Цюэцяо – CZ-4C – Сичан (XSLC) – 20.05.2018, 21:28 UTC

[Astro Cat]

Бгг. Судя по траектории ретранслятора по последнему ролику точка Лагранжа L2 обладает притяжением? Вокруг нее и будет вращаться ретранслятор? )))

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Jonathan McDowell‏Подлинная учетная запись @planet4589 2 ч. назад

The Queqiao communications relay spacecraft, the two Longqiao science satellites, and the CZ-4C third stage rocket are now about 120,000 km from the Moon and will enter the lunar sphere of influence about 2000 UTC.

2 ч. назад

Queqiao will make a 100 km flyby above the lunar surface at 1340 UTC May 25 before heading out to EML2.

2 ч. назад

The CZ-4C third stage will make a 9900 km flyby of the Moon at 1403 UTC May 25 and end up in a 17000 x 444000 km x 14.5 deg orbit in the Earth-Moon system

2 ч. назад

The Longjiang 1 and 2 science satellites are expected to be in a 200 km lunar flyby trajectory and will perform braking burns to enter 200 x 9000 km lunar orbits, inclination unknown

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Jonathan McDowell‏Подлинная учетная запись @planet4589 8 мин.8 минут назад


Queqiao is now 37000 km from the Moon, under 10 hours to flyby closest approach. It should reach EML2 around 0645 UTC May 26.

[sol]

Astro Cat пишет:
Бгг. Судя по траектории ретранслятора по последнему ролику точка Лагранжа L2 обладает притяжением? Вокруг нее и будет вращаться ретранслятор? )))

Ну что Вы.... Это просто точка равновесия сил.
КОгда вы стоите на полу - Вас ведь не пол притягивает...

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Andrew Jones‏ @AJ_FI 52 мин. назад

Queqiao Chang'e-4 satellite performs Moon flyby, makes successful braking manoeuvre

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Andrew Jones‏ @AJ_FI 32 мин. назад

While #queqiao is on its way to the 2nd Earth-Moon Lagrange point, the Longjiang-1 & -2 microsatellites (aka DSLWP-A & B) have successfully entered lunar orbit.

BG2BHC‏ @bg2bhc 33 мин. назад

DSLWP-B now orbiting moon @AMSAT @AmsatUK @cgbassa @n6rfm @scott23192 @ea4gpz @HAMSATNL @HarryKeizer

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Cosmic Penguin‏ @Cosmic_Penguin 2 ч. назад

The perilune burn has been successfully performed at 13:32 UTC and has sent the S/C to a transfer orbit towards EM-L2.

2 ч. назад

Source: https://weibo.com/6528178851/GikE78yqy ...?

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https://gbtimes.com/queqiao-change-4-satellite-performs-moon-flyby-makes-successful-braking-manoeuvre

Queqiao Chang'e-4 satellite performs Moon flyby, makes successful braking manoeuvre
by Andrew Jones | May 25, 2018 18:27 | CHINA ▪ BEIJING ▪ MOON


A rendering of the Queqiao Chang'e-4 lunar satellite performing its communications relay functions beyond the Moon. Chinese Academy of Sciences

The Queqiao Chang'e-4 relay satellite has passed the Moon and successfully performed a propulsive manoeuvre to slow itself and send it towards its intended destination beyond the Moon.

The Beijing Aerospace Control Centre (BACC) issued the command at 21:32 Beijing time (13:32 UTC), and by 21:46 confirmed through telemetry that Queqiao had performed the burn and entered a transfer orbit towards the second Earth-Moon Lagrange point, People's Liberation Army Daily reported.

The spacecraft passed the Moon at 100 km above the surface at closest approach. Failure to perform the braking manoeuvre would have seen the spacecraft head back towards the Earth.

Спойлер

The Queqiao satellite was launched on late on Sunday, and its main role is to act as a communications relay between the Earth and a lander and rover than China aims to launch to the far side of the Moon late this year.

It also carries a pioneering low-frequency astronomy instrument that will attempt to detect a signal from the cosmic dark ages.

For latest news and developments on the mission, see our feature on China's Chang'e-4 mission to the far side of the Moon


An animated demonstration of the role of the Queqiao Chang'e-4 lunar relay satellite. CAS

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Синьхуа

http://www.xinhuanet.com/english/2018-05/26/c_137206894.htm

Chinese relay satellite brakes near moon for entry into desired orbit
Source: Xinhua | 2018-05-26 01:28:23 | Editor: yan

BEIJING, May 25 (Xinhua) -- A Chinese relay satellite Friday braked near the Moon, completing a vital step before entering a desired orbit, according to the China National Space Administration.

