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#80 by Phil Stooke on 28 Feb, 2018 03:10
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This paper is currently in press in Planetary and Space Science:
Jia, Y., Zou, Y., Ping, J., Xue, C., Yan, J. and Ning, Y., 2018b. The scientific objectives and payloads of Chang’E−4 mission. Planetary and Space Science, doi: 10.1016/j.pss.2018.02.011.
It is a translation of a paper in the Journal of Deep Space Exploration a month earlier.
It identifies 9 potential landing areas on the far side, 4 in the north, 5 in the south. The Von Karman site discussed for the last year or so is approximately in one of those areas. But this paper favors a site they call S5 which is south of Apollo basin, close to the central SPA region targeted by Moonrise (if it flies). -
#81 by zandr on 12 Apr, 2018 20:00
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http://www.xinhuanet.com/english/2018-04/12/c_137106225.htmQuote
Flowers on the Moon? China's Chang'e-4 to launch lunar spring
BEIJING, April 12 (Xinhua) -- China's Chang'e-4 lunar probe is expected to do many things unprecedented in space history after it launches later this year, such as touching down softly on the far side of the Moon and taking the first flowers to blossom on the lifeless lunar surface.
The probe will carry a tin containing seeds of potato and arabidopsis, a small flowering plant related to cabbage and mustard, and probably some silkworm eggs to conduct the first biological experiment on the Moon.
The "lunar mini biosphere" experiment was designed by 28 Chinese universities, led by southwest China's Chongqing University, a conference on scientific and technological innovation of Chongqing Municipality has heard.
The cylindrical tin, made from special aluminum alloy materials, is 18 cm tall, with a diameter of 16 cm, a net volume of 0.8 liters and a weight of 3 kilograms. The tin will also contain water, a nutrient solution, air and equipment such as a small camera and data transmission system.
Researchers hope the seeds will grow to blossom on the Moon, with the process captured on camera and transmitted to Earth.
Although astronauts have cultivated plants on the International Space Station, and rice and arabidopsis were grown on China's Tiangong-2 space lab, those experiments were conducted in low-Earth orbit, at an altitude of about 400 kilometers. The environment on the Moon, 380,000 kilometers from the Earth, is more complicated.
Liu Hanlong, chief director of the experiment and vice president of Chongqing University, said since the Moon has no atmosphere, its temperature ranges from lower than minus 100 degrees centigrade to higher than 100 degrees centigrade.
"We have to keep the temperature in the 'mini biosphere' within a range from 1 degree to 30 degrees, and properly control the humidity and nutrition. We will use a tube to direct the natural light on the surface of Moon into the tin to make the plants grow," said Xie Gengxin, chief designer of the experiment.
"We want to study the respiration of the seeds and the photosynthesis on the Moon," said Liu.
"Why potato and arabidopsis? Because the growth period of arabidopsis is short and convenient to observe. And potato could become a major source of food for future space travelers," said Liu. "Our experiment might help accumulate knowledge for building a lunar base and long-term residence on the Moon."
The public, especially young people, are being encouraged to participate in the Chang'e-4 mission. The China National Space Administration (CNSA) launched a contest among students across China in 2016, collecting ideas on the design of the payloads.
The "lunar mini biosphere" experiment was selected from more than 200 submissions, according to the CNSA. -
#82 by Phil Stooke on 22 Apr, 2018 18:19
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This link is to the current issue of China's Journal of Deep Space Exploration:
http://jdse.bit.edu.cn/sktcxben/ch/reader/issue_list.aspx
A very interesting set of papers about the CE4 landing site including several suggestions for landing sites and even rover traverse routes. Chinese language with English abstract, but Google document translation will help, and the illustrations carry a lot of information even without translation. Many of these papers will probably appear in English elsewhere at a later date. -
#83 by Galactic Penguin SST on 20 May, 2018 16:37
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I have found some academic papers regarding the scientific instruments on Chang'e 4 from Chinese forums and other websites. Here's a list and some technical specifications of all of them: (info from JIA Yingzhuo, ZOU Yongliao, XUE Changbin, PING Jinsong, YAN Jun, NING Yuanming. Scientific objectives and payloads of
Chang’E-4 mission (in Chinese). Chin. J. Space Sci., 2018, 38(1): 118-130.; doi 10.11728/cjss2018.01.118)
Lander:
1. Landing Camera (LCAM)
2. Terrain Camera (TCAM)
3. Low Frequency Radio Spectrometer (LFS)
A. Lunar Lander Neutrons and Dosimetry (LND) (Kiel University, Germany)
Rover:
1. Panoramic Camera (PCAM)
2. Visible and Near-Infrared Imaging Spectrometer (VNIS)
3. Lunar Penetrating Radar (LPR)
B. Advanced Small Analyzer for Neutrals(ASAN) (Swedish Institute of Space Physics)
Relay satellite:
C. Netherlands-China Low-frequency Explorer (NCLE) (Radboud University Nijmegen, Netherlands)
Of the 6 Chinese instruments, 5 of them are apparently the same model as the ones from Chang'e 3. Only the Low Frequency Radio Spectrometer for radio astronomy observations is new.
