China launches dark matter satellite to put DAMPE-ner on US goal of being first to unravel the secrets of the universe
Champions of the Dark Matter Particle Explorer (DAMPE), which took off from Inner Mongolia on Thursday morning, say the unique design will offset its diminutive size to beat ISS-supported AMS-02 to the prize
China launched its Dark Matter Particle Explorer (DAMPE) from the Jiuquan Satellite Launch Centre in the Gobi desert on Thursday morning with the ambitious goal of overtaking its chief US rival in the race to detect dark matter and, potentially, unravel some of the secrets of the universe.
Dr Chang Jin, its designer, considers at least the first goal to be achievable. He told Chinese state media that even though the DAMPE may not look like much from the outside, its cosmic ray detection range is “ten times that of AMS-02”, referring to the US probe.
Moreover, it is over three times as accurate, he told Xinhua news agency.
“As long as it operates normally, it will open a new window for us,” he was quoted as saying.
The probe was launched after a nearly six-month delay at 8.12am (local time) using a Long March-2D launch vehicle from the 603 Launch Pad from within Ejin Banner of Inner Mongolia’s Alxa League, about 1,600 kilometres north of Beijing.
Its primary task will be to locate WIMPs, or weakly interacting massive particles. In astrophysics, these are the leading hypothetical candidates for the basic building blocks that make up dark matter.
Dark matter is a hypothetical kind of matter that physicists now believe makes up over 80 per cent of the total mass of the universe. Telescopes cannot pick it up, but the WIMP particles are considered a key to unlocking some of its mysteries.
Technically, the Chinese probe is considered superior to its US counterpart, the AMS-02 (Alpha Magnetic Spectrometer) that Nasa has mounted on the International Space Station (ISS).
But Chinese scientists say the jury is still out on whether either one will find what it is looking for. Success would almost inevitably lead to the awarding of another Nobel Prize, however, and China seems hungry for more of these after pharmaceutical chemist Tu Youyou collected this year’s medicine prize earlier this month in Stockholm for her revolutionary work on finding a treatment for malaria
WATCH: China launches its first Dark Matter Particle Explorer (DAMPE) satellite with a Long March II-D rocket
The DAMPE is one of five satellite missions running under the umbrella of the Strategic Pioneer Research Programme in Space Science of the Chinese Academy of Sciences (CAS). Others include a hard X-ray modulation telescope and quantum experiments at space scale.
At first glance, it doesn’t look like it can hold a candle to the AMS-02. At under 2 tonnes, it’s less than a quarter the weight of its US rival. To put this in real terms: A single magnet on the US probe is heavier than the entire Chinese space vehicle.
Yet the AMS-02 is benefiting from a generous head start. It was launched several years ago but began generating real results from 2011. As of this April it had recorded over 60 billion cosmic ray “events”, according to Nasa. Cosmic rays originate outside of our solar system and are of mysterious origin.
In contrast, researchers do not expect to get their hands on the DAMPE’s first set of data until late in 2016.
They will also have less time to collect said data as the Chinese probe has a considerably shorter expected lifespan of just three years. It will operate at a sun-synchronous orbit and an altitude of 500km.
But the AMS-02’s space mission is due to last over a decade given its amply energy supply and maintenance support from the ISS.
Weighing in on the argument of which country has the superior piece of equipment, Dr Chen Xin, an assistant professor of physics at prestigious Tsinghua University in Beijing, said the DAMPE may be able to achieve a better performance despite its diminutive size because of the way it was designed.
For example, instead of using a huge magnet to capture the extremely faint cosmic rays that are emitted when WIMPs collide - at least, this is one hypothesis - the DAMPE uses layers of carbon fibre, silicon strips and tungsten plates to detect traces of such collisions that occur in distant galaxies.
The DAMPE has another distinct advantage over the AMS-02, according to Dr Zhou Ning, another physicist who studies dark matter at Tsinghua.
The US probe has only been able to detect anti-electrons (positrons) in the cosmic rays produced by the collision of WIMPs, while the DAMPE’s unique design enables it to detect anti-photons, which should increase its chances of making a new discovery, he said.
But Zhou cautioned that even positive results from both probes may not be sufficient to prove the existence of dark matter as neither one aims to directly observe WIMPs, but rather the possible result of their brutal encounters.
However, the same or similar results could also come from different sources such as a supernova, or stellar explosion that radiates huge amounts of energy, he said.
Meanwhile, to shore up their chances of success, Chinese physicists have adopted two more approaches in a bid to detect WIMPs more directly.
First, they have placed special detectors in deep underground facilities like the China Jinping Underground Laboratory in Sichuan province, which is located almost 7km beneath ground level.
At this depth, most background “noise” can be shielded by the thick layers of rock. Eradicating all interference, for example radio activity, is important as any WIMP signal would be extremely weak, like trying to hear a leaf falling on the street, scientists say.
Second, they created WIMPs using massive particle colliders to see if their properties aligned with modern theories of dark matter.
“Only when observations from space match observations on the ground can we confirm the existence of WIMPs,” said Zhou.
Even though no sign of WIMPs have ever been spotted by underground detectors or collider experiments anywhere around the world, Zhou remained optimistic that they may turn something up.
“Columbus set out to find China and India and never succeeded, but he discovered a whole new continent,” he said.
“The same may happen in the journey to search for dark matter in space.”