China's Tiangong-1 Space Lab to Fall to Earth by April 2018
The United Nations Office for Outer Space Affairs (UNOOSA) has reissued a notification by China on the future uncontrolled re-entry of the country's robotic Tiangong-1 space lab, which is expected to take place in the next eight months.
Tiangong-1, which has been orbiting Earth since September 2011, ceased functioning on March 16, 2016. To date, the spacecraft has maintained its structural integrity.
The space lab's operational orbit is under constant and close surveillance by China. Its current average altitude is 217 miles (349 kilometers), but its orbit is decaying at a daily rate of approximately 525 feet (160 meters), according to the notification.
Re-entry date
The lab's re-entry is expected between October 2017 and April 2018. According to the calculations and analysis that have been carried out, most of Tiangong-1's structural components will be burned up during the craft's re-entry into Earth's atmosphere.
"The probability of endangering and causing damage to aviation and ground activities is very low," the notification adds.
Taking measures
The notice advises that China attaches great importance to the re-entry of Tiangong-1 and will take the following measures to monitor its fall and provid public information:
— China will enhance monitoring and forecasting and make strict arrangements to track and closely keep an eye on Tiangong-1 and will publish a timely forecast of its re-entry
— China will make use of the international joint monitoring information under the framework of the Inter-Agency Space Debris Coordination Committee in order to be better informed about the descent of Tiangong-1.
— China will improve the information reporting mechanism. Dynamic orbital status and other information relating to Tiangong-1 will be posted on the website of the China Manned Space Agency in both Chinese and English. In addition, timely information about important milestones and events during the orbital decay phases will be released through the news media.
— As to the final forecast of the time and region of re-entry, China will issue the relevant information and early warning in a timely manner and bring it to the attention of the United Nations Office for Outer Space Affairs and the Secretary-General of the United Nations through diplomatic channels.
Possible leftovers
Tiangong-1 was launched into Earth orbit on September 29, 2011. It conducted six successive rendezvous and dockings with the spacecraft Shenzhou-8 (uncrewed), Shenzhou-9 (crewed) and Shenzhou-10 (crewed) as part of China's human space exploration activities. The vehicle weighed 18,740 lbs. (8,500 kilograms) at launch.
According to the Aerospace Corporation, based on Tiangong-1's inclination, the lab will re-enter somewhere between 43 degrees north and 43 degrees south latitudes. As for leftovers, "it is highly unlikely that debris from this reentry will strike any person or significantly damage any property," Aerospace Corporation representatives wrote in a Tiangong-1 re-entry FAQ.
They added: "Potentially, there may be a highly toxic and corrosive substance called hydrazine on board the spacecraft that could survive re-entry. For your safety, do not touch any debris you may find on the ground nor inhale vapors it may emit."
The Aerospace Corporation will perform a person and property risk calculation for the Tiangong-1 re-entry a few weeks prior to the event.
Quelle: SC
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Update: 14.10.2017
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Tiangong-1: Chinese space station will crash to Earth within months
Pieces weighing up to 100kg could make it to the surface, says expert, when out-of-control 8.5-tonne laboratory breaks apart in the atmosphere
An 8.5-tonne Chinese space station has accelerated its out-of-control descent towards Earth and is expected to crash to the surface within a few months.
The Tiangong-1 or “Heavenly Palace” lab was launched in 2011 and described as a “potent political symbol” of China, part of an ambitious scientific push to turn China into a space superpower.
It was used for both manned and unmanned missions and visited by China’s first female astronaut, Liu Yang, in 2012.
But in 2016, after months of speculation, Chinese officials confirmed they had lost control of the space station and it would crash to Earth in 2017 or 2018. China’s space agency has since notified the UN that it expects Tiangong-1 to come down between October 2017 and April 2018.
Since then the station’s orbit has been steadily decaying. In recent weeks it has dipped into more dense reaches of Earth’s atmosphere and started falling faster.
“Now that [its] perigee is below 300km and it is in denser atmosphere, the rate of decay is getting higher,” said Jonathan McDowell, a renowned astrophysicist from Harvard University and a space industry enthusiast.
“I expect it will come down a few months from now – late 2017 or early 2018.”
Although much of the craft is expected to burn up in the atmosphere, McDowell says some parts might still weigh up to 100kg when they crash into the Earth’s surface.