The satellite, Queqiao, braked 100 km above the surface of the Moon in line with instructions from a ground control center in Beijing, and then entered a transfer orbit from the moon to the second Lagrangian (L2) point of the Earth-Moon system.

"There was only a short window for the braking," said Zhang Lihua, project manager of the mission. "And Queqiao had only one chance due to limited fuel."

Спойлер

The relay satellite was launched Monday to set up a communication link between Earth and the planned Chang'e-4 lunar probe that will explore the Moon's mysterious far side.

The satellite is expected to adjust orbit several times before it reaches a halo orbit around the L2 point, about 455,000 km from the Earth.

It will be the world's first communication satellite operating in that orbit.

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[hlynin]

del

[tnt22]

Ув hlynin, мне кажется, что  Ваш пост #110 всё-таки более подходит для темы про собственно лунную миссию Чанъэ-4, нежели для данной темы - про ретранслятор для основной миссии. Сама тема основной миссии здесь. 

[hlynin]

согласен. Я просто тему не нашёл - давно не постили. Ладно, перенесу

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Jonathan McDowell‏Подлинная учетная запись @planet4589 11 мин. назад

So it looks like Longjiang-2 (DSLWP-B) is in a 350 x 13800 km x 21 deg lunar orbit. Longjiang-1 seems to have failed on May 21 and presumably remains in distant Earth orbit following its lunar flyby

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https://gbtimes.com/queqiao-update-change-4-lunar-relay-satellite-establishing-halo-orbit-after-approaching-lagrange-point

Queqiao update: Chang'e-4 lunar relay satellite establishing halo orbit after approaching Lagrange point
by Andrew Jones | Jun 01, 2018 09:58 | CHINA ▪ MOON ▪ CHINA'S SPACE PROGRAM


A view of the far side of the Moon and the distant Earth, captured by the service module for the 2014 Chang'e 5-T1 mission. Chinese Academy of Sciences

It has been a week since the Queqiao Chang'e-4 lunar relay satellite made its lunar swing-by, sending it on a transfer trajectory towards the second Earth-Moon Lagrange Point (EML2). There have been no official updates fr om China, so wh ere is the spacecraft now?

Спойлер

Having launched late on May 20 UTC, Queqiao made its lunar swing-by on May 25, performing a braking burn at 13:32 UTC to send the communications satellite towards EML2, some 60-80,000 km beyond the Moon.

EML2 is one of five libration points in the Earth-Moon system that allow a much smaller third body to orbit while maintaining its position relative to the larger two, making it a perfect place for Queqiao to perform its main objective.

Queqiao should have approached the EML2 point by May 29 after two orbital corrections, but no updates have come from China. This has brought confusion, but making the distinction between reaching EML2 and establishing the desired orbit around it helps bring clarity.

On approaching EML2, assuming all is well, Queqiao will have begun manoeuvres required to obtain a halo orbit (or more accurately a Lissajous orbit shown below) around EML2 with a radius sufficient to allow it constant line of sight with both tracking stations on the Earth and the lunar far side, on which a lander and rover are planned to set down in late 2018.


A demonstration of the Lissajous/halo orbit to be used by the Queqiao Chang'e-4 relay satellite mission. CASC

According to the illustration below - showing the planned trajectory, manoeuvres and orbit for Queqiao - the spacecraft will have made a gravitational capture manoeuvre around May 29 to begin a 15-day segment of its journey to obtain a halo orbit around EML2, which is its mission orbit.

This fits with the preliminary flight profile design outlined in an article published in Science China - Technological Sciences in 2017 titled An Overview of the Mission and Technical Characteristics of Change'4 Lunar Probeauthored by senior figures from the China Academy of Space Technology (CAST) and the Institute of Spacecraft System Engineering in Beijing.


A chart laying out the trajectories for the Queqiao Chang'e-4 lunar relay satellite to obtain a halo orbit around the second Earth-Moon Lagrange point.

The paper outlined three transfer options for arriving at EML2, with the lunar swing-by chosen over direct and low-energy transfers. The flight profile outlines that the spacecraft will make three orbital corrections after the EML2 capture phase to establish the halo orbit.

According to the outlined schedule, the halo orbit may not be obtained until mid-June, which may also be the next time we get an official Queqiao mission update. Hopefully this will include images from the onboard cameras.

