China Space Military：Recon, Satcom, Navi, ASAT/BMD, Orbital Vehicle, SLV, etc.

[Enemy]

Chang´e-3 probe enters lunar orbit CCTV News - CNTV English

China’s moon probe entered its lunar orbit just hours ago after rocket scientists decided it did not need to perform a third trimming of its trajectory.

Does it mean, it may go through the final stage of landing on the surface before the scheduled landing?

 

[shuttler]

China's Jade Rabbit Moon rover is on its way
By Brian Dodson

December 3, 2013


China's Yu Tu (Jade Rabbit) venturing forth on the lunar surface (Image: Xingua)

China's lunar probe Chang'e-3 was placed into an Earth-Moon transfer orbit on Monday by a Long March 3B launch vehicle from the Xichang Satellite Launch Centre. It has on board a lunar landing module, containing the Yu Tu (Jade Rabbit) lunar rover. If all continues to go well, on December 14 Chang'e-3 will land in Sinus Iridum on the Moon's northern hemisphere. It will be the first spacecraft to make a soft landing on the Moon in 37 years.
Chang’e-3 mission incorporates two major components, a Lander and a Rover named Yu Tu, or Jade Rabbit, named after the companion of the Moon goddess Chang'e in Chinese mythology. The Lander is 0.83 m (33 in) high, the octagonal body is about 3.8 m (12.5 ft) across, and the four extendable landing legs span 4.76 m (15.6 ft). Fully fueled and carrying the Rover, the Lander has a mass of about 3,780 kg (8,300 lb), about 2,600 kg (5,700 lb) of which is fuel for the lunar descent and landing.
The three-stage Chang Zheng 3B (Long March 3B) launch vehicle used to send the Chang'e-3 probe to the Moon is roughly a functional equivalent of the SpaceX Falcon 9.


The three-stage Chang Zheng 3B (Long March 3B) launch vehicle (Image: China Academy of Launch Vehicle Technology)

The Long March 3B is about 55 m (180 ft) in length, has a diameter of 3.35 m (11 ft), and weighs about 426 metric tons at liftoff. The first two stages and the booster rockets use a N2O4/UDMH (Nitrogen Tetroxide/Unsymmetrical DiMethylHydrazine) oxidizer/fuel combination, while the third stage has a cryogenic hydrogen/oxygen rocket engine. The 3B can lift 12 metric tons into low Earth orbit, 5.1 metric tons into a geostationary orbit, and 3.3 metric tons into an independent orbit around the Sun.

The third stage provides two crucial burns; the first occurs just after separation from the second stage. The purpose of this burn is to inject the third stage and the Chang'e-3 probe into a parking orbit. The rocket follows this parking orbit while the proper orientation is achieved for insertion into the translunar orbit.


Orbital maneuvers on the way to the Moon landing (Image: Beijing Institute of Spacecraft System Engineering via Xingua)
A second burn of the third stage engines then pushed the Chang'e-3 into a highly elliptical translunar orbit. Taking the Chang'e-3 to an apogee of 368,000 kilometers, this maneuver was completed about 19 minutes after takeoff. Deployment of Chang'e-3's landing legs and two power-generating solar arrays also was carried out without a hitch. Now the probe will slumber for a few days, until it burns its own engines to enter lunar orbit on December 6.

Then will come the tricky bit, landing safely without any input from controllers on Earth. This requires a combination of inertial guidance, extremely precise range and velocity measurements, image recognition, and a pretty fast computer – not to mention a certain amount of luck.


Landing sequence for Chang'e-3 (Image: Beijing Institute of Spacecraft System Engineering via Xingua)
Chang'e-3 will pass through several distinct stages during the landing procedure. Initially in a circular 100 x 100 km (63 x 63 mi) orbit, it will lower itself into an orbit whose closest approach to the lunar surface is 15 km (9.3 mi). The next step is to break out of that orbit, beginning the landing approach.

As the probe approaches the landing site, it begins to examine the area to look for unexpected hazards. Once over a good tract of land, Chang'e-3 will hover on its rockets, and do a thorough examination of the landing site. It will then avoid any hazards while slowly lowering itself toward the ground. The rockets will cut out when the craft is 4 meters (13 ft) above the soil, allowing it to free-fall until impact with the ground is absorbed by the landing legs. This may sound like harsh treatment, but in a fall of 4 meters under lunar gravity, the impact velocity is only 3.6 m/s, or about 8 mph.


The Yu Tu lunar rover being offloaded from the Chang'e-3 lander (Image: Beijing Institute of Spacecraft System Engineering via Xingua)

Once landed, the Chang'e-3 lander will carry out some housekeeping tasks and then unload the Yu Tu rover. The lander uses a combination of solar panels and a radioactive thermoelectric generator to supply its power needs, both for operating electricity and for heating during the two week lunar nights. The rover uses only solar panels and batteries to operate during the days, and to store maintenance power for the nights.

