The first science meeting for an ultraviolet telescope was held at KIAA at Peking University on October 19. The prospective telescope, named LOTUS for "L2 Orbital Telescope for Ultraviolet Spectroscopy", would be primarily designed and engineered by Changchun Institute of Optics and Fine Mechanics (CIOMP), the same institute that has built the Chinese Space Station Telescope (CSST), due to launch next year.
LOTUS_meetingphoto caption: Participants in the first LOTUS Science Meeting attended from 10 universities and institutes on mainland China and two in Hong Kong SAR.
The meeting brought together academicians, technical experts, and scientific leaders from 10 leading institutes in China Mainland and two in Hong Kong SAR to discuss the design and scientific motivations for an ultraviolet telescope. The meeting opened with encouraging remarks from Academician Gang Zhao of NAOC and KIAA Director Luis Ho. Academician Jiansheng Chen of NAOC and formerly of PKU and Prof. Bing Zhang, Director of the Hong Kong Institute of Astronomy at Hong Kong University, provided their supporting opinions about the telescope and development paths at the end of the meeting.
Prof. Suijian Xue, Group Leader and former Deputy Director of NAOC, gave the opening talk to describe the broad motivations and design of the telescope. CIOMP engineers Dr. Boqian Xu and Lingping He gave technical talks on the design and UV instrumentation for the proposed telescope. The scientific motivation, covering topics from comets and exoplanets to the Intergalactic Medium and Little Red Dots, was described in talks by Profs. Jiangtao Li (PMO) and Taotao Fang (XMU), Cheng Li (THU), Haining Li (NAOC), Yuhan Yao (PKU), Jianning Fu (BNU), Jianqi Qin (PKU), Jianheng Guo (YNAO), Xian Shi (SHAO), Gregory Herczeg (PKU), Xuebing Wu (PKU), and Mr. Chenghao Chen (PKU), alongside a talk on the UV instrument LyRIC for the CSST by Prof. Li Ji (PMO).
Three talk photos: Prof. Luis Ho, Prof. Jianning Fu, and and Dr. Lingping He discuss the science and design of LOTUS.
LOTUS is envisioned as a 2-m spectroscopic telescope at the L2 Lagrangian Point between the Earth and the Sun. Ultraviolet photons do not penetrate the earth's atmosphere, so observations can only be obtained in space. Placing the mission at L2 would reduce the background from geocoronal emission, facilitating much more sensitive observations in Ly-alpha and many other lines.
The 30 meeting attendees were all excited about the prospects of China leading a ultraviolet spectroscopic mission. "Ultraviolet spectroscopy at high resolution provides unique probes of energetic physics and of the baryon cycle, with compelling applications across most astronomical fields," said Gregory Herczeg, Associate Director for Science at KIAA.
The only current options for high-resolution spectroscopy are the STIS and COS instruments on Hubble Space Telescope, both of which are now old and rely on outdated technology. The upcoming UVEX NASA mission is a smaller telescope and will be limited to moderate spectral resolution. Habitable Worlds Observatory is expected to have high-resolution UV capability but will not be ready until the 2040s.
"We have an enormous opportunity for China build a powerful ultraviolet telescope, providing the Chinese and global community with a facility that can fill in this major gap in the electromagnetic spectrum," said Suijian Xue.
The next steps in the development of LOTUS will include technical feasibility studies and quantitative assessments of the science goals. "While this would be a challenging mission to design, I am extremely impressed by the capabilities of CIOMP. Their unique mirror designs and detector technology would allow them to build the most sensitive UV telescope ever built." said Luis Ho, Director of KIAA. "The angular resolution in the far-ultraviolet is essentially the same as a next-generation