#头条创作挑战赛#人类最了解的两颗星体, the Moon and Mars.
Now that the time for humans to land on the moon again is getting closer and closer, it is believed that after conquering the moon, the next step must be to land on Mars.
Let's talk about landing on Mars today.
The history of human exploration of Mars.
Mars and Earth have many similarities, for example, it takes 24 hours, 37 minutes and 23 seconds for Mars to rotate one cycle, which is only 41 minutes longer than Earth's rotation.
The earth revolves around the sun sideways, which gives the earth the four seasons, and Mars is the same, it also revolves sideways around the sun, so Mars also has four seasons.
Earth has the moon as a moon, while Mars has two moons.
There are so many similarities between Earth and Mars that many scientists believe that Mars should have life.
Therefore, Mars has become the first goal for human beings to land in space and explore planets.
Since the sixties of the last century, humans have been sending probes to Mars, and as of 2008, a total of 38 probes have been launched, but unfortunately only half of them have succeeded.
Of these half probes, five more passed at a distance from Mars, and then seven successfully became Martian moons, orbiting Mars, and seven more successfully landed on Mars.
And these nineteen Mars probes have also allowed human beings to unveil the mystery covering Mars layer by layer, so as to see some insignificant secrets on Mars.
It is worth mentioning here that with the development of aerospace technology, the exploration of Mars has been put on the agenda in recent years.
From 2008 to 2013, in just five years, humans have launched five more probes to Mars.
But there is only one success.
Therefore, the success of Mars exploration and the progress of science and technology have increased the probability of success, but the element of luck still accounts for a large proportion.
So what do you explore about Mars?
The main thing is information about water.
Why water?
There are two reasons, one is that scientists believe that there may be life on Mars, or that life has been conceived, so whether there is water on Mars, or whether there was water in the past, will be a very important evidence.
Second, the footsteps of human beings must be to explore deep space, if the manned landing on the moon is the first step into deep space, then the manned landing on Mars will be the first step for mankind to leave the solar system.
Therefore, the establishment of a base on Mars is an inevitable result, and if you want to survive on Mars, water is an essential substance.
Water is not only drinkable, but it also breaks down the oxygen and hydrogen that humans need.
The result of exploration today is that Mars had a large number of rivers and lakes 3.5 billion years ago, but because the gravity of Mars is too small, the water can easily get rid of the constraints of Mars' gravity, so most of the water has escaped into space, and this process is irreversible.
So how does this process happen?
Mars is protected by a lack of dipolar magnetic fields.
The Sun is a star that has to lose its temper from time to time, and when its solar wind blows on Mars, the water will be bombarded into hydrogen ions and cations.
Under this bombardment, the two ions gain energy and the speed increases.
The binding force of Mars is very small, and it is easy for the two ions to reach escape velocity, so these two ions leave Mars and escape into space.
So human beings have seen that Mars, which is now desolate and lonely, can refer to the lifeless desert Gobi to imagine the situation on Mars.
Now scientists are focusing on the groundwater of Mars, or water ice.
The escape of water cannot be stopped, but because of the fact that there was water, groundwater and water ice became the main sources of water on Mars.
Now, under the observation of orbiters, water ice under the subsurface of Mars has been detected, and even permafrost has been found.
In addition to the investigation of water, then it is necessary to find a way to get soil and rock samples on Mars.
These things are like a recorder on a planet, recording many changes in Mars from year to year in detail.
For a long time in the past, humans wanted to know something about Mars, and they could only know it through Martian meteorites.
Although there are currently 57,000 meteorites included in the International Committee on Meteorite Nomenclature, there are only 159 meteorites from Mars.
These Martian meteorites can only give humans a little bit of a glimpse of Mars, and if you want to understand Mars more specifically, you can only wait for the study after the Mars samples return to Earth.
It should be noted here that although the United States has long been preparing for the return of Mars samples, it has been continuously postponed for various reasons, so that China is likely to become the first country to get Mars samples.
This can also be regarded as overtaking in the corner, and the latecomer will prevail.
I'm looking forward to seeing something different from the samples returned.
So how long does it take to get to distant Mars?
Mars is 22,790 kilometers away from the Sun, which is 1.52 times the distance of the Earth from the Sun.
So Mars takes longer to orbit the Sun than Earth, 687 days.
