Sweden joins China's historic mission to land on the far side of the Moon
ANDREW JONES
2016/05/16
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. (Photo: CAS)
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Sweden may not be a country that is readily associated with exploration of the Moon, but the Nordic nation has played an interesting role.
If you’ve seen still images of Nasa's Apollo Moon landings then you’ve witnessed the
work of modified Swedish Hasselblad cameras.
And Sweden’s presence is soon to be felt on the Moon once again, this time on another unprecedented journey - China’s
Chang’e-4 mission to the untouched lunar far side, which is never visible from Earth due to gravitational or tidal locking.
Following an agreement signed with the National Space Science Centre (
NSSC) in Beijing, the Swedish Institute of Space Physics (
IRF) in Kiruna in the country’s remote far north will provide one of the scientific payloads on the mission that will further our understanding of our celestial neighbour.
Above: Kiruna Space Campus (Image: Torbjörn Lövgren, IRF).
Chang'e-4 involves a lander and rover and is currently scheduled to launch in late 2018, once a relay satellite has been sent into a halo orbit around the
Earth-Moon L2 Lagrange point in order to facilitate communication and control of the Chang'e-4 lander and rover on the Moon's far side.
The instrument, developed by Martin Wieser and colleagues in Kiruna, is the Advanced Small Analyzer for Neutrals (ASAN), a detector for
energetic neutral atoms.
It will reveal how solar wind interacts with the lunar surface and perhaps even the process behind the formation of lunar water. An earlier version of the instrument flew on India’s Chandrayaan I orbiter which launched in 2008.
Above: The Advanced Small Analyzer for Neutrals (ASAN) instrument built by the Swedish Institute of Space Physics (IRF) in Kiruna (Image: M. Wieser, IRF).
“In the mission with India we discovered that about 20 percent of this solar wind which hits the lunar surface is reflected back to space as the so-called energetic neutral atoms. That was completely unexpected: The lunar surface is very porous, so it was thought everything would be absorbed," Wieser explains.
"The physics of the reflection process at the surface are still a bit of a mystery...And that's where our interest comes from for trying to put a detector for such energetic neutral atoms directly onto the lunar surface."
This time, the detector will be on the mobile rover which take its instruments away from the contaminated blast area of touchdown and will explore an area of the fascinating South Pole-Aitken Basin.
The NSSC, operating under the Chinese Academy of Sciences (CAS) under
Dr Wu Ji, will be responsible for integrating the payloads onto Chang'e-4, as it does for subsystems for
space science missions and China's
Shenzhou human spaceflight missions and
Tiangong space labs.
Above: A colour-coded topographical map of the far side of the Moon showing the South Pole-Aitken Basin, with blue indicating lowest areas, red the highest (NASA).
Wieser says the sensor will allow scientists to see how solar winds interact with lunar regolith, as the material on lunar surface is called.
And it could give insights into the presence of one of the most interesting and useful compounds on the Moon, which could be harnessed by In-situ resource utilisation (IRSU) techniques for fuel for missions into deep space – water.
“[Solar wind] is one of the proposed mechanisms to produce water on the Moon,” Wieser says. “You have heard the stories that various missions discovered water on the lunar poles, and it's completely unclear so far which mechanism makes it”.
The lunar water present in the permanently shadowed craters at the Moon's poles is attracting a lot of attention, and is crucial to the viability of concepts for a lunar base, such as the Moon Village vision proposed by European Space Agency Director-General
Johann-Dietrich Woerner.
Carrying out this detection on the far side is especially interesting for Wieser as it is far more exposed to solar winds than the near side. For a large part of the Moon's orbit around the Earth, the near side is either facing away from the Sun or within the Earth’s protective magnetosphere.
“So for us, the lunar far side is a very interesting place because that's where the action is,” Wieser explains.
'Monumental mission'
The lunar far side is more than a mere curiosity due to its isolation, but a scientifically intriguing area that was marked out as a priority for exploration in the National Research Council's planetary science Decadal Survey 2013-2022, which strongly influences the space science undertaken by the United States.
