Science

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

Perhaps you are tired of hearing about how NASA is doing in space and have seen the great success China has had in space.

Space exploration is no longer the business of one or two countries either, this time we turn our attention to the European Space Agency (ESA). What ESA's spacecraft has experienced is perhaps something no other spacecraft has ever experienced before, is it any different?

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

ESA's Rosetta finally reached its goal after a 10-year chase, where it saw a different kind of landscape. Through the information passed back by the Rosetta, people were deeply aware of the infinite possibilities in interstellar space.

Why did ESA choose a comet as a research object? What process did Rosetta go through? What happens to Rosetta today? And what research has Rosetta provided to scientists? This article will answer these questions from two aspects of ESA's Rosetta and interstellar space exploration, followed by a look at what the spacecraft saw on top of the comet after a 10-year chase of hundreds of millions of kilometers.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

Comet Survey Mission

When Halley's comet re-skimmed the Earth in 1986, many space exploration organizations sent their own probes to explore it, one of the best known being ESA, but it was clear that the comet only passed by the Earth for a brief moment, and further study of the comet would require dedicated followers.

By November 1993, ESA approved the Rosetta mission and established it as a long-term space science program with the primary mission objective of working with Comet 46-P Virtanen. This mission was later shelved, however, and ESA re-established a target for it, comet 67P-Churyumov-Grahimenko.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

After two launch problems, ESA finally launched Rosetta from the French Guiana Space Center in March 2004. After a 10-year chase, Rosetta came close to Comet 67P for the first time, and that's when its general shape really became apparent.

The comet is at least 200~500 million kilometers away from the Earth, and it is so inconspicuous in the dark interstellar space that one would hardly notice the comet if not for close observation. Rosetta was less than 100 kilometers away from the comet when scientists saw the comet, which looked like a potato block.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

ESA's decision to land Rosetta on the comet's surface was a very difficult one for the probe.

The ESA staff even joked that if the landing failed, then everyone would have to be laid off. In order to complete the landing, Rosetta needed to choose a place larger than a soccer field. In the end, under the decision of mission leader Jensen, Rosetta chose a relatively suitable place for landing, which is not good overall.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

With ESA's engineering design, Rosetta carries the Philae lander on top, and the lander system has a harpoon system, which allows the probe to hold on to the comet. As a result, during the mission, the Philae lander did not open the harpoon system in time for the landing, which caused the lander to jump up like a spring and the whole mission almost failed.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

After two landing attempts, the probe finally completed a successful landing and took the first pictures on Comet 67-P. At this point the probe still had 54 hours of power to support its work, and scientists had to make as many detections as possible in the limited time available.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

Celestial bodies from far away

In interstellar space, ESA has used Rosetta to see what a comet really looks like, and also to get a new perspective on what it would be like to be far from the sun. Dark, cold, and with an endless frontier, we were able to see a different view in the photos that came back from Rosetta.

For ESA, such a unique style of scenery is indeed rare, but more important is to complete the relevant mission expedition, although Rosetta after two days because the comet gradually away from the sun, so the solar cells can no longer re-function. Instead, the related study gave scientists a wealth of data, which can provide many new studies in the future.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

Comet 67P looks like a large integrated potato from the image, and of course some say it looks like a rubber duck floating in space. It was not until 2015 that scientists understood through data analysis that this comet is actually a binary comet. That is to say, it is composed of two comets after a slight collision, and finally gradually fused together, scientists speculate that this happened about 4 billion years ago.

Also regarding the study of the comet's topography, it was previously unknown how complex the comet's geography was until high resolution image data was returned, and most people thought the comet was nothing more than a large space rock.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

But in fact Comet 67P has a complex and varied topography, with cliffs and canyons on top of it, in addition to those tiny cracks and dark craters. And the geological state varies from region to region, some are like sand and some are like hardened asphalt.

When we look at the picture of this comet, careful people will find that there seems to be something floating on the comet, what exactly are those white light streaks? In fact, that is the water and various gases evaporated from the comet by the solar wind. The Philae lander has also detected hydrogen sulfide, ammonia and hydrogen cyanide in its sensors.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

In addition, the presence of the amino acids glycine and phosphorus on the comet, which are indispensable key components for life, and which make up DNA and cell membranes, has been detected in related organic matter. These ammonia salts and aliphatic organic compounds have given scientists the audacity to imagine that perhaps life could really come from outer space.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

Further analysis, however, suggests that comets may not have anything to do with extraterrestrial moisture, and in previous scientific explorations, a portion of the population believed that the moisture on Earth may have come from the early impact of comets on Earth. But scientists said after analyzing Comet 67P, the comet does exist above the water, but its chemical characteristics are completely different from the Earth's.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

In terms of ESA's mission execution results, the comet landing mission was quite successful, and despite a few hiccups in the middle, it was the first time ESA had completed a comet landing.

Mission Origin

The whole mission plan has been in ESA before and after 30 years, and in the early years ESA and NASA are related mission cooperation. But the Challenger spacecraft explosion left a shadow on NASA, which also directly led to NASA withdrew from the sample return mission, so the comet-related plans are all in the hands of ESA.

It is not easy to accomplish a comet landing, knowing that comets have more variable orbits than planets and may have many unknown factors. The space probe must be in the right place, at the right time and at the right speed to rendezvous with Comet 67P.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

The U.S. withdrawal also puts a lot of pressure on the ESA, most notably the demand for power. Many previous European spacecraft designs required U.S. nuclear battery technology, such as Voyager and Cassini, so ESA later decided to use solar cells and Russian thrusters.

To ensure that the spacecraft had enough power and landed just right on Comet 67P, scientists designed a circular runway route for Rosetta. Starting from Earth, it passes by Earth and Mars twice and brushes by another comet, making perfect use of the gravitational slingshot effect to power the probe.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

The course of the mission thereafter is basically known to everyone, and the 10-year chase is the most desired cosmic deep space for human beings. The ESA exploration experience can be said to be unique to humans, who were always keen to find the secrets of the planets, but now we know that there are also a variety of possibilities on comets.

10 years of space chase! Spaceship sees another view at a celestial body hundreds of millions of kilometers away

Even eight years after the completion of Rosetta's mission, European scientists are still working on the problem between asteroids and comets, and the relevant data are still being analyzed, and finally the entire mission of ESA is written in the history. Looking into the night sky, those twinkling stars are the signals from the past to the future, and comets are no exception.