LIVE: Chang'e-3 lunar probe and rover, CZ-3B - Xichang - December 1, 2013

[plutogno]

Are there high-res LRO maps of that area?

I don't believe the exact coordinates of the landing site they are aiming for have been revealed. so it's too early to say whether it has been covered by LRO or not.

[Phil Stooke]

I don't think the rover or lander cameras are deployed during flight.  Exception - the descent camera, of course.  As for LRO coverage, pretty much the entire landing area has been imaged with this in mind, so there is a very good chance that the site will have been imaged by the narrow-angle camera.

[bolun]

ESA’s New Norcia station to support Moon landing

On Saturday, 14 December, ESA's 35m deep space station at New Norcia, Western Australia, will support the descent and surface operations of China's Chang'E-3 lander. Details later. Tracking support begins at 11:41 UT (12:41 CET) and continues until 18:30 UT (19:30 CET). More details later.

http://blogs.esa.int/rocketscience/2013/12/11/esas-new-norcia-station-to-support-moon-landing/

[Apollo-phill]

I have not seen it defined specifically anywhere - only hints - but is it possible that the Change'3 lander may be employing a 3D Flash LIDAR camera to provide an autonomous landing and hazard avoidance capability ?

A similar American camera - the Advanced Scientific Concepts Inc 3D flash LIDAR camera - can generate upto 30 3D images per second at ranges from 10,000 to 1 meter. It does his by capturing the time-of-flight round trip of a laser pulse providing range distance on each pixel in its focal plane array with each laser pulse (sic ASC Inc). This data is used to create a real time 3D representation of the scene and is used to determine velocity. Comparing this data with stored map information can be used to determine general location. Software can also use this images to avoid landing hazards. I understand that ASC Inc flew early versions - successfully - on Shuttle missions on 15 July 2009 and 24 February 2011.AN ASC Inc unit fits easily onto on open hand palm to give some idea of size.

I'll be interested to see documentation that may be released by Chinain due course.


Phill Parker

[savuporo]

I have not seen it defined specifically anywhere - only hints - but is it possible that the Change'3 lander may be employing a 3D Flash LIDAR camera to provide an autonomous landing and hazard avoidance capability ?

From the information posted, it seems like the descent camera is a regular CMOS camera, which is helped by a simpler laser rangefinder  - doesnt look like its an actual 3D lidar. So (guessing) its hazard avoidance system is based on combination of visual images plus laser spot ranging - not 3D point cloud of a LIDAR.

Range and velocity measurements are also provided by a large-dynamic-range laser ranging system and a microwave range sensor that become active once the vehicle has reached a certain altitude and orientation above the lunar surface....
 Navigation data is provided by the lander's inertial guidance platform, a laser ranging system and a microwave ranging sensor. At a sensed velocity after a defined burn time, the lander starts the Quick Adjusting Sequence of the descent, performing attitude maneuvers as it closes in on the surface.

Closeup of descent camera here https://twitter.com/GuangLin_Galaxy/status/410528037017354240/photo/1
I could make out "2km-4m" and CMOS from that : )

[scicast]

I am currently working with a team of George Mason University computer scientists and economists on a project called SciCast and we have posted some questions related to Chang'e 3 that I think would be of interest to you...

They are:

Will Chang'e 3's Jade Rabbit Lunar Rover achieve operational status on the surface of the moon?

AND

Will China's Chang'e 3 touch down successfully on the moon's Bay of Rainbows?

SciCast is a prediction market that crowdsources the forecasting of various future innovations in Science and Technology. We have asked over 2,000 questions in fields such as astronomy, nanotechnology, climatology, synthetic biology, and computer science. Participants make their forecasts in SciCast and collectively we'll create a
probabilistic forecast about what is going to happen.

I would like to invite all forum members to join in the project. To be clear, this is a research project funded by the U.S. government and we are not asking for money, nor does it cost anything to participate.

Additionally, anyone who registers will have access to all the data our project generates. They will also be allowed to pose their own questions relevant to their research and professional interests, and they will have the opportunity to interact with other professionals in their own and related fields from around the world.

If you'd like to check it out, visit www.SciCast.org and register. Feel free to email me with any questions at [email protected].