In addition, the orbit of Mars around the Sun is an ellipse, so there is a distinction between perihelion and aphelion, which makes the temperature difference between Mars in the two positions extremely large, with a difference of 160 degrees.
Then the distance between the Earth and Mars is also a variable value.
At the closest point, they were only 55 million kilometers, and at their farthest they were more than 400 million kilometers.
So if you want to land from Earth to Mars, you need to calculate a very good departure time.
Nowadays, there are many pathfinder probes that have been launched, and they have also accumulated experience and found an optimal orbit.
When the spacecraft embarks on this optimal orbit, it can fly to Mars at the initial minimum speed, which can save fuel.
So how do you find this best track?
It can be found by the superposition of the two methods.
The first is to find the location of a line called a Hohmann track.
This orbit is easy to find, make an entangent orbit with the Earth, and this tangent line inscribes with the orbit of Mars, which forms a called a double tangent elliptical orbit.
The characteristic of this Hohmann orbit is that it allows the incoming spacecraft to have a small speed and saves energy, but the disadvantage is that the flight time is long.
The Hohmann orbit was proposed in 1925 by an Austrian scientist named Hohmann, and it is suitable for landing on the orbits of all the planets in the solar system.
Speaking of this, many people will wonder whether this kind of double-tangent elliptical orbit can make different orbital lines at different positions between Mars and the Earth, and there are countless routes to land on Mars.
No, there is only one best route to Mars, which requires a second approach.
Second, both the Earth and Mars orbit the Sun, so the positions of Mars and the Earth will constantly change.
But this change is also cyclical, so the closest Mars is to Earth is also cyclical.
This closest distance is when the Earth is sandwiched between Mars and the Sun, forming a straight line.
This period of time is called Mars opposition.
The wonder seen from Earth is that the Sun and Mars are on opposite sides of the Earth, and when the sun sets, Mars rises in the east, and when the sun rises, Mars sets in the west.
This moment is the brightest time for the Earth to see Mars.
Make a Hohmann orbit during this time period, then the best orbital route from Earth to Mars appears.
And this best track line only appears once every 779 or 782 days.
Therefore, the best time to land on Mars will only occur once every two years.
Moreover, the opposition of Mars does not mean that the distance between the Earth and Mars is fixed every time, and it is also constantly changing.
For example, on August 27, 2003, there was a Mars opposition, and the distance between the two was about 55,758,000 kilometers, which was the closest Mars has been to the Earth in 60,000 years.
In 2012, there was also a Martian opposition, and the distance between the two was 100 million kilometers.
If you drive a car and imagine the track as a straight highway, I'm sorry, it will take you 228 years to reach the terminal on Mars.
Of course, if you use a spacecraft, it will take you 57 days to reach the shortest distance between Mars and Earth, and 208 days if you want to set off at the farthest distance.
Of course, this is the ideal arrival time in an environment where nothing goes wrong, and if something unexpected happens, you don't know.
On the way to Mars, there will be every kind of difficulty imaginable.
The first is the issue of fuel, which is the minimum guarantee for the fuel that the spacecraft can reach Mars.
In the event of other contingencies, such as orbit changes, the support fuel will simply not be enough to get the spacecraft to Mars.
Scientists have also provided a number of options for this purpose, one of which is very important to scientists, which is to use different sources of fuel in engine rotation.
This includes solar power, ion propulsion, and even the use of carbon dioxide and water from the Martian atmosphere as fuel.
This means that an engine can use different fuels as power.
It's hard to listen to.
And then there's the food.
The capacity of the Mars spacecraft is very small, and when a manned person lands on Mars, how to deal with the food?
So it may be a good idea to try to grow in space, but it will require a lot of space, after all, the area is small, and whether the output is enough to eat is a problem.
Next, what to do if the equipment fails?
What should I do if I need to replace parts? Space is limited, and it is impossible to carry enough parts to prepare for such a situation.
Of course, 3D printers may solve this problem, but some materials have particularities, can the materials of 3D printers have such particularities?
The most important thing is the impact on the human heart.
What happens when a person is in a small space—horror, loneliness, boredom, boredom—will have a very important impact on future tasks.
Therefore, before departure, it is necessary to fully understand the occurrence of this situation.
Landing on Mars requires not only the physical fitness of astronauts, but also the psychological quality of astronauts.
The last one – radiation.
Flying to Mars in the vast universe, astronauts have to encounter a lot of cosmic radiation, how to deal with it?
This has to be prepared in advance.