We are also awaiting an update on the status of the one of two microsatellites (Longjiang-1/-2 or DSLWP-A/B) launched along with Queqiao. While Longjiang-2 successfully entered an elliptical lunar orbit, there has been silence from Longjiang-1.


The Longjiang-1 and -2 (aka DSLWP-A/B) microsatellites launched to the Moon with the Queqiao Chang'e-4 lunar relay satellite on May 20 UTC, 2018. Harbin Institute of Technology

Landing, astronomy and...sample return?

Queqiao is expected to be able to operate in this orbit for at least three years, with the fuel requirement for station keeping at EML2 being relatively low. It will use a 4.2 m diameter parabolic antenna and s- and x-band frequencies to facilitate data relay between the Earth and far side of the Moon.

The lander and rover for the mission, to be launched on a Long March 3B from Xichang in November or December, in March underwent thermal vacuum testing, which are the last of a range of space environment tests which began in January before the Chang'e-4 spacecraft can leave the Assembly, Integration and Testing (AIT) Centre.

After the initial landing and roving section of the mission, with the rover designed to operate for at least three months, a low-frequency radio astronomy antenna, NCLE, will be deployed to determine the activity in the solar system at frequencies between 1-30 MHz, and eventually attempt to detect a signal from the cosmic 'Dark Ages'.

The relay satellite could facilitate future international missions, or a lunar far side sample return with Chang'e-6, should the 2019 near side Chang'e-5 sample return mission be successful.


China's Chang'e-3 lander and Yutu (Jade Rabbit) rover operating on the Moon after landing in late 2013.

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Уже неплохо

Jonathan McDowell‏Подлинная учетная запись @planet4589 23 мин. назад

Report that DSLWP-A1 may not be dead after all. (anyone want to translate the Chinese?). What orbit it's in is another matter...

liuyi‏ @LiuyiYiliu 5 ч. назад

message from Harbin Institute of Technology , confirmed already already received the signal from Longjiang1 (DSLWP-A1).

Joe‏ @zzbar 17 мин. назад

В ответ @planet4589

Received signal from both Longjiang1 and 2, everything normal, the two has not yet synchronized, Can inhale now!

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https://spaceflightnow.com/2018/06/03/chinese-data-relay-satellite-taking-up-post-over-far-side-of-the-moon/

Chinese data relay satellite nears post over far side of the moon
June 3, 2018 | Stephen Clark


Artist's illustration of the Queqiao spacecraft. Credit: China Aerospace Science and Technology Corp.

A Chinese communications satellite carrying a Dutch radio astronomy instrument launched last month is expected to maneuver into position around a gravitationally-stable point beyond the moon in the coming days, ready to relay telemetry and data between Earth and the Chang'e 4 lander set to attempt the first landing on lunar far side late this year.

Launched at 2128 GMT (5:28 p.m. EDT) May 20 from China's Xinhua space center aboard a Long March 4C rocket, the relay probe completed an engine firing as it flew around 60 miles (100 kilometers) from the moon May 25, setting a course for a perch around 280,000 miles (450,000 kilometers) from Earth.

The relay craft is named Queqiao, which means "magpie bridge" and comes from a Chinese folk tale in which a flock of birds form a bridge across the galaxy to reunite two lovers.

Queqiao will park itself in a "halo" orbit around the Earth-moon L2 Lagrange point around 37,000 miles (60,000 kilometers) beyond the moon. At that location, the combined effect from gravity from Earth and the moon will keep Queqiao at roughly the same distance as the moon completes each 28-day orbit.

Спойлер

China developed the Queqiao spacecraft, which weighed roughly 900 pounds (400 kilograms) fully fueled for launch, to link ground controllers and scientists with the Chang'e 4 lander and rover, the country's next robotic mission to the moon.


The Queqiao spacecraft launched May 20 (May 21 in China) aboard a Long March 4C rocket. Credit: Xinhua

Chang'e 4 is scheduled for launch in November or December, and it will attempt the first soft landing on the far side of the moon. A direct radio signal between ground controllers and the Chang'e 4 spacecraft will be impossible on lunar far side, which always faces away from Earth.

The Queqiao relay craft will pass data between mission control and Chang'e 4 during the lander's final descent, and during the rover's drives after touchdown. Carrying a 13.8-foot (4.2-meter) deployable antenna which unfurled shortly after launch, the communications satellite will connect with rover and lander in an X-band frequency, and beam signals to a ground station on Earth in S-band.

