President Donald Trump's recent announcement of sending astronauts to Mars within four years has sparked skepticism, particularly given NASA's ongoing delays in returning humans to the Moon. While the goal is ambitious, experts question its feasibility.
The mission is expected to rely heavily on SpaceX's Starship rocket, still under development. A recent test flight on January 16 saw the Super Heavy booster successfully land, but the upper stage exploded due to a propellant leak. Despite this setback, SpaceX aims for uncrewed Mars missions by 2026 and a crewed mission in 2028.
A study published in Scientific Reports by Volker Maiwald and his team at the German Aerospace Center (DLR) raises concerns about Starship's carrying capacity. The required payload, including astronauts, equipment, fuel, and consumables, may exceed the spacecraft's limits.
One key challenge is resource recycling. While higher recovery rates for food, water, and air would reduce the amount transported, a 100% recovery rate is unrealistic. Another challenge is producing fuel on Mars using in-situ resource utilization (ISRU). While SpaceX's Starship relies on liquid methane and oxygen, the technology to extract these from Martian resources is still in its infancy. NASA's MOXIE experiment, part of the Perseverance rover mission, successfully extracted oxygen from Mars' atmosphere, but at a scale far too small for a human mission. Launching four astronauts off Mars would require 7,000 kg of fuel and 25,000 kg of oxygen, far beyond MOXIE's capabilities.
Space radiation presents another major obstacle. Astronauts would be exposed to cosmic rays and solar radiation levels up to 700 times higher than on Earth. A six-month journey to Mars would expose astronauts to 60% of their lifetime recommended radiation dose. Even on the Martian surface, radiation exposure remains a concern. While shielded areas within Starship might provide some protection during solar storms, they would not eliminate the risk entirely. Research into improved shielding materials is ongoing but still in development.
Prolonged exposure to microgravity can also harm the human body. Astronauts on the International Space Station (ISS) experience muscle atrophy and changes in eyesight. Studies suggest that microgravity may contribute to early-onset cataracts. While these effects have been reversible after astronauts return to Earth, the long-term health risks of a Mars mission remain uncertain.
Planetary protection is another concern. Humans carry a vast array of microbes, and a crewed mission would inevitably introduce some Earth-based microorganisms to Mars. While strict sterilization protocols exist for robotic missions, they would be difficult to apply to human missions. Contamination could interfere with future efforts to determine whether Mars ever hosted native life.
To improve the chances of a successful Mars mission, Maiwald's team recommends several steps: uncrewed test missions to evaluate technologies for producing oxygen, growing food, and generating fuel on Mars; pre-positioning supplies ahead of crewed flights; advancing life support systems to reduce payload mass; and international collaboration to share technological development and financial costs.
Despite these recommendations, the goal of landing humans on Mars by 2029 remains highly unlikely. The necessary technological advancements require significant time and effort. While the ambition is admirable, achieving it within the next four years seems improbable.