Mars has no rings today, but it already carries the material for one.

Phobos, the larger and innermost of the planet’s two small moons, is moving towards Mars by about 1.8 centimetres each year. That drift is measurable. What happens at the end is modelled rather than observed, and depends heavily on how much strength is hidden beneath the moon’s battered surface.

One influential analysis suggests the weakest parts of Phobos could be pulled apart in 20 to 40 million years, spreading into a temporary ring while stronger fragments continue down towards Mars.

It is a dramatic future assembled from a very small motion.

Phobos completes three orbits during one Martian day

Phobos is an irregular body measuring roughly 27 by 22 by 18 kilometres. According to NASA’s Phobos overview, it circles Mars three times per day at an altitude of about 6,000 kilometres above the surface.

The European Space Agency gives its orbital period as 7 hours and 39 minutes. That is much shorter than the time Mars takes to rotate once. To an observer on much of the Martian surface, Phobos would therefore appear to rise in the west and set in the east, the reverse of the familiar daily motion of Earth’s Moon.

The short orbit is also the reason Phobos is in trouble. It lies inside the altitude where a moon’s orbital period would match the planet’s rotation. The tidal bulge it raises on Mars consequently lags behind the fast-moving moon. Their gravitational interaction removes orbital energy from Phobos and transfers it to Mars.

Losing orbital energy does not make a moon hover more slowly at the same height. It drops into a lower orbit, where it travels faster and raises stronger tides. The descent gradually accelerates.

A yearly drift cannot simply be extended in a straight line

NASA expresses the present decay as 1.8 metres every century, while ESA gives the equivalent figure of 1.8 centimetres per year. A simple division of the moon’s current altitude by that rate would produce a timescale of hundreds of millions of years.

That calculation is misleading because the rate will not remain constant. As Phobos approaches Mars, the strength of the tidal interaction increases. The last part of its inward spiral is expected to proceed much faster than the motion measured today.

This is why public estimates differ. NASA says Phobos could strike Mars or break into a ring in about 50 million years. ESA uses the broader phrase “within 100 million years.” These are not scheduled events with a precise date. They reflect different assumptions and levels of rounding applied to a nonlinear process over geological time.

The measured direction is the firm part: Phobos is moving inward.

The ring prediction depends on a damaged interior

Whether Phobos reaches the surface mostly intact or comes apart first depends on its internal strength. The moon has a nine-kilometre impact scar called Stickney crater, fine surface dust, grooves and evidence of repeated impacts. Its exterior looks less like a solid, pristine rock than an object that has been worked over for billions of years.

In a 2015 analysis published in Nature Geoscience, Benjamin Black and Tushar Mittal combined geological observations, spectral measurements, orbital theory and a geotechnical model of Phobos’s strength. They concluded that much of the moon may consist of weak, heavily damaged material.

Their model placed tidal dispersal of the weakest material about 20 to 40 million years in the future. Once Mars’s gravity pulls more strongly on the near side of Phobos than the moon’s own cohesion can resist, that material would no longer remain a single body.

This is one model, not a direct measurement of the interior. No spacecraft has drilled through Phobos or mapped its structure in full. A stronger, more coherent moon could survive closer to Mars, while a loose aggregate would begin failing farther out.

The grooves are intriguing, but they are not a visible countdown

Long grooves cross much of Phobos, and their origin has generated several explanations. Some have been linked to debris launched from impacts on Mars. Others may have been cut by boulders rolling away from Stickney crater.

A 2016 study in the Journal of Geophysical Research: Planets, led by Terry Hurford, tested another possibility. Its stress models found that tidal forces acting on a weak interior could produce fractures with a pattern similar to some observed grooves.

That does not establish that every groove is a stretch mark caused by orbital decay. Surface features can have several origins, and the competing explanations involve different sets of grooves. The study is better read as evidence that tidal damage is physically plausible for a weak Phobos, not that the moon is visibly splitting today.

