CategoriesHumans in Space, Lunar, Tech by

China Grows Cotton on the Moon

Discussions about sending humans to the Moon and Mars have brought many challenges waiting to be solved, and among them is how to feed people in space. Astronauts aboard the International Space Station (ISS) have been growing and consuming lettuce in space for a few years now, China has achieved a historic event by sprouting cotton seeds on the surface of the Moon. The news and corresponding photos were announced by Chinas government. The seeds were part of a biosphere experiment which, if it performs as intended, will provide helpful data towards the development of sustainable agriculture in environments other than Earth.

China’s Chang’e 4 craft lunar lander arrived January 3, 2019 on the far side of the Moon, and part of its cargo included an aluminum alloy canister equipped with materials necessary for not only plant growth, but a self-sustaining biological environment lead by Chongqing University. Along with cotton seeds, the experiment included rapeseed, potato, and arabidopsis seeds, as well as fruit fly eggs and yeast to form a simple, tiny biosphere. A heat control system and two cameras were also part of the makeup.

Each member of the experiment was chosen with a bioprocess purpose in mind: Potato seeds represented a primary food supply for future space travelers (see also: The Martian), rapeseed could be used to produce oil, cotton seeds for clothing/supply fabric, the fruit fly would act as the consumer, and the yeast could regulate the oxygen and carbon dioxide being exchanged between the fly and the plants. The arabidosposis seeds contribute via its photosynthesis and could be a food source, but the plant is generally considered to be weed with a short growth cycle that could be useful for observation. The seeds and eggs were kept dormant until their lunar arrival, after which time they were watered by the lander. The germination of the cotton seeds alone has not yet been determined or specified by China’s space agency, the China National Space Administration (CNSA).

Categoriesastronomy, Featured, Tech by

China builds world’s first space-ground integrated quantum communication network

The first quantum-safe video conference was held between President Chunli Bai of the Chinese Academy of Sciences in Beijing and President Anton Zeilinger of the Austria Academy of Sciences in Vienna, as the first real-world demonstration of intercontinental quantum communication on September 29th.

Private and secure communications are fundamental human needs. In particular, with the exponential growth of Internet use and e-commerce, it is of paramount importance to establish a secure network with global protection of data. Traditional public key cryptography usually relies on the perceived computational intractability of certain mathematical functions. In contrast, quantum key distribution (QKD) uses individual light quanta (single photon) in quantum superposition states to guarantee unconditional security between distant parties. Previously, the quantum communication distance had been limited to a few hundred kilometers, due to the channel loss of fibers or terrestrial free space. A promising solution to this problem is exploiting satellite and space-based link, which can conveniently connect two remote points on the Earth with greatly reduced channel loss because most of the photons’ propagation path is in empty space with negligible loss and decoherence.

A cross-disciplinary multi-institutional team of scientists from the Chinese Academy of Sciences, led by Professor Jian-Wei Pan, has spent more than ten years in developing a sophisticated satellite, named Micius, dedicated for quantum science experiments (for the project timeline, see Appendix), which was successfully launched on 16th August 2016, from Jiuquan, China, orbiting at an altitude of ~500 km . The satellite is equipped with three payloads: a decoy-state QKD transmitter, an entangled-photon source, and a quantum teleportation receiver and analyzer. Five ground stations are built in China to cooperate with the Micius satellite, located in Xinglong (near Beijing, 40°23’45.12”N, 117°34’38.85”E, altitude 890m), Nanshan (near Urumqi, 43°28’31.66”N, 87°10’36.07”E, altitude 2028m), Delingha (37°22’44.43”N, 97°43’37.01″E, altitude 3153m), Lijiang (26°41’38.15”N, 100°1’45.55”E, altitude 3233m), and Ngari in Tibet (32°19’30.07”N, 80°1’34.18”E, altitude 5047m).

Within a year after the launch, three key milestones that will be central to a global-scale quantum internet have been achieved: satellite-to-ground decoy-state QKD with kHz rate over a distance of ~1200 km (Liao et al. 2017, Nature 549, 43); satellite-based entanglement distribution to two locations on the Earth separated by ~1200 km and Bell test (Yin et al. 2017, Science 356, 1140), and ground-to-satellite quantum teleportation (Ren et al. 2017, Nature 549, 70). The effective link efficiencies in the satellite-based QKD were measured to be ~20 orders of magnitudes larger than direct transmission through optical fibers at the same length at 1200 km.

The satellite-based QKD has now been combined with metropolitan quantum networks, in which fibers are used to efficiently and conveniently to connect many users inside a city with a distance scale of ~100 km. For example, the Xinglong station has now been connected to the metropolitan multi-node quantum network in Beijing via optical fibers. Very recently, the largest fiber-based quantum communication backbone has been built in China by Professor Pan’s team, linking Beijing to Shanghai (going through Jinan and Hefei, and 32 trustful relays) with a fiber length of 2000 km. The backbone uses decoy-state protocol QKD and achieves an all-pass secure key rate of 20 kbps. It is on trial for real-world applications by government, banks, securities and insurance companies.

The Micius satellite can be further exploited as a trustful relay to conveniently connect any two points on the earth for high-security key exchange. Early this year, the Chinese team has implemented satellite-to-ground QKD in Xinglong. After that, the secure keys were stored in the satellite for 2 hours until it reached Nanshan station near Urumqi, by a distance of ~2500 km from Beijing. By performing another QKD between the satellite and Nanshan station, and using one-time-pad encoding, secure key between Xinglong and Nanshan were then established. To test the robustness and versatility of the Micius, QKD from the satellite to Graz ground station near Vienna has also been carried out successfully this June, as a collaboration between Professor Pan and Professor Anton Zeilinger’s group. Upon request, future similar experiments are also planned between China and Singapore, Italy, Germany, and Russia.