After a long space mission, the Rosetta comet probe followed the instructions and hit the surface of the comet and started the detection instrument to record its fall to death, transmitting a close-up of the comet's surface.
Its solitary movement is coming to an end, but with gorgeous syllables: after a long space mission, the Rosetta comet probe, as instructed by the European Space Agency, hit the surface of the comet 67p/churyumov-gerasimenko and turned on the detection instrument, recording its descent to death and transmitting close-ups of the comet's surface. A few seconds before hitting the comet, Rosetta closed down completely and began to slide silently into the abyss of the universe. The British newspaper The Times quoted Mark McColin, senior scientific adviser to the European Space Agency, as saying: "This comet will take Rosetta to jupiter. ”
Comet Rosetta probe
The last time Rosetta received so much attention was in 2014. On November 12, 2014, the Rosetta probe released a lander named Philae, which successfully landed on comet 67p/Chulyumov-Grahimenk (where Rosetta eventually died out) after a seven-hour landing process. The Rosetta probe has made many scientific explorations during its many years of missions, and today I will take stock of this probe.
The so-called comet, the ancients called it "broom star", is a celestial body moving around the sun, from far away from the sun into the interior of the solar system, the brightness and shape will change with the distance between it and the sun, a cloud-like unique appearance, in the back as if dragging a tail (broom). Comet 67p/Chulyumov-Grachymenk is a comet with an orbital period of 6.45 years and a diameter of about 4 km. It reached perihelion (its elliptical orbit closest to the Sun) on August 13, 2015. On 2 March 2004, the European Space Agency launched the Rosetta comet probe with the goal of detecting the comet.
The main imager of the Rosetta probe photographs the comet's neck on September 5, 2014
The Rosetta takes its name from the Rosetta Stone. The stele was discovered in 1799 in the Egyptian harbor city of Rosetta, hence the name. The stele is engraved with three paragraphs written in Egyptian hieroglyphs, popular scripts and Greek. Because the content of the text is exactly the same, scientists finally deciphered the hieroglyphs of ancient Egypt in 1822, opening the door to the historical civilization of ancient Egypt. The discovery of the Rosetta Stone was key to the successful interpretation of ancient Egyptian hieroglyphs. Speaking of comets, it is composed of material from the early days of the birth of the solar system, because of its own extremely low temperature and extremely low temperature in the universe, so in the 4.6 billion years since the birth of the solar system, comets have almost always maintained the initial state of formation, and studying it will help human beings to unravel the mystery of the formation of the solar system. The European Space Agency hopes that the instrument, by detecting comets, can also play a breakthrough role in space exploration, especially in understanding the origin of celestial bodies in the solar system, so it is named after Rosetta. As for the lander "Philae", its name is derived from the name of a small island in the Nile, where an obelisk was found and assisted in the interpretation of the Rosetta Stone.
Rosetta Stone
As early as 1991, the Rosetta Comet Nucleus Sampling Program was included in the plans of the European Space Agency (ESA) and NASA. Scientists plan to use comet probes to send a lander and a return capsule to a specific comet. The lander will then take samples from the comet's surface and return to the capsule to bring those samples back to Earth. They hope the probe will provide information about the early solar system that the comet has preserved for billions of years to study the mystery of the formation of the solar system.
The Rosetta probe was originally scheduled to launch on January 12, 2003, and meet with Comet 46p in 2011, but this plan was canceled by the failure of an Aryan V carrier rocket on December 11, 2002. Missing the launch, the new plan changed the target to Comet 67p, with the probe scheduled for launch on February 26, 2004, and meeting in 2014. However, as the plan changed, the lander equipment had to be modified due to the comet's greater mass and consequent increased impact velocity. After two attempts to cancel launches, the Rosetta probe was finally launched on 2 March 2004 at 7:17 GMT (so-called universal time) at the Kuru Space Launch Center (located in the Kourou region of central French Guiana in northern South America, just off the equator).
Rosetta is targeting Comet 67p – but it needs to undergo four orbital adjustments before arriving. Not only did it complete the orbital braking in orbit around the Earth, flying over the Earth 3 times, and in 2007 it also "passed by" Mars. In these several overflights, Rosetta uses the gravitational pull of Earth or Mars to adopt the principle of relative motion, like a slingshot, to greatly increase the flight speed and save flight energy when flying away.
The trajectory of the Rosetta
Of these four orbital adjustments, rosetta flew over Mars at an altitude of just 250 kilometers in 2007. When it was at the far end of Mars, it couldn't receive any sunlight for 15 minutes, so it couldn't use solar panels, so the entire spacecraft went into standby mode, couldn't communicate, and flew on batteries — however, the orbit change was related to delayed launches and changing targets, and the batteries were not designed for the change, so it was also called a "billion dollar gamble" at the time. Fortunately, the overflight was so successful that rosetta was able to continue its mission.
On August 6, 2014, after 10 years and a flight distance of 6 billion kilometers, Rosetta finally connected with Comet 67p, orbiting the sun at a maximum speed of 135,000 kilometers per hour, less than 100 kilometers away from the comet, becoming the first space vehicle in human history to enter the orbit of a comet. The camera it carried took pictures of the comet's surface. Due to the difficulty of charging the solar panels away from the sun, rosetta experienced 31 months of "dormancy" before January 2014. After the connection, rosetta began to prepare to shoot the lander to land the comet.
