On January 2nd, 2019, China’s Chang’e-4 lander made a successful landing on the far side of the Moon. The China National Space Administration (CNSA) and the Chinese Lunar Exploration Program (CLEP) report that after 9 days on the surface, the mission is in good shape. The Yutu-2 rover has been deployed and has begun exploring the Von Karman crater.
CNSA has released some video of the mission, including a video of Chang’e-4’s historic descent. Thanks to the hard-working people at the Planetary Society, and to Andrew Jones who reports on the Chinese Space Program, we have a handful of new videos and images of the Chang’e-4’s mission to enjoy.
Since the turn of the century, China has worked hard to become one of the fastest-rising powers in space. In 2003, the Chinese National Space Administration (CNSA) began sending their first taikonauts to space with the Shenzou program. This was followed by the deployment of the Tiangong-1 space station in 2011 and the launch of Tiangong-2 in 2016. And in the coming years, China also has its sights set on the Moon.
But before China can conduct crewed lunar missions, they must first explore the surface to locate safe landing spots and resources. This is the purpose behind the Chinese Lunar Exploration Program (aka. the Chang’e program). Named after the Chinese goddess of the moon, this program made history yesterday (Thursday, Jan. 3rd) when the fourth vehicle to bear the name (Chang’e-4) landed on the far side of the Moon.
In recent decades, China’s space program has advanced considerably. In addition to deploying their first space station (Tiangong-1) and developing a modern rockets (the Long March 5), the nation has also sent robotic mission to the lunar surface and plans to conduct crewed missions there in the coming years. To this end, China is looking to create a new series of rockets that will enable them to explore the Moon and maybe even Mars.
One of the rockets they use to accomplish these goals is known as the Long-March 8, which is expected to make its maiden flight around 2021. According to a statement made by the chief rocket designer (Long Lehao) during a recent space conference in Harbin, China, the rocket will also include a reusable first stage. This latest announcement shows that China is also pursuing reusable launch vehicles to lower costs and increase their presence in space.
According to the China Space Report, the Long March 8 (Changzheng 8, or CZ-8) is a medium-lift vehicle intended for Sun-Synchronous Orbit (SSO) missions – i.e. where payloads are delivered to a nearly polar orbit around a planet. Consisting of two stages and two boosters, this rocket will reportedly have a payload capacity of 3000 to 4,500 kg (6600 to 9900 lbs) to SSO.
The first stages on this rocket are believed to be based on the first-stage of the Long March 7, which are powered by two single-chamber YF-100, 1,200 kN-thrust engines fueled by LOX/kerosene. Based on Long’s statement, the first stages and boosters are expected to be retrieved through vertical landing (similar to SpaceX’s Falcon 9 and Falcon Heavy rockets).
However, according to Bao Weimin, the director of the Science and Technology Commission of the China Aerospace Science and Technology Corporation, the Long March 8 will use different technologies that those employed by SpaceX. The purpose of this rocket will be to provide commercial launch services to customers from around the world.
As Long indicated during the course of the conference (according to China Daily):
“China’s aerospace industry is making efforts to develop low-cost vehicles that can enter space rapidly to support future large-scale space exploration and promote a commercial space industry.”
In addition, Long also emphasized that China will be making efforts to address an ongoing problem with its younger Long March rockets, which is controlling where they fall. Currently, landing areas have to be are evacuated at every launch since these rockets rely on toxic chemicals. And with launches becoming more frequent, controlling where these rockets fall is becoming a major priority.
“As the current Long March 2, 3, 4 series rockets are fueled by toxic propellants, they cannot be recycled,” said Long. “But we are developing technologies to precisely control the fall of the rocket remains to ensure safety.”
Lastly, Long indicated what lies ahead for China’s space program and commercial spaceflight. By 2025, he claimed, reusable carriers will be developed for conducting suborbital space flights. By 2030, China National Space Agency will be conducting launches with rockets that rely on two reusable stages and will have achieved complete reusability by 2035. He also hinted how by 2040, China will be using reusable carrier rockets that will rely on hybrid-power sources.
All of this will allow for cheaper and more efficient launch services, facilitate spaceflight for private citizens, and allow for the commercialization of Low Earth Orbit (LEO). These goals are in keeping with what space agencies like NASA and private aerospace companies like SpaceX have in mind for the coming decades. In this sense, China is indicating that it intends to parallel other major powers in space by following a similar path.
