China to launch lunar orbiter next week

[gpit]

China counts down to man on moon
Wed Oct 17, 2007 9:43am EDT

BEIJING (Reuters) - China launches its first lunar orbiter next week as it counts down to putting a man on the moon within 15 years, state media said on Wednesday.

Advanced cameras and x-ray "spectrometers" have been installed on the orbiter, the Chang'e One, for mapping 3D images of the moon's surface and analyzing moon dust, Xinhua news agency said.

The next step in the program is to launch a moon vehicle, and bring it back to Earth, and to put a man on the moon "within 15 years", the China Daily said.

"We have taken hundreds of preventative measures directed towards a successful launch," Zhang Qingwei, minister in charge of the Commission of Science, Technology and Industry for National Defense, told reporters.

Zhang said the probe had already been transported to the launch site in Xichang in the southwestern province of Sichuan.

"Although the risks are great, we have confidence it will be a success."

The launch is set for next Wednesday, a date chosen "with the consideration of weather and celestial conditions", Zhang said.

China's space exploration program has come far since late leader Mao Zedong lamented that China could not even launch a potato into space.

In 2003, it became only the third country after the former Soviet Union and the United States to launch a man into space aboard its own rocket. In October 2005, it sent two men into orbit and plans a space walk by 2008.

But China's space plans have faced increasing international scrutiny. Fears of a potential space arms race with the United States and other powers have mounted since it blew up one of its own weather satellites using a ground-based missile in January.

Japan plans to launch its first mission to land a spacecraft on the moon in the next decade -- a feat so far achieved only by the former Soviet Union and the United States.

American Neil Armstrong became the first man to walk on the moon in 1969.

China counts down to man on moon | Science | Reuters

 

[gpit]

The orbiter Chang'e 1 has been successfully launched at Xichang satellite launch center at 18:00pm local time.

The orbit weighs 2.3 tons, spans 18 meter when its solar wings are fully expanded.

If every thing goes smooth, data from the Moon are expected by the end of November.

 

[Tiki Tam Tam]

Congratulations, China!

 

[Sena Lee]

This is good news.

 

[PakForce Unlimited]

Analysts say it is a key step towards China's aim of putting a man on the Moon by 2020, in the latest stage of an Asian space race with Japan and India

Earlier this month, a Japanese lunar probe entered orbit around the Moon.

India is planning a lunar mission for April next year.

Now Asia has its own space race and USA also want to put man back on the moon. Let us see who wins

Link: BBC NEWS | Asia-Pacific | China launches first Moon orbiter

 

[kvLin]

China's first lunar probe completes first orbital transfer
2007-10-25 03:26:21 Xinhua English

BEIJING, Oct. 25 (Xinhua) -- China's first lunar probe Chang'e-1 completed its first orbital transfer Thursday afternoon, another key move in its 380,000 kilometer journey to the moon.

The orbital transfer began at 5:55 p.m. and succeeded after 130seconds. The probe was transferred to an orbit with a perigee of about 600 km, up from the former 200-km perigee, according to the Beijing Aerospace Control Center (BACC).

Chang'e-1, named after a mythical Chinese goddess who, according to legend, flew to the moon, blasted off on a Long March3A carrier rocket at 6:05 p.m. Wednesday from the Xichang Satellite Launch Center in the southwestern province of Sichuan.

The circumlunar satellite will experience another three accelerations, which will further shorten its distance to the moon orbit, Zhou said.

The probe will complete its second orbital transfer on Friday, in which it will enter a 24-hour trajectory and orbit the earth along the new trajectory for three days.

It is expected to enter earth-moon transfer orbit on Oct. 31 and arrive in the moon's orbit on Nov. 5.

The 2,300-kg moon orbiter carried eight probing facilities, including a stereo camera and interferometer, an imager and gamma/x-ray spectrometer, a laser altimeter, a microwave detector, a high energy solar particle detector and a low energy ion detector.

It will fulfill four scientific objectives, including a three-dimensional survey of the Moon's surface, analysis of the abundance and distribution of elements on lunar surface, an investigation of the characteristics of lunar regolith and the powdery soil layer on the surface, and an exploration of the circumstance between the earth and the moon.

The satellite will relay the first picture of the moon in late November and will then continue scientific explorations of the moon for a year.

China's lunar orbiter project has cost 1.4 billion yuan (about 133 to 187 million U.S. dollars) since research and development of the project was approved at the beginning of 2004.

The launch of the orbiter marks the first step of China's three-stage moon mission, which will lead to a moon landing and launch of a moon rover at around 2012.

In the third phase, another rover will land on the moon and return to earth with lunar soil and stone samples for scientific research around 2017.