At the present decay rate, human observations cover almost none of the remaining process.

A Martian ring could outlast species and still be temporary

Black and Mittal estimated that the resulting ring could persist for one million to 100 million years. Its initial mass density might be comparable with Saturn’s rings, although that does not tell us exactly how bright or broad it would appear from the Martian surface.

The ring would not be Phobos’s only ending. Material strong enough to avoid disruption would keep descending and eventually strike Mars in oblique, relatively low-speed impacts. Smaller particles in the ring would also evolve, collide and gradually move towards the planet.

On geological timescales, a ring lasting millions of years can still be a passing phase.

The contrast with Earth’s Moon helps show why. NASA’s lunar measurements show that our Moon is receding by about 3.8 centimetres per year. Earth rotates faster than the Moon orbits, so Earth’s tidal bulge transfers energy outward to the Moon. Phobos orbits faster than Mars rotates, reversing the exchange.

The same broad physics can push one moon away and pull another towards destruction.

Mars offers a ring system in slow preparation

Nothing about Phobos’s fate is urgent on a human scale. Twenty million years is more than four thousand times the span of recorded history. The moon will look effectively unchanged to any mission operating this century.

Its inward motion still matters because it lets planetary scientists observe one stage of a process otherwise inferred from finished ring systems, impact deposits and missing moons. Mars is not merely a planet that may acquire a ring in the distant future. It is a planet whose tides are already preparing the material.

The 1.8 centimetres measured in a year is almost nothing. Given enough time, it is the beginning of an ending.

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For roughly the last three billion years, half of the Moon has been hiding. Earth’s gravity caught the Moon early in its existence and slowed its spin until the same face was permanently turned toward us — a process called tidal locking, completed somewhere between three and four billion years ago, which left every human civilisation that ever existed staring at the same single hemisphere of the same single satellite for the entire duration of human history. No human being saw the other half until 7 October 1959, when the Soviet Luna 3 probe transmitted the first photographs from a flyby trajectory. No human or human-built object touched the far side until 3 January 2019, when China’s Chang’e-4 mission soft-landed Yutu-2, a small rover, into Von Kármán crater. No spacecraft of any nationality had ever collected and returned physical material from the far side to a laboratory on Earth — until 25 June 2024, when the return capsule of Chang’e-6 parachuted into the grasslands of Inner Mongolia carrying 1,935.3 grams of lunar soil and rock fragments scooped and drilled from the South Pole-Aitken Basin.

According to a comprehensive reference summary of the Chang’e-6 mission architecture and operational sequence, the mission’s four-component spacecraft — a lander, an ascent vehicle, an orbiter, and an Earth-return capsule — launched from Wenchang Space Launch Site on Hainan Island aboard a Long March 5 rocket on 3 May 2024. The spacecraft entered lunar orbit on 8 May, then spent approximately three weeks mapping potential landing sites and refining its trajectory. On 1 June, the lander and ascent vehicle separated from the orbiter and descended autonomously toward the surface, communicating with mission control in Beijing through the Queqiao-2 relay satellite that had been launched into a high lunar halo orbit in March 2024 specifically to bridge communications between far-side surface operations and Earth. Direct radio contact with the far side is impossible — the lunar mass itself blocks the signal — and every far-side mission, beginning with Chang’e-4 in 2019, has required a dedicated communications relay positioned to see both Earth and the lunar surface simultaneously.

Where the lander touched down

Chang’e-6’s landing site was within the Apollo Basin, a 538-kilometre-wide impact crater that sits inside the much larger South Pole-Aitken Basin — the largest, oldest, and deepest confirmed impact structure in the entire solar system. As reported by Scientific American’s coverage of the Chang’e-6 sample return and the scientific significance of the landing site, the South Pole-Aitken Basin stretches approximately 2,500 kilometres across the lunar surface and reaches depths of approximately 8 kilometres below the surrounding terrain. The basin was formed approximately 4 billion years ago, in the period of intense bombardment that followed the formation of the solar system, by an impact substantial enough to potentially have excavated material from the Moon’s mantle and brought it to the surface. If true — and the question of whether SPA Basin ejecta actually includes mantle material has been an open scientific question for decades — then samples from the basin would represent the first physical material from beneath the lunar crust that humans had ever held in a laboratory.