Over the weekend, multiple space agencies’ had their instruments fixed on the skies as they waited for the Tiangong-1 space station to reenter our atmosphere. For the sake of tracking the station’s reentry, the ESA hosted the 2018 Inter Agency Space Debris Coordination Committee, an annual exercise that consists of experts from 13 space agencies taking part in a joint tracking exercise.
And on April 2nd, 02:16 CEST (April 1st, 17:16 PST), the US Air Force confirmed the reentry of the Tiangong-1 over the Pacific Ocean. As hoped, the station crashed down close to the South Pacific Ocean Unpopulated Area (SPOUA), otherwise known as the “Spaceship Cemetery”. This region of the Pacific Ocean has long been used by space agencies to dispose of spent spacecraft after a controlled reentry.
The confirmation came from the Joint Force Space Component Command (JFSCC) on April 2nd, 0:400 CEST (April 1st, 19:00 PST). Using the Space Surveillance Network sensors and their orbital analysis system, they were able to refine their predictions and provide more accurate tracking as the station’s reentry time approached. The USAF regularly shares information with the ESA regarding its satellites and debris tracking.
As with the ESA’s coordination with other space agencies and European member states, JFSCC’s efforts include counterparts in Australia, Canada, France, Germany, Italy, Japan, South Korea, and the United Kingdom. As Maj. Gen. Stephen Whiting, the Deputy Commander of the JFSCC and Commander of the 14th Air Force, indicated in a USAF press release:
“The JFSCC used the Space Surveillance Network sensors and their orbital analysis system to confirm Tiangong-1’s reentry, and to refine its prediction and ultimately provide more fidelity as the reentry time approached. This information is publicly-available on USSTRATCOM’s website www.Space-Track.org. The JFSCC also confirmed reentry through coordination with counterparts in Australia, Canada, France, Germany, Italy, Japan, South Korea, and the United Kingdom.”
The information is available on U.S. Strategic Command’s (USSTRATCOM) website – www.Space-Track.org. Holger Krag, the head of ESA’s Space Debris Office, confirmed the reentry of Tiangong-1 shortly thereafter on the ESA’s Rocket Science Blog. As he stated, the reentry was well within ESA’s earlier reentry forecast window – which ran from April 1st 23:00 UTC to 03:00 UTC on April 2nd (April 2nd, 01:00 CEST to 05:00 CEST):
“According to our experience, their assessment is very reliable. This corresponds to a geographic latitude of 13.6 degrees South and 164.3 degrees West – near American Samoa in the Pacific, near the international date Line. Both time and location are well within ESA’s last prediction window.”
China’s Manned Space Agency (CMSA) also made a public statement about the station’s reenty:
“According to the announcement of China Manned Space Agency (CMSA), through monitoring and analysis by Beijing Aerospace Control Center (BACC) and related agencies, Tiangong-1 reentered the atmosphere at about 8:15 am, 2 April, Beijing time. The reentry falling area located in the central region of South Pacific. Most of the devices were ablated during the reentry process.”
As Krag noted, the ESA’s monitoring efforts were very much reliant on its campaign partners from around the world. In fact, due to when the station entered the Earth’s atmosphere, it was no longer visible to the Fraunhofer FHR institute’s Tracking and Imaging (TIRA) radar, which provides tracking services for the ESA’s Space Debris Office (SDO).
Had the station still been in orbit by 06:05 CEST (21:00 PST), it would have still been visible to the institute’s TIRA radar. Some unexpected space weather also played a role in the station’s reentry. On March 31st, the Sun’s activity spontaneously dropped, which delayed the Tiangong-1’s entry by about a day.
“This illustrates again the dependence that Europe has on non-European sources of information to properly and accurately manage space traffic, detect reentries such as Tiangong-1 and track space debris that remains in orbit – which routinely threatens ESA, European and other national civil, meteorological, scientific, telecomm and navigation satellites,” said Krag.
While news of the Tiangong-1’s orbital decay caused its share of concern, the reentry happened almost entirely as predicted and resulted in no harm. And once again, it demonstrated how international cooperation and public outreach is the best defense against space-related hazards.
