According to the National Aeronautics and Space Administration (NASA) official website reported on November 26, at 3:54 am on November 27th, Beijing time, the agency's "Insight" Mars probe ended a six-month journey, sailing 484 million Kilometers, successfully landed on the flat and wide Ehrlich Plain north of the Martian equator, became the first human sentiment to listen to Mars "inner heart". Shortly after landing, the "Insight" passed back the first image of Mars.
NASA Director Jim Bridedenstin said: "Our spacecraft has successfully landed on Mars for the eighth time. The 'Insight' will study the interior of Mars and will provide us with valuable information."
Listen to Mars "inner heart"
NASA has sent a number of messengers to Mars, such as "Courage", "Opportunity", "Curious", etc., but these devices are studied on the surface and the atmosphere. To further understand the internal conditions of Mars, such as what constitutes the Martian kernel, how active geological activities, etc., we must go deep into the Mars underground, which is why scientists send "insight".
The “Evaluation” of “$800 million” was launched on May 5 this year. Lori Graz, Acting Director of the Planetary Science Department of the NASA Scientific Mission Council, said: "Now we will finally explore the interior of Mars - the Martian crust, the mantle and the Earth's core."
The “Insight” will focus on three studies: First, through the “Internal Structure Seismic Test” (SEIS) instrument, measuring the Martian earthquake and the tremor caused by meteorite impact, using the collected vibration data to map the various layers inside Mars, relevant The results of the analysis may help identify liquid water or plumes; the second is to determine the detailed location of the "insight" in space with a pair of extremely accurate radio transmitters, observe how it moves, and gradually map the rotation of Mars. Tiny jitter. These jitters reflect the internal structure of Mars, especially whether the core is solid or liquid (more sloshing); the third is to use the "Heat Flow and Physical Property Detection Kit" (HP3) to measure how the heat rises, helping to find out where the heat comes from. And study how heat flows through the surrounding rocks to learn more about the Martian rock.
Scientists will interpret these data to understand the history, internal structure, and activities of Mars to answer one of the most fundamental problems in the planetary and solar sciences—how the formation and evolution of rocky planets, including the Earth, in the solar system.
Mini satellite report
The "Insight" went to the distant Mars, and every move touched the hearts of the engineers. To determine if the detectors land safely, they usually need a communications satellite that sweeps over the top of the detector at the right time to transmit the data back to Earth.
This time, the "Mars" (MarCO) carried by the "Insight" is used as a "small broadcast." MarCO is a six-unit cube satellite that includes two mini-satellite "Wall-E" and "Eva" (Eva), the first appearance and testing of Cube Satellite technology in deep space. After the successful landing, "Eva" took the first map of Mars.
MarCO Systems Engineer Anne Marina said: "We are preparing for MarCO's next test, when it will serve as a new intermodal communication relay model."
Graz said: "The 'Insight' on the safe landing of Mars is exciting, but the performance and data collected after landing is more exciting. It will begin to collect valuable information about the internal structure of Mars, which will help us Understand the formation and evolution of all rocky planets, including the Earth's homeland."
Mars detection success rate is only 50%
Mars is also about 50 million kilometers away from Earth, and the probes need to fly hundreds of millions of kilometers to reach Mars. They have high requirements for launch, orbit, control, communications and power.
Pang Zhihao, the chief scientific communication expert of space exploration technology in China, told the Science and Technology Daily reporter that the mission to land on Mars is divided into four stages: launch, cruise, descent and landing, and surface operation. Many detectors are "dead" in the down and landing stages. Humans have so far launched more than 40 Mars probes with a success rate of only about 50%, so some people refer to Mars as the "detector cemetery."
Pang Zhihao said that the rocket's carrying capacity, accuracy and reliability are important prerequisites for Mars exploration. It is best to use a large thrust launch vehicle to accelerate the detector to a second cosmic speed of 11.2 kilometers per second, directly into the ground fire transfer orbit, otherwise it will consume the detector's own fuel and longer flight time acceleration, which will affect the life of the detector. . In the Mars program announced in China, the launch of the Long March V rocket with the largest thrust will be used.
Communication is not easy because of the distance. Pang Zhihao said that the radio signal sent from the Earth to Mars has a one-way delay of about 20 minutes, which requires the detector to have strong autonomous control.
At the same time, compared to the lunar probe, the Mars probe has to perform more and more accurate orbit corrections in order to reach the destination accurately. Pang Zhihao said that if the detector has a speed difference of 1 meter per second or a height difference of 1 kilometer in the vicinity of the ground fire transfer orbit, the position error when reaching the vicinity of Mars can reach 100,000 kilometers. The US "Courage" has revised four routes before landing on Mars.
Near Mars, the detector needs to enter Mars orbit accurately. This action is described as "playing a golf ball from Paris and a hole in Tokyo." Pang Zhihao said that if the detector cuts into the orbit of Mars, if the point of entry is slightly farther from Mars, it cannot be captured by Mars. If the point is too close, it may break into the atmosphere of Mars.
At present, there are three main ways for the detector to land softly on Mars: one is the airbag bouncing type, which is simple and low in cost, but can only meet the landing requirements of smaller detectors, and the landing accuracy is not high; Landing leg type, this method is more complicated and costly, but it can meet the landing requirements of heavy detectors, and the landing accuracy is high; the third is the aerial crane type, which is the most complicated, the most costly, and the most advanced technology. Meet the soft landing requirements of larger weight detectors. All of the Mars landers have so far used a rigid reducer and a "disc-seam-belt" parachute program to complete the supersonic deceleration.
However, due to the small density of Mars, the weight of the manned spacecraft is too large, and the three existing landing methods cannot be used. To this end, the United States is developing a new Mars landing device, the "low-density supersonic speed reducer." Pang Zhihao said that when the lander enters the Martian atmosphere at a speed of about Mach 3.5, the device can be inflated as quickly as the Hawaiian squid to increase air resistance and reduce the speed of the lander to Mach 2. At this time, the giant supersonic cyclone parachute with a diameter of 33 meters opened to help the lander safely land. (Reporter Liu Xia Fu Yifei)
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