The lander spent approximately 49 hours on the surface, using a robotic scoop to collect material from the immediate surface and a drill to extract samples from up to two metres below ground. Per the Planetary Society’s overview of the Chang’e-6 surface operations and sample-handling sequence, a small 5-kilogram rover named Jinchan (“Golden Cicada”), which had been kept secret during the launch preparations, was deployed from the side of the lander and photographed the spacecraft from a distance of several metres — producing the first close-up image of a lunar far-side lander taken from the lunar surface. The collected samples were transferred into a sealed container inside the ascent vehicle, which lifted off from the top of the lander on 3 June at 23:38 UTC, rendezvoused with the orbiter in lunar orbit on 6 June, transferred the sample container into the Earth-return capsule, and was subsequently crashed back into the lunar surface. The orbiter and return capsule then began the journey back to Earth, with the return capsule separating from the orbiter shortly before atmospheric entry and executing a skip-reentry trajectory — bouncing off the upper atmosphere once to shed velocity before completing the descent — to a soft landing in Inner Mongolia on 25 June. Total mission duration was 53 days.

Why far-side samples matter

The asymmetry between the lunar near side and far side is, by every available scientific measure, one of the larger unsolved problems in planetary science. The near side — the half of the Moon humans see from Earth — is covered for approximately 30 percent of its surface by basaltic maria, the dark plains of solidified ancient lava that the early astronomers mistook for seas. The far side has almost none. As detailed in a planetary scientist’s analysis of what the Chang’e-6 samples could reveal about lunar history, less than 1 percent of the far side is covered by maria. The far side’s crust is substantially thicker than the near side’s. The far side contains substantially lower concentrations of the geochemically distinctive elements collectively known as KREEP — potassium, rare earth elements, and phosphorus — that dominate the near-side surface chemistry. Why the two halves of the same body should differ so dramatically in their geological and chemical composition has been a subject of active research and unresolved theorising since the first far-side photographs were transmitted by Luna 3 in 1959.

Initial analyses of the Chang’e-6 samples have already begun producing scientifically substantial results. As covered in a November 2024 paper in Science by Cui et al. of the Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, fragments of volcanic basalt from the samples have been dated to approximately 2.83 billion years old — substantially younger than most far-side material had been expected to be, suggesting that volcanic activity persisted on the far side for far longer than existing models predicted. A parallel analysis led by Zhang et al. at the Institute of Geology and Geophysics, published in Nature the same month, produced essentially the same age estimate using a different sample fraction. Earlier work led by Wang et al. on volcanic glass beads from the Chang’e-5 mission to the lunar near side had identified evidence of unexpectedly recent volcanism dated to approximately 120 million years ago. Whether comparably young volcanism occurred on the far side remains an open question that the continued analysis of Chang’e-6 samples may eventually address. The far-side basalts that have been dated so far contain substantially lower concentrations of radioactive heat-producing elements than near-side basalts of comparable age, which raises a new puzzle: if the far-side magma source was as chemically cool as the analyses suggest, what kept it molten long enough to produce volcanism extending into the relatively recent geological past? The current working hypothesis, which the analysis of the remaining samples over the coming years will substantially refine, is that the thin crust beneath the South Pole-Aitken Basin allowed mantle material to remain partially molten and to erupt through the comparatively thinner overlying rock long after the rest of the far side had cooled.