China’s Tiangong-1 space station has been the focus of a lot of international attention lately. In 2016, after four and half years in orbit, this prototype space station officially ended its mission. By September of 2017, the Agency acknowledged that the station’s orbit was decaying and that it would fall to Earth later in the year. Since then, estimates on when it will enter out atmosphere have been extended a few times.
According to satellite trackers, it was predicted that the station would fall to Earth in mid-March. But in a recent statement (which is no joke) the Chinese National Space Agency (CNSA) has indicated that Tiangong-1 will fall to Earth around April 1st – aka. April Fool’s Day. While the agency and others insists that it is very unlikely, there is a small chance that the re-entry could lead to some debris falling to Earth.
For the sake of ensuring public safety, the European Space Agency’s (ESA) Space Debris Office (SDO) has been providing regular updates on the station’s decay. According to the SDO, the reentry window is highly variable and spans from the morning of March 31st to the afternoon of April 1st (in UTC time). This works out to the evening of March 30th or March 31st for people living on the West Coast.
“Reentry will take place anywhere between 43ºN and 43ºS. Areas above or below these latitudes can be excluded. At no time will a precise time/location prediction from ESA be possible. This forecast was updated approximately weekly through to mid-March, and is now being updated every 1~2 days.”
In other words, if any debris does fall to the surface, it could happen anywhere from the Northern US, Southern Europe, Central Asia or China to the tip of Argentina/Chile, South Africa, or Australia. Basically, it could land just about anywhere on the planet. On the other hand, back in January, the US-based Aerospace Corporation released a comprehensive analysis on Tiangong-1s orbital decay.
Their analysis included a map (shown below) which illustrated the zones of highest risk. Whereas the blue areas (that make up one-third of the Earth’s surface) indicate zones of zero probability, the green area indicates a zone of lower probability. The yellow areas, meanwhile, indicates zones that have a higher probability, which extend a few degrees south of 42.7° N and north of 42.7° S latitude, respectively.
The Aerospace Corporation has also created a dashboard for tracking Tiangong-1 (which is refreshed every few minutes) and has come to similar conclusions about the station’s orbital decay. Their latest prediction is that the station will descend into our atmosphere on April 1st, at 04:35 UTC (March 30th 08:35 PST), with a margin of error of about 24 hours – in other words, between March 30th to April 2nd.
And they are hardly alone when it comes to monitoring Tiangong-1’s orbit and predicting its descent. The China Human Spaceflight Agency (CMSA) recently began providing daily updates on the orbital status of Tiangong-1. As they reported on March 28th: “Tiangong-1 stayed at an average altitude of about 202.3 km. The estimated reentry window is between 31 March and 2 April, Beijing time.”
The US Space Surveillance Network, which is responsible for tracking artificial objects in Earth’s orbit, has also been monitoring Tiangong-1 and providing daily updates. Based on their latest tracking data, they estimate that the station will enter our atmosphere no later than midnight on April 3rd.
Naturally, one cannot help but notice that these predictions vary and are subject to a margin of error. In addition, trackers cannot say with any accuracy where debris – if any – will land on the planet. As Max Fagin – an aerospace engineer and space camp alumni – explained in a recent Youtube video (posted below), all of this arises from two factors: the station’s flight path and the Earth’s atmosphere.
Basically, the station is still moving at a velocity of 7.8 km/sec (4.8 mi/s) horizontally while it is descending by about 3 cm/sec. In addition, the Earth’s atmosphere shrinks and expands throughout the day in response to the Sun’s heating, which results in changes in air resistance. This makes the process of knowing where the station’s will make its descent difficult to predict, not to mention where debris could fall.
However, as Fagin goes on to explain, once the station reaches an altitude of 150 km (93 mi) – i.e. within the Thermosphere – it will begin falling much faster. At that point, it be much easier to determine where debris (if any) will fall. However, as the ESA, CNSA, and other trackers have emphasized repeatedly, the odds of any debris making it to the surface is highly unlikely.
If any debris does survive re-entry, it is also statistically likely to fall into the ocean or in a remote area – far away from any population centers. But in all likelihood, the station will break up completely in our atmosphere and produce a beautiful streaking effect across the sky. So if you’re checking the updates regularly and are in a part of the world where it can be seen, be sure to get outside and see it!
