Why has Dongfanghong No.1 still not fallen into the atmosphere?

2020-10-21 | Science on the planet Original |

Today, artificial satellites are the largest, most versatile and fastest-growing spacecraft launched by mankind. As the first artificial earth satellite in China’s aerospace history, Dongfanghong-1’s successful launch has made China the world’sThe fifth country that can independently develop and launch satellites is of epochal significance. The sensation caused at that time is definitely not lost to the launch of Tianwen-1.

It is reported that when Dongfanghong-1 was designed, it only had a flight life of 20 days, but in fact it worked for 28 days. What is more surprising is that it has been in operation for 50 years. So Dongfanghong-1Why can we circle the earth for decades without falling into the atmosphere?

Dongfanghong-1 satellite.

On April 24, 1970, the Dongfanghong-1 satellite independently developed by China carried the Long March 1 rocket successfully ascended to the sky at the Jiuquan Satellite Launch Center in Gansu, and entered the scheduled orbit at 21:48 on the same day-the perihelion isAn elliptical orbit with an apogee of 441 kilometers, an apogee of 2368 kilometers, and an inclination of 68.44 degrees.

According to the data, the Dongfanghong-1 satellite has a diameter of about 1 meter, a weight of 173 kg, and a shape similar to a sphere. The outer skin has 72 faces and there are several long antennas outside. Its transmitting and tracking receiving technology is ChineseIt is the first time for aerospace to test the achievements of launch vehicle development, satellite development, and ground inspection system construction.

Its main work content is to measure satellite engineering parameters and space environment and carry out orbital measurement and control, and play the song "Dongfanghong" in space. Due to conditions, Dongfanghong-1 was only equipped with silver-zinc battery packs.

So the scientists originally designed it for a lifespan of only 20 days, but it was not until May 14 that Dongfanghong-1 successfully operated for 28 days to complete various tasks, and stopped signal transmission because the battery was exhausted, officially ending itselfwork……

Dongfanghong-1 is still flying around the earth.

As of now, Dongfanghong-1 has been launched for 50 years, and after 28 days of work, it has completely lost contact with the earth. Dongfanghong-1's orbit is a large ellipse around the earth, and its perigee is 439Kilometers, the apogee is 2384 kilometers, which is the choice of most satellites in this area.

It stands to reason that it can orbit the earth at a constant speed forever. But the facts are not so beautiful. Dongfanghong-1 will still be affected by gravity and slowly slow down its movement speed, and eventually fall into the earth’s atmosphere.And burned out by the atmosphere.

Although the Dongfanghong-1 satellite has already finished its work and lost contact with the earth, my country's aerospace measurement and control team has not given up on tracking and monitoring the Dongfanghong-1 satellite, and is still paying attention to its work. Orbit changes.

Why is Dongfanghong-1 still flying in space?

In fact, this is mainly due to the orbit of Dongfanghong-1. The orbit chosen for Dongfanghong-1's launch was a perigee of 441 kilometers and an apogee of 2,368 kilometers. The initial launch orbit is very high.

This altitude is the choice of many satellites. In this area, its movement is not affected by any, because the earth's gravity is relatively small.

Similarly, Dongfanghong-1 is the same as the space junk in the earth's orbit. It will not be affected by external forces, so it can revolve around the earth day after day.

There is another point of inertia, because the trajectory of Dongfanghong No.1 is an ellipse. When doing circular motion, the centrifugal force and the attraction of the earth balance each other, so under ideal circumstances, there is no air resistance.Down, Dongfanghong-1 will move around the earth forever.

Last point, the service life and operating time of satellites are two different things. Satellites originally have certain functions, but energy is needed to realize these functions. For example, satellites that need to work for a long time usually carry solar panels as their own energy.origin of.


Since Dongfanghong-1 did not carry solar panels at the time, it took 28 days to finish its work. However, the operation of satellites in orbit does not require energy, so Dongfanghong-1 can be in spaceFlying in China for 50 years.

In an ideal state, according to the conservation of momentum, the satellite should be able to maintain its own state of motion, but in fact, the spacecraft on the earth orbit will rub against the earth’s atmosphere at all times, causing speed attenuation, which in turn leads to orbit attenuation, butThe length of time is a matter of time, so one day in the future, Dongfanghong-1 will also crash into the earth’s atmosphere.

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