Recently, Elon Musk announced that he would launch 1,000 spacecraft to transport 100,000 people to Mars. Since Mars is the only planet in the Solar System other than Earth that can be habitable, some countries have proposed many plans for manned exploration of Mars and have created many technical reserves. Moreover, three probes landed on Mars in a year, which again caused the “Martian fever”. So how will humans land on Mars in the future?
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In the face of numerous technical tests
The process of a manned Mars exploration mission is very complicated. It can be roughly divided into such stages as launch from the Earth’s surface, assembly in Earth orbit, fuel transfer from Earth, landing, and ascent to Mars, rendezvous, and docking in Mars orbit, and return to Earth. Each stage faces serious technical problems.
Earth is far from Mars
Mars is very far from Earth. Every 26 months, a window will open for the convergence of Mars and Earth. The nearest distance between them is 55 million kilometers. It can reach a maximum of 400 million kilometers. A manned spacecraft is sent to Mars on a one-way trip lasting at least 6 months. Given the launch window for returning from Mars, astronauts may have to work on the surface of Mars for almost 500 days, and one manned Mars exploration mission may take up to 900 days. During the nearly three-year space journey, it is almost impossible for astronauts to get a second supply of supplies, so a manned Mars exploration mission must carry a lot of supplies and energy.
Taking into account the need for astronauts to work and live on the surface of Mars for a long time, as well as devices for lifting and returning that take off from the surface of Mars, people need to transport at least 40 tons of supplies to the surface of Mars in combination with vehicles, residential modules used by astronauts on the surface of Mars, manned spacecraft and other vehicles, it is expected that almost 1,000 tons will need to be launched into orbit.
Such a huge launch mass far exceeds the payload capacity of the current rocket, which requires various modules to be launched into near-Earth orbit in batches, assembled in near-Earth orbit, and then flown to Mars. This is due to technical problems, such as the development of a general plan for manned exploration of Mars, orbit optimization, storage, and management of low-temperature fuel and assembly in orbit.
An imaginary image of people landing on Mars with the help of a spaceship
The flight to explore Mars is long. Astronauts have been living in radiation and microgravity for a long time. They need to study long-term food storage technologies, technologies, and equipment for radiation protection, medical diagnostic and therapeutic equipment, as well as encourage astronauts to conduct activities in a closed environment to relieve physical and psychological stress and provide comprehensive health protection measures.
In addition, long distances create communication difficulties. Two-way communication between Mars and Earth will be delayed for 6-44 minutes, and a new communication line must be established to maintain reliable communication.
There is a delay in communication between Earth and Mars
During the entry into Mars orbit and landing, due to the presence of a meager atmosphere on Mars, a large amount of pneumatic heating will be generated during the flight of the descent vehicle at hypersonic speed, and it is necessary to apply thermal protection technology. At the same time, due to the rarefied atmosphere of Mars, the effect of the deceleration umbrella is not obvious during landing, and innovative thrust reversers must be used to decelerate.
In addition, due to the long delay, it is difficult for Earth personnel to provide appropriate support for the landing process on Mars, which also puts higher demands on the autonomy, reliability, and safety of manned Mars exploration, and it is necessary to develop more advanced guidance and control technologies.
Composition of the manned Mars exploration system
To complete the manned Mars exploration mission, the future research system will include unmanned research systems, space transport systems, coating systems on the surface of Mars, as well as measurement and control systems.
The unmanned research system mainly includes equipment such as a Mars orbiter, an unmanned rover launched to Mars at an early stage of the mission, and a radio beacon. It is used for the study of the Martian environment explored by astronauts, the selection of landing sites for astronauts, as well as for technical verification, and radio navigation.
The space transport system includes various types of vehicles for various stages of the flight of manned exploration of Mars, including launch vehicles, as well as ground facilities on Mars.
Among them, the launch vehicle will send all the mission payloads and astronauts to Earth orbit, and the transfer stage from the earth will be responsible for the transfer between Earth orbit and the orbit of Mars, sending astronauts and materials to Martian space.