The specifications of the instruments are as follows (not sure about some of the translations of the technical terms - I did badly with my undergraduate physics!
):
Landing Camera (LCAM)
Observation Wavelength - 419-777 nm
Focal distance - 4 m - infinity
Effective pixels - >= 1024 x 1024
Observation field - 45 x 45° (error <5%)
Modulation Transfer Function - >=0.20 (all fields)
Signal to noise ratio - >= 40 dB at highest SNR; >= 30 dB for albedo 0.09 and Sun angle 30°)
Terrain Camera (TCAM)
Observation Wavelength - 420-700 nm (with RGB capability)
Focal distance - 5 m - infinity
Effective pixels - >= 2352 x 1728
Observation field - 22.9 x 16.9° (error <5%)
Modulation Transfer Function - >=0.20 (all fields)
Signal to noise ratio - >= 40 dB at highest SNR; >= 30 dB for albedo 0.09 and Sun angle 30°)
Panoramic Camera (PCAM)
Observation Wavelength - 420-700 nm (with RGB and full color capability)
Focal distance - 3 m - infinity
Observation field - 19.7 x 14.5° (error <5%)
Modulation Transfer Function - >=0.20 (all fields)
Signal to noise ratio - >= 40 dB at highest SNR; >= 30 dB for albedo 0.09 and Sun angle 30°)
Low Frequency Radio Spectrometer (LFS)
Observation frequency - 0.1-40 MHz
Receiver Sensitivity - <= 10 nV·Hz^−1/2
Dynamic Range - >= 75 dB
Frequency resolution - 1-10 kHz for 0.1-1.0 MHz range and 100-200 kHz at 1.0-40 MHz range
Visible and Near-Infrared Imaging Spectrometer (VNIS)
Observation Wavelength - 450-950 nm (visual - NIR channel) & 900-2400 nm (NIR - short wave IR channel)
Spectral resolution - 2-10 nm (visual - NIR channel) & 3-12 nm (NIR - short wave IR channel)
Observation field - >= 6 x 6° (visual - NIR channel) & >= 2 x 2° (NIR - short wave IR channel)
Modulation Transfer Function - >0.1
Signal to noise ratio - >= 40 dB at highest SNR; >= 30 dB for albedo 0.09 (Sun angle 45° for visual - NIR channel & 15° for NIR - short wave IR channel)
Lunar Penetrating Radar (LPR)
Channel 1
Transmitter Voltage - 1000 V (error <5%)
Transmitter Pulse frequency - 0.5, 1, 2 kHz
Transmitter Pulse time of arrival - <= 5 ns
Receiver frequency - 10-175 MHz
Receiver input dynamic range - >90 dB
Antenna central frequency - 60 MHz
Antenna bandwidth - >=40 MHz
Standing wave function - <= 3
Maximum detection depth - >= 100 m
Depth resolution - 1 m
Channel 2
Transmitter Voltage - >= 400 V (error <5%)
Transmitter Pulse frequency - 5, 10, 20 kHz
Transmitter Pulse time of arrival - <= 1 ns
Receiver frequency - 10-1000 MHz
Receiver input dynamic range - >90 dB
Antenna central frequency - 500 MHz
Antenna bandwidth - >=450 MHz
Standing wave function - <= 2.5
Maximum detection depth - >= 30 m
Depth resolution - <= 30 cm
And here are the specifications of the European instruments:
Lunar Lander Neutrons and Dosimetry (LND)
Detection capability for:
Fast neutrons - 2-20 MeV (32 channels)
Neutron flux rate - 10-104 min^-1
Protons - 7-30 MeV (32 channels)
Electrons - 60-500 keV (32 channels)
Alpha Particles - 7-20 MeV/n (32 channels)
Heavy ions - 10-30 MeV/n (32 x 32 array)
LET - 0.1-430 keV/μm (64 channels)
Time resolution - 1 min for flux rate; 5 min for protons and electrons; 30 min for heavy ions
Advanced Small Analyzer for Neutrals(ASAN)
Observation range - 10 eV - 10 keV
Mass resolution - Neutral atoms - capable of distinguishing H atoms and +ve ions of mass to charge ratio of 1, 2, 4, 8, 16, 32
Energy resolution - 7% (+ve ions) and 30% (Neutral atoms)
Time resolution - 10 s
Netherlands-China Low-frequency Explorer (NCLE)
Observation frequency/Frequency resolution - 100 kHz∼1MHz/1 kHz; 1∼10MHz/10 kHz; 10∼80MHz/100 kHz
Clock stability - <5 x 10^-11
Receiver Sensibility - <-160 dBm.Hz^-1 (10 MHz)
Dynamic Range - >= 84 dB
Interferometer base line - >400000 km
Interferometer resolution - <= 1 Mbit.s^-1
I'll translate other details mentioned in the paper when I have time. -