After its lunar flyby maneuver May 25, Queqiao is expected to arrive on station in its halo orbit around June 10, according to information released by the China Aerospace Science and Technology Corp.

Then ground controllers will ready Queqiao for its role in Chang'e 4's landing late this year.

Using spare hardware built for China's Chang'e 3 lunar lander and rover, which arrived at the moon in December 2013, Chang'e 4 will target Von Karman crater, an impact site located in the moon's South Pole-Aitken basin.

Some of Chang'e 3's science instruments are still functioning, but the rover ceased driving a few weeks after landing. The Chang'e 3 rover, named Yutu and designed to drive up to 6 miles (10 kilometers), traveled around 374 feet (114 meters) before losing its mobility, according to Chinese scientists.

"There are plenty of successful missions with successful landings on the near side of the moon, including Chang'e 3 in Mare Imbrium," said Jun Huang from the Planetary Science Institute at the China University of Geosciences, in a presentation to U.S. scientists in March at the Lunar and Planetary Science Conference in Texas. "This mission has lasted for nearly five years, and it increased our knowledge about the moon greatly, however, we don't have (until Chang'e 4) a mission dedicated to taking precision mesurements of the far side of the moon."


Diagram of the Queqiao spacecraft's data relay function between Earth and the Chang'e 4 lander and rover. Credit: CASC

There are some key differences between Chang'e 3 and Chang'e 4. For example, the lander heading for the far side of the moon will not carry a robotic arm or an Active Particle X-ray Spectrometer, an instrument capable to measuring the chemical elements in lunar rocks and soil.

In addition to a suite of cameras on both the stationary lander and rover, the mission aims to deliver a new set of sensors to the lunar surface, some of which are provided by European scientists.

The landing module, which will make a rocket-powered landing on the moon like Chang'e 3, will carry a low frequency radio spectrometer developed by Chinese scientists for astrophysics research. A German-developed neutron and dosimetry instrument will measure radiation levels at the Chang'e 4 landing site, collecting data that could be useful in planning human exploration of the lunar far side, studying solar activity, and gauging the underground water content in Von Karman crater.

The Chang'e 4 rover will host a ground-penetrating radar to study geologic layers buried under the landing site, and a visible and near-infrared spectrometer to gather data on soil composition. Chinese officials approved the addition of a Swedish instrument to study the interaction between the solar wind and the lunar surface, which is not shielded by an atmosphere from the bombardment of charged particles originating at the sun.

Chang'e 4 will also deliver to the moon a student-designed carrier containing potato seeds and silkworm eggs. University students and scientists will monitor the growth of the organisms, which will be housed inside a chamber and fed natural light and nutrients once on the lunar surface.

As soon as next year, China plans to launch Chang'e 5, a robotic mission to retrieve lunar samples and return them to Earth.


A camera aboard the Chang'e 3 lander captured this view of the Yutu rover in December 2013. Credit: Chinese Academy of Sciences/NAOC/Science and Application Center for Moon and Deepspace Exploration

Science and technological experiments from the Netherlands and Saudi Arabia are flying on the Queqiao relay craft and two lunar microsatellites that accompanied it to the moon, preceding the international instrument complement on Chang'e 4.

A low-frequency radio receiver on Queqiao was built by a consortium of Dutch companies and research institutions to test the feasibility of using the unique environment near the far side of the moon to probe the ancient universe.

The Dutch payload riding piggyback on the Queqiao mission was developed in less than two years, an unusually fast time for a space instrument, according to Heino Falcke, a radio astronomer at Radboud University in the Netherlands who led development of the Netherlands-China Low-Frequency Explorer.

"This is as much a technological experiment as it is a sociological experiment in collaborating with our Chinese partners," Falcke said in an interview with Spaceflight Now. "This is, to my understanding, the first Western experiment they've had in their exploration program."

It turns out the far side of the moon, and the region of space around it, is prime real estate for astronomers who seek to study a time a few hundred million years after the Big Bang, before the first stars were born, a period known as the cosmic dark ages.

"You had the Big Bang. The universe was cooling, and particles were coming into existence, and at some point it became cool enough that hydrogen was formed, and that's when the universe became optically thin," Falcke said. "So you had this hot plasma, which goes into the neutral hydrogen phase.