The chance that anyone will be harmed by the debris is considered remote but China told the United Nations “Committee on the Peaceful Uses of Outer Space” in May that it would carefully monitor the craft’s descent and inform the United Nations when it begins its final plunge.
Predicting where it is going to come down would be impossible even in the days ahead of its landing, McDowell said.
“You really can’t steer these things,” he said in 2016. “Even a couple of days before it re-enters we probably won’t know better than six or seven hours, plus or minus, when it’s going to come down. Not knowing when it’s going to come down translates as not knowing where it’s going to come down.”
McDowell said a slight change in atmospheric conditions could nudge the landing site “from one continent to the next”.
There have been many uncontrolled re-entries of larger spacecraft and none have ever been reported to have caused injuries to people.
In 1991 the Soviet Union’s 20-tonne Salyut 7 space station crashed to Earth while still docked to another 20-tonne spacecraft called Cosmos 1686. They broke up over Argentina, scattering debris over the town of Capitán Bermúdez.
Nasa’s enormous 77-tonne Skylab space station came hurtling to Earth in an almost completely uncontrolled descent in 1979, with some large pieces landing outside Perth in Western Australia.
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Quelle: theguardian
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Update: 8.11.2017
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ESA BETEILIGT SICH AN WIEDEREINTRITTS-KAMPAGNE
ESOC-Hauptkontrollraum
6 November 2017
Experten des Büros für Weltraumschrott bei der ESA werden eine internationale Kampagne betreuen, um für Anfang des kommenden Jahres den Wiedereintritt einer Raumstation in die Atmosphäre zu planen.
Anfang 2018 soll die chinesische Raumstation Tiangong-1 nach dem Ende ihrer Betriebszeit wieder in die Atmosphäre eintreten. Es wird erwartet, dass dabei der größte Teil der Raumstation aufgrund von Reibung verbrennen wird.
Das IADC besteht aus Experten von 13 Raumfahrtagenturen und -organisationen, u. a. NASA, ESA, nationalen europäischen Raumfahrtagenturen, JAXA, ISRO, KARI, Roscosmos und der nationalen Raumfahrtbehörde von China.
Die Mitglieder des IADC werden den Wiedereintritt der Raumstation nutzen, um ihre jährliche Testkampagne durchzuführen, bei der die Teilnehmer ihre jeweiligen Prognosen für das Zeitfenster des Wiedereintritts sammeln und ihre Tracking-Daten von Radaren und anderen Quellen bündeln. Ziel der Testkampagne ist die Verifizierung, Kreuzanalyse und Verbesserung der Genauigkeit von Wiedereintritts-Prognosen für alle Mitglieder.
Die ESA wird wie bei den 20 bisherigen IADC-Testkampagnen, die seit 1998 durchgeführt wurden, als Betreuer und Administrator der Kampagne fungieren. Ein Sonderfall für die ESA war die Wiedereintritts-Testkampagne, die das IADC 2013 während der unkontrollierten Wiedereintritts des ESA-eigenen GOCE-Satelliten durchgeführt hat.
Ein himmlischer Palast
Die Raumstation Tiangong-1 ist 12 m lang, hat einen Durchmesser von 3,30 m und hatte eine Startmasse von 8506 kg. Sie ist seit 2013 unbesetzt, seit 2016 existiert kein Kontakt mehr.
Die chinesische Raumstation Tiangong-1
Die Raumstation befindet sich momentan in einer Umlaufbahn in etwa 300 km Höhe und wird irgendwann zwischen Januar und März 2018 zerfallen, woraufhin es zu einem unkontrollierten Wiedereintritt in die Atmosphäre kommen wird.
„Aufgrund der Geometrie der Umlaufbahn der Station können wir bereits die Möglichkeit ausschließen, dass Fragmente weiter nördlich als 43 Grad nördlicher Breite oder weiter südlich als 43 Grad südlicher Breite herunterfallen werden“, sagt Holger Krag, Leiter des Büros für Weltraumschrott bei der ESA.