China carried out its maiden piloted space flight in October 2003, making it only the third country in the world after the Soviet Union and the United States to have sent men into space. In October 2005, China completed its second manned space flight, with two astronauts on board.

Japan launched its first lunar probe, nicknamed Kaguya after a moon princess in an ancient Japanese folktale, in mid-September, and India is planning to send its own lunar probe into space next April.

But Luan Enjie, chief commander of China's lunar orbiter project, said that "China will not be involved in moon race with any other country and in any form."

"China will, in the principle of pursuing a policy of peaceful use of airspace, share the achievements of the lunar exploration with the whole world," he told Xinhua.

 

[Sena Lee]

Thanks for the update kvLin.

 

[Neo]

Congrats China and Chinese friends, its a great day for you!

 

[gpit]

Now Asia has its own space race and USA also want to put man back on the moon. Let us see who wins

Link: BBC NEWS | Asia-Pacific | China launches first Moon orbiter

Referring to BBC link, according to a CCTV interview with an official, no man landing program is planned before 2020.

 

[gpit]

The following is an interesting website of China National Space Administration (CNSA) with respect to China's lunar exploration activities.

http://www.cnsa.gov.cn/n615709/n772514/n772543/index.html

Excerpt:

Orbit Selection for Chang’e-1－－China’s Lunar Exploration Program(&#8547
Date：2007-03-08


Chief Commander for Chang'e Program, Luan Enjie

Orbit selection is a very important part of technical content in Chang’e Program. This is the first time for us to make a voyage of 400,000 kilometers.

Orbit selection should meet the following requirements:

To meet the requirements of the scientific objectives: For observing the global lunar surface to the full extent, the lunar polar orbit is selected.

To meet the requirement of acquiring data with the same resolution: The circular low lunar orbit is adopted.

To meet the requirement of high image resolution: The orbit is kept within 100-200km.

To meet the requirement of one-year lifetime: Considering the abnormality of the lunar gravity field, Chang’e-1 may fall on the lunar surface within half a year if a 100km orbit is selected, so a 200km orbit is selected for Chang’e-1 if it does not conduct special probe for lunar gravity field.

To meet the requirement of lunar coverage: This is easy to be realized, because the Moon has a long rotation period, and the adjacent orbital spacing at the equator

is only 35km, the Moon can be fully covered once every month (27 days). (Here the imaging width of the imaging system should be considered.)

To meet the conditions for illumination: During the flight orbiting the Moon for one year, it can not meet the requirements by only relying on the single-axis rotation of the solar panels, so the satellite is designed to be capable of 90º rotation by adopting two orthogonal flight attitudes.

The included angle between the lunar equator and ecliptic is about 1.5º, so they are nearly parallel.

In the sun, the shadow angle for the satellite is:

and the shadow time is min.

Therefore, during one orbital period, the maximum orbital shadow time is 45min, and the illuminating time is 127-45=82min.

(45min, 82min) occurs when the included angle between the sun and the orbital plane is 0º or 180º.

The short period lunar orbit has a little change, but the long period lunar orbit has a large change because of the complicated lunar gravity field. A circular orbit with an initial altitude of 200km may have an orbit decay of about 100km in a year, so it is very important to keep the orbit altitude of the lunar satellite. The orbit of Chang’e-1 will be adjusted once every two months or so.

A highly elliptical orbit with an apogee of 380000 km is selected to realize the translunar flight. Chang’e-1 will have a perigee of 600km and gradually increase its perigee velocity so as to raise its apogee altitude.

In the current concept, three accelerations will make Chang’e-1’s apogee reach about 51,000km, 71,000km and 120,000km respectively with their corresponding orbital periods 16h, 24h and 48h, which are beneficial to the operation of the ground TT&C system and can realize the conditional orbital waiting.

Lunar acquisition is the most essential point in the orbit design in Chang’e Program. If lunar acquisition is not designed perfectly, the satellite will fly by or impact the Moon, which may lead to grave consequence. With the support of the TT&C system, Chang’e-1 satellite will conduct three decelerations to make its orbital period change from 12h and 3.5h to 127min of a circular polar orbit around the Moon (See the following Figure).

 

[gpit]

If I remember correctly, after the last orbit transfer, the orbiter will leave the gravity of the Earth, traveling towards the lunar orbit with the Moon and orbiter approaching each other. This voyage will take about 7 days.

When it gets close to the Moon, it will reversely propel itself to reduce the speed, so as to be captured by the gravity of the Moon. Once within the gravity, it needs yet couple of orbit transfers to get into a right position.

To use the minimal fuel, there is only one day every month that is suitable for launching a Moon orbiter. Within the day, there are only 35 minutes time window for the launch.

