Europe’s Mars Express spacecraft has delved deeper than ever before on Mars’ moon Phobos and has found clues to unknown structures that may be clues to the moon’s origin.
Mars ExpressThe spacecraft, a 19-year veteran orbiting Mars, arrived within 51.6 miles (83 kilometers) of Phobos in September. 22, 2022 and managed to probe below the lunar surface using upgraded software On the MARSIS instrument (Mars Advanced Radar for Underground and Ionosphere Drilling).
understand the internal structure phobias may be the key to unraveling the mystery of its origin. “We are still at an early stage of our analysis, but we have already seen possible signs of previously unknown features under the lunar surface,” said Andrea Cicchetti, a member of the MARSIS science team at the Italian National Institute INAF. astrophysics, a Declaration (opens in new tab).
Related: How Did Mars Get the Moon Phobos Troughs?
Anthem It has two satellites. Phobos and Deimos After the gods of ‘fear’ and ‘panic’ in Greek mythology. Unlike our big moons solar systemThe Phobos and Deimos are small, only 16.7 miles (27 kilometers) and 9.3 miles (15 kilometers) across, respectively. They have a similar composition to carbonaceous C-type asteroids and are irregularly shaped. asteroids This led to the suspicion that they were in fact rogue asteroids captured by the gravity of Mars. However, the orbits of both Phobos and Deimos around the red planet are above Mars’ equator, and both orbits are extremely circular, suggesting that they formed around Mars. If they were caught, they would be expected to have more elliptical orbits in different planes.
“It’s an open question whether the two small moons of Mars are made of asteroids or material ripped off Mars during a collision,” said Colin Wilson, a scientist working on the European Space Agency’s Mars Express mission. Declaration (opens in new tab).
MARSIS contains a 40 meter long antenna that emits low frequency radio waves to the surface. Most radio waves are reflected directly from the surface, but some penetrate deeper, where they encounter transitions between layers of different composition and structure and are reflected back by these boundaries. The stronger the reflection in the resulting ‘radargram’, the brighter the returning radio signal.
The radargram, taken over a narrow track in Phobos, shows a bright line bisected and labeled A–C and D–F, respectively. Section A–C was captured using legacy MARSIS software for comparison with D–F, which uses the newer software and shows much more detail. The main bright streak is reflection from Phobos’ surface, but underneath there is evidence of fainter streaks that could be interference or ‘clutter’ from features on the surface, but these could also be caused by structures below the surface. .
MARSIS was designed to probe the interior of Mars at an orbital distance of more than 155 miles (250 kilometers), but a recent software upgrade has allowed MARSIS to operate at much closer distances, allowing it to be used during close transits of the moons.
Getting even closer to Phobos will give the radargrams more resolution than is achieved here. The plan over the next few years is to use MARSIS as close as 40 kilometers (24.9 miles) from Phobos.
“The orbit of Mars Express was fine-tuned to get us as close to Phobos as possible during a handful of flights between 2023 and 2025,” Cicchetti said. Said.
Mars Express isn’t the only mission focused on Phobos. Japan Aerospace Exploration Agency (JAXA) in September 2024 Martian Moon Exploration (MMX) spacecraft. like that of JAXA Hayabusa2 Sampling mission from near-Earth asteroid Ryuguwill capture at least 10 grams of regolith from the surface of MMX Phobos. MMX is also a small mobile Before we set off to get a good look at Mars’ second moon, deimosand then back to Earth with precious Phobos samples to be analyzed here in the scientists’ laboratories. Soil.
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