Spring Couplet is one of the most emblematic signs for Chinese people in celebrating Chinese New Year.  That is no exception for three astronauts of Shenzhou 13 who are now on the China Tiangong space station and delivering blessings to their fellow countrymen in the ground with couplets on the eve of Year of Tiger.  Kindly see following report at:   

盛世中华！宇宙级的祝福来了！ (guancha.cn) 

It has long been established that people writing and pasting Spring Couplet on the first day of lunar new year, but it seems that Mr. Wang Anshi set up the norms a thousand years ago:

試譯 王安石: 元日 - kkuo0810的部落格 - udn部落格