After the second orbit correction, "Tianwen No. 1" has to consider the issue of keeping warm
Yang Lu Song Xingguang reporter Fu Yifei
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 my country's first Mars exploration mission, the four 120N engines of the "Tianwen-1" probe ignited 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 on orbit.
Up to now, "Tianwen-1" has been in orbit for 60 days, about 19 million kilometers away from the earth, and a flight distance of about 160 million kilometers. The detector systems are in good condition, and the ground measurement and control communication centers and stations are tracking normally.
Midway correction generally refers to the correction of the orbit deviation caused by various reasons during the flight of the probe, so that the probe can fly closer to the theoretical orbit.
According to the Beijing Aerospace Flight Control Center, during the "Tianwen-1" flying to Mars, it will be affected by the gravitational force of the sun and other planets in the solar system. The gravitational force of some planets will interfere with the probe, which will cause it to fly during the long-term accumulation process. The trajectory and speed change.
Because the probe is in unpowered flight for a long time, tiny position and speed errors will gradually accumulate and amplify. The ground measurement and control system needs to fly the probe based on the deviation between the actual flight track calculated by the measured orbit and the theoretical design track during the flight. The orbit is corrected to ensure that the probe is always flying on the predetermined orbit.
The second midway correction is arranged between the first midway correction and the deep space maneuver. It is mainly for correcting the residual error of the first midway correction, aiming at the position of the theoretical deep space maneuvering point, and testing four 120N engines at the same time. spray.
For this reason, the center adopts the orbit control strategy of the second halfway correction and the joint optimization control of deep space maneuvering. Under the premise of meeting the minimum start-up time of the engine this time, for the designated halfway correction time, the orbit control direction is corrected in the inertia by the midway correction. The space search is optimized to minimize the amount of deep-space maneuver control, aim at the nominal near-fire point parameters, and calculate the midway correction control parameters.
Because the "Tianwen-1" launch into orbit and the first midway correction accuracy is very high, this correction amount is very small, the engine startup time is about 20 seconds.
At present, "Tianwen No. 1" is still flying smoothly under the strict monitoring and control of Beijing Flight Control Center, and the mileage is about to reach 200 million kilometers.
Attentive readers may ask: Why is the distance between it and the earth less than 20 million kilometers after flying more than 100 million kilometers?
This is because when the "Tianwen No. 1" is flying to Mars, it flies in an arc along a maneuvering orbit and will keep moving away from the earth.
But at the same time, both the earth and Mars are revolving around the sun in their respective orbits, showing a state of "you go and I go".
Therefore, relative to the space position at the time of launch, the mileage of "Tianwen No. 1" is accumulating rapidly, while the distance to the earth is not so fast.
In a flash, the "Tianwen No. 1" has been flying for nearly two months. The earth has changed from summer to autumn. The northern region of my country will even start heating soon. Need to consider the issue of warmth.
According to experts from Beijing Flight Control Center, as the distance from the sun changes, the attitude of Tianwen-1 will also change: when it was launched, it was closer to the sun, and its solar panels were not directly facing 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, the excess power cannot be consumed, and the battery life will be damaged.
Keeping the windsurfing board at a certain angle can not only meet the power supply needs, but also make the detector body temperature normal.
Compared with the earth, Mars is farther from the sun, and the illumination is less than the average solar radiation constant at the position of the earth. During the process of earth fire transfer, 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 midway correction.
While 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 encounter the situation of insufficient solar heat energy. At that time, it can only receive light energy through solar panels, but does not have enough heat energy to maintain body temperature, which requires it. Power up yourself to heat up and keep your equipment running normally.
However, compared with the heating in our lives, the heating of "Tianwen No. 1" is more accurate.
It can identify which part of the body is too cold, and accurately "heat" according to the area, saving energy while ensuring equipment safety.