Fi­nance sought for ra­dio te­le­scope in Antarc­tica

Astronomers hope to ob­serve elec­tro­mag­netic waves from the lo­ca­tion known as Dome A

China Daily (Hong Kong) - - CHINA - By CHENG YINGQI chengy­ingqi@chi­nadaily.com.cn

Chi­nese astronomers are ap­ply­ing for govern­ment fund­ing to be­gin con­struc­tion of a ra­dio te­le­scope in Antarc­tica that could help solve the mys­ter­ies be­hind stars and galax­ies.

The pro­posed fa­cil­ity, to be built on a gi­ant ice cap known as Dome A, has been de­signed to ob­serve ter­a­hertz, a band of elec­tro­mag­netic waves nor­mally too weak for ground­based sta­tions to re­ceive.

“The high al­ti­tude and low tem­per­a­tures at Dome A make it pos­si­ble for as­tro­nom­i­cal ob­ser­va­tion of ter­a­hertz,” said Shi Sheng­cai, a re­searcher at Pur­ple Moun­tain Ob­ser­va­tory, a fa­cil­ity in Nan­jing af­fil­i­ated with the Chi­nese Academy of Sciences. “The thick at­mo­spheric lay­ers in most other places ab­sorb too much of the sig­nal.”

Tem­per­a­tures at Dome A can fall as low as -80 C. The ex­treme en­vi­ron­ment is per­fect for sci­en­tific ex­per­i­ments, but few were able to make use of it be­fore the Polar Re­search In­sti­tute of China and its in­ter­na­tional part­ners set up the Plateau Ob­ser­va­tory, or Plato, in 2008.

Shi’s academy and the State Oceanic Ad­min­is­tra­tion now are ap­ply­ing for fund­ing from the Na­tional De­vel­op­ment and Re­form Com­mis­sion to build a 5-me­ter ter­a­hertz te­le­scope at Dome A. If ap­proved, con­struc­tion will start soon and last up to five years.

The cost of the project has not been re­leased. How­ever, once com­plete, the fa­cil­ity is ex­pected to be the only one of its kind on Earth.

The project has been boosted by anal­y­sis of mul­ti­ple ter­a­hertz fre­quen­cies ob­served by equip­ment placed at Dome A over 19 months in 2010 and 2011. A pa­per on the ob­ser­va­tion data was pub­lished on Tues­day by the science jour­nal Na­ture As­tron­omy.

“The ini­tial suc­cess is en­cour­ag­ing,” Shi said, ad­ding that pre­lim­i­nary re­search for the ter­a­hertz te­le­scope has been com­pleted.

Elec­tro­mag­netic ra­di­a­tion trav­els through space in the form of light waves and is dis- tin­guished by wave­length. In or­der of de­creas­ing wave­length, there are ra­dio waves, mi­crowaves, in­frared, vis­i­ble light, ul­tra­vi­o­let, X-rays and gamma rays.

The wave­length of ter­a­hertz, which lies be­tween mi­crowaves and in­frared, is im­por­tant in ob­serv­ing the fea­tures of the dom­i­nant forms of car­bon and thus could an­swer as­tro­nom­i­cal mys­ter­ies re­lated to the for­ma­tion and evo­lu­tion of stars and galax­ies.

“Ter­a­hertz have been a fruit­ful en­ergy band for as­tro­nom­i­cal ob­ser­va­tion, although in the past, sci­en­tists had to ob­serve the band us­ing space or air­borne tele­scopes,” said Zhang Qizhou of the Smith­so­nian Astro­phys­i­cal Ob­ser­va­tory in the United States.

The Euro­pean Space Agency’s Her­schel, the first space ob­ser­va­tory to spot a broad­band op­ti­cal spec­trum that in­cluded ter­a­hertz, was re­tired in 2013 after pro­vid­ing ex­cit­ing re­sults in many ar­eas of as­tron­omy.

NASA’s Strato­spheric Ob­ser­va­tory for In­frared As­tron­omy, a mod­i­fied Boe­ing 747SP air­craft car­ry­ing a 2.5-me­ter te­le­scope, can be used for ob­ser­va­tion for only about 10 hours dur­ing each flight.

In 2008, in­ter­na­tional part­ners in­clud­ing China, the US and Aus­tralia set up a ra­diome­ter in prepa­ra­tion for a High El­e­va­tion Antarc­tic Ter­a­hertz Te­le­scope. How­ever, that project was later sus­pended.

“Astronomers thought it (ob­serv­ing ter­a­hertz) couldn’t be done on Earth,” Zhang said. “In fact, a ground-based ob­ser­va­tory has ob­vi­ous ad­van­tages, as it can hold a larger te­le­scope and is much more flex­i­ble be­cause astronomers can go there — it’s dif­fi­cult, but it’s reach­able — to main­tain and up­grade the te­le­scope.”

Hu Zhong­wen from the Na­tional As­tro­nom­i­cal Ob­ser­va­to­ries, also af­fil­i­ated with the CAS, said Chi­nese sci­en­tists have ac­cu­mu­lated ex­pe­ri­ence in de­ploy­ing and op­er­at­ing so­phis­ti­cated equip­ment in the ex­treme con­di­tions at Dome A.

“The harsh weather poses se­vere chal­lenges to equip­ment there, and it wasn’t pos­si­ble to send peo­ple to check and fix it re­peat­edly, so we de­vel­oped some mea­sures to en­sure the equip­ment is bet­ter suited to the en­vi­ron­ment,” Hu said.

“It would be risky to build large sci­en­tific fa­cil­i­ties in the polar en­vi­ron­ment with­out any ex­pe­ri­ence. Ex­per­i­ments with the spec­trom­e­ter have got­ten us pre­pared for a larger project.”

Di­a­gram of a ra­dio te­le­scope that astronomers pro­posed to be built in Antarc­tica.

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