En­coun­ters of the space kind

China Daily (Canada) - - ANALYSIS -

Spher­i­cal Tele­scope, now be­ing built deep in the moun­tains of Guizhou prov­ince in South­west China, will be­come the world’s largest ra­dio tele­scope once com­pleted in Septem­ber.

With a dish the size of 30 foot­ball fields, FAST is 500 me­ters in di­am­e­ter and made of 4,450 pan­els. Sci­en­tists have de­picted it as a su­per-sen­si­tive ear that will be able to de­tect very weak mes­sages — if there are any — from any rel­a­tives we may have out there.

It will be 10 times more sen­si­tive than the te­le­scopes in the Break­through Lis­ten project, a $100 mil­lion ini­tia­tive by Rus­sian ty­coon Yuri Mil­ner to search for ex­trater­res­trial civ­i­liza­tions, said Li Di, chief sci­en­tist with the ra­dio astron­omy de­part­ment of the Na­tional Astro­nom­i­cal Ob­ser­va­to­ries of China.

Werthimer is seek­ing co­op­er­a­tion with Chi­nese astronomers to de­velop a SETI@home project for FAST. “We hope to work with China to do SETI at the same time the tele­scope car­ries out sky sur­veys to search for pul­sars, fast ra­dio bursts and to map the gal­axy as planned.”

Though un­sure of how such col­lab­o­ra­tion would work, Li Di is in­ter­ested in work­ing with the SETI@ home project. “With their ex­pe­ri­ence and advanced tech­nolo­gies, they will help us im­prove the tele­scope’s sci­en­tific ca­pa­bil­i­ties and op­er­at­ing con­di­tions. It’s like stand­ing on the shoul­ders of a gi­ant.”

Chi­nese sci­en­tists have also par­tic­i­pated in the prepa­ra­tions for the Square Kilo­me­ter Ar­ray, a large multi-ra­dio tele­scope project to be built in Aus­tralia and South Africa.

It will even­tu­ally use thou­sands of dishes and up to a mil­lion an­ten­nas, which will en­able astronomers to mon­i­tor the sky in un­prece­dented de­tail and sur­vey the en­tire sky much faster than any sys­tem now op­er­at­ing. The search for ex­trater­res­trial life is one of its key science pro­grams.

Sci­en­tists have sur­veyed the en­tire sky with ra­dio te­le­scopes for a half­cen­tury now, and they have found in­ter­est­ing sig­nals oc­ca­sion­ally.

On Aug 15, 1977, a strong nar­row­band ra­dio sig­nal, bear­ing the ex­pected hall­marks of ex­trater­res­trial ori­gin, was de­tected by Jerry Eh­man, an as­tronomer work­ing on a SETI project at the Big Ear ra­dio tele­scope of Ohio State Univer­sity. The sig­nal ap­peared to come from the con­stel­la­tion Sagittarius and lasted 72 sec­onds.

Eh­man cir­cled the sig­nal on the com­puter print­out and wrote the com­ment “Wow!” be­side it, which that event is now com­monly called. But it has never been de­tected again.

“Some strange sig­nals have been found, but it’s hard to con­firm their ori­gins, be­cause these sig­nals do not re­peat,” Li Di said.

“We look for not only tele­vi­sion sig­nals, but also atomic-bomb sig­nals. We shall give full play to our imag­i­na­tions when pro­cess­ing the sig­nals. It’s a com­plete ex­plo­ration, as we don’t know what an alien is like.”

Ra­dio te­le­scopes some­times mis­read sig­nals from astro­nom­i­cal ob­jects. For ex­am­ple, astronomers once mis­took sig­nals from a pul­sar for ex­trater­res­trial signs, be­cause a pul­sar can also give out very sta­ble pe­ri­od­i­cal sig­nals.

“We don’t know when earth­lings will dis­cover ET,” Werthimer said. “It could be 1,000 years from now, or in our life­times. It could be next year, when FAST gets go­ing on the sky sur­veys.”

How­ever, with no clues of ex­trater­res­trial life over the past 50 years, ques­tions are con­stantly asked as to whether the search methods are ap­pro­pri­ate.

Even on Earth, land and sea host com­pletely dif­fer­ent forms of life. “It is highly pos­si­ble that life on other plan­ets is en­tirely dif­fer­ent from that on Earth, and it might not be car­bon-based,” said Jin Hairong, deputy cu­ra­tor of Bei­jing Plan­e­tar­ium.

Liu Cixin, a Chi­nese science-fic­tion writer and win­ner of the Hugo Award for his novel TheThree­Body Prob­lem, said the cur­rent method as­sumes that aliens also com­mu­ni­cate in ra­dio waves. “But if it’s a truly advanced civ­i­liza­tion, it is pos­si­ble to use other more advanced forms of com­mu­ni­ca­tion, such as grav­i­ta­tional waves.”

LIU XU / XINHUA

The 500-me­ter aper­ture spher­i­cal tele­scope in Ping­tang county, Guizhou, to be com­pleted in Septem­ber, is ex­pected to be the world’s largest, over­tak­ing Puerto Rico’s Arecibo Ob­ser­va­tory, which is 300 me­ters in di­am­e­ter.

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