In the past decade, China’s space program has advanced by leaps and bounds. In recent years, the Chinese National Space Agency (CNSA) has overseen the development of a modern rocket family (the Long March series), the deployment of a space station (Tiangong-1) and the development of the Chinese Lunar Exploration Program (CLEP) – otherwise known as the Chang’e Program.
Looking to the future, China plans to create new classes of heavy rockets in order to conduct more ambitious missions. These include the Long March 9 rocket (aka. the Changzheng 9), a three-stage, super-heavy rocket that would allow for crewed missions to the Moon. According to a recent story from Aviation Weekly, China hopes to conduct an engine demonstration of this rocket, and could do so as early as later this year.
This demonstration is part of a research effort intended to create engines for the first stage of the Long March 9. According to statements made by the Academy of Aerospace Propulsion Technology (AAPT) – part of the China Aerospace and Technology Corporation (CASC) and the one’s responsible for developing the hardware – these engines would be capable of delivering 3,500 to 4,000 metric tons (3,858 to 4,409 US tons) of thrust.
AAPT also indicated that work on a second-stage and third-stage engine – which would be capable of generating about 200 metric tons (440,000 lbs) and 25 metric tons (55,000 lbs) thrust, respectively – is also in progress. All told, this is roughly six times the thrust that China’s heaviest rocket (the Long March 5) can generate and would make it comparable to theSaturn V – the Apollo-era rocket that took the NASA astronauts to the Moon.
For starters, the Saturn V‘s engines delivered roughly 3,400 metric tons of thrust, and the rocket was capable of delivering 140 metric tons (310,000 lbs) to Low Earth Orbit (LEO) and about 48 metric tons (107,100 lbs) to a Lunar Transfer Orbit (LTO). By comparison, the Long March 9 will reportedly have the ability to 140 metric tons to LEO and at least 50 metric tons (110,000 lbs) to LTO.
According to Li Hong, the head of the China Academy of Launch Vehicle Technology (the CASC unit responsible for overall development and production of most Chinese space launchers), a massive turbopump has also been built for the main engine. A pump of this size is necessary, since the engine will generate four time the thrust of the largest Chinese rocket engine to date – AAPT’s YF-100, which generates 120 metric tons (265,000 lbs) of thrust.
While the full specifications of the rocket are not yet available, the China News Service has indicated that the rocket will measure 10 meters (33 ft.) in diameter. According to statements made by both Li and Lui, the first-stage engine will burn kerosene and achieve a thrust of 480 metric tons (529 US tons) – comparable to the Saturn V F-1 engine’s 680 metric tons (750 US tons) of thrust – while the second and third stage engines will likely burn hydrogen fuel.
At their current rate of progress, an engine demonstration could be taking place later this year. As AAPT President Liu Zhirang stated in an interview with Science and Technology Daily (part of the state-owned China News Service):
“A complete prototype for the engine in the 500-metric-ton class can be built and assembled this year… Because of the great parameter changes that come with rises in thrust, the current test and verification equipment cannot satisfy requirements [of the Moon rocket propulsion program]. We cannot always do 1:1 scale tests. As a result, only simulations and scaled-down tests can be done for some technology and hardware. This increases the degree of difficulty for the program.”
If successful, the Long March 9 will join the ranks of super heavy-lift launch vehicles, such as the SpaceX Falcon Heavy, the KRK rocket (currently under development in Russia), and the Space Launch System being developed by NASA. These and other rockets are being built for the purpose of bringing astronauts to the Moon, Mars, and even beyond in the coming decades.
Beyond a possible demonstration of the Long March 9′s engine technology, the CNSA has many other ambitious plans for 2018. These include a planned 35 launches involving the Long March series, fourteen of which will be carried out by the Long March-3A and six by the Long March-3C rockets. Most of these missions will involve the deployment of Beidou satellites, but will also include the launch of the Chang’e-4 lunar probe later this year.
This year is also when China hopes to conduct mission using its newest rocket – the Long March 5 – in preparation for China’s lunar probe and Mars probe missions. This year is also expected to see a lot of developments in the Long March 7 series, which is likely to become the main carrier when China begins construction of its new space station (Tiangong-2, which is scheduled for completion in 2022).
