The journey to Mars is not as easy as it looks and scientists need to ensure a lot of things before sending a manned mission to Mars.

Humanity was forced to search for an alternative habitat, other than the Earth, due to the drastic changes on the surface of the Earth. The climate of our planet is becoming more and more hostile towards life and this poses a serious threat to the human species. Our immediate neighbor in our solar system, Mars, is the most popular candidate in this regard for a number of reasons. First and foremost, it is closest to Earth among all the potential candidates of life. This is an extremely important factor given the fact that distances in space are regularly measured in millions of light years. In addition to that, different missions to the red planet have indicated that life could be possible there.

The exploration and colonization of Mars have certainly come a long way as the ideas of a human mission to Mars have been circulating around the scientific community since the 19^th century. Hollywood movies, like The Martian and Life, used science fiction to predict what we may find on our celestial neighbor once we reach there. Similarly, national space agencies like NASA are considering it a top priority mission for decades now. All these steps clearly indicate the inclination of humans to find another habitat for them and surely Mars is the most preferred candidate. NASA wants to send a manned mission to Mars by 2030 while Elon Musk, the CEO of SpaceX, believes they can achieve this feat by 2024.

Initially, it was believed that a small group of human explorers, ranging from 2 to 8 astronomers, should be sent to the Mars for a period of few weeks. However, things changed considerably over time as the idea of colonizing the red planet for permanent came across. The frequent exploration of Mars in novels, films, and other work of science fiction might have also played a part in urging the scientists to consider it a potential habitat. A lot of space agencies from China, Europe, and the United States have announced that they intend to send a human mission to Mars. According to their claims, they are currently working on the required technologies needed for carrying out these revolutionary missions.

The Synodic Period helps us to determine the lowest energy needed for a transfer between planetary orbits. For an Earth-Mars trip, it usually lasts for 26 months and most missions are scheduled by coinciding with these windows. According to a rough estimate due to the eccentricity of the Mars’ orbit, these low-energy windows appear once every 15 years. Following these calculations, the next low-energy window will occur in 2033. Numerous types of missions have been proposed but the one which requires minimum energy transfer to Mars is known as ‘Hohmann Transfer Orbit’. It will need a 9-month journey from Earth to Mars and will require a stay of 500 days on the red planet before coming back to Earth. The mentioned length of the waiting period is to ensure that the transfer window of Earth is there when you start your 9-month journey back towards home.

Other than that, shorter Mars missions are also possible but they require higher energy. For example, a fast Mars mission can be concluded in 245 days but it is not possible without an ‘On-orbit Staging’. In order to minimize the fuel needs, all the spacecraft designed for the Mars mission are equipped with ‘Aero-braking’. This leads us to the landing of a Mars mission once it reaches the orbit of the red planet. The two possible ways of dropping into the atmosphere of Mars are ‘Aerocapture’ and the use of rockets to slow the spacecraft down.

Scientists studied the Aerocapture in detail by reviewing multiple Mars studies of the 20^th century. They found that 24 out of 93 used Aerocapture for landing on Mars or the Earth. They observed that a lot of things were to be considered before choosing Aerocapture and a ‘maximum G-limit to experience’ is quite important for a manned mission. They found that 5 times Earth’s gravity was a common limitation that must be followed given numerous landers could be there on a spacecraft. In addition to that, scientists agreed that they may have to avoid a scientifically interesting site to ensure a safe landing in case of a surface touchdown. All these signs are pretty promising but there are quite a lot of challenges in terms of logistics and planetary protection that needs to be resolved before sending humans to the red planet.