Ian Crawford, professor of planetary science and astrobiology at Birkbeck University of London, says the mission could have monumental significance.
“If China is successful in landing Chang'e 4 on the far side of the Moon, this will be an enormously significant event in the history of space exploration, in the exploration of the Moon, and a tremendous boost for lunar science,” Crawford says.
Zou Yongliao of CAS revealed at the 46th Lunar and Planetary Science in March that the landing site would be near the centre of the South Pole-Aitken Basin; a huge impact crater that could offer deep insights into the Moon’s interior and its formation.
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Yongliao: Chang'e 4 will land near center of south-pole Aitken basin, launching late 2018 or early 2019.
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Crawford explains that the 2,500 kilometre diameter and roughly 13-kilometre-deep impact crater is an intriguing site, which could tell us more about the deep interior of the Moon than any other landing site so far.
“Both the age and the composition of the subsurface in the South Pole-Aitken basin are of interest. The basin is so deep that it’s certainly penetrating it down into the lower crust of the Moon, so far deeper than any near-side samples or measurements made.
“And it's possible that even parts of the lunar mantle might be exposed,” Professor Crawford adds.
Chang’e-4 is the now-repurposed backup to the Chang’e-3 mission that successfully put a lander and the Yutu (‘Jade Rabbit’) rover on the near side of the Moon in late 2013.
Above: China's Yutu ('Jade Rabbit') lunar rover on the Moon (CAS).
That mission carried a ground-penetrating radar and was one of the most exciting aspects of Chang’e-3, according to Crawford, and would be valuable on Chang’e-4, as it could increase our understanding of the structure of lunar regolith.
“I think by far the most interesting observations Chang’e-4 could make anywhere is the geochemical composition of the surface materials, the surface rocks and soils. This is done with instruments like X-ray florescent spectrometers or from alpha particle X-rays,” Crawford says.
It is not certain that the mission will include instruments such as an Alpha Particle X-ray Spectrometer (APXS) as Chang’e-3 did, but Chang’e-4 is though is expected to carry cameras similar to those of Chang’e-3 which returned spectacular shots of the Moon.
It will also carry telescopes working on various frequencies which will take advantage of the ‘quiet’ provided by being outside of Earth’s ionosphere, and the shielding of the Moon from our planet’s electromagnetic interference.
More details on Chang'e-4's payloads and objectives are likely to be revealed at the
European Luanr Symposium in the Netherlands later this week.
Lunar water
Another instrument confirmed for Chang’e-4 is the
Lunar Lander Neutron Dosimetry (LND) project developed by Kiel University in Germany.
The experiment will measure radiation on the Moon in preparation for future manned missions and could also measure the water content of the ground beneath the landing unit.
This, together with the choice of Kiruna’s ASAN detector, suggests that water on the Moon is of great interest to China, hinting that the Chang’e-4 mission has an eye on future human exploration and utilisation of the Moon.
Beyond Chang’e-4, there are hopes that, if next year’s
Chang’e-5 lunar sample return mission succeeds, its backup – Chang’e-6 – could attempt to retrieve samples from the far side. Such a mission would offer a much better opportunity to answer questions of lunar geology.
But what is certain is that a successful Chang’e-4 mission will be a major event, regardless of its makeup, Crawford says.
“Scientifically, it will be of great interest because the far side is different from the near side. And geopolitically, it will be a huge propaganda kill for China because they will be able to say quite correctly that no-one's done it before.
“And so just in the history of space exploration, it will be significant for that reason.”
http://gbtimes.com/china/sweden-joins-chinas-historic-mission-land-far-side-moon
Both Swedish and Dutch contributions to the mission. Reported at
European Lunar Symposium
Quote
After Sweden, Holland will also join China's Chang'e4 with a radio antenna telescope! #moonvillage
http://forum.nasaspaceflight.com/index.php?topic=30377.40