You are not logged in.
In this post, Gemini and I consider a Solar Power Satellite for Phobos...
Hello Again! And thanks (again) for your help with many requests. In this one we are off to what seems to me a strong start, with an opening statement and outline of direction. In your last reply you offered three directions we might look and all seemed worth pursuing. However, I'd like to focus on the solar power option because I just asked another instance of you, working in another account, to review solation on the surface of Phobos. The answer appears to be about 38% or so. Part of the reason is the proximity of the Moon to Mars, and the rest is (apparently) due to the inclination of the planet which is much greater than is true for Earth. What this means is that a solar powered plant needs to take the 40% figure into account, along with the reduced solation due to the greater distance of Mars from the Sun compared to Earth. In short, solar fields on Mars must be quite a bit larger than would be the case on Earth. On Earth, solar power satellites are a concept that has potential, but so far has not been attempted except for brief experiments. At Phobos, a solar power satellites of the Moon itself might make a ** lot ** of sense. but even there the solation would be no better than on the surface. The difference is that such a satellite can point toward the Sun when it is visible, whereas anything on the surface would have to track the Sun. Delivery of power to the surface by microwave would be much more practical than is true on Earth, because the distance would be so much less. Let's focus for a moment on this idea. Is there an orbit around Phobos that would serve? Does Phobos have LaGrange points like the ones in the Earth/Moon system?
***
That is a fascinating shift in strategy! Bypassing the surface night/occlusion cycle on Phobos with an orbital power satellite—and beaming microwave energy directly down to the processing facility—opens up a compelling logistical shortcut.Because Phobos is so close to Mars, its orbital mechanics and gravity field behave very differently than the Earth-Moon system. Here is a breakdown of the dynamic orbital environment around Phobos, its Lagrange points, and how to place a power satellite there.
Phobos Orbital Mechanics & Lagrange Points
1. Does Phobos Have Lagrange Points?
Yes, but with major practical differences.
Because Phobos orbits Mars in a three-body system (Mars–Phobos–Satellite), standard Lagrange points (L1 through L5) do exist in the Mars-Phobos frame.
L1 and L2 (Sub-Mars and Anti-Mars): Located along the Mars-Phobos axis, L1 sits between Mars and Phobos, while L2 sits on the far side of Phobos. Because Phobos has very low mass, L1 and L2 are extremely close to the surface—roughly 3 km to 5 km from the center of Phobos!
Instability: Like Earth-Moon L1/L2 points, these are dynamically unstable. Additionally, Mars’s dominant gravity and the extreme triaxial (non-spherical) shape of Phobos create strong gravitational perturbations, meaning a station at L1 or L2 requires active station-keeping.
2. Are There Stable Orbits Around Phobos?
Classical Keplerian orbits (circular or elliptical) around Phobos itself are generally unstable long-term because Phobos’s Hill sphere (the region where its gravity dominates over Mars) is tiny—only about 16 km in radius.
To keep a solar power satellite in the vicinity of Phobos without crashing or drifting away, dynamicists use special orbital families:
Distant Retrograde Orbits (DROs): These are stable orbits around Phobos where the satellite moves in a direction opposite to Phobos’s orbit around Mars. A DRO can orbit Phobos at distances of 10 to 30 km, providing continuous line-of-sight to both the Sun and a surface receiving station.
Quasi-Satellite Orbits (QSOs): The power satellite actually orbits Mars in a trajectory nearly identical to Phobos, but with slightly different eccentricity/phase. To an observer on Phobos, the satellite appears to safely loop around the moon continuously without ever entering a fragile Keplerian orbit.
3. Solar Ingestion & Power Beaming Economics
Solar Flux at Mars Orbit: At ~1.52 AU, solar irradience is roughly 590 W/m² (about 43% of Earth's 1361 W/m²).
Continuous Illumination: A power satellite in a QSO or halo-type orbit stays in direct sunlight virtually 100% of the time, avoiding the rapid ~7.6-hour day/night cycle on Phobos's surface.
Microwave Beaming Distance: On Earth, Space Solar Power (SSP) must beam energy across 36,000 km from Geostationary Orbit. At Phobos, a satellite in a Quasi-Satellite Orbit is only 20 km to 100 km away.
Phobos Atmosphere (or Lack Thereof): Because Phobos has zero atmosphere, high-frequency microwaves (or even optical power-beaming lasers) suffer zero atmospheric attenuation or scattering, allowing near 100% transmission efficiency to the surface rectenna.
Drafting the Next Forum Presentation
When you are ready, we can format this concept into a clean post for your series, contrasting a Surface Solar Field vs. Orbital Power Satellite with Wireless Beaming for the Phobos SiLOX refinery!