"That's 390,000 years after the Big Bang, and that's when you get the cosmic microwave background radiation," he said, referring to the faint heat fingerprint left over from the Big Bang. "Then, for a few hundred million years, there's essentially nothing but this atomic hydrogen, and there's nothing to be seen. It's just an ocean of hydrogen, more or less, with some dark matter in the background. No stars, no planets, no heat or light, except the cosmic microwave background radiation."

Astronomers need to detect low-frequency waves to investigate this part of the universe's ancient past, and Earth's atmosphere blocks most of the signals from reaching ground-based radio observatories. And interference from Earth's own radio emissions introduce noise to listening posts that could be launched into Earth orbit.

The far side of the moon is a "radio quiet" zone free of such interference, and the Netherlands-China Low-Frequency Explorer, or NCLE, aboard the Queqiao spacecraft will demonstrate the potential of sending future radio astronomy missions to such an observation post.


Three antennas for the Queqiao spacecraft's Netherlands-China Low-Frequency Explorer stowed before launch. Credit: ASTRON

The idea for the Dutch-Chinese collaboration hatched in 2015 during a trade mission to China by Dutch King Willem-Alexander, Falcke said. By early 2016, the plans came together and Dutch scientists received the formal go-ahead for the roughly $3.5 million (3 million euro) instrument.

But teams had to design and build the instrument, which includes three extendable low-frequency antennas, without the use of U.S. components. U.S. export restrictions prevent U.S.-built space hardware from launching on Chinese rockets.

Falcke said the antennas for such an experiment would typically purchased from a U.S. contractor.

"They're the main experts for low-frequency antennas," Falcke said. "But that wasn't possible, so we had to build them from scratch."

The three monopole antennas will unfurl to a length of more than 15 feet — about 5 meters — in early 2019, once the Queqiao spacecraft's prime data relay mission is complete, allowing the radio astronomers' tech demo campaign to commence.

Lessons learned from the Dutch-led experiment could help scientists and engineers design more sensitive equipment to fly on future spacecraft, but Falcke said the payload on Queqiao might shed some light on astronomers' long-held questions about the nature of the universe before the first stars formed.

"If we integrate long enough, we could see it," Falcke said. "The reason why I'm careful to not claim that we can is because we have not demonstrated that we can do this ... It's a new receiver, of course, but we are on this satellite on which we don't really know its properties, its electromagnetic properties. It has not been particularly designed to be very radio quiet."

Two microsatellites, dubbed Longjiang 1 and Longjiang 2, accompanied Queqiao on its May 20 launch.

Developed by the Harbin Institute of Technology, the twin Longjiang spacecraft, also known by the acronym DSLWP, were programmed to loop into orbit around the moon as Queqiao flew by en route to its operating station beyond the moon.

Both microsatellites carry amateur radio transmitters, the first such payloads to fly in lunar orbit. But engineers and enthusiasts listening to the Longjiang radio broadcasts apparently lost contact with one of the satellites — Longjiang 1, or DSLWP-A — shortly after it was to enter orbit around the moon, according to a GB Times report.

Amateur radio enthusiasts later reported detecting signals from both microsatellites, suggesting they are healthy after arriving in lunar orbit.

The twin Longjiang spacecraft are designed to fly in formation to validate technologies for low-frequency radio astronomy observations, similar to the objectives of the Dutch experiment aboard the Queqiao relay craft.

The microsatellites also carry optical cameras from Saudi Arabia, another example of the Chinese space program's expanding portfolio of international partnerships.

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[azeast]

http://tass.ru/kosmos/5289664

Спутник-ретранслятор для китайской лунной миссии "Чанъэ-4" вышел на заданную орбиту

Спутник, получивший название "Цюэцяо", вышел на гало-орбиту возле точки Лагранжа (L2) на расстоянии порядка 65 тыс. км от Луны в 11:06 по местному времени (06:06 мск) после более чем 20 дней полета. "Данный спутник стал первым в мире, который начал работу на этой орбите. Он послужит основой для миссии аппарата "Чанъэ-4", который, как ожидается, станет первым в мире зондом, совершившим мягкую посадку на обратной стороне Луны", - приводит агентство "Синьхуа" заявление руководителя Китайской академии космических технологий (CAST) Чжан Хунтая.

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http://www.xinhuanet.com/english/2018-06/14/c_137253216.htm

Relay satellite for Chang'e-4 lunar probe enters desired orbit
Source: Xinhua | 2018-06-14 11:55:14 | Editor: Yurou

BEIJING, June 14 (Xinhua) -- The relay satellite for the planned Chang'e-4 lunar probe, which is expected to land softly on the far side of the Moon at the end of this year, has entered its mission orbit, the China National Space Administration announced Thursday.

