A Lightweight Plane on Mars
1. Context and Motivation
Between 2020 and 2024, Claude Nicollier and I supervised the work of Master’s level students at EPFL on the feasibility of an airship in the Martian atmosphere. We concluded that this feasibility was possible during favorable seasons or hours in the day (denser atmosphere) and in low-altitude regions, but that it was only possible year-round in the lowest region of Mars, namely Hellas Planitia (the most favorable region being the northwest of this area, the lowest and closest to the equator). The reason for this limitation was that we were unable to get sufficient lift for a minimal mass to overcome them.
The airship operates on the principle that lift results exclusively from Archimedes’ principle. I would now like to study the feasibility of an aircraft on Mars, that is, a craft whose lift results primarily from its speed.
2. General Concept
2.1 Mission and Onboard Equipment
The objective is to design a craft capable of carrying at least one human pilot, perhaps with a passenger, wearing spacesuits and equipped with:
(1) A life support system: oxygen, heating, water;
(2) Minimal radiation protection and communication equipment (with the Martian base, via geostationary satellite);
(3) Observation equipment: camera, spectrometer or hyperspectral camera, ground-penetrating radar with data storage capacity;
(4) Assistance from a humanoid robot;
(5) Solar panels.
2.2 Energy Source
The energy would come from sunlight. Collected by solar panels, it would be stored in batteries and power the rotation of propellers.
3. Three-Level Horizontal Architecture
The structure would consist of three horizontal levels, held together by a sufficient number of tensairity beams for good cohesion, positioned on either side of the cockpit, at the wingtips and at the rear of the plane.
3.1 Level 2 (intermediate) — The wings and the CFJ
The intermediate level would be a pair of wings with vertical ailerons at the tips, forming an angle of less than 90° (to be determined) with a horizontal panel leading to the horizontal stabilizer supporting the tail. The wings and the tail fins would be equipped with CoFlow Jets (CFJ), as conceived by Dr Gecheng Zha (Miami University) for his MAGGIE concept:
3.2 Level 1 (Upper) — Solar Panels, Rudder, and Tail Assembly
Above the intermediate level, which precisely follows the wing and fuselage plane, there would be a first level consisting of solar panels mounted on an aerogel plate, all protected by an aluminum leading edge. The vertical tail assembly (rudder), attached to this level, would be positioned behind the plane of the solar panels. A 20 cm gap between the aerogel plate and the wings (or the rear fins) would create a compression effect and feed the CFJ, generating a flat nozzle effect that would increase the local velocity of the incoming air.
Note: This flat nozzle effect, which to our knowledge has not yet been studied in this specific context, results from reasoning by analogy with conventional convergent nozzles, applied to the particular geometry of this aircraft.
The same principle would be applied to the horizontal rear fins: a solar panel array, mounted on an aerogel plate, would be positioned above each of the two fins (on either side of the rudder), creating a 20 cm flat nozzle that would feed a CFJ integrated into the tail. This device would increase the lift of the tail while also increasing the total solar energy collection area—a significant advantage given the reduced solar intensity at Mars (approximately 43% less than at Earth’s surface).
Note: Since the tail fins chord (1.5 m) is shorter than that of the wings (2.5 m), the 20 cm flat nozzle represents approximately 13% of the chord (compared to approximately 8% on the wings). This proportion remains perfectly acceptable for a lifting airfoil whose primary function is stabilization and contributing to lift. With the CFJ accelerating the airflow over the upper surface, the overall aerodynamic effect remains favorable.
3.3 Intermediate Volume – Hydrogen Enclosure and Cockpit
Between levels 2 and 3, an inverted « teardrop » filled with hydrogen would be installed, defined by a Mylar envelope lined with Dyneema. To limit the height while maintaining sufficient volume, the teardrop would be 2.5 meters high—slightly less than its 3.5-meter width at its widest point—and 9 meters long, for a total volume of approximately 40 m³.
This slight vertical compression simultaneously widens the central section of the teardrop. Reinforced by stiffening tensioners, this widening improves the teardrop’s aerodynamics and reduces its susceptibility to crosswinds. The resulting lower mass distribution, laterally on either side of the teardrop’s axis, also enhances overall stability.