The 1,935 grams of lunar soil in a laboratory in Beijing now represent the only physical samples humans have ever recovered from a hemisphere of the Moon that, for the entire duration of human civilisation and for billions of years before it, has been permanently hidden from view. The next missions in the series — Chang’e-7 in 2026 and Chang’e-8 in 2028 — will focus on the lunar south pole, searching for water ice and testing in-situ resource utilisation in preparation for the International Lunar Research Station that China plans to begin building by 2035. The same techniques that produced the Chang’e-6 sample return will be used, with modifications, for the Tianwen-3 Mars sample return mission scheduled to launch in 2028 — a mission that, on its current schedule, will deliver the first samples from the surface of another planet to Earth in approximately five years.

The post In June 2024, a small Chinese spacecraft called Chang’e-6 became the first machine in human history to return samples from the far side of the Moon — drilling and scooping roughly 2 kilograms of lunar soil from a region no spacecraft had ever sampled, and delivering it back to Earth, giving humanity its first physical material from the half of the Moon that has been permanently turned away from our planet since it became tidally locked billions of years ago appeared first on Space Daily.

Every 26 months, the orbits of Earth and Mars align in a particular geometric configuration that allows spacecraft to travel between them with the lowest possible fuel expenditure. The window lasts approximately one month. Miss it, and the next opportunity is more than two years away. The next such window opens in November 2026 and closes in December. SpaceX, the private launch company founded by Elon Musk in 2002 with the stated long-term goal of making humanity a multi-planet species, has been preparing for this specific window for years. Musk has publicly committed to launching up to five uncrewed Starship V3 vehicles toward Mars during the 2026 window, carrying cargo, scientific experiments contracted by the Italian Space Agency, and a small fleet of Optimus humanoid robots built by Tesla. The robots are intended to demonstrate operational capability on the Martian surface — the first robotic ambassadors of a private company on another planet, if the mission succeeds.

According to Space.com’s coverage of Musk’s most recent Mars announcement in May 2025, Musk himself has characterised the probability of meeting the 2026 deadline as approximately 50-50. The primary technical bottleneck is orbital refuelling. Starship, the largest rocket ever built at approximately 120 metres tall fully stacked, uses essentially all of its fuel reaching low Earth orbit. To travel to Mars with usable payload, each Starship must be refuelled in orbit by additional Starship tanker flights — approximately 8 to 12 refuelling flights per Mars-bound vehicle, by current published estimates. Five Mars-bound Starships would therefore require approximately 40 to 60 launches within the brief 2026 transfer window — a launch cadence that no rocket programme in history has ever achieved, and that SpaceX itself has not yet demonstrated. Orbital propellant transfer between Starship vehicles, which is the technological prerequisite for all of this, has been tested at small scale but not yet demonstrated at the level the Mars missions would require.

The history of slipping Mars timelines

The honest framing of any prediction about a 2026 Starship Mars mission requires acknowledging Musk’s track record of slipping Mars timelines. As documented by Aerospace America’s analysis of SpaceX’s Mars plan, Musk first publicly committed to landing on Mars in 2018 — at the 2016 International Astronautical Congress, where he proposed sending a variant of the Dragon capsule to the planet within two years. That mission never happened. In 2017, he revised the target to 2022, this time using the still-nascent Starship. That mission did not happen either. By 2024, the target had moved to a 2026 uncrewed mission with crewed flights potentially following in 2028 to 2030. The pattern across the eight-year sequence is roughly consistent: Musk announces an ambitious Mars timeline approximately five years in advance, SpaceX makes substantial but not complete progress on the prerequisite technologies, the announced date arrives without the mission, and a new target is announced for the next transfer window.

