Shulou(Shulou.com)11/24 Report--

The title of the original text: "the most prolific Mars probe sent the last picture back to Earth."

This may be the last photo sent back by Insight on November 13, 2022. Photo: NASA / JPL-Caltech, whether it's a retreat after years of data collection or a gorgeous disintegration after a free fall, Mars, the red planet, has buried too many explorers. There is no banquet that must come to an end, and the Mars rover Insight is about to be added to this growing list. And the photo above may be the last photo it sent back to the earth's home.

InSight, the Mars rover may not be as familiar as Tianming I, nor nuclear-powered like Perseverance, let alone flying on Mars like Ingenuity. Compared with the previous probes, Insight is just a lander and cannot be moved. But that doesn't stop Insight, which landed in the western part of Mars' Elysium Planitia plain in the early hours of November 27, 2018 Beijing time, as one of the most prolific Mars probes. It was born to study the internal structure of Mars, and it is a pure planetary physical probe.

On the right of the photo at the beginning of the article is the Internal structure Seismometer (Seismic Experiment for Interior Structure,SEIS), the biggest contributor of Insight. Is this a seismograph (or should it be called a "fire seismograph"? Its collection of Martian earthquake data has spawned dozens of papers that have unveiled the mysteries of the interior of Mars. It updated the model of the deep circle of Mars, refreshed people's understanding of the Martian core, detected the strongest earthquake in the solar system outside Earth, and heard the sound of meteorites hitting Mars. It also confirms that Mars is still alive-it still has geological activity. The data it collects is a treasure that humans can still rely on to improve their understanding of the interior of Mars in the coming decades.

Source: SCIENCE Vol 373, Issue 6553 pp. 388-389 DOI: 10.1126 / science.abj8914 at the top of the photo at the beginning of the article is the robotic arm of the Insight. Four years ago, Insight, like a doll, placed the hero seismograph on the surface of Mars so that it could more accurately capture Martian seismic signals.

The photo taken by Insight on November 13, 2022 was taken one minute earlier than the photo at the beginning of the article. Source: NASA / JPL-Caltech, but a photo sent back almost at the same time contains the unforgettable pain of Insight-the thermal sensing physical property box on the left side of the photo (Heat Flow and Physical Properties Package,HP ³). This is a heat flow probe, which is planned to drill five meters below the surface of Mars and use a series of temperature sensors to detect the flow of heat underground on Mars. Because of the special way it is drilled, it is affectionately called "mole" by the researchers. However, due to the misestimation of the friction of the Martian soil, the design of the Mole was flawed and was never able to get into the ground. Although the scientific team tried their best to fix it, after more than two years of trying, they had to accept the failure of the Mole.

In the past four Earth years, Insight has sent back 6600 photos. Looking back at these photos, it is clear that the red dust on Mars gradually covered everything over the course of four years. Insight is powered by solar panels. When it first landed in November 2018, it received 5 kilowatt hours of electricity for each Martian day (the rotation period of Earth and Mars is similar, and one Martian day is about one Earth day). At a news conference on May 17 this year, the Insight mission team said it could only get 0.5 kilowatt hours per Martian day. Now that Mars is entering winter, with more dust and less sunshine, Insight will soon be unable to hold up. The picture at the beginning of the article may be the last picture it sent to us. After that, Insight will lose power and can no longer communicate with Earth.

In the selfie of Insight on December 6, 2018, under the two covers of the instrument platform are its seismograph and heat flow meter. Source: NASA / JPL-Caltech

A selfie of Insight on April 24, 2022. Photo: NASA / JPL-Caltech I don't know whether to say lucky or unlucky, but there are very few dust devil where Insight landed. On the one hand, the sophisticated instruments on Insight are difficult to cope with the interference of dust tornadoes, but on the other hand, dust tornadoes are an excellent dust removal tool when solar panels are covered by dust.