„Das bedeutet, dass der Wiedereintritt an irgendeinem Punkt auf der Erde erfolgen kann, der sich zwischen diesen Breitengraden befindet. In diesem Bereich liegen beispielsweise mehrere europäische Länder. Das Datum, die Zeit und der geographische Fußabdruck des Wiedereintritts können nicht mit Sicherheit vorhergesagt werden. Selbst noch kurz vor dem Wiedereintritt kann man die Prognose nur auf ein sehr großes Zeit- und geografisches Fenster eingrenzen.“
Aufgrund der Masse und der Konstruktionsmaterialien der Station besteht die Möglichkeit, dass einige Teile von ihr den Wiedereintritt überstehen und die Erdoberfläche erreichen.
Tiangong-1 beim Andockmanöver
In der Geschichte der Raumfahrt gab es bislang keinerlei bestätigte Todesfälle durch herunterfallenden Weltraumschrott.
Das Büro für Weltraumschrott bei der ESA, das im Europäischen Satellitenkontrollzentrum ESOC in Darmstadt angesiedelt ist, wird in der Woche des 28. Februars 2018 einen internationalen Experten-Workshop durchführen, bei dem es um Wiedereintritts-Prognosen und Studien zur atmosphärischen Fragmentierung geht. Dabei können die Experten neueste Forschungserkenntnisse zu diesen und verwandten Themen austauschen.
Unabhängig von der IADC-Kampagne wird die ESA die Behörden ihrer Mitgliedstaaten wie bei allen derartigen Vorkommnissen regelmäßig mit aktuellen detaillierten Informationen über den Wiedereintritt versorgen.
Über das IADC
Das Inter-Agency Space Debris Coordination Committee (IADC) ist ein internationales Forum zur weltweiten Koordination gemeinsamer staatlicher Aktivitäten zum Thema natürlicher und von Menschen verursachter Weltraumschrott. Die Hauptziele des IADC sind der Austausch von Informationen über Aktivitäten in der Weltraumschrott-Forschung zwischen den zugehörigen Raumfahrtagenturen, die Erleichterung von Kooperationsmöglichkeiten in der Weltraumschrott-Forschung, die Überprüfung der Fortschritte laufender kooperativer Aktivitäten und die Identifizierung von Optionen zur Verringerung von Weltraumschrott.
Das Büro für Weltraumschrott koordiniert die Forschungsaktivitäten der ESA zum Thema Weltraumschrott, koordiniert solche Aktivitäten mit nationalen Forschungsbemühungen und bietet auch operative Dienstleistungen an. Das Büro koordiniert zudem die Forschungsaktivitäten der ESA in allen wichtigen Disziplinen rund um Weltraumschrott, u. a. Messung, Modellierung, Schutz und Vermeidung, und es koordiniert solche Aktivitäten mit nationalen und internationalen Forschungsbestrebungen.
Quelle: ESA
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Update: 1.01.2018
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A Chinese space station is falling to Earth next year — but it’s the last thing to worry about
The odds are in your favor
Sometime in late March of next year, a Chinese space station named Tiangong-1 is going to fall back down to Earth — and some big pieces may survive the reentry. The module’s descent has caused a bit of concern about debris raining form the sky. But in reality, a falling space station is the last thing anyone should be worried about.
Satellites and spacecraft fall to Earth all the time. Vehicles in lower orbits get bombarded by small particles in the planet’s upper atmosphere, and that eventually drags them downward. But usually, these falling objects are small enough or shaped in such a way that they’ll burn up safely while re-entering the atmosphere.
The problem with Tiangong-1 is that it’s rather massive. Launched in 2011, Tiangong-1 — or “Heavenly Place” — served as China’s first ever crewed space station. The module weighs nearly 19,000 pounds and it’s pretty dense too. And it’s estimated that around 10 to 40 percent of a spacecraft will make it down the ground. For small satellites, that’s not much. For Tiangong-1, that’s between 2,000 and 8,000 pounds.
With space vehicles of this size or bigger, operators usually have a plan to safely get rid of them when they’ve reached the end of their mission. If a large vehicle has thrusters, it’s possible to use the spacecraft’s remaining fuel to fire those engines intentionally and dump it over the ocean. Or you can send up another spacecraft with an engine to dock with the decay vehicle and plunge it somewhere safe.