Each wheel of the six-wheeled rover is powered by an independent brushless DC motor. When combined with a rocker-bogie suspension system similar to that used by the Mars rovers, the Yu Tu can travel at an amazing one-eighth of a mile per hour, climb 20 degree slopes, and roll over obstacles 20 cm (8 in) in size. The rover is steered by a control system that integrates local hazard analysis with teleoperation by controllers on Earth.


Artist's model of the Chang'e-3 lunar lander on the Moon's surface (Image: Xingua)

The lander comes equipped with a sophisticated assortment of scientific instrumentation. One is the Lunar Ultraviolet Telescope, or LUT. It is designed to act as a long-term astronomical observatory, the first ever placed on the Moon's surface. The vacuum environment and slow rotation of the lunar environment make an ideal location for near-UV observations that cannot be carried out from beneath the Earth's obscuring atmosphere. The LUT is a 15 cm (6 in) aperture Ritchey-Chretian telescope equipped by a CCD image sensor sensitive to light having wavelengths between 245 and 340 nanometers.

Another optical instrument is the Extreme Ultraviolet Camera intended to monitor the Earth's plasmasphere, which is a magnetically active region within the magnetosphere but above the ionosphere. It works by viewing light with a wavelength of 30.5 nm which is scattered from helium ions in the plasmasphere. The lander is also hosting several other cameras and a lunar soil probe.


The Yu Tu (Jade Rabbit) lunar rover (Image: Xingua)


Jade Rabbit is arguably fitted out with more sophisticated scientific equipment than any previous rover. Most notable is a powerful ground-penetrating radar capable of penetrating up to 30 meters (100 ft) of lunar soil or about 100 m (330 ft) of lunar crustal material, and analyzing the underlying structure.

The rover is also equipped with an Alpha Particle X-ray Spectrometer (APXS) installed with a sensor head on a robotic arm. The electronics inside remain protected within the rover. APXS, which comes equipped with a 30 millicurie radioactive alpha source, can use particle-induced X-ray emission and X-ray fluorescence to determine the abundance of elements within rock and soil samples, and can also find hidden materials, such as water of crystallization, which is otherwise difficult to detect remotely.

An imaging spectrometer that operates in the visible and near-infrared can quickly obtain data that can guide an initial guess for the identity of a mineral found during a lunar survey. The design that made its way onto the Yu Tu rover is particularly sophisticated, using an acoustic-optic tunable filter to control the imaging wavelengths. Again, there are additional stereo imaging and other special-purpose cameras.


X marks the spot? Conjectured landing site for Chang'e-3 within Sinus Iridum (Image: NASA)


The landing site for Chang'e-3 is in the general area of Sinus Iridum, the remains of a large impact crater which was subsequently flooded with basaltic lava. A precise location has not yet been announced, but speculation centers in the vicinity of crater Laplace A, a small crater that is nearly on the transition region between the lava floods and the more common crustal formations. An exciting prospect – we are likely to learn something new about the Moon in the next few weeks!

Source: NASA Spaceflight.com

Credit: China's Jade Rabbit Moon rover is on its way

 

[shuttler]

Chang'e 3 Lunar Mission - whole process
Video 3-D animation:

link: 3D动画模拟嫦娥三号发射全程—在线播放—优酷网，视频高清在线观看

 

[JSCh]

Chang´e-3 probe enters lunar orbit CCTV News - CNTV English

China’s moon probe entered its lunar orbit just hours ago after rocket scientists decided it did not need to perform a third trimming of its trajectory.

Does it mean, it may go through the final stage of landing on the surface before the scheduled landing?

The timing of the landing is determined by position of the lunar orbit. Optimally to land on the dawn of a lunar-day. Such that to give Yutu the lunar rover the longest continuous period to work in daylight(lunar daylight lasted about 14 earth-day). Before going into hibernation to endure the lunar night(also about 14 earth-day).

Also the current plane of the lunar orbit of CE-3 do not fly above/over the intended landing site. CE-3 has to wait for the rotation of the moon such that the landing site is under the plane of orbit.

Therefore the answer is no, the landing has to go by the schedule.

 

[Enemy]

The timing of the landing is determined by position of the lunar orbit. Optimally to land on the dawn of a lunar-day. Such that to give Yutu the lunar rover the longest continuous period to work in daylight(lunar daylight lasted about 14 earth-day). Before going into hibernation to endure the lunar night(also about 14 earth-day).