 

[kvLin]

The key orbital transfer will be the 4th out of 14, to enter an 114 hour transfer path towards the moon, and it's when the satellite reaches the perigee again at full throttle.

I think it's something like trapeze or big dipper, to escape from gravit with assistance of inertia force.

 

[gpit]

This is what the orbiter is supposedly to do, more or less , with the following instruments:


To study lunar surface topography using 3D imaging of the lunar surface:

•CCD Stereo Camera
–60 km swath
–120 meter/pixel ground resolution
–0.50 to 0.75 μm spectral range
•Laser Altimeter
–~200 meter footprint
–1064 nm laser wavelength
–~5 meter ranging resolution

To analyze abundance of element and distribution of surface materials on the moon using spectroscopy:

•Imaging Interferometer
–25.6 km swath
–200 meter/pixel ground resolution
–0.48 to 0.96 μm spectral range

•Gamma ray / X-ray Detectors
–Energy range: Th, U, K, Fe, Ti, Si, O, Al, Mg, Ca, Lu, Gd
•Gamma ray: 300 keVto 9 MeV
•X-ray: 0.5 to 60 keV
–Energy resolution:
•Gamma ray: 8% @ 662 keV
•X-ray: 3.3% @ 5.9 keV
–Ground resolution:
•Gamma ray: 170x170 km (cell)
•X-ray: ~10 km (cell)

To survey the global properties of the lunar regolith by measuring surface microwave radiation:

•Microwave Radiometer
–Ground resolution:
•56 km @ 3.0 GHz
•30 km @ others
–Bandwidth and center frequency:
•100 MHz @ 3.0 GHz
•200 MHz @ 7.8 GHz
•500 MHz @ 10.35 GHz
•500 MHz @ 37 GHz

To probe the space environments in the vicinity of the moon:

•High Energy Solar Particle Detector
–Electron energy flux: ≥0.095 MeVand ≥2.2 MeV, 2-channel
–Proton energy flux: 4 –400 MeV, 6-channel
–Alpha-particle energy flux: 13 –130 MeV; 34-260 MeV; 117-730 MeV, 3-channel
•Low Energy Solar Wind Ion Detector
–Energy range: 0.5 –20 keV
–48 energy channels
–3.4°x 180°instantaneous field of view

 

[gpit]

Update: the oribiter is in its 24 hour orbit.

China's lunar probe in good conditions
China's lunar probe in good conditions

BEIJING, Oct. 27 (Xinhua) -- All the systems of China's lunar probe Chang'e-1 are in good conditions with the high energy solar particle detector and the low energy ion detector functioning properly on Saturday, according to the moon probe team.

The Chang'e-1, China's first moon orbiter, is currently moving on a 24-hour orbit with an apogee of 70,000 kilometers after it entered the orbit following its second orbital transfer at 5:33 p.m. on Friday, according to the Beijing Aerospace Control Center (BACC).

The lunar probe has traveled more than 500,000 kilometers so far. It has to travel a total of 1.59 million kilometers before it reaches the moon orbit as planned, said Ji Gang, an engineer of monitoring and controlling branch of the moon probe program.

The BACC said the VLBI beaconing machine on board the satellite has started operation in the early hours on Saturday, and China's four ground monitoring stations with the application of the VLBI, or "Very Long Baseline Interferometry", technology have monitoringChang'e-1.

The VLBI technology helps to reduce the time needed for orbit determination, according Ji.

Ji said the probe will stay on the 24-hour orbit before it moves further from the earth to a 48-hour orbit on Oct. 29, which runs more than 260,000 kilometers.

The satellite is expected to fly to the moon in a real sense after it enters the earth-moon transfer orbit on Oct. 31, and it is planned to arrive in the moon's orbit on Nov. 5.

The lunar probe completed its first orbital transfer Thursday afternoon, in which it was transferred to a 16-hour orbit with a perigee of about 600 kilometers from 200 kilometers.

Chang'e-1, named after a mythical Chinese goddess who, according to legend, flew to the moon, blasted off on a Long March3A carrier rocket at 6:05 p.m. Wednesday from the Xichang Satellite Launch Center in the southwestern province of Sichuan.

The satellite will relay the first picture of the moon in late November and will then continue scientific explorations of the moon for a year.

A telescope used for monitoring China's first moon orbiter, Chang'e-1, is seen at the Urumqi observatory, in Urumqi, capital of northwest China's Xinjiang Uygur Autonomous Region, Oct. 24, 2007. Observatories in Shanghai, Beijing, Kunming and Urumqi monitored the orbiter after it took off at 6:05 p.m. on Wednesday. (Xinhua/Wang Fei)

 

[Bushroda]

Thanks for sharing gpit

Congrtulations to China & Chinese people who made it possible.