Cosmology stands at a potential turning point, with the NASA James Webb Space Telescope (JWST) poised to address longstanding issues in the field. For years, the standard cosmological model has been the gold standard, explaining the universe’s composition as 68 percent dark energy, 27 percent dark matter, and 5 percent ordinary matter. This model has provided accurate predictions about cosmic structures and the distribution of matter, but recent observations are challenging its assumptions.

The Hubble Tension

A significant issue is the “Hubble tension,” which arises from differing measurements of the universe’s expansion rate, according to an article published by The Conversation. Observations using Cepheid variables suggest a rate of 73 km/s/Megaparsec, while theoretical predictions propose 67.4 km/s/Megaparsec. This 8 percent discrepancy has led to debates about whether current measurements are biased or if the cosmological model needs revising. Despite the JWST’s advanced capabilities, it has yet to definitively resolve this tension.

Researchers are now considering measurements from other types of stars, such as Tip of the Red Giant Branch (TRGB) and J-region Asymptotic Giant Branch (JAGB) stars, which have provided mixed results.

The S8 Tension

Another challenge is the “S8 tension,” which involves the predicted versus observed clumpiness of matter in the universe. The standard model suggests matter should be more clustered than observed, creating about a 10 percent discrepancy. One potential solution involves revising our understanding of dark matter, possibly incorporating fast-moving particles or considering the effects of galactic winds on matter distribution.

Looking Ahead

The JWST has also revealed that early galaxies appear unexpectedly massive, which could either indicate new physics or reflect limitations in current measurement techniques. Future observations, including those from the Dark Energy Spectroscopic Instrument (DESI) and the Vera Rubin Observatory, will be crucial in addressing these issues.

In summary, while the JWST has yet to provide definitive answers, it is clear that cosmology is at a crossroads. The next few years could either reinforce the existing model or usher in new physics, potentially transforming our understanding of the universe.

A unique gravity map of Mars has been unveiled by scientists at the Europlanet Science Congress 2024. This map reveals the presence of significant structures beneath Mars’ ancient ocean and highlights how mantle processes are influencing Olympus Mons, the largest volcano in the Solar System. The study draws on data from NASA’s InSIGHT (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission and small satellite deviations.

Reevaluating Martian Geology

The upcoming paper, “The global gravity field of Mars reveals an active interior,” led by Bart Root from Delft University of Technology and published in Universe Today, challenges established geological theories. It questions the concept of flexural isostasy, which traditionally describes how a planet’s lithosphere, comprising the crust and upper mantle, reacts to large-scale loading.

On Earth, such loading typically causes a downward bending of the lithosphere, with surrounding areas uplifted slightly. However, Mars’ Tharsis Montes, a vast volcanic region, contradicts this model. Instead of sinking, Tharsis Montes is notably elevated.

Mars’ Hidden Features

The researchers suggest that active processes within Mars’ mantle are pushing Tharsis Montes upward, according to a Science Alert report. They identified a large mass approximately 1,750 kilometres across and 1,100 kilometres deep, likely a mantle plume exerting enough force to counteract the downward pressure from the volcanic region’s mass.

Additionally, the study uncovered dense, mysterious structures beneath Mars’ northern polar plains. These anomalies, buried under a smooth sediment layer, are around 300–400 kg/m³ denser than their surroundings. While similar structures on Earth’s Moon are linked to impact basins, Mars’ northern hemisphere anomalies show no such surface traces.

Future Exploration Plans

To further investigate these enigmatic structures and Mars’ gravity, the researchers advocate for the Martian Quantum Gravity (MaQuls) mission. Dr. Lisa Wörner from the German Aerospace Center (DLR), who presented the mission at EPSC2024, explained that MaQuls would employ technology akin to that used in the GRAIL and GRACE missions. This mission could provide deeper insights into Mars’ subsurface features and ongoing mantle convection, improving our understanding of the planet’s dynamic processes.

New research from the Hubble Space Telescope and NASA‘s Mars Atmosphere and Volatile Evolution (MAVEN) mission reveals that Mars sheds water more quickly when it is closest to the Sun. These seasonal changes are tied to the planet’s orbit, where the increased solar heating during perihelion accelerates the escape of hydrogen atoms from Mars’ atmosphere. Over three billion years ago, Mars was warm and rich in water, but today, it has lost most of its water, transforming into a dry, desolate world.

Seasonal Effects on Water Loss

According to John Clarke from Boston University, Mars loses water in two main ways: freezing into the ground or breaking into atoms and escaping into space. The planet still retains some water in its underground reservoirs and ice caps, but much of it has been lost over time. During the Martian summer, water vapour rises into the upper atmosphere, where solar radiation splits water molecules. The hydrogen atoms then escape into space, carried by the solar wind.

Hubble and MAVEN’s New Observations

The collaboration between Hubble and MAVEN has shown that the hydrogen escape rate is highest during perihelion when Mars is closest to the Sun. During this time, dust storms heat the atmosphere, accelerating water loss. MAVEN’s data reveals that hydrogen escape rates are 10 to 100 times higher at perihelion than at the planet’s farthest point from the Sun, called aphelion. The instruments have detected that Mars has lost enough water over its history to form a global ocean up to hundreds of kilometres deep.

This new understanding of Mars’ water loss provides crucial insight into the planet’s evolution and its potential for past life.