[ad_1]
After the second orbit correction, “Tianwen No.1” has to consider the question of keeping warm
Fu Yifei, reporter for Yang Lu Song Xingguang
The reporter learned from the National Space Administration that at 23:00 on September 20, 2020, under the control of the flight control team of China’s first Mars exploration mission, the four 120N engines of the probe “Tianwen-1” lit up for 20 seconds at the same time, successfully completing the second. The sub-orbit was corrected midway and the actual performance of the 120N engine was verified in orbit.
So far, “Tianwen-1” has been in orbit for 60 days, about 19 million kilometers from Earth and at a flying distance of about 160 million kilometers. Detector systems are in good condition, and control and measurement communication centers and stations on the ground perform normal monitoring.
Midway correction generally refers to correcting for orbit deviation caused by various reasons during the probe’s flight, so that the probe can fly closer to the theoretical orbit. According to the Beijing Aerospace Flight Control Center, during the “Tianwen-1” flight to Mars, it will be affected by the gravitational pull of the sun and other planets in the solar system. The gravitational force of some planets will interfere with the probe, causing it to fly during the long-term accumulation process. The trajectory and speed change. Because the probe is in flight without power for a long time, small position and speed errors will gradually accumulate and amplify. The ground control and measurement system needs to fly the probe based on the deviation between the actual flight path calculated by the measured orbit and the theoretical design path during the flight. The orbit is corrected to ensure that the probe is always flying in the predetermined orbit.
The second intermediate correction is placed between the first intermediate correction and the deep space maneuver. It is mainly to correct the residual error of the first intermediate correction, targeting the position of the theoretical maneuvering point in deep space and testing four 120N engines at the same time. spray. For this reason, the center adopts the orbit control strategy of the second midway correction and the joint optimization control of deep space maneuvers. Under the premise of meeting the minimum engine start time this time, for the designated midway correction time, the orbit control direction is corrected in inertia by the midway correction. Spatial search is optimized to minimize the amount of maneuver control in deep space, target the nominal parameters of the near-fire point, and calculate the intermediate correction control parameters.
Because the launch of “Tianwen-1” into orbit and the first intermediate correction precision is very high, this correction amount is very small, the engine start time is about 20 seconds.
At present, “Tianwen No. 1” still flies smoothly under the strict control and supervision of the Beijing Flight Control Center, and the mileage is about to reach 200 million kilometers. Attentive readers may wonder: Why is the distance between him and Earth less than 20 million kilometers after flying more than 100 million kilometers?
This is because when the “Tianwen No. 1” flies to Mars, it flies in an arc along a maneuvering orbit and will continue to move away from Earth. But at the same time, both the Earth and Mars are rotating around the Sun in their respective orbits, showing a state of “you go and I go”. Therefore, relative to the spatial position at the time of launch, the mileage of “Tianwen No. 1” is accumulating rapidly, while the distance to the ground is not so fast.
In an instant, “Tianwen No. 1” has been flying for almost two months, and the land has changed from summer to autumn. The northern part of China will even start to heat up soon, and the “Tianwen No. 1” that “goes to the fire” also I need to consider the issue of warmth.
According to experts at the Beijing Flight Control Center, as the distance from the sun changes, Tianwen-1’s attitude will also change: When it launched, it was closer to the sun and its solar panels were not looking directly at the sun. An angular offset will be added. If the solar panel is facing the sun at that time, it will absorb too much solar energy, resulting in excessive power generation, and the excess power cannot be consumed, which will damage the battery life. Holding the windsurfing board at a certain angle can not only meet the power supply needs, but also make the detector’s body temperature normal.
Compared to Earth, Mars is farther from the Sun and the illumination is less than the average solar radiation constant at Earth’s position. During the terrestrial fire transfer process, the solar energy obtained by “Tianwen-1” will become weaker and weaker. The solar panels are fully deployed to meet the power supply. This windsurfing change will be implemented after the second intermediate correction.
When adjusting the angle of the solar panels, it is also necessary to adjust and control the attitude of the “Tianwen No. 1” itself to ensure that it communicates smoothly with the ground. It is necessary to precisely control the solar windsurfing board and adjust the attitude of the probe, which places high requirements on the attitude control of the Beijing Flight Control Center.
As time goes by, “Tianwen No. 1” will also find insufficient solar thermal power situation. At that time, it can only receive light energy through solar panels, but it does not have enough thermal energy to maintain body temperature, which requires it. Power yourself up to warm up and keep your equipment running normally.
However, compared to the warming in our lives, the warming of “Tianwen No. 1” is more accurate. It can identify which part of the body is too cold and accurately “heat” based on the area, saving energy and ensuring equipment safety.
