According to NASA, engineers are already considering ambitious mission goals to Saturn's moon Titan. According to experts' calculations, the use of nuclear propulsion systems makes such a mission feasible.
In particular, the concept of a space vehicle with a nuclear-thermal propulsion unit called Copernicus, which uses liquid hydrogen and uranium-235 as fuel, allows you to fly to Titan for 220 days. Total duration of the mission, taking into account work on the surface, will be approximately 1000 days. Such a mission poses critical and new threats to the biological defense of its personnel. The Copernicus project was originally developed at NASA's research center to provide accelerated manned missions to Mars. Later, the concept was adapted for flight to Titan, which even at the moment of closest approach is located in 17 times farther from Earth, than Mars. An additional increase in fuel tanks could theoretically reduce the time of a one-way flight to 90 days, however, this will lead to a significant increase in the launch mass of the vehicle and a significant increase in the cost of the mission. Engineers are also considering alternative nuclear technologies. VASIMR nuclear-electric plasma rocket launcher would allow to reduce the flight time to 149 days. A promising fusion engine could provide a full round trip in 2-2.6 years. At the same time, none of these technologies solves the key problem — the creation of easy and effective protection against cosmic radiation.
Despite the extreme conditions on the surface of Titan (the temperature is about –179 °C, weak solar radiation and gravity, which is approx 1/7 earthly), the satellite has a number of important advantages compared to Mars. Its nitrogen atmosphere is six times denser than Earth's, which makes it possible to use aerodynamic braking for landing without significant fuel consumption. The dense atmosphere provides additional protection from cosmic radiation after landing. An important resource is the presence of liquid hydrocarbons in the soil (methane and ethane), which can potentially be used to produce fuel for the return flight.
The most serious problem of such a flight remains the impact of a prolonged space journey of about 1000 days on the human body and psyche. Radiation damage begins immediately after leaving the Earth's magnetosphere. Today, there are no light materials, capable of effectively protecting the crew from high-energy particles. Мікрогравітація призводить до втрати щільності кісткової тканини, muscle atrophy and impairment of visual functions due to increased intracranial pressure. The psychological consequences of long-term isolation in a confined space also remain poorly understood.
Before manned missions to the outer part of the solar system, large-scale robotic research will necessarily be carried out. IN 2034 NASA plans to land the Dragonfly quadcopter on Titan, who will conduct a detailed study of the surface, проаналізує хімічний склад ґрунту, will assess the level of radiation and the stability of the terrain. The results of this mission will be critical in determining the possibility of a future human presence on Titan.
Source: https://universemagazine.com