#84 by EgorBotts on 21 May, 2018 09:20
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Thanks for these descriptions.
Does is mean that the Queqiao relay satellite doesn't carry a (even low res) camera? I would have hoped for a good PR that they would embed something on the relay spacecraft: their picture of the moon's far side with the earth on the background taken during Chang'e 5 TI is one of my favorite ever. -
#85 by Phil Stooke on 21 May, 2018 22:39
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There is a small camera on one of the small satellites accompanying the relay satellite. It was provided by Saudi Arabia, and I don't think we know much yet about how it will be used.
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#86 by mansourgh on 22 May, 2018 22:17
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Ive read about this from the Saudi Press Agency just yesterday, it didn't specify the Chang'e-4 mission but these are the specs of the camera. It weighs around 630g, a resolution of 38m at 300km and 88m at 9000km from the lunar surface. They even shared pictures of it on the SPA Arabic twitter account.
Link in Arabic *Didn't use google translate as I am an Arabic speaker
https://www.spa.gov.sa/1768149 -
#87 by Steven Pietrobon on 24 May, 2018 06:57
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Here are images of the camera.
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#88 by Phil Stooke on 24 May, 2018 17:19
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"a resolution of 38m at 300km and 88m at 9000km from the lunar surface"
That's not exactly how the text gives those numbers, and they don't sound right - resolution should scale linearly with distance. So the orbit varies from 300 to 9000 km altitude, and the image resolution may indeed be 38 m (per pixel, presumably) at 300 km, but in that case the 88 m is probably the cut-off resolution beyond which they don't take images (at c. 700 km altitude). In other words, imaging only near periapsis. -
#89 by mcgyver on 13 Jun, 2018 07:31
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I cant'find any info about relay satellite status.
Did it arrive at L2?
Is there any official site/twitterpage?
About resolution:
http://win98.altervista.org/telescopio.html
There is a missing "0" in resolution from 9000 km !
Errata:
"a resolution of 38m at 300km and 88m at 9000km from the lunar surface"
Corrige:
"a resolution of 38m at 300km and 880m at 9000km from the lunar surface"
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#90 by mcgyver on 15 Jun, 2018 06:44
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Queqiao in position!
http://spacenews.com/change-4-relay-satellite-enters-halo-orbit-around-earth-moon-l2-microsatellite-in-lunar-orbit/
Saudi Arabia camera first image:
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#91 by mcgyver on 15 Jun, 2018 06:50
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Better images from Saudi Arabia camera onboard Longjiang-2 satellite, the only survivor of the two small satellites launched together with Queqiao:
http://www.planetary.org/blogs/jason-davis/2018/20180614-longjiang-2-earth-pics.html -
#92 by mcgyver on 19 Jul, 2018 07:00
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did anybody find any official site with regular updates on the mission? (both satellite and lander)
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#93 by GELORD on 16 Aug, 2018 02:09
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China Focus: China unveils Chang'e-4 rover to explore Moon's far side
BEIJING, Aug. 15 (Xinhua) -- China's moon lander and rover for the Chang'e-4 lunar probe, which is expected to land on the far side of the moon this year, was unveiled Wednesday.
