Less than half of the success rate of human “fire detection” why step by step

At present, the high-profile multinational exploration of Mars has begun. Due to weather conditions, the UAE Mars rover Hope has postponed the launch until July 17. China’s Mars rover “Tianq 1” has arrived at the Wenchang space launch site, according to the scheduled launch, the launch will take place around July 23.

In fact, compared with Mars exploration, humans have made a lot of attempts to explore the moon, and have achieved great success. On January 2, 1959, the Soviet Union successfully launched “Moon One”, which kicked off the human exploration of the moon; in 1969, American astronaut Armstrong landed on the moon, his small leap on the moon; in 1994, the United States launched the “Clementine” probe, which obtained the most detailed image of the lunar surface at the time, and found that there may be a large amount of water ice in the moon’s south pole; The moon’s thin atmospheric composition is analyzed, and in 2019, China’s Chang’e-4 will realize the first human probe landing and surveillance on the back of the moon.

It’s been more than 50 years since humans first landed on the moon, and Mars is still alive. So what are the differences between Mars exploration and lunar exploration?

Historical mars exploration success rate of only 43%

Mars is one of the most similar planets in the solar system to Earth, and its natural environment is similar to Earth. Humans have been exploring Mars since 60 years ago.

In October 1960, the Soviet Union launched two probes to Mars, Mars 1A and Mars 1B, but unfortunately, the third stage of the rocket after the launch of Mars 1A failed to ignite, only to the ground 120 kilometers high on the scrapping, “Mars 1B” rocket engine directly exploded, the debris falling in the air even contaminated the entire Kobainur launch site.

The U.S. exploration of Mars was also a bad start, and in 1964, the newly established NASA launched the Mariner 3 Mars rover, and when it passed through the Earth’s atmosphere, a shield of the probe failed to roll in, resulting in all the instruments failed to open, and the first attempt by the United States failed.

In October 1964, the Us Mars 4 Mars rover sent back the first closest image of the surface of Mars to Earth, along with more than 5 million bits of scientific information, a mission that could say it ushered in a new era of human space exploration.

However, in the following years, the Soviet Union launched a probe near Mars experienced several failures, the development of the “Mars 2” probe has the ability to land in orbit, but in the course of landing is encountering a large-scale dust storm on the surface of Mars, “Mars 2” head into the basin on Mars, the operation ended with the lander crash. Twenty seconds after the Mars 3 rover landed on Mars, it lost contact with Earth. This is similar to NASA’s experience in 1992, when the Mars Observer quickly lost contact after it entered Mars orbit.

In the 21st century, the exploration of Mars with orbiters ushered in a golden age. The United States and the European Space Agency have successfully launched a Mars rover. India has also joined the Mars exploration race, launching its first Mars Orbiting Mission probe. However, humans are exploring Mars.

The journey has not been smooth. In 2011, Russia’s “Fireone-Soil” interstellar probe failed to put it into orbit to Mars due to engine failure, and the Chinese Mars rover Firefly One also declared the fire failure.

Data show that since 1960, the United States, the Soviet Union/Russia, Japan, Europe and India have carried out 44 Mars exploration projects, but only 23 successful and partially successful missions, with a full success rate of 43%, and the rest have had probes crashed, failed or disappeared. What is partial success? “Such as the Soviet ‘Mars 3’ probe, after landing on Mars, only 20 seconds after the signal lost, some experts say success, some people say not successful, ” Pang Zhihao, the country’s chief scientific communication expert in space exploration technology, explained in an interview with Science Daily. “

One might ask, is the success rate of lunar exploration higher? In this regard, Pang said, the success rate of lunar exploration is not too high, the full success rate of about 53%, especially in the early years, the failure rate is also relatively high. Overall, the success rate is slightly higher than mars, due to different statistical methods, such as differences in understanding of success and partial success, so some statistical results are about 60%, there are statistical results show that 50%.

How difficult it is to explore Mars compared to the moon

In the industry, Mars is known as the “detector cemetery”, its detection difficulty can be imagined.

According to Pang, Mars is about 400 million kilometers away from Earth, and recently about 56 million kilometers, the probe to Mars need to fly such a long distance, launch, orbit, control, communications, power, orbit, landing and other technologies have high requirements.

In terms of launch, the launch capability, orbit accuracy and reliability of the rocket are important prerequisites for the exploration of Mars. The lunar probe’s speed into earth-moon transfer orbit is 10.9 km/s. The Mars rover must reach at least a second cosmic speed (11.2 km/s) to enter the Earth’s fire transfer orbit. Therefore, when launching a lunar and Mars rover of the same mass, the latter must use a more thrust rocket to allow the probe to go directly into the Earth-fire transfer orbit, otherwise it will consume the probe’s own fuel and longer flight time acceleration, which will affect the life of the probe.

“The biggest difficulty with Mars exploration is landing on Mars, which is often called a seven-minute horror process, as it goes through the orbiting, descent and landing process.” It takes seven minutes to reduce the probe’s speed from 20,000 km/h to zero in marsea-thin atmospheric conditions, which requires a combination of aerodynamic deceleration, parachute deceleration and back-pushing, and each link must be accurate and as difficult as “playing a golf ball in Paris to land in a hole in Tokyo,” Pang said.

Pang explained that while Mars has an atmospheric density of only 1% of Earth’s, the rover has one more link to enter the atmosphere and open its parachute than when it lands on the moon. Because the Martian atmosphere can play a certain role in deceleration, so the landing deceleration needs to be particularly precise control, when to enter, enter the posture, angle, etc. can not have the slightest error. However, humans now have a relatively limited understanding of the Martian atmosphere, coupled with the long delay of measurement and control signals, before entering the Martian atmosphere to adjust the posture, angle and speed must be carried out autonomously by the probe. During the rover’s entry into Mars orbit, it cannot be captured by the gravitational pull of Mars and pass over Mars if it is too far away, and if the entry point is too close to Mars, it may crash into the Martian atmosphere. In addition, after entering the Martian atmosphere, the probe should also be self-opening on time to slow down, cut the umbrella on time, on time to drop the bottom, on time to hover the barrier, on time to shut down, etc. , a slight loss will lead to failure.

Because of the distance, it takes 260 to 320 days for the Mars rover to reach orbit, and communication is also a big problem. Radio signals sent from Earth to Mars have a one-way delay of about 20 minutes, Pang said. At the same time, the farther away, the weaker the signal will be, and the noise interference in the universe is a very big challenge for signal inglisal technology. In order to cope with the problem of signal attenuation, the detector needs to be equipped with high gain, high reliable communication equipment, and the ground should also have a large diameter deep space measurement and control antenna, so as to avoid the detector due to communication failure and “lost”.

If all goes well, the probe will finally land on Mars, but it won’t be easy to get it to work. Mr Pang said that working on the moon’s surface would require a long moon night, equivalent to 14 days on Earth, with temperatures as low as minus 180 degrees Celsius. The temperature difference on Mars is not so great, and it is 24 hours a day. But dust storms on Mars are so large that they are six times more powerful than the 12-magnitude typhoons on Earth, which will cover the rover’s solar panels and render it unfunctioning. Historically, the first and second generation mars rovers in the United States were shut down by sandstorms. “This requires a full increase in energy efficiency, including efficient solar cell technology and high-efficiency battery technology, to improve the power quality ratio of energy systems, such as solar panels as much as possible, and higher efficiency of photovoltaic conversion.” Pang said.