Undoubtedly, the debut of FAST (Five-hundred-meter Aperture Spherical Telescope) once again brought the Chinese scientific community to the world. On October 10, the appearance of FAST team together with its result about pulsar has immediately attracted attention both at home and abroad. George Hobbes, the director of world-famed CSIRO Parkes Radio Telescope, commented: this is one of the most exciting event for world astronomy.
But what is little-known is that even in the eve of FAST debut, scientists in The National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) are still struggling to have more new pulsars to receive international system certification. At that time, FAST, the world’s most sensitive radio telescope located in Guizhou, China, has found six new pulsars. Two of them was certified.
Even so, at the news conference held in the next day, Yan Jun, the director of NAOC, only introduced the two certified pulsars. FAST, he said, had detected dozens of high-quality pulsar candidates, but the telescope is in debugging stage, precaution. So to be prudent, Chinese scientists will release more after “one hundred percent affirmed” by foreign telescopes.
Of course, stories like above may have drowned among explosive reports about achievements, such as Listen! Pulsar Signal 16,000 Light Years Away and The First Time that Chinese Radio Telescope Discovered a New Pulsar. But for every scientist involved, the “debut” of “China’s telescope” is complete only with these details.
In the most delightful moment, “debut” time, also, they did not forget Nan Rendong, the initial project initiator, chief scientist and chief engineer of FAST. Though he could never see the debut. Before the launching ceremony, the host temporarily added another agenda: everyone present stands up for a minute of silence for Nan Rendong.
A week before: the discovery announces the upcoming of new era
In the office building of NAOC in Beijing on Oct 10, the first batch of pulsar signals captured by FAST were debut to the outside world.
“Toot, toot, toot –”
“Du — du –”
At the site, both scientists and media workers picked up their ears and listened carefully to the pulse signals respectively from 16,000 light years and 4100 light-years away.
Li Di, researcher of NAOC and deputy chief engineer of FAST, said one was like child’s heartbeat, faint and slow; the other was like adult’s, short and powerful.
It is these two voices that have enabled China to achieve “breakthrough of zero”: the first pulsars discovered by China’s independently designed and manufactured astronomical equipment. Over the previous 50 years, humans have observed more than 2,700 pulsars.
Pulsar, a kind of dead star, is high-speed neutron star that is named for its periodic pulse signal. Such pulse signals are like the flickering light emitted from lighthouse. When it was initially found, it was regarded as a sign sent by alien looking for friend.
Li said the pulsar also has an unusually fast rotation rate with precise rotating period, and thus is called as the most accurate astronomical clock in the universe. This feature lets pulsars have extreme physical properties that cannot be achieved in the ground lab. Thus, it is ideal for astrophysics laboratory. The Nobel Prize in physics twice awarded findings about the pulsar.
However, since the pulsar signal is weak and susceptible to be interfered by artificial electromagnet, only a small fraction can be observed at present. Lee said, FAST is the only radio telescope in the world whose working frequency covers 300MHZ~3GHZ. FAST is the ideal equipment for pulsars. Its working frequency band has ultra-high sensitivity and can “see” each pulse clearly.
Such claims have also been endorsed by George Hobbs, who claimed to expect FAST’s future research output. A necessary background is that almost half of the world’s pulsars were discovered by Australian Parkes Radio Telescope, which was run by George Hobbs.
The pulsars that have been found are mostly in the Milky Way, while FAST can explore space about two million light-years away, said Li. Through “drift” scanning, FAST could sky patrol and scan neutral hydrogen, pulsars, the galaxy structure and molecular spectral line and other scientific objects at the same time, which has never been achieved by other telescopes in the world.
What’s more, FAST discovered another four pulsars after the first two pulsars were discovered respectively on August 22 and August 27. And just in the past National Day Holidays, the latest-discovered pulsars have also passed international certification.
“Systematic scientific output has begun,” said Li. FAST is starting the “exciting” era when China’s radio band mega scientific device system discovered new findings.
25 days ago: the father of FAST died
It is worth noting that the time of discovering pulsar is still in the “early stage” of FAST telescope. The next step is two-year trial. It is like before the warrior gets fully equipped with weapons and equipment to the battlefield, he has beaten the enemy. Li Di said, it was due to effective early scientific plans and talent and technology reserves that FAST could show its scientific prowess earlier. Behind the results, Nan Rendong, the project’s founder and chief architect, cannot be forgotten.
He died 25 days ago at the age of 72. At Nan Rendong Deed Report held in NAOC, scientists expressed their common regret: before FAST shined, Nan had passed away.
Zhang Haiyan, Nan Rendong’s student and deputy director of the FAST engineering office, told reporters that Nan Rendong said repeatedly that “people need to do something when they are alive”.
And building FAST is what he calls as “doing something”. He did it for more than 20 years.
Today, FAST led by Nan finally opens its “sharp eyes” and looks at the universe.
The “debut” of FAST, perhaps, is the best comfort for Nan Rendong. Some netizens suggested that the first pulsar discovered by FAST should be named as “Nan Rendong star”.
44 days ago: FAST stably acquired target signals
After the “debut”, some people doubt that since FAST was completed as early as September 25 last year, why didn’t it have any scientific output until after nearly one-year debugging?
Peng Bo, researcher at NAOC and deputy project manager of FAST, said for large radio telescopes of same type, generally, 3 to 5 years of debugging were necessary after completion. China’s telescope obtained preliminary results only after one-year debugging. It is a progress exceeding the international practice of similar equipment.
In the case of FAST itself, the difficulty of debugging is “enormous”. Yan said, the whole debugging was related to multidisciplinary fields such as measurement, control, mechanics, electronics and astronomy. And for Chinese scientists, FAST working mode is different from traditional telescope, so there is no mature experience for reference.
FAST is now a popular scene in Guizhou Province, will scientific observations be interfered by tourists’ mobile phones?
Jiang Peng told a reporter, scientists were glad to see local economy development. Meanwhile, they believe that the telescope’s scientific output will further promote the local tourism industry. It will be a win-win situation. The local government has also made a policy of “no interference with telescope detection within the range of 5KM”.
However, he noted that as the telescope was not fully equipped for electromagnetic shielding, the corresponding interference phenomenon existed and they would strengthen it in the future. He said, “whether it’s sunny or rainy, we will make sure that FAST can work every day, ensuring effective observation hours to promote more and better scientific output.”
FAST achieved tracking observation and steadily gained a signal from the target source on August 27,44 days before the debut. Yan told reporters that FAST has basically completed the functional debugging of the telescope, which is a very important stage result in telescope debugging phase.
To put it simply, “FAST is already a very powerful radio telescope, and it fully validates the telescope’s sensitivity”.
According to Yan, the trial observation plan for the year was 500 hours. So far, FAST has accumulated 700 observation hours and has already outperformed the target ahead of schedule.
Behind each of these hours, there is a painstaking effort by researchers. Li said, for each scan, researchers need to not only design software and need to pay more “manual labor” in data processing, which is why “drift scan” approach is rarely used in the pulsar search.
Fortunately, the telescope can detect one to two high quality pulsar candidates each time.
Nan Rendong ever said, he wished through FAST, a giant telescope, we could explore interstellar interaction information, observe dark matter, measure black hole weight and even search for possible “civilization in outer space”.
Li didn’t evade this topic. He says, searching for extraterrestrial civilizations is a serious scientific goal, but FAST is currently in debugging phase and has not carried out a similar study.
According to George Hobbs, a person who has had the experience, 20% time of Parkes Radio Telescope is allocated to “looking for aliens”, but so far nothing has been found.
As for China’s telescope, Hobbs says, “it could detect farther”.