Between all of these developments, it is clear that the age of renewed space exploration is upon us. Whereas the Space Race was characterized by two superpowers competing for dominance and “getting their first”, the current one is defined by both competition and cooperation between multiple space agencies and lucrative partnerships between the public sector and private industry.
And while the specter of renewed competition by space powers has a tendency to make many people nervous (especially those who are concerned about military applications), it is a testament to how humanity is growing as a space-faring species. By the time 2050 rolls around, we may just see many flags being planted on the Moon and Mars, and not just Old Glory.
Orbital debris (aka. space junk) is one of the greatest problems facing space agencies today. After sixty years of sending rockets, boosters and satellites into space, the situation in the Low Earth Orbit (LEO) has become rather crowded. Given how fast debris in orbit can travel, even the tiniest bits of junk can pose a major threat to the International Space Station and threaten still-active satellites.
It’s little wonder then why ever major space agency on the planet is committed to monitoring orbital debris and creating countermeasures for it. So far, proposals have ranged from giant magnets and nets and harpoons to lasers. Given their growing presence in space, China is also considering developing giant space-based lasers as a possible means for combating junk in orbit.
For the sake of their study, the team conducted numerical simulations to see if an orbital station with a high-powered pulsed laser could make a dent in orbital debris. Based on their assessments of the velocity and trajectories of space junk, they found that an orbiting laser that had the same Right Ascension of Ascending Node (RAAN) as the debris itself would be effective at removing it. As they state in their paper:
“The simulation results show that, debris removal is affected by inclination and RAAN, and laser station with the same inclination and RAAN as debris has the highest removal efficiency. It provides necessary theoretical basis for the deployment of space-based laser station and the further application of space debris removal by using space-based laser.”
This is not the first time that directed-energy has been considered as a possible means of removing space debris. However, the fact that China is investigating directed-energy for the sake of debris removal is an indication of the nation’s growing presence in space. It also seems appropriate since China is considered to be one of the worst offenders when to comes to producing space junk.
Back in 2007, China conducted a anti-satellite missile test that resulted in the creation over 3000 of bits of dangerous debris. This debris cloud was the largest ever tracked, and caused significant damage to a Russian satellite in 2013. Much of this debris will remain in orbit for decades, posing a significant threat to satellites, the ISS and other objects in LEO.
Of course, there are those who fear that the deployment of lasers to LEO will mean the militarization of space. In accordance with the 1966 Outer Space Treaty, which was designed to ensure that the space exploration did not become the latest front in the Cold War, all signatories agreed to “not place nuclear weapons or other weapons of mass destruction in orbit or on celestial bodies or station them in outer space in any other manner.”
In the 1980s, China was added to the treaty and is therefore bound to its provisions. But back in March of 2017, US General John Hyten indicated in an interview with CNN that China’s attempts to develop space-based laser arrays constitutes a possible breach of this treaty:
“They’ve been building weapons, testing weapons, building weapons to operate from the Earth in space, jamming weapons, laser weapons, and they have not kept it secret. They’re building those capabilities to challenge the United States of America, to challenge our allies…We cannot allow that to happen.”
Such concerns are quite common, and represent a bit of a stumbling block when it comes to the use of directed-energy platforms in space. While orbital lasers would be immune to atmospheric interference, thus making them much more effective at removing space debris, they would also lead to fears that these lasers could be turned towards enemy satellites or stations in the event of war.
As always, space is subject to the politics of Earth. At the same time, it also presents opportunities for cooperation and mutual assistance. And since space debris represents a common problem and threatens any and all plans for the exploration of space and the colonization of LEO, cooperative efforts to address it are not only desirable but necessary.
It’s no secret that China’s growth in the past few decades has been reflected in space. In addition to the country’s growing economic power and international influence, it has also made some very impressive strides in terms of its space program. This includes the development of the Long March rocket family, the deployment of their first space station, and the Chinese Lunar Exploration Program (CLEP) – aka. the Chang’e program.
Given all that, one would not be surprised to learn that China has some big plans for 2018. But as the China Aerospace Science and Technology Corporation (CASC) announced last Tuesday (on January 2nd, 2018), they intend to double the number of launches they conducted in 2017. In total, the CASC plans to mount over 40 launches, which will include the Long March 5 returning to flight, the Chang’e 4 mission, and the deployment of multiple satellites.