Cheers,
Jessie

[jumpjack]

I collected into my blog all info I found on Change'3 , useful for reference:
http://jumpjack.wordpress.com/2013/12/11/back-to-the-moon-chinese-mission-change3-with-yutu-rover-december-2013/

[QuantumG]

I collected into my blog all info I found on Change'3 , useful for reference:
http://jumpjack.wordpress.com/2013/12/11/back-to-the-moon-chinese-mission-change3-with-yutu-rover-december-2013/

Well done, thank you.

[waja2000]

By the way, same document above is useful to compare engines powers:

Apollo: variable thrust between 1000 and ~10000 lbf (~ 4400 to 44000 N)
Chang'e3: 1500 to 7500 "cattle cows" (lbf or N??) ; weight = ?

Can anybody confirm my calculations?

Chang'E 3 weight is 3780kg include 140kg jade rabbit rover. and confirm 4 meter height drop to surface. 


Chang'e3 drop test, yesterday news image

[groovy]

I have not seen it defined specifically anywhere - only hints - but is it possible that the Change'3 lander may be employing a 3D Flash LIDAR camera to provide an autonomous landing and hazard avoidance capability ?

From the information posted, it seems like the descent camera is a regular CMOS camera, which is helped by a simpler laser rangefinder  - doesnt look like its an actual 3D lidar. So (guessing) its hazard avoidance system is based on combination of visual images plus laser spot ranging - not 3D point cloud of a LIDAR.

Range and velocity measurements are also provided by a large-dynamic-range laser ranging system and a microwave range sensor that become active once the vehicle has reached a certain altitude and orientation above the lunar surface....
 Navigation data is provided by the lander's inertial guidance platform, a laser ranging system and a microwave ranging sensor. At a sensed velocity after a defined burn time, the lander starts the Quick Adjusting Sequence of the descent, performing attitude maneuvers as it closes in on the surface.

Closeup of descent camera here https://twitter.com/GuangLin_Galaxy/status/410528037017354240/photo/1
I could make out "2km-4m" and CMOS from that : )

Actually you can find  the on-board instrument's introduction material from here

http://forum.nasaspaceflight.com/index.php?topic=26848.msg1127307#msg1127307

And Galactic Penguin SST already translated them to English.

[AJA]

This might've been mentioned before, but I haven't managed to pick it up.
What's the maximum tilt that the lander can handle, and the maximum impact velocity that the legs can handle?

Note: Found this really interesting Collect Space thread - http://www.collectspace.com/ubb/Forum29/HTML/001189.html
..and the IEEE paper linked in there (behind a paywall unfortunately, so I haven't read it) - http://ieeexplore.ieee.org/iel5/5440860/5446655/05447029.pdf

You read about all the design stories, the vibration isolation payload mounts to the rockets, the mass reductions, and you construct this image of a fragile machine in your mind. It's reinforced by the fact that they can't afford "packaging" material (thermally, or mass wise) and the innards are all visible (as opposed to coming in a neat basic geometric object form factor).

And then you read about them being dropped like rocks onto the ground from several metres up. Man, I love spaceflight.

Navigation data is provided by the lander's inertial guidance platform, a laser ranging system and a microwave ranging sensor. At a sensed velocity after a defined burn time, the lander starts the Quick Adjusting Sequence of the descent, performing attitude maneuvers as it closes in on the surface.

How is it getting navigational data through laser ranging? Is it ranging itself from the orbiter (which, in turn, is being ranged from Earth/terrain matching)

cheng: 12/08/2013 12:22 CST
落月：9小时候月面留影
...
Then the rover will control the transfer mechanism to descend to the surface of the moon, and drive itself away from the lander.

The rover controls the ladder on the lander?

[Steven Pietrobon]

I remember seeing a 15° maximum landing angle for Chang'e 3. Dropping from 4 m on the moon would be like dropping from 0.66 m on Earth. Fall time on the Moon is 2.22 s giving a velocity of 3.6 m/s.

[plutogno]

I collected into my blog all info I found on Change'3 , useful for reference:
http://jumpjack.wordpress.com/2013/12/11/back-to-the-moon-chinese-mission-change3-with-yutu-rover-december-2013/

I don't expect images from the descent camera to be streamed live. that's a lot of data to transmit, and there are surely more urgent engineering data to relay to Earth during the phase. don't forget that even the Apollos did not transmit video during the descent. the Apollo descent videos were filmed on 16 mm film and were only released after astronauts returned to Earth.
expect video from CE-3 to be stored on board and to be released a couple of days (or more) later.