Images displayed at Wednesday's press conference showed the rover was a rectangular box with two foldable solar panels and six wheels. It is 1.5 meters long, 1 meter wide and 1.1 meters high.
Wu Weiren, the chief designer of China's lunar probe program, said the Chang'e-4 rover largely kept the shape and conditions of its predecessor, Yutu (Jade Rabbit), China's first lunar rover for the Chang'e-3 lunar probe in 2013.
However, it also has adaptable parts and an adjustable payload configuration to deal with the complex terrain on the far side of the moon, the demand of relay communication, and the actual needs of the scientific objectives, according to space scientists.
Like Yutu, the rover will be equipped with four scientific payloads, including a panoramic camera, infrared imaging spectrometer and radar measurement devices, to obtain images of moon's surface and detect lunar soil and structure.
It will also endure vacuum, intense radiation and extremes of temperature. The moon has a large temperature difference between day and night, which can reach more than 300 degrees Celsius.
Both the lander and rover will carry international payloads for other countries.
The Chang'e-4 lunar probe will land on the Aitken Basin of the lunar south pole region on the far side of the moon, which is a hot spot for scientific and space exploration.
Direct communication with the far side of the moon, however, is not possible, which is one of the many challenges for the Chang'e-4 lunar probe mission.
China launched a relay satellite, named Queqiao, in May, to set up a communication link between the Earth and Chang'e-4 lunar probe.
The global public will have a chance to name the rover, according to State Administration of Science, Technology and Industry for National Defense.
Participants can submit their proposed names for the rover through the internet from Aug. 15 to Sept. 5, and the official name will be announced in October after several selection rounds.
Winners will be rewarded at most 3,000 yuan and invited to watch the lunar probe launch.
The name Yutu was chosen from 200,000 proposals submitted over two months worldwide.
http://www.xinhuanet.com/english/2018-08/15/c_137393174.htm
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#94 by SciNews on 16 Aug, 2018 17:51
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Chang’e-4 lunar rover
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#95 by Phil Stooke on 19 Sep, 2018 19:38
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http://www.spaceflightfans.cn/39192.html#more-39192
Summarizing from the above link, using Google translation:
The Chang'e 4 rover will have a name soon. A competition was held starting on 15 August, and on 18 September a shortlist of the many submitted names was announced after a meeting in Beijing.
The shortlisted names are:
dream-by-dream
Guangming [= bright or brightness]
Yutu No.2
exploration
journey
elf
fearless
Wangshu (one of the former kingdoms of China 1000 years ago)
walker
golden rabbit
(the first one looks like a bad translation)
The final name will be picked in October. -
#96 by Phil Stooke on 19 Sep, 2018 23:58
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A bit more on the above.
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#97 by Phil Stooke on 20 Sep, 2018 19:48
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https://gbtimes.com/change-4-shortlist-of-10-names-revealed-for-chinas-lunar-far-side-rover?cat=chinas-space-program
Andrew Jones has more details:
逐梦 - Zhu Meng (chasing the dream, dream catching)
光明 - Brightness
玉兔二号 - Yutu II (Jade Rabbit 2)
探索 - Exploration
征途 - Expedition
精灵 - Genius (Fairy or elf)
无畏 - Fearless
望舒 - Wang Shu (a god that drives for the Moon in Chinese mythology; also can be used to refer to the Moon)
行者 - Stroller or Hiker
金兔 - Golden Rabbit
I would interpret 'genius' like the latin 'genius loci' or spirit of a place (in this case the moon), not the modern English meaning of Genius.
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#98 by zubenelgenubi on 02 Oct, 2018 17:59
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Has anyone calculated the launch window in December? I haven't found any such sources.
(Other than CNSA trajectorians and any others who are not at liberty to share their results)
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#99 by Phil Stooke on 07 Oct, 2018 02:09
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I don't know about launch dates, but it's possible to suggest a landing date. Assuming a landing in Von Karman crater, we can see when the sun rises at that longitude. The landing would most likely be a day or two after that, allowing a fairly long lunar day of operation before the first sunset.
The sun would rise at Von Karman on 29 December 2018, suggesting a landing on Dec. 30 or 31. The previous sunset would be on 14 Dec., so a very early December launch might allow a landing before sunset, but I don't think that is likely. Chang'e 3 launched on 1 Dec. and landed on 14 Dec., but that was early in the lunar day, 2 days after sunrise.
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