVID-19 "emergency mode" before Winter Olympics.
  5. Variant tracker
1 hour ago - World

UK government: Kremlin has plan "to install pro-Russian leadership" in Ukraine

British Foreign Secretary Elizabeth Truss. Photo: Gints Ivuskans / AFP via Getty Images

The United Kingdom's Foreign Secretary on Saturday night said the government has "information that indicates the Russian Government is looking to install a pro-Russian leader in Kyiv as it considers whether to invade and occupy Ukraine."

Driving the news: U.S. National Security Council spokeswoman Emily Horne called the intelligence "deeply concerning" in a statement to Axios. The Biden administration has said Russia is actively manufacturing a pretext for invasion and warned that Putin could use joint military exercises in Belarus as cover to invade from the north.