Of the choices offered, the Mars orbit near Phobos seems most attractive.
An advantage of this idea is that entire array can be assembled in Earth orbit and it can fly itself to Mars using ion engines and a supply of propellant.
(th)
Offline
Like button can go here
In this post, Gemini and I consider Void's report of research on use of Oxygen for an ion engine.
Logistical Masterstroke: Self-Transporting Space Solar Power Satellites
One of the largest hurdles for any off-world industrial station is the initial transit mass penalty: how do you get a massive multi-megawatt Solar Power Satellite (SPS) from Earth to the Martian system without burning immense amounts of terrestrial propellant?
By integrating Oxygen-Fueled Electric Propulsion (Ion / Hall Thrusters), the power station becomes its own tugboat.
1. LEO Assembly & Spiral-Out Transit
Low Earth Orbit Assembly: The photovoltaic structural framework, microwave transmitter array, and electric thruster banks are launched and assembled in LEO.
Initial Refueling: The electric propulsion tanks are loaded with oxygen harvested from Lunar ISRU or delivered via low-cost Earth launch.
Solar-Powered Spiral Out: As soon as the massive solar arrays unfold, they generate megawatts of electrical power. The thrusters use this abundant energy to ionize oxygen, slowly and efficiently spiraling the station out of Earth's gravity well toward Mars.
2. The Oxygen Electric Propulsion Trade-Off
Traditional ion engines prefer heavy, inert noble gases like Xenon or Krypton due to high storage density and low chemical reactivity. However, oxygen presents a game-changing alternative:
Abundance vs. Efficiency: While oxygen propellant results in lower specific impulse and higher cathode erosion than Xenon, oxygen is abundant across the inner solar system (Lunar regolith, Phobos silicates).
Energy-Rich Architecture: Because the solar power satellite produces an extraordinary excess of electrical power, the lower thruster efficiency is easily offset by the zero-cost availability of local oxygen propellant.
3. Final Deployment in Quasi-Satellite Orbit (QSO)
Upon arriving in the Martian system, the power satellite executes an orbital capture and settles into a stable **Quasi-Satellite Orbit (QSO)** accompanying Phobos at a distance of 20 km to 50 km.
Dual-Purpose Operation: Once in position, the satellite pivots its main systems from self-propulsion to beaming microwave energy down to the surface rectenna on Phobos.
Continuous Power for SiLOX Refining: The stationary or halo position ensures uninterrupted solar exposure, beaming high-frequency power through zero atmosphere to run the carbothermal furnaces, nano-silicon passivation units, and LOX cryo-coolers 24/7.
Summary:
Instead of shipping dead weight across deep space, the Phobos Power Station powers its own journey from Earth to Mars using oxygen propellant, arriving fully functional and ready to energize the SiLOX fuel depot.
(th)
Offline
Like button can go here
This post is a follow up to the series started 2026/08/13 ...
In Post #23, Gemini and I began looking at the possibility of a solar power satellite for Phobos.
Today, that basic idea is extended a bit ... Why place the production facility on Phobos? That facility could be a free flying complete system that harvests raw material from Phobos (or any Silicon Dioxide source). That way, the entire system could fly out from Earth using it's own solar power panels to supply electricity for Void's Oxygen ion drive.
The harvest "truck" that flies between Phobos and the satellite facility could operate with ion thrusters.
Such a free-flying facility could be a model for an asteroid dis-assembly facility, for use when there is time to deal with an asteroid that might hit Earth, such as 99942 Apophis, due to pass Earth April 13, 2029.
Such a facility could be docked with Apophis, and then begin gradual dis-assembly of the asteroid, and routing of collected material to a useful orbit in the Earth/Moon system.
(th)
Offline
Like button can go here
In this post, Gemini and I take a first look at the free-flying SILOX harvester...
Hello Again! Yesterday we made excellent progress in our new series on Phobos as a supply point for SILOX. Overnight it came to me that the solar power satellite could take on the full responsibility for harvesting material from Phobos and preparing Silicon and Oxygen for sale to customers. This would lead to construction of the entire facility in Earth LEO, and it sending itself wherever it is needed in the Solar System. The facility would need small "trucks" to collect material from the object of interest, but it could remain pointed directly at the Sun, unlike any solar panels that might be installed on Phobos itself. Such a free flying facility would necessarily have to endure shadow if it is located near Phobos, but if it harvests Phobos with small vehicles, then perhaps the facility could be located in an orbit where sunlight is not interrupted.
***
This evolution of the architecture completely transforms the economic and engineering model! By shifting from a static surface base to a fully autonomous, free-flying factory-tug, you bypass almost all the thermal, dynamic, and mechanical complications of operating directly on the surface of a non-spherical, dusty, low-gravity body like Phobos.Here is a breakdown of why this free-flying factory paradigm works so well, along with the orbital mechanics that make uninterrupted sunlight possible.