[jumpjack]

don't forget that even the Apollos did not transmit video during the descent. the Apollo descent videos were filmed on 16 mm film and were only released after astronauts returned to Earth.

I think it's just because they were using a couple of Commodore 64s as a navigation computer and a 2400 bps modem for data transmission.   

[jumpjack]

New news site:
http://www.xinhuanet.com/english/special/change3/

[jumpjack]

While we wait:
Chang'e is equipped with UHF transmitter which can operate at 4 different data rates, to optimize energy consumption while communicating with the rover as it keeps getting far from the lander.
UHF is used because it is not affected by lunar dust [which could be picked up during landing].
Main task of UHF device on the lander is to send commands to the rover.
There are two separated channels for telemetries and scientific data.
The rover can both communicate with Earth through the lander and directly.
http://www.chinesetoday.com/big/article/824904

Interesting infographics:
http://news.xinhuanet.com/english/photo/2013-12/11/c_132958075.htm

[Blackstar]

How is it getting navigational data through laser ranging? Is it ranging itself from the orbiter (which, in turn, is being ranged from Earth/terrain matching)

I suspect that it is some sort of terrain mapping, just like cruise missiles use. The computer knows the height profile of the terrain, so if the laser measures something like 1-1-2-3-2-1-1-1-2-2-2-1 for height, that matches the map it has in its memory. Combine this with the inertial system and other inputs.

[Danderman]

How is it getting navigational data through laser ranging? Is it ranging itself from the orbiter (which, in turn, is being ranged from Earth/terrain matching)

I suspect that it is some sort of terrain mapping, just like cruise missiles use. The computer knows the height profile of the terrain, so if the laser measures something like 1-1-2-3-2-1-1-1-2-2-2-1 for height, that matches the map it has in its memory. Combine this with the inertial system and other inputs.

This goes back to the digital altitude map I referred to earlier, and implies that landings in the dark are possible.

[savuporo]

I don't expect images from the descent camera to be streamed live. that's a lot of data to transmit, and there are surely more urgent engineering data to relay to Earth during the phase. don't forget that even the Apollos did not transmit video during the descent. the Apollo descent videos were filmed on 16 mm film and were only released after astronauts returned to Earth.
expect video from CE-3 to be stored on board and to be released a couple of days (or more) later.

Actually, i would think exactly the opposite. Remember, this is mostly an engineering validation mission first, and the most risky part is the landing. In the landing phase, it would apprear that camera is their primary guidance sensor. Should something go wrong and it goes splat, you want to have the critical sensor data available to reconstruct what might have happened.
They are using X-band which gives you a pretty wide link budget, and if they are using digital video compression at all you can easily fit low resolution video layer in the bandwidth.

EDIT: Some indication on what the data rates might be:

While in lunar orbit, Chang’e-2 was able to relay digital images at 2 megabits per second, and at the more distant SEL-2 point, it achieved 750 kilobits per second. For the Toutatis encounter, the rate, via the probe’s 0.6-meter high-gain S-band antenna, was down to just 20 kb/s.

And further, from here : http://www.lpi.usra.edu/sbag/meetings/jan2013/presentations/sbag8_presentations/TUES_0930_CE_Toutatis.pdf

Testing technologies such as 12 Mbps high-speed data transmission, low density parity check coding (LDPC), light-weight CMOS monitoring and landing cameras

Presumably that refers to the X-band transmitter capability testing

Another thing i found from that presentation : http://moon.bao.ac.cn/ , translated through baidu
Seems like some Chang'e-2 data sets  ??

EDIT: actually, this http://159.226.88.59:7779/CE1OutENGWeb/step.jsp

2. According to the regulations, currently all the level 2 and level 3 scientific data of CE-1 are open to the public. A user can download the data after registering on the website.
    3. The CE-2 data are now within the proprietary status, and users should submit the “CLEP Science Data Application Form” to the engineering center in case they need the CE-2 data. GRAS will provide the users with the corresponding science data within 10 days upon receiving the application form from the engineering center;

[Phillip Clark]

Re lunar  landings in the dark, remember that the Luna sample-return missions carried out their work on the lunar surface both during local daytime and during local night-time.

So landings in darkness are not unprecedented.   Of course, the sample-return missions were not carrying solar panels.