The front of the spherical section of the teardrop would be protected by a conical tip made of carbon fiber. The tip of the cone would be offset upwards (towards the flat nozzle) to avoid creating vortices beneath the solar panel array. The base of the cone would have a shallower but longer slope.
Inside this volume, at the edge of the teardrop’s leading edge, a cockpit-habitat (4.5 cubic meters, half the size of SpaceX’s Crew Dragon designed for four people) would be housed for the pilot and a potential passenger1, as well as the aircraft’s controls and life support system. It would rest on the chassis (third horizontal plane), protected by an aluminum plate. The anti-radiation water mattress (15 cm thick, 100 cm in diameter, ~12 kg) would be positioned above the passengers in this same space.
The most comfortable cockpit, and the one recommended, would be an egg-shaped cellulose acetate bubble, pressurized to 0.5 bar with 42% oxygen and an inert gas, plus a CO2 captor and an oxygen cylinder. The alternative would be a windproof setting only (windows at the front, cellulose acetate side protection) without pressurization. In both cases, the pilot would keep his spacesuit on, but in the first option, he could temporarily remove it after landing at a stopover.
Radiation protection would be provided by the water mattress described above and partially by the hydrogen enveloping the top and rear of the cockpit-habitat. Passengers would also wear Astrorad protection (Stemrad company): a radiation cap-shield around the helmet and a vest over the spacesuit.
1. A system can also be designed to allow the pilot to retrieve an injured person or a lone individual who has lost his means of transport.
3.4 Level 3 (Lower) — Chassis, Wheels, and Robot
Below the intermediate level, at approximately 3 meters, an aluminum chassis frame would support three 80 cm high wheels (two at the front, one at the rear), equipped with shock absorbers (based on technology developed for Martian rovers). This allows for landing on uneven ground and adjustment of the craft’s position. Batteries and observation and communication equipment would also be installed at this level, in accordance with the principle of lowering moving masses to optimize balance.
An Optimus robot would travel lying on the chassis plate behind the pilot, a plate reinforced and softened by a layer of aerogel. It would be responsible for tasks that would allow the pilot to remain within the cockpit (collecting a rock sample, taking a photograph from a few meters away, etc.). It would be powered by electrical energy generated by the solar panels.
3.5 Propulsion — MAGGIE Propellers
The main propellers would be held in position by rigid metal loops, located in front of the flat nozzle, between the solar panels and the wings. They would be of the MAGGIE type (coaxial counter-rotating propellers) to maximize airflow.
The blades would be no larger than 50 cm in diameter, so that the tip speed would not exceed the speed of sound on Mars (~240 m/s). Their number would depend on the total mass of the loaded aircraft (four or six units). Each propeller could have up to 6 blades: a large number of blades increases the surface area of the « screw » created upon entering the air, which is particularly advantageous in a thin atmosphere.
Two additional propellers of the same type, but with shorter blades (40 cm), would be placed under the two rear tail fins, one on each side of the rudder. All propellers would be tiltable. Vertical takeoff and landing are essential, given the absence of any prepared runway on Mars.
4. Weight Reduction Analysis
During our study of the airship at EPFL, to achieve positive buoyancy at an altitude of -2000 m (the average altitude of a flight in Valles Marineris) for a mass of 700 kg, we would have needed a balloon with a diameter of 29 m (12,000 m³ of hydrogen). In our aircraft, weight reduction cannot be achieved through the buoyancy of the hydrogen volume. Indeed, the very low density of the Martian atmosphere (~0.020 kg/m³) makes the buoyant force very weak: ρ × gMars = 0.020 × 3.72 ≈ 0.074 N/m³, so a volume of 40 m³ of hydrogen would only reduce the mass by about 0.80 kg.
In this aircraft, the hydrogen envelope therefore plays an essentially aerodynamic role (reducing drag through its teardrop shape). Radiation protection (partial radiation moderation around the cockpit) plays a secondary role, and thermal protection (insulation), a tertiary role. Weight reduction will therefore come only from the choice of materials (tensairity, aerogel, mylar/dyneema, carbon fiber) and a generous wing area, combined with the effect of the CoFlow Jet.