The Rosetta probe weighs about 3 tons and is about 12 cubic meters in size, and is equipped with a total of 10 scientific detection instruments for analyzing the physical and chemical composition of comets and their electromagnetic and gravitational properties. It is equipped with a pair of solar arrays each measuring 14 meters long, with an area of more than 60 square meters providing a minimum of 400 watts of power. Rosetta's lander "Philae" will drill a hole in the surface of the comet's nucleus at a depth of more than 20 centimeters, extract material from below the surface of the comet's nucleus, and then put it under the microscope to study, so as to study the surface of the comet nucleus, as well as the composition, hardness, density, etc. under the surface layer, and it will also be equipped with a special camera, which will transmit the photos taken by it back to the earth's ground control center. At the same time, rosetta also observed the gradual sublimation of material (mainly ice) on the comet nucleus as it flew around the comet nucleus, forming a coma and tail.
After the European Aerospace Agency (ESA) issued instructions to the probe, at 4:35 p.m. on November 12 (Beijing time), the Rosetta probe dropped the lander "Philae" 22.5 kilometers from the comet, and because the distance between the Rosetta spacecraft and the Earth exceeded 500 million kilometers, the communication delay between the Rosetta spacecraft and the Earth was as long as 28 minutes and 20 seconds. Then, the instructions issued by scientists will have to wait about 1 hour to know how the lander is performing. After confirming that the lander had sent a signal on the comet, the scientists were really happy, but immediately found that the two "harpoons" on the lander did not "anchor" as expected. The reason the lander designed the Harpoon was that the comet's gravitational pull was only one hundred thousandth of Earth's, and the probe had to anchor to the comet. The failure of the Harpoon system caused the lander's initial landing to rebound.
Photographs of comets taken during the landing of the lander
The site where the lander first touched the comet's surface was called "agilkia", then bounced and hovered in the air for more than 2 hours, eventually stopping at an area called "abydos" on the smaller side of the 67p comet. however. Three days after landing, Philae quickly ran out of the remaining power in its batteries and began to go into deep dormancy, only to briefly wake up and establish communication with the Rosetta probe between June and July 2015, as the comet arrived near perihelion, when Philae's solar panels received more power. The lander encountered great difficulties and lost contact with the earth for a long time.
However, on September 5, 2016, the European Space Agency announced that the high-resolution camera of the Rosetta probe captured on September 2 that the Philae lander was stuck in a dark crack in comet 67p. At that time, Rosetta was only 2.7 kilometers away from Comet 67p, and because of the proximity, the photo resolution reached a staggering 5 cm/pixel, and scientists were able to clearly identify the main body of the Philae lander and the three landing legs.
The location of the "Philae" lander
The image allowed scientists to finally determine the precise position of Philae on Comet 67p and to figure out why Philae had difficulty communicating with Rosetta since landing on Comet November 12, 2014 — Philae was in the shadow of a cliff that could only get an hour and a half of sunlight a day (12.4 hours a comet day), and the lander's solar cells couldn't provide enough electricity for its continued work when there was insufficient daylight.
Identify the body of the Philae lander as well as the three landing legs
Cecilia Tibiana, from rosetta's spectral and infrared remote sensing system (OSIRIS) imaging team, said: "Although Rosetta is only a month away from its mission, it is very happy to be able to photograph Philae and to be able to see such amazing detail. Patrick Martin, ESA's Mission Manager for rosetta, said: "At the end of this long, arduous search, we finally made an amazing discovery. We thought we were going to lose Philae forever, but incredibly, we shot it at the last minute. ”
Although the Philae was discovered, rosetta's life span has come to an end after all. Previously, the nearest distance between Rosetta and the comet was no less than 1.9 kilometers. Now, it's heading toward the comet. Rosetta's descent orbit is designed to maximize the use of solar energy, descending about 19 kilometers or so through about 13.5 hours of freefall (about 1 meter per second in the final stage), and it will not have a chance to take another look at Philae. But its last low-altitude flyby probe is expected to see high-quality images elsewhere in the comet, possibly yielding high-resolution images of millimeter-scale pixels about 15 meters above the comet's surface. Scientists hope to use the onboard camera to see the interesting structure of the crater wall of the "Matt Pit", which may hide the secret of how comet 67p/Chulyumov-Gracimenko formed. Other devices will be used for the first time in history to detect gases, dust and ionized particles. In the last few seconds before hitting the ground, Rosetta struggled to transmit valuable data information.
Rosetta flew towards the comet
Although the lander has been missing for a long time, Rosetta has completed a variety of scientific exploration missions. In addition to the large number of photographs used to study the evolutionary process of comets, Rosetta discovered molecular nitrogen at comet 67p. Scientists believe the discovery of molecular nitrogen suggests that the solar system already had some molecules of life early in its formation. Because the comet comes from the edge of the solar system, the extremely low temperature allows molecular nitrogen to be preserved in a frozen environment, and scientists have previously found similar molecular nitrogen on satellites and planets in orbit on the outer side of the solar system, which can be speculated that there is a larger family of comets behind Comet Glasink, and nitrogen molecules are one of the basic characteristics of this family. In the early explorations, scientists mainly detected nitrogen in ammonia or hydrogen cyanide compounds on titan, Pluto and Neptune's moons, and this is the first time that molecular nitrogen has been found.
In addition, Rosetta discovered that Comet 67p has no magnetic field, allowing scientists to rule out some theories about the mechanism of Earth's formation. Rosetta also found that Comet 67p contains water different from Earth's: much of the gas ejected by 67p is water vapor, and the amount of deuterium in these water vapors is higher than in Earth's water bodies (deuterium is an isotope of hydrogen, and its atomic nucleus has an extra neutron). Rosetta's high-resolution images show that large clouds of gas and dust ejected by the comet comet come from massive collapse voids and cliff collapses on the comet's surface, which explains why the surface of the comet's nucleus is so porous.
Rosetta photographed the surface of the comet's nucleus at close range