It’s not easy for a manned spacecraft to land on Mars
The lander and the lift are mainly responsible for transporting personnel and materials both ways between the orbit and the surface of Mars. As a rule, they consist of a two-stage aircraft. Fuel can be produced using Martian resources and some resources are transported after reaching the surface of Mars.
To ensure the execution of transport missions between the surface of Mars and orbit, it is also necessary to build some infrastructure on the surface of Mars, including on-site resource utilization equipment, energy systems, landing control systems, and launch pads. Among them, on-site resource utilization equipment can use Mars’ resources to produce energy, fuel, etc.
The system of application to the surface of Mars includes a residential module, a module for scientific experiments, an environmental control and health protection system, a rover, an extravehicular activity system, and a power system. Among them, the environmental control and health protection system is used to ensure the living conditions of astronauts, and the rover helps astronauts move quickly on the surface of Mars.
The measurement and control system includes a ground-based measurement and control system and a space-based measurement and control system. The first includes various ground-based measurement and control networks, while the second includes relay satellites, and navigation and communication satellites. The measurement and control system can provide communication between equipment on the surface of Mars and Earth researchers, transmit experimental data and allow Earth researchers to intervene in solving problems with equipment on the surface of Mars.
The process of astronauts flying back and forth
All this time, the United States, Russia, etc. have been actively exploring the possibility of manned missions to explore Mars and have put forward several proposals. Thus, the process can be divided into several stages.
The first stage is the transfer of materials. The launch vehicle will deliver payloads, such as ferry crossing, components of the cargo transfer stage, landing and ascent to Mars, ground facilities on Mars, etc., to low Earth orbit in batches and collect them at the stages of cargo transfer in orbit. The ferry stage transports the cargo transfer stage to high Earth orbit and returns to low Earth orbit. The launch vehicle will then launch a refueling vehicle, refuel the ferry stage in orbit and wait for the ferry’s next mission.
An imaginary picture of a manned spacecraft flying to Mars
The cargo transfer stage passes through the transfer orbit. After a long journey, he goes into orbit and waits for manned spaceships and astronauts. At the same time, it frees the Mars ground objects, lands on the surface of Mars, and performs fuel preparation.
In the second stage, the launch vehicle will deliver payloads in batches, such as components of the manned transfer stage and residential modules for deep space, to low Earth orbit, assemble the manned transfer stage in orbit and transfer it to high Earth orbit using a ferry stage.
As soon as the Mars ground facilities and the manned spacecraft transfer stage waiting in high Earth orbit are functioning normally, and when the appropriate launch window is reached, the launch vehicle will launch the manned spacecraft into the specified orbit, dock with the manned spacecraft transfer stage, and then the manned spacecraft transfer stage will send astronauts to the transfer orbit.
In the third stage, the transfer stage of the manned spacecraft will enter the orbit of the Ring of Fire. The manned spacecraft will dock with the lander and riser on Mars, which previously entered the orbit of the Ring of Fire. Astronauts will enter the lander and riser on Mars, land on the surface of Mars, and conduct operations and scientific research.
An imaginary picture of a manned spacecraft taking off from Mars
In the fourth stage, after the astronauts complete the mission to the surface of Mars, they will add fuel to the lander and the lift to Mars, climb the lift, return to the orbit of the Ring of Fire and complete the docking with the transfer stage of the manned spacecraft waiting in the orbit of the ring of fire.
Finally, the manned transfer stage enters the transfer orbit and returns to near-Earth space.
It should be noted that some technologies of the current manned Mars exploration missions based on conventional propulsion systems have been tested. With sufficient budget support, people can gradually achieve landing on the surface of Mars. However, the long flight time led to the creation of a large-scale research system, which put a lot of pressure on the existing level of human engineering technologies and the psychology and physiology of astronauts. If we want to reduce the time of manned exploration missions to an acceptable level, we still need to achieve many revolutionary achievements in aerospace technology, especially in nuclear-thermal engine systems.