5. Mass Balance
The wing area breaks down as follows: each wing is 11 m long, with a total wingspan of 25 m and a chord of 2.5 m (compared to the SolarStratos: wingspan 24.8 m, chord 0.9 m); a horizontal stabilizer with a wingspan of 6 m and a chord of 1.5 m; and a fuselage 12 m long and 1 m wide. The wing area of the wings themselves will be 62.5 m²; that of the horizontal stabilizer will be 9 m²; and the fuselage plate, 12 m². Total effective wing area: 83 m². The rear tail assembly (~32 kg) is comprised of the following components: flexible solar panels covering 9 m² (~15 kg), an aerogel plate (~1.5 kg), an aluminum leading edge (~2 kg), CFJ compressors (~5 kg), and two 40 cm MAGGIE propellers with motors and mounting hardware (~8 kg). This component is identical regardless of the number of passengers.
| Items | 1 pers. | 2 pers. |
| Pilote (70 kg) + spacesuit, vest, life support (130 kg) | 200 kg | 360 kg |
| cockpit, seats, commands, O₂ | 90 kg | 105 kg |
| Omnibus & tools | 80 kg | 80 kg |
| Systems, solar pannels, batteries, 3 wheels | 80 kg | 80 kg |
| Setting rear tail fins (solar panels, aerogel, CFJ, 2 MAGGIE propellers) | ~32 kg | ~32 kg |
| Structure (aluminium, aerogel, tensairity) | 200 kg | 200 kg |
| H₂ enveloppe (mylar, dyneema, carbon, graphene) | 20 kg | 20 kg |
| Anti-radiation water ceiling | ~12 kg | ~12 kg |
| TOTAL (estimated) | ~714 kg | ~889 kg |
6. Estimated Performance
With 83 m² of total effective wing area and the active CFJ, 300 km/h becomes a comfortable cruising speed, well above the stall speed. The minimum flight speed could even drop to around 160 km/h depending on the CFJ activity.
The cruising speed required to generate lift is reduced from ~700 km/h (pure aerodynamic lift, without CFJ) to ~300 km/h thanks to weight reductions and the CFJ—a major reduction, very beneficial for slow observation phases.
6.1 Aerodynamic Validation — Lift Coefficient
The aerodynamic consistency of the concept can be verified by calculating the lift coefficient CL required to maintain flight in its most heavily loaded configuration (2 people, 889 kg) at a cruising speed of 300 km/h:
CL = 2mg / (ρ × v² × S)
With: m = 889 kg, gMars = 3.72 m/s², ρ = 0.020 kg/m³, v = 300 km/h = 83.3 m/s, S = 83 m²
CL = (2 × 889 × 3.72) / (0.020 × 83.3² × 83) = 6614 / 11543 ≈ 0.57
A lift coefficient of 0.57 is quite realistic for a well-profiled wing at high speed. With the active CFJ, CL greater than 1.5 are achievable, confirming that 300 km/h is a comfortable cruising speed and that the stall speed can be reduced to ~160 km/h. The ~32 kg mass increase associated with the tail assembly does not significantly alter these conclusions.
This calculation validates the aerodynamic consistency of the concept and constitutes one of the strongest scientific arguments in favor of the feasibility of this aircraft on Mars.
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Autonomy will be determined less by available energy than by the pilot’s life expectancy away from their base (comparable to an EVA around the ISS or the Space Shuttle). Apart basic living requirements such as excretory functions, onboard oxygen, water, and food, the main problem will be the radiation dose, which will prevent exposure of more than two hours per day (approximately). In the long run (depending on advancements in robot control technology), these aircrafts will be piloted remotely from a Martian base, with only humanoids on board.
NB: In this article, computations have been made by the artificial intelligence claude.ai.
Copyright: Pierre Brisson
links:
Cellulose acetate:
https://pubs.acs.org/doi/10.1021/cen-v013n024.p479
MAGGIE et CoFlow Jet sur Mars :