In 2017, China hoped to conduct around 30 launches, which would consist of the launch of a new Tianzhoui-1 cargo craft to the Tiangong-2 space lab and the deployment of the Chang’e 5 lunar sample return mission. However, the latter mission was postponed after the Long March 5 rocket that would have carried it to space failed during launch. As such, the Chang’e 5 mission is now expected to launch next year.
That failed launch also pushed back the next flight of Long March 5, which had conducted its maiden flight in November of 2016. In the end, China closed the year with 18 launches, which was four less than the national record it set in 2016 – 22 launches. It also came in third behind the United States with 29 launches (all of which were successful) and Russia’s 20 launches (19 of which were successful).
Looking to not be left behind again, the CASC hopes to mount 35 launches in 2018. Meanwhile, the China Aerospace Science Industry Corporation (CASIC) – a defense contractor, missile maker and sister company of CASC – will carry out a number of missions through its subsidiary, ExPace. These will include four Kuaizhou-1A rocket launches in one week and the maiden flight of the larger Kuaizhou-11 rocket.
In addition, Landspace Technology – a Beijing-based private aerospace company – is also expected to debut its LandSpace-1 rocket this year. In January of 2017, Landspace signed a contract with Denmark-based satellite manufacturer GOMspace to become the first Chinese company to develop its own commercial rockets that would provide services to the international marketplace.
But of course, the highlights of this year’s launches will be the Long March 5’s return to service, and the launch of the Chang’e 4 mission. Unlike the previous Chang’e missions, Chang’e 4 will be China’s first attempt to mount a lunar mission that involves a soft landing. The mission will consist of a relay orbiter, a lander and a rover, the primary purpose of which will be to explore the geology of the South Pole-Aitken Basin.
For decades, this basin has been a source of fascination for scientists; and in recent years, multiple missions have confirmed the existence of water ice in the region. Determining the extent of the water ice is one of the main focuses of the rover mission component. However, the lander will also to be equipped with an aluminum case filled with insects and plants that will test the effects of lunar gravity on terrestrial organisms.
These studies will play a key role in China’s long-term plans to mount crewed missions to the Moon, and the possible construction of a lunar outpost. In recent years, China has indicated that it may be working with the European Space Agency to create this outpost, which the ESA has described as an “international Moon village” that will be the spiritual successor to the ISS.
The proposed launch of the Long March 5 is also expected to be a major event. As China’s largest and most powerful launch vehicle, this rocket will be responsible for launching heavy satellites, modules of the future Chinese space station, and eventual interplanetary missions. These include crewed missions to Mars, which China hopes to mount between the 2040s and 2060s.
According to the GB times, no details about the Long March 5’s return to flight mission were revealed, but there have apparently been indications that it will involve the large Dongfanghong-5 (DFH-5) satellite bus. In addition, no mentions have been made of when the Long March 5B will begin conducting missions to Low Earth Orbit (LEO), though this remains a possibility for either 2018 or 2019.
Other expected missions of note include the deployment of more than 10 Beidou GNSS satellites – which are basically the Chinese version of GPS satellites – to Medium Earth Orbits (MEOs). A number of other satellites will be sent into orbit, ranging from Earth and ocean observation to weather and telecommunications satellites. All in all, 2018 will be a very busy year for the Chinese space program!
One of the hallmarks of the modern space age is the way in which emerging powers are taking part like never before. This of course includes China, whose presence in space has mirrored their rise in terms of global affairs. At the same time, the Indian Space Research Organization (IRSO), the European Space Agency, JAXA, the Canadian Space Agency, the South African Space Agency, and many others have been making their presence felt as well.
In short, space exploration is no longer the province of two major superpowers. And in the future, when crewed interplanetary missions and (fingers crossed!) the creation of colonies on other planets becomes a reality, it will likely entail a huge degree of international cooperation and public-private partnerships.
It would be no exaggeration to say that we live in an age of renewed space exploration. In particular, the Moon has become the focal point of increasing attention in recent years. In addition to President Trump’s recent directive to NASA to return to the Moon, many other space agencies and private aerospace companies are planning their own missions to the lunar surface.