Why was no dedusting device designed during the launch of Insight? For Insight's research and development team, this is one of the most difficult choices in engineering. Whether it is compressed air or similar to the wiper on a car, the dust removal system will increase the weight of the Insight. This will cost more money, both in the design of the probe itself and in sending it to the surface of Mars. For projects that cost nearly $1 billion, the necessity of each system has to be carefully considered. As a result, the R & D team decided that the dedusting system was unnecessary.

The key factor leading to this decision is that the expected duration of the Insight mission is relatively short. In the plan, the Insight mission is scheduled to run 709 Mars days, equivalent to 728 Earth days, from the moment of landing. But now Insight has been operating on the Martian surface for nearly four years, and it has exceeded its service by 100%.

However, the lack of a dust removal system does not mean that the Insight can only be "broken". In addition to expecting occasional dust tornadoes, Insight is also working on its own plight, with a team of engineers trying to use robotic arms to dig dust from the Martian surface. Because Martian dust carries static electricity, the team can use it to clean solar panels on windy days on Mars. Insight was ordered to scoop up a ladle of Martian soil and slowly pour it on the edge of the solar panel, so that the dust originally covered on the surface of the solar panel would be attracted by the newly fallen dust, eventually using dust to remove dust. This witty trick increases the already dusty Insight's energy output by 5% at a time. The research team tried this approach from May 22, 2021, and by May 17, 2022, they had tried it six times. Soon after that, the robotic arm was shut down because of a lack of electricity.

On May 22, 2021, Insight attempted to fight ash with ash. Photo Source: NASA / JPL-Caltech 's last perseverance turn to NASA's news list and you can see that Insight is getting worse:

The headline on May 17, 2022 was "NASA's Insight is still detecting earthquakes as energy levels drop." Insight no longer has enough energy to detect earthquakes throughout the day, so it can only turn off the seismograph during the day and detect earthquakes at night when it is quieter and of higher data quality.

On June 21, the scientific probe of Insight was extended for a few more weeks. The research team decided to extend the use of the seismograph, but this requires higher power consumption, which will cause Insight to run out of power earlier.

On October 7, Insight is waiting for the storm to end. At this point, Insight could only get 275 watt-hours of power per Martian day, and Insight had to shut down the seismograph completely within two weeks of the storm.

On November 1, NASA prepared to say goodbye to Insight. With only 20% of its original generating capacity, Insight had to shut down all its other scientific instruments, leaving only the most sensitive parts of the seismograph to continue to operate. Even so, however, the seismograph can only run for a few more weeks at most. Every few days, Insight sends back two photos to Earth, but the interval is getting longer and longer. Maybe in the future, or after the one at the beginning of the article, Insight will no longer be able to send us a picture of the surface of Mars.

The artistic imagination of Insight before launch. Photo source: NASA / JPL-Caltech is reluctant to admit it, but Insight is about to die. NASA says their Mars relay satellite is still receiving signals from Insight. When they do not receive the "insight" signal twice in a row, they will declare the "insight" mission over.

But that doesn't mean Insight has completely lost its chance. Although the chances are slim, a sudden strong wind may blow off the dust from the solar panels, and Insight will find us again. Until then, the Mars relay satellite will still be listening for possible signals from Insight.

For most of us, maybe it's time to say goodbye to Insight. Of course, the probe that has uncovered countless secrets inside Mars will not be forgotten, and decades later, when humans are finally able to land on Mars, it can be reborn just by wiping the thick dust off its solar panels-or Insight is a good way to get back in touch with Earth when some hapless guy is trapped on Mars to grow potatoes.

References:

Https://mars.nasa.gov/insight/mission/overview/

Https://www.nasa.gov/feature/jpl/nasa-prepares-to-say-farewell-to-insight-spacecraft

Https://www.universetoday.com/155950/insight-is-losing-power-it-probably-will-be-shut-down-in-a-few-months/

Https://www.universetoday.com/158553/this-is-probably-the-last-picture-well-see-from-insight-on-mars/#more-158553

This article comes from the official account of Wechat: global Science (ID:huanqiukexue), written by Wang Yu

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