Also the current plane of the lunar orbit of CE-3 do not fly above/over the intended landing site. CE-3 has to wait for the rotation of the moon such that the landing site is under the plane of orbit.

Therefore the answer is no, the landing has to go by the schedule.

Thank you.

So far as I know, such missions are pre programmed, as I listened to a CNTV commentator during the launch. Can the operators upload further commands if they follow any contingency plan?

 

[JSCh]

Yes, they can upload command.

There is a time lapse of about 2 sec. for communications between Earth and Moon. That would hinder time-critical process which require real time response. Because of that the soft landing are autonomous. i.e. the lander processor would make real time decision without Earth response.

 

[Enemy]

Yes, they can upload command.

There is a time lapse of about 2 sec. for communications between Earth and Moon. That would hinder time-critical process which require real time response. Because of that the soft landing are autonomous. i.e. the lander processor would make real time decision without Earth response.

Then contingency plans must be pre programmed if Jade Rabbit is supposed to go full auto. Besides, scientists should find means to reduce the time lapse.

 

[JSCh]

Yes, the lander CE3 presumably would have contingency plans pre-programmed for soft landing.

The time lapse, unfortunately is limited by the distance between earth-moon and the speed of light which is a fundamental limitation. There is no known theory to reduce it unless one resort to exotic science like quantum communication.

It is impossible to know or predict the precise location of the landing spot because of the complexities of the factors involved. Therefore it is impossible to plan for everything only limited scenarios. Jade Rabbit or YuTu which is the name of the rover would have its own direct communication link to Earth. YuTu has to be remote controlled but it is also autonomous in that it is able to automatically avoid hazard and obstacle.

 

[Enemy]

Yes, the lander CE3 presumably would have contingency plans pre-programmed for soft landing.

The time lapse, unfortunately is limited by the distance between earth-moon and the speed of light which is a fundamental limitation. There is no known theory to reduce it unless one resort to exotic science like quantum communication.

It is impossible to know or predict the precise location of the landing spot because of the complexities of the factors involved. Therefore it is impossible to plan for everything only limited scenarios. Jade Rabbit or YuTu which is the name of the rover would have its own direct communication link to Earth. YuTu has to be remote controlled but it is also autonomous in that it is able to automatically avoid hazard and obstacle.

Yes, YuTu is a sophisticated robot.

Quantum communication will be another success, I am sure.

 

[xuxu1457]

The Chang Zheng 4B experienced its first launch failure on 9 December 2013, with the loss of the CBERS-3 satellite. A Chang Zheng 4B launched from LC-9 at the Taiyuan Satellite Launch Centre carrying the CBERS-3 satellite for the China National Space Administration and Brazilian Space Agency，but fail into right obit;
中国-巴西资源1号03星发射失利 未进入预定轨道|轨道_凤凰资讯
This is the 1st fail among 20 launches of CZ-4B rocket, also the 14th launch of China in 2013, the 4th fail of the world in 2013, the 76th launch of the world in 2013;

Long March 4B:
Height45.8 metres (150 ft)
Diameter3.35 metres (11.0 ft)
Mass249,200 kilograms (549,400 lb)
Stages3
Capacity
Payload to
LEO4,200 kilograms (9,300 lb)
Payload to
SSO2,800 kilograms (6,200 lb)
Payload to
GTO1,500 kilograms (3,300 lb)
Associated rockets
FamilyLong March

Launch history
StatusActive
Launch sitesLC-7/LC-9, TSLC
LA-4/SLS-2, JSLC
Total launches20
Successes19
First flight10 May 1999

 

[tomluter]

Unfortunately,CZ-4 was a "Gold" rocket in the CZ series.
There is no more launches before this year end ,I think,Many important launches will be postponed next half year.

 

[xuxu1457]

Unfortunately,CZ-4 was a "Gold" rocket in the CZ series.
There is no more launches before this year end ,I think,Many important launches will be postponed next half year.

I think other 2 lauches will still go on, nothing new for fail if you launch 16 times a year, Russia failed 3 times of 28 launches in 2013

 

[Gessler]

What went wrong?

 

[tomluter]

I think other 2 lauches will still go on, nothing new for fail if you launch 16 times a year, Russia failed 3 times of 28 launches in 2013

We are not Russia,We have sufficient funds,sufficient manpower and slack budget policy for it. and the CBERS-3 was not easy to go this far, many times was faced with termination during the period of cooperation. It is a hit to Brazilian and the coorperation .

 

[shuttler]

I think other 2 lauches will still go on, nothing new for fail if you launch 16 times a year, Russia failed 3 times of 28 launches in 2013

That blemishes our launch-success records a bit but it is still very impressive at 94.65% (otherwise @95.19% if this launch is successful)

List of Long March launches - Wikipedia, the free encyclopedia