A good example is the Chinese Lunar Exploration Program (CLEP), otherwise known as the Chang’e Program. Named in honor of the ancient Chinese lunar goddess, this program has sent two orbiters and one lander to the Moon already. And later this year, the Chang’e 4 mission will begin departing for the far side of the Moon, where it will study the local geology and test the effects of lunar gravity on insects and plants.
The mission will consist of a relay orbiter being launched aboard a Long March 5 rocket in June of 2018. This relay will assume orbit around the Earth-Moon L2 Lagrange Point, followed by the launch of the lander and rover about six months later. In addition to an advanced suite of instruments for studying the lunar surface, the lander will also be carrying an aluminum alloy container filled with seeds and insects.
As Zhang Yuanxun – chief designer of the container – told the Chongqing Morning Post (according to China Daily):
“The container will send potatoes, arabidopsis seeds and silkworm eggs to the surface of the Moon. The eggs will hatch into silkworms, which can produce carbon dioxide, while the potatoes and seeds emit oxygen through photosynthesis. Together, they can establish a simple ecosystem on the Moon.”
The mission will also be the first time that a mission is sent to an unexplored region on the far side of the Moon. This region is none other than the South Pole-Aitken Basin, a vast impact region in the southern hemisphere. Measuring roughly 2,500 km (1,600 mi) in diameter and 13 kilometers (8.1 mi) deep, it is the single-largest impact basin on the Moon and one of the largest in the Solar System.
This basin is also source of great interest to scientists, and not just because of its size. In recent years, it has been discovered that the region also contains vast amounts of water ice. These are thought to be the results of impacts by meteors and asteroids which left water ice that survived because of how the region is permanently shadowed. Without direct sunlight, water ice in these craters has not been subject to sublimation and chemical dissociation.
Since the 1960s, several missions have explored this region from orbit, including the Apollo 15, 16 and 17 missions, the Lunar Reconnaissance Orbiter (LRO) and India’s Chandrayaan-1 orbiter. This last mission (which was mounted in 2008) also involved sending the Moon Impact Probe to the surface to trigger the release of material, which was then analyzed by the orbiter.
The mission confirmed the presence of water ice in the Aitken Crater, a discovery which was confirmed about a year later by NASA’s LRO. Thanks to this discovery, there have been several in the space exploration community who have stated that the South Pole-Aitken Basin would be the ideal location for a lunar base. In this respect, the Chang’e 4 mission is investigating the very possibility of humans living and working on the Moon.
Aside from telling us more about the local terrain, it will also assess whether or not terrestrial organisms can grow and thrive in lunar gravity – which is about 16% that of Earths (or 0.1654 g). Previous studies conducted aboard the ISS have shown that long-term exposure to microgravity can have considerable health effects, but little is known about the long-term effects of lower gravity.
The European Space Agency has also been vocal about the possibility of building an International Lunar Village in the southern polar region by the 2030s. Intrinsic to this is the proposed Lunar Polar Sample Return mission, a joint effort between the ESA and Roscosmos that will involve sending a robotic probe to the Moon’s South Pole-Aitken Basin by 2020 to retrieve samples of ice.
In the past, NASA has also discussed ideas for building a lunar base in the southern polar region. Back in 2014, NASA scientists met with Harvard geneticist George Church, Peter Diamandis (creator of the X Prize Foundation) and other parties to discuss low-cost options. According to the papers that resulted from the meeting, this base would exist at one of the poles and would be modeled on the U.S. Antarctic Station at the South Pole.
If all goes well for the Chang’e 4 mission, China intends to follow it up with more robotic missions, and an attempted crewed mission in about 15 years. There has also been talk about including a radio telescope as part of the mission. This RF instrument would be deployed to the far side of the Moon where it would be undistributed by radio signals coming from Earth (which is a common headache when it comes to radio astronomy).
And depending on what the mission can tell us about the South Pole-Aitken Basin (i.e. whether the water ice is plentiful and the radiation tolerable), it is possible that space agencies will be sending more missions there in the coming years. Some of them might even be carrying robots and building materials!
In September of 2011, China officially joined the Great Powers in Space club, thanks to the deployment of their Tiangong-1 space station. Since then, this prototype station has served as a crewed orbital laboratory and an experimental testbed for future space stations. In the coming years, China hopes to build on the lessons learned with Tiangong-1 to create a larger, modular station in 2023 (similar to the International Space Station).
