Shanghai, 10 Feb (Xinhua) -- On the opening day of the Beijing Winter Olympics, a blessing from the orbit of Mars traveled through a long interstellar journey of 320 million kilometers to reach Earth. The Tianwen-1 probe, which is on the mainland's first interplanetary exploration mission, sent back to Earth the same frame of photos of the five-star red flag, the emblems of the Beijing Winter Olympics and the Winter Paralympic Games, and sent a "supreme" Winter Olympic gift.
The "Tianwen-1" probe, the five-star red flag and the emblems of the Beijing Winter Olympic and Paralympic Games are once again in the same frame. (Photo courtesy of China National Space Administration)
This precious group photo turned out to be a "cosmic-level selfie", and the retake camera was developed by the 803 Institute of the Eighth Academy of China Aerospace Science and Technology Corporation. According to Wu Di, the designer in charge of the 803 product, the backlash camera is installed at the end of the selfie stick. The selfie stick is a variable structure locking and stretching device, made of special materials, which are in a state of convergence during the launch of Tianwen-1 and its flight to Mars. After reaching the orbit of Mars, the selfie rod is partially heated by the heating plate, so that it is unfolded outwards by four folded and folded states, and the length after full extension can reach 1.6 meters.
"Such a long selfie stick can make the lens of the back-timer camera face the Mars Orbiter and steadily monitor the flight of the Mars Orbiter." Wu Di said, "In order to expand the camera field of view as much as possible, the development team used a lens with a larger field of view, the horizontal field of view and vertical field of view are more than 100 °, and the back-time camera can achieve stable close-up continuous shooting and obtain more flight details." ”
In everyday photography, lighting conditions are very important to the photographer. Taking photos in orbit on Mars, especially selfies, is more difficult. Since the orbiter in mars orbit is in flight, the lighting conditions, the range of illumination, and the angle of the selfie stick after extension will lead to continuous changes in the optical characteristics of the five-star red flag, the emblem of the Beijing Winter Olympic and Paralympic Games, and the orbiter body. The uncertainty created by these changes is the biggest challenge for optical cameras to automatically take pictures.
In addition, due to the use of a lens with a larger field of view, the surrounder "into the mirror" area is large, it may be possible that part is in the extremely bright (illuminated by the sun's rays) state, part is in the extremely dark (shadow area) state, and as the orbiter flies rapidly in orbit, the light and dark areas of the surrounder body are also in change.
"Considering many shooting conditions, we designed an adaptive exposure imaging control strategy centered on the five-star red flag. Through the calculation of the acquired image situation, the exposure time is adjusted autonomously, and in the case of continuous changes in the lighting conditions, it is ensured that a clear five-star red flag image can be obtained. Wu Di said.
In the video transmitted back by "Tianwen No. 1", it can be seen that the position of the golden orbiter reflecting the sunlight is gradually changing, gradually moving from the lower right corner to the middle, until the strong sunlight shines on the five-star red flag, and the five-star red flag is always clearly visible.
Rendering of the actual state of the simulated selfie stick (Courtesy of the Eighth Academy of China Aerospace Science and Technology Corporation)
Since the launch of the "Tianwen-1" probe on July 23, 2020, a variety of cameras developed by the Eighth Academy 803 have shown their skills, and in addition to successfully guaranteeing various engineering survey tasks in the first autonomous Mars exploration trip of the mainland, the "Easter eggs" have been frequently produced, leaving many unforgettable moments, leaving a large number of valuable process images for the mainland's first independent Mars exploration, and enriching the mission results.
For example, on July 27, 2020, the optical navigation sensor on the Tianwen-1 probe "looked back" at the Earth's home 1.2 million kilometers away from the Earth and took a "Group Photo of the Earth and the Moon". The Earth and the Moon, which are in the shape of a "new moon", look at each other and shine in the vast universe.
This is a group photo taken by the Tianwen-1 probe on July 27, 2020 using optical navigation sensors. (Photo courtesy of China National Space Administration)
On October 1, 2020, on the occasion of the national celebration of the National Day and the Mid-Autumn Festival, the "Tianwen-1" probe took a deep space selfie for the first time, and through the way of "separation monitoring", threw out a separation camera, took WIFI communication to transmit back the pictures taken, and expressed birthday wishes to the motherland.
On October 1, 2020, on the occasion of the national celebration of the National Day and the Mid-Autumn Festival, the China National Space Administration released the flight image of the "Tianwen-1" probe, the first Mars exploration mission on the mainland, and the five-star red flag on the map was dazzling, showing a bright Chinese red. (Photo courtesy of China National Space Administration)
On New Year's Day 2022, the "Tianwen-1" probe sent back a set of exquisite images from distant Mars, which was taken by another separate camera and jumped again, and the wonderful picture of the Martian Arctic ice sheet, the local close-up of the orbiter and the surrounding device and the mars was perfectly presented in front of people's eyes, and holiday greetings were extended to the people of the whole country.
The orbiter poses with Mars. Xinhua News Agency (Photo courtesy of China National Space Administration)