But that’s not what happened with Tiangong-1. The space station wasn’t really meant to last past 2013, but China decided to extend its lifespan for a couple of years. Then in 2016, the Chinese Space Agency announced it had lost contact and control of the space station. And its orbit has been slowly degrading ever since, meaning it will ultimately make an uncontrolled re-entry. Or in other words: “We don’t know where it’s coming down.”
The United States Space Surveillance Network and other nations’ space agencies have been tracking it, and all we really know is that it’s going to come down somewhere between 43 degrees North and 43 degrees South latitude. That may seem like a big area, but most of the Earth’s surface included in that region is covered in ocean. And most of the land that’s included is unpopulated.
So the odds of this thing coming down on your head are actually infinitesimal. There’s a little over a 1 in 10,000 chance it will hit any person or property at all. Plus, it may sound scary to hear 2,000 to 8,000 pounds of debris falling from the sky, but a lot of that gets broken up into pieces, some pretty small, that can spread across a range of many miles.
And this is definitely not the first time something this large, or even bigger, has made an uncontrolled reentry before. In 2011, the launch of a Russian spacecraft intended for Mars failed, leaving the vehicle stranded in lower Earth orbit. Called Phobos-Grunt, the spacecraft weighed nearly 30,000 pounds and it fell back to Earth in 2012, ultimately entering over the Pacific Ocean. NASA’s old space station Sky Lab also made an uncontrolled reentry -- and it weighed nearly 160,000 pounds when it fell to Earth.
Plus, in the more than 50 years we’ve been launching rockets, only one person is known to have been hit by space debris. Her name is Lottie Williams, and a tiny piece of a Delta rocket brushed her shoulder when she was out for a walk.
The good news is that Tiangong-1 will help experts better refine their space debris models. An international group of state agencies known as the IADC has picked this space station to track as it comes down, and following its descent will allow them to refine their prediction models. Unfortunately, they won’t be providing any warnings though. They’ll probably be able to pin down the time of reentry within plus or minus three hours, but exactly where and when this will happen is going to be uncertain for a while.
Quelle: The Verge
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Update: 18.01.2018
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A space station is falling to Earth. Here's where it could land.
Experts say there's no need to panic.
A defunct Chinese space station is expected to plunge to Earth from its orbital perch in late March.
The Tiangong-1 station will mostly burn up as it plummets through Earth’s atmosphere. Some fragments could survive the fiery reentry, but experts say the risk to humans on the ground is small.
“I personally wouldn’t be fearful at all about being struck by space debris,” said Dr. Andrew Abraham, a senior member of the technical staff at the Aerospace Corporation, a federally funded research organization based in El Segundo, California, that has been modeling the 18,000-pound station's reentry path.
“It’s much more common to be hit by lightning,” said Dr. William Ailor, principal engineer for the Center for Orbital and Reentry Debris Studies at Aerospace.
But figuring out exactly where debris from Tiagong-1 could end up is no small task.
“It’s challenging to predict the time of reentry, and even more challenging to get the location,” Abraham said. “One thing we do know is that [Tiangong-1] will reenter between 43 degrees North and 43 degrees South latitude, but beyond that we don’t know the precise location.”
For now, ground stations are able to track Tiangong-1 as it speeds along at 16,000 miles an hour some 180 miles above Earth. But as gravity exerts its inexorable pull and the station’s orbit decays, it becomes hard to predict the station’s position over the planet.
Researchers won’t be able to determine with any reliability the ground track — the path along which debris could fall — until roughly a day or two before the satellite falls, Ailor said.
“Once it starts to break apart, each of the pieces will fall along the track, but they can be spread out by several hundred miles,” he added.
It’s not clear whether China can still control the space station. In a May 2017 update provided to the United Nations, China said Tiangong-1 “ceased functioning” on March 16, 2016 but provided no additional details about the status of the orbiting outpost.
Recently, a top Chinese spaceflight engineer denied that the space station was out of control, Reuters reported. But Ailor challenged that assertion, saying it’s more likely that Tiangong-1 will make an uncontrolled reentry.
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What goes up must come down
China’s Tiangong-1 space station is expected to fall to Earth in late March, but it’s hardly the first (or most massive) manmade object to plunge through the planet’s atmosphere. At nearly 19,000 pounds, Tiangong-1 is huge, but here’s how the space station stacks up to other structures that have plummeted back to the planet. And for comparison, we’ve included the International Space Station, which is still in operation but may one day be decommissioned in a similar manner.