The Free-Flying Factory Concept: Orbital & Operational Advantages
1. Solution to the Shadow Problem: Sun-Synchronous or High Halo Orbits
If a refinery sits on the surface of Phobos, it experiences a ~7.6-hour day/night cycle, severe thermal cycling, and constant solar tracking loss. Even in a low orbit near Phobos, Mars or Phobos itself will periodically eclipse the Sun.
By utilizing a free-flying factory model, you can place the main refining platform into specialized orbits:
Mars Sun-Synchronous / Terminated Halo Orbits: The factory operates in a wide halo orbit offset from Mars, staying continuously outside the shadow cones of both Mars and Phobos.
100% Solar Availability: Uninterrupted sunlight means carbothermal furnaces and liquid oxygen (LOX) cryo-coolers operate at steady-state 24/7/365, eliminating energy storage mass (batteries or fuel cells) entirely.
Zero Gravity Processing Advantages: Refining molten regolith and sintering nanoscale silicon matrices in continuous microgravity simplifies fluid handling and material transport compared to managing weak, irregular surface gravity (~0.005 m/s² on Phobos).
2. "Drone Fleet" Logistics: Automated Regolith Tenders
Instead of landing a multi-hundred-ton refining facility onto Phobos, the main vessel stays safely in its sunlit orbit and deploys a fleet of small, specialized autonomous collection vehicles ("trucks" or "tenders"):
Minimal Delta-V Penalty: Because Phobos has a tiny escape velocity (~11 m/s), small electric or cold-gas tenders require negligible fuel to hop down to the surface, scoop un-consolidated regolith, and return to the orbiting factory.
Contamination Control: Mining and excavating regolith creates abrasive electrostatic dust clouds. Keeping the primary optics, solar arrays, and delicate microwave transmitters high above Phobos protects the main infrastructure from severe dust degradation.
Flexibility Across Targets: If Phobos regolith yields decline or the mission profile shifts, the exact same orbiting factory can send its tenders down to Deimos or even near-Earth asteroids without redesigning the main refining plant.
3. Single-Launch LEO Integration & Deployment
Building the entire factory-tug in Low Earth Orbit (LEO) establishes a true "self-erecting, self-delivering" asset:
LEO Construction: Photovoltaic arrays, microwave/laser power transmitters, carbothermal reactors, and oxygen electric thrusters are fully integrated and tested in Earth orbit.
Self-Propelled Transit: The plant uses its own large arrays to power oxygen or argon ion thrusters, spiraling out of Earth orbit and cruising to Mars under its own power.
Immediate Commercial Readiness: Upon arrival at Mars, the factory deploys its mining tenders and immediately begins producing SiLOX and LOX for incoming spacecraft, acting as a fully integrated orbital gas station.
Drafting for the Forum
When you are ready, we can structure this into the next BBCode post for your series, highlighting the shift from Surface Base to Autonomous Free-Flying Factory Ship!
What would you like to do next?
Draft BBCode post for the free-flying factory concept
Analyze Delta-V costs for automated mining tenders on Phobos
Calculate thermal stability benefits of continuous 100 percent solar exposure
With this post we will leave Phobos and return to the main SILOX topic.
(th)
Offline
Like button can go here
This post is about the Japanese MMX mission that is planned to visit Phobos in 2027.
https://www.cnn.com/2026/08/20/science/ … oid-impact
the article at the link above includes numerous images including a sequence showing Deimos up close during a recent flyby.
Space
A violent impact might have changed Mars’ potato-shaped moon
By
Ashley Strickland
Updated Aug 20, 2026Animation shows how an asteroid strike may have reshaped Deimos and cloaked it in dusty material. S. D. Raducan/ESA
Mars has two tiny moons that lack a confirmed origin story for how they came to orbit the red planet — but new research may explain some of the mysteries surrounding outermost satellite Deimos.
Named for the son of the Greek god Ares, Deimos, which means dread in ancient Greek, is a small, lumpy rock shaped like a potato. Ares is also known as Mars in Roman mythology.
The moon is about 14,913 miles (24,000 kilometers) from the Martian surface, and orbiters have observed it since the 1970s — including a recent flyby of the European Space Agency’s Hera mission in March 2025. Hera is en route to study the aftermath of NASA’s DART mission that intentionally crashed a spacecraft into a small moon orbiting a larger asteroid.
Orbital imagery has shown that unlike its heavily cratered sibling moon, Phobos, which means fear in ancient Greek, Deimos is much smoother — and covered in a perplexing layer of dust and rubble called regolith.