Though the station’s mission was originally meant to end in 2013, the China National Space Agency extended its service to 2016. By September of 2017, the Agency acknowledged that they had lost control of the station and indicated that it would fall to Earth later in the year. According to the latest updates from satellite trackers, Tianglong-1 is likely to be reentering our atmosphere in March of 2018.
Given the fact that the station measures 10 by 3.35 meters (32.8 by 11 ft), weighs a hefty 8,506 kg (18,753 lb) and was built from very durable construction materials, there are naturally concerns that some of it might survive reentry and reach the surface. But before anyone starts worrying about space debris falling on their heads, there are a few things that need to be addressed.
For starters, in the history of space flight, there has not been a single confirmed death caused by falling space debris. Tthanks to the development of modern tracking and early warning systems, we are also more prepared than at any time in our history for the threat of falling debris. Statistically speaking, you are more likely to be hit by falling airplane debris or eaten by a shark.
Second, the CNSA has emphasized that the reentry is very unlikely to pose a threat to commercial aviation or cause any impact damage on the surface. As Wu Ping – the deputy director of the manned space engineering office – indicated at a press conference back on September 14th, 2017: “Based on our calculation and analysis, most parts of the space lab will burn up during falling.”
In addition, The Aerospace Corporation, which is currently monitoring the reentry of Tiangong-1, recently released the results of their comprehensive analysis. Similar to what Wu stated, they indicated that most of the station will burn up on reentry, though they acknowledged that there is a chance that small bits of debris could survive and reach the surface. This debris would likely fall within a region that is centered along the orbital path of the station (i.e. around the equator).
To illustrate the zones of highest risk, they produced a map (shown below) which indicates where the debris would be most likely to land. Whereas the blue areas (that make up one-third of the Earth’s surface) indicate zones of zero probability, the green area indicates a zone of lower probability. The yellow areas, meanwhile, indicates zones that have a higher probability, which extend a few degrees south of 42.7° N and north of 42.7° S latitude, respectively.
“When considering the worst-case location (yellow regions of the map) the probability that a specific person (i.e., you) will be struck by Tiangong-1 debris is about one million times smaller than the odds of winning the Powerball jackpot. In the history of spaceflight, no known person has ever been harmed by reentering space debris. Only one person has ever been recorded as being hit by a piece of space debris and, fortunately, she was not injured.”
Last, but not least, the European Space Agency’s Inter Agency Space Debris Coordination Committee (IADC) will be monitoring the reentry. In fact, the IADC – which is made up of space debris and other experts from NASA, the ESA, JAXA, ISRO, KARI, Roscosmos and the China National Space Administration – will be using this opportunity to conduct a test campaign.
During this campaign, participants will combine their predictions of the reentry’s time window, which are based on respective tracking datasets obtained from radar and other sources. Ultimately, the purpose of the campaign is to improve prediction accuracy for all member states and space agencies. And so far, their predictions also indicate that there is little cause for concern.
As Holger Krag, the Head of ESA’s Space Debris Office, indicated in a press statement back in November:
“Owing to the geometry of the station’s orbit, we can already exclude the possibility that any fragments will fall over any spot further north than 43ºN or further south than 43ºS. This means that reentry may take place over any spot on Earth between these latitudes, which includes several European countries, for example. The date, time and geographic footprint of the reentry can only be predicted with large uncertainties. Even shortly before reentry, only a very large time and geographical window can be estimated.”
The ESA’s Space Debris Office – which is based at the European Space Operations Centre in Darmstadt, Germany – will follow this campaign in February with an international expert workshop. This workshop (which will run from February 28th to March 1st, 2018) will focus on reentry predictions and atmospheric break-up studies and allow experts in the field of space debris monitoring to share their latest findings and research.
In the current age of renewed space exploration and rapidly improving technology, every new development in space is an opportunity to test the latest instruments and methods. The reentry of Tiangong-1 is a perfect example, where the reentry of a space station is being used to test our ability to predict falling space debris. It also highlights the need for tracking and monitoring, given that humanity’s presence in orbit is only going to increase in the coming years.
In the meantime, it would not be inadvisable to keep your eyes on the skies this coming March. While there is little chance that debris will pose a hazard, it is sure to be spectacular sight for people who live closer to the equator!