It’s not uncommon for rocket parts, old satellites, and other bits of space debris to fall back to Earth. And if it does fall, Tiangong-1 won’t be the largest structure to plummet back to the planet. That distinction is held by the 268,000-pound Russian Mir space station, which made a controlled descent and splashed down in the Pacific Ocean in March 2001.
To date, only one person — Lottie Williams of Tulsa, Oklahoma — is known to have been hit by space debris. She was struck on the shoulder by a small piece of a rocket’s fuel tank in 1997 while out for a walk.
Tiangong-1, which translates to “Heavenly Palace,” was launched in 2011 but hasn’t hosted any astronauts since 2013.
Quelle: nbcnews
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Dieses Bild zeigt die chinesische Raumstation Tiangong-1, was "Himmelspalast" bedeutet. Die Aufnahme vom 27.11.2017 stammt von dem französischen Astrophotographen Alain Figer.
EIN HIMMLISCHER PALAST
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Dieses Bild zeigt die chinesische Raumstation Tiangong-1, was auf Deutsch "Himmelspalast" bedeutet, und wurde am 27. November 2017 von dem französischen Astrophotographen Alain Figer aufgenommen. Die Aufnahme entstand in einem Skigebiet in der Haute-Alpes-Region in Südostfrankreich als die Raumstation in der Abenddämmerung über den Photografen hinwegflog.
Die Raumstation erkennt man rechts unten in der Ecke als weißen Streifen, was durch die mehrere Sekunden lange Belichtung hervorgerufen wurde, gleich über dem verschneiten Gipfel des Berges Eyssina (2837m Höhe). Einige Bildelemente wurden aus dem Original entfernt.
Tiangong-1 ist 12m lang, hat einen Durchmesser von 3,3m und ein Startgewicht von 8506 kg. Der "Himmelpalast" ist seit 2013 unbemannt, ehe schließlich 2016 der Kontakt abbrach. Die Station befindet sich derzeit in einer Umlaufbahn in einer Höhe von 280km und wird im März oder April 2018 unausweichlich Richtung Erde absinken und in der Atmosphäre verglühen.
"Der orbitalen Geometrie verdanken wir es, dass wir bereits die Möglichkeit ausschließen können, dass Fragmente auf irgendeinen Punkt weiter nördlich als 43ºN oder weiter südlich als 43ºS fallen", sagt Holger Krag, Leiter des ESA-Büros für Weltraumschrott.
"Das bedeutet, dass der Wiedereintritt an irgendeinem Punkt zwischen diesen Breitengraden stattfinden kann, was zum Beispiel auch einige europäische Länder beinhaltet. Das Datum, die Zeit und der geographische Fußabdruck können nur mit großen Unsicherheiten vorhergesagt werden. Sogar kurz vor dem Wiedereintritt kann nur ein großes zeitliches und geographisches Fenster abgeschätzt werden", so Krag weiter.
Die chinesische Raumstation Tiangong-1
Deutschland, Österreich und die Schweiz liegen nördlich des 43. Breitengrades.
Durch die Masse der Station und durch die Materialien, aus der sie gefertigt ist, besteht die Möglichkeit, dass einzelne Teile den Wiedereintritt überstehen und den Erdboden erreichen. In der Geschichte der Weltraumfahrt wurden bislang keine Opfer von herabgefallenem Weltraumschrott bestätigt.
Die ESA wird eine Testkampagne zur Begleitung des Wiedereintritts betreuen, die von dem Inter Agency Space Debris Coordination Committee durchgeführt wird, einer Gruppe der weltweit führender Raumfahrtagenturen wie unter anderem der ESA, der NASA und der China National Space Administration.
Quelle: ESA
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Update: 22.01.2018
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Tiangong 1
Details:
I imaged Tiangong 1 on 1-20-18 from my backyard. Max pass was 62° at 17:58:37pm EST. The telescope was an Hedge HD 14 with a 2X barlow. Imaging camera was ZWO ASI174 mono with an astrodon red filter.
Experts currently predict that the space station will fall somewhere over Europe, and could even hit land.
The European Space Agency is issuing regular updates about Tiangong-1s descent to earth, with the latest saying a crash is likely to happen very soon.