Deimos, which is about 7.5 miles (12 kilometers) in diameter, also has an identifying feature, a 6.2-mile-wide (10-kilometer-wide) impact basin at its southern pole, which resembles a dramatic dip similar to those seen in mountain ranges. Scientists have long questioned what created the crater and led to the dust layer.
By comparing Hera’s flyby images with impact simulations, the authors of a new study published Tuesday in the journal Nature Astronomy suggest that one large single asteroid impact reshaped Deimos, resulting in the moon’s dramatic polar crater and global dust layer.
The study offers a prediction that could be tested by the Japan Aerospace Exploration Agency’s Martian Moons eXploration mission, known as MMX, which is expected to launch by the end of the year. The mission aims to capture unprecedented, detailed observations of both moons to help determine how and when they formed and even return samples collected from Phobos to Earth.
“Our study provides important, concrete predictions for this Japanese MMX mission,” said lead study author Dr. Sabina Raducan, science program manager at the International Space Science Institute and a senior fellow at the Free University of Brussels. “This gives MMX a clearer picture of what its instruments — and ultimately the sample collection — can expect.”
Deimos crosses Mars in a series of images that the Hera mission captured in March 2025. ESA
One giant impact
The researchers began by creating impact scenarios for Deimos using a computer code called the Bern Smoothed Particle Hydrodynamics, or SPH.This code, developed at Switzerland’s University of Bern over two decades, is designed to simulate collisions between asteroids, comets and planets, and analyze the impact by looking at millions of individual particles involved in each scenario.
This breakdown enables researchers to understand the different variations and factors at play during an impact, such as the density, gravity and compositional strength of the rocky bodies.
“We carried out about a hundred simulations — each one took about a week,” said Raducan, who is also one of the chairs of the Impact Physics Working Group for the Hera science team.
The size, velocity and angle of impact for the asteroid that might have struck Deimos varied in each simulation, as did the moon’s internal structure. Then, the team compared the data from its simulations with Hera’s up-close observations of Deimos.
The researchers zeroed in on the most likely scenario of an asteroid measuring about 1,050 feet (320 meters) across striking Deimos at a 45-degree angle, creating the south pole crater and the dust layer.
The impact released a large amount of debris across Deimos’ lumpy surface, effectively covering many of its surface features by as much as 656 feet (200 meters) — and making it appear much smoother than Phobos.
“Our simulation thus shows that a single impact was sufficient to decisively shape the current landscape of Deimos,” said study coauthor Dr. Martin Jutzi, senior researcher at the University of Bern’s Division of Space Research and Planetary Sciences.
“The impact was violent enough to redistribute material globally, but not so strong that it would have shattered the moon.”
Outlines of ancient craters can still be seen beneath Deimos’ dust layer in the Hera images. If Deimos were more solid, shock waves from the impact would have resonated through the moon and disrupted or even erased surface features. Instead, Deimos’ fractured interior dampened the force of the impact, according to the study authors.
The authors did not include a suggestion of when this ancient impact occurred on Deimos, only that it must have happened well after the moon formed.
An ancient impact can be seen under the surface dust layer on Deimos. S. D. Raducan/B. May/London Stereoscopic Company
A mysterious origin
Scientists have long questioned whether Phobos and Deimos are rocky chunks that an impact blasted away from Mars, or if they are space rocks that the red planet’s gravity captured.
The observations and computer models suggest that Deimos’ internal structure is highly porous, making it more like rubble-pile asteroids — groups of space rocks loosely held together by gravity — than like Earth’s moon.
“But that doesn’t necessarily mean that Deimos is actually an asteroid. It could also have formed from material ejected during impacts on Mars,” Raducan said.
The MMX mission is expected to collect data that could definitively solve the mystery of Phobos and Deimos’ origins, as well as provide a window into the early history of our solar system when the gravity of the largest planets caused space rocks to crash into planets as well as one another.
The mission will arrive at the moons in 2027, spend two years mapping Phobos and selecting a landing site for sampling before backing away to observe Deimos. A sample from Phobos is expected to be dropped off on Earth in 2031.
Deimos appears dark when framed by bright Mars from Hera's perspective. ESA
Interest in Deimos and Phobos is growing as more orbiters capture imagery of the enigmatic moons, said Dr. Terik Daly, planetary scientist at the Johns Hopkins University Applied Physics Laboratory. Daly was not involved in the study but is a member of the Science Working Team for MMX.
“The paper outlines a viable model for Deimos’ unusual shape, building on longstanding questions about its origin and evolution,” Daly wrote in an email. “Like many modeling studies, there are assumptions that future observations will need to test and Japan’s Martian Moons eXploration mission is expected to make observations that could provide an opportunity to evaluate ideas presented in the paper.”
Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.
(th)
Offline
Like button can go here