The satellite, named Queqiao, or Magpie Bridge, launched on May 21, entered the Halo orbit around the second Lagrangian (L2) point of the Earth-Moon system about 65,000 km from the Moon at 11:06 a.m. Beijing Time Thursday after a journey of more than 20 days.

"The satellite is the world's first communication satellite operating in that orbit, and will lay the foundation for the Chang'e-4, which is expected to become world's first probe soft-landing and roving on the far side of the Moon," said Zhang Hongtai, president of the China Academy of Space Technology.

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Синьхуа

http://russian.news.cn/2018-06/14/c_137253398.htm

Спутник-ретранслятор для лунного зонда "Чанъэ-4" вышел на ожидаемую орбиту
2018-06-14 14:20:11丨Russian.News.Cn

Пекин, 14 июня /Синьхуа/ -- Спутник-ретранслятор для лунного зонда "Чанъэ-4", который будет запущен в конце нынешнего года и, как ожидается, совершит мягкую посадку на обратной стороне Луны, вышел на намеченную орбиту, сообщило в четверг Государственное космическое управление КНР.

Спутник "Цюэцяо" /"Сорочий мост"/, который был запущен 21 мая с космодрома Сичан на юго-западе Китая, вышел на гало-орбиту вокруг точки Лагранжа L2 системы Земля-Луна примерно в 65 тыс. км от Луны 14 июня в 11:06 по пекинскому времени.

Это первый в мире спутник связи, который находится на этой орбите и заложит фундамент для миссии лунного зонда "Чанъэ-4", который предположительно совершит первую в истории человечества мягкую посадку на обратной стороне Луны, сказал президент Китайской академии космических технологий /CAST/ Чжан Хунтай.

Спойлер

Как сообщается, лунный зонд "Чанъэ-4" совершит первую в истории человечества посадку на обратной стороне Луны, но прямая связь с обратной стороны Луны невозможна, и решить эту проблему поможет спутник-ретранслятор, который будет отвечать за передачу сигналов между "Чанъэ-4" и наземной станцией.

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http://www.xinhuanet.com/english/2018-06/14/c_137253487.htm

Relay satellite for Chang'e-4 lunar probe enters orbit
Source: Xinhua | 2018-06-14 15:00:38 | Editor: mmm

BEIJING, June 14 (Xinhua) -- The relay satellite for the planned Chang'e-4 lunar probe, which is expected to land on the far side of the Moon at the end of the year, has entered orbit, the China National Space Administration (CNSA) announced Thursday.

The satellite named Queqiao (Magpie Bridge) launched on May 21 and entered the Halo orbit around the second Lagrangian (L2) point of the Earth-Moon system, about 65,000 km fr om the Moon, at 11:06 a.m. Thursday after a journey of more than 20 days.

"The satellite is the world's first communication satellite operating in that orbit, and will lay the foundation for the Chang'e-4, which is expected to become the world's first soft-landing, roving probe on the far side of the Moon," said Zhang Hongtai, president of the China Academy of Space Technology.

The concept of the Halo orbit around the Earth-Moon L2 point was first put forward by international space experts in 1950s.

While in orbit, the relay satellite can see both the Earth and the far side of the Moon. The satellite can stay in the Halo orbit for a long time due to its relatively low use of fuel, since the Earth's and Moon's gravity balances the orbital motion of the satellite.

"From Earth, the orbit looks like a halo of the Moon, which is wh ere it got its name," said Zhang Lihua, project manager of the relay satellite.

He said the Halo orbit was a three-dimensional irregular curve. It is extremely difficult and complex to maintain the satellite in orbit.

"If there is a tiny disturbance, such as gravitational disturbance from other planets or the Sun, the satellite will leave orbit. The orbit period is about 14 days. According to our current plan, we will conduct orbit maintenance every seven days," Zhang said.

"Queqiao is like a little kid running wild in orbit. If there's even the slightest negligence by our team, the satellite will be lost forever," said Guan Bin, a designer for the satellite's control system.

"It's a new type of orbit, we don't have any experience. We ran a number of simulations to make sure the design is feasible and reliable," Zhang said.

In order to set up a communication link between Earth and the planned Chang'e-4 lunar probe, astrophysicists must keep the satellite stable and control its altitude, angle and speed with high precision.

Next, the team will test the communication function of the relay satellite.