The current estimated window is 17 March to 21 April; this is highly variable.
Re-entry will take place anywhere between 43ºN and 43ºS (e.g. Spain, France, Portugal, Greece, etc.).
New Tiangong-1 reentry window estimate: March 25 to April 17
Shenzhou-10 'chasing', rendezvousing and docking with the Tiangong-1 module in Earth orbit in June 2012. CCTV/Framegrab
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New analysis of the orbit of Tiangong-1 by ESA's Space Debris Office indicates a new estimated window of March 25 to April 17 for the uncontrolled atmospheric reentry of China's 8.5 tonne space lab.
The Tiangong-1 space lab was launched in 2011 to test docking technology and life support by hosting two crews, but loss of control over the spacecraft's propulsion means it cannot be deorbited in a controlled manner.
The spacecraft's orbit is decaying due to atmospheric drag and that process is accelerating as Tiangong-1 runs into denser concentrations of particles at lower altitudes.
European Space Agency’s Space Debris Office is based at the ESOC mission control centre in Darmstadt, Germany, and is providing regular updates of Tiangong-1's decaying orbit as well as estimates for its atmospheric reentry.
The estimates - the latest published on February 7 - are highly variable. The Space Debris Office states that, for an uncontrolled reentry, accurate predictions are beyond current technical capabilities due to complexities of modelling the atmosphere, the dynamics of the reentering object and limitations in observing the spacecraft.
The activity of the Sun is another unpredictable variable which can greatly affect the Earth's atmosphere and thus impact rates of orbital decay for spacecraft.
The estimated timeframe for reentry of Tiangong-1 issued by ESA's Space Debris Office on February 7, 2018. ESA
Current orbit
Tiangong-1's perigee, or closest point to Earth in its orbit, is currently 254 kilometres, with an apogee of 279 km, according to USSTRATCOM's Joint Space Operations Center, which detects, tracks and identifies all artificial objects in Earth orbit.
In a communiqué from the Permanent Mission of China to the United Nations in Vienna to the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) in December, it is stated that, "China has set up a special working group, made relevant emergency preparedness plans and been working closely with its follow-up tracking, monitoring, forecasting and relevant analysing".
The China Manned Space Agency (CMSA) is providing weekly updates of the orbit of Tiangong-1, but so far no possible time frames for reentry.
A test campaign to track the descent of Tiangong-1 will be conducted early in 2018 by the Inter Agency Space Debris Coordination Committee (IADC), with ESA acting as host and administrator.
A rendering of the Tiangong-1 space lab in orbit. CMSA
Danger from reentry?
Most of Tiangong-1 is expected to burn up on reentry due to the heat generated by superheated air as it is compressed by the speeding spacecraft.
However, some chunks of the space lab are expected to reach the Earth's surface, though the chances of these hitting individuals is widely considered to be remote.
Tiangong-1's orbit takes it from 43 degrees North to 43 degrees South, meaning as far south as southern Chile and Argentina, and a little farther north than New York and Chicago in the US and Rome in Italy, so debris that does not burn up on reentry could land at any point on within this zone.
Liu Yang engaged in mission activities aboard Tiangong-1 in June 2012. CNS
Tiangong-1's position and path can be seen and followed here, which also gives an indication of the expanse of ocean and uninhabited areas that the space lab passes over.
The spacecraft will not come close to being the largest uncontrolled reentry in the 60-year history of spaceflight. That title belongs to NASA's Skylab, at 74 metric tonnes, which reentered the atmosphere in July 1979.
Russia's 120 tonne Mir Space Station was deorbited into the South Pacific in a controlled manner in 2001.
Tiangong-1 background
The Tiangong-1 spacecraft was launched in 2011 from Jiuquan with a wet mass of 8.5 tonnes. It aimed to first prove orbital docking technology and techniques, and then life support systems by hosting two crews.
A view of the Tianhe living compartment, with five Control Moment Gyroscopes (CMGs) visible. CCTV/framegrab
The original plan was for Tiangong-1, or 'Heavenly Palace-1', to use its own propulsion to perform a controlled deorbiting, making the spacecraft mostly burn up over the South Pacific, with any remaining debris harmlessly crashing into the ocean - just as China's first cargo spacecraft, Tianzhou-1, did last year.