The 2026 target is now within a few months. Several of the prerequisite technologies — Starship V3, orbital refuelling, heat-shield durability for atmospheric re-entry at Mars-return velocities, the autonomous Mars landing system itself — remain in active development. The Wall Street Journal reported on 6 February 2026 that SpaceX had told investors it would prioritise a March 2027 uncrewed lunar landing over Mars. Two days later, on 8 February 2026, Musk himself publicly confirmed the shift in a post on X, writing that “SpaceX has already shifted focus to building a self-growing city on the Moon, as we can potentially achieve that in less than 10 years, whereas Mars would take 20+ years.” Musk added that the company would “strive to build a Mars city and begin doing so in about 5 to 7 years,” pushing the substantive Mars settlement effort back to approximately 2031-2033 rather than 2028-2030. The 2026 Mars launches remain nominally on the company’s stated agenda, but they are no longer the near-term priority. The Moon, in Musk’s revised framing, is the faster and more strategically viable destination — partly because lunar transfer windows open every 10 days rather than every 26 months, allowing the kind of rapid iteration that Mars trajectories do not permit.

If the 2026 launches still happen

The implications of a successful 2026 mission, however unlikely on the revised SpaceX priorities, would be substantial. As reported by Daily Galaxy’s coverage of the Mars launch window and its prerequisites, the five uncrewed Starships, if they reach Mars intact in mid-2027, would represent the largest delivery of mass to the Martian surface in the history of space exploration. Every previous successful Mars mission — NASA’s Viking 1 (1976), Viking 2 (1976), Pathfinder (1997), Spirit (2004), Opportunity (2004), Phoenix (2008), Curiosity (2012), InSight (2018), Perseverance (2021), and China’s Zhurong (2021) — has delivered, in aggregate, only a few tonnes of equipment to the surface. A successful Starship landing would deliver, in a single mission, more mass than the cumulative total of all previous Mars landings combined.

Whether the 2026 attempt occurs in any form is now substantially more uncertain than it was a year ago. The February 2026 pivot to lunar priority does not formally cancel the November-December Mars launches, but it does redirect SpaceX’s engineering, financial, and political capital toward the Moon. The crewed Mars mission timeline that Musk floated in 2024 — first humans on Mars in 2028 or 2030 — is now effectively delayed by at least three to five years, with the official Musk Mars-city target now sitting in the 2031-2033 window. Whether any of this happens on anything close to Musk’s stated timeline is, by his own assessment and revised priorities, highly uncertain. Whether it happens at all within the next two decades is the more substantive question on which the various Mars-relevant technologies are now converging.

What is genuinely new

The aspect of the SpaceX Mars effort that is genuinely new, regardless of whether the November launches occur, is the institutional configuration behind it. Every previous attempt to send humans or substantial cargo to Mars has been a government programme — NASA, the Soviet space programme, or China’s space agency. The SpaceX Mars effort is, for the first time in human history, a private corporation attempting to send mass to another planet on its own initiative, with its own rockets, on its own timeline, with its own payload manifest. Per SpaceX Stock’s analysis of the 2026 Mars transfer window and SpaceX’s commercial strategy, the eventual SpaceX commercial Mars programme — whether it materialises in 2026, 2031, or later — represents a structural shift in how the species approaches interplanetary travel. Mars exploration is moving from being a government activity to being a commercial activity, with all the attendant changes in funding mechanism, accountability, regulatory framework, and pace of iteration that the shift implies.

For approximately 200,000 years, anatomically modern Homo sapiens have lived on a single planet. Twelve human beings have walked on the Moon. Approximately 700 have travelled to low Earth orbit. None have travelled to another planet. The probability that this changes in the late 2020s is now genuinely uncertain — substantially less than the original SpaceX Mars timeline suggested, with the company’s February 2026 pivot to lunar priority pushing the substantive Mars settlement effort into the early 2030s at the earliest. The first Mars-bound launches, if they occur at all in late 2026, will function less as the opening of a Mars era than as a technology demonstration for a programme whose human-scale implementation is now substantially further away than the company was claiming a year ago. Whether and when the species reaches another planet remains open. The 2026 window will clarify part of the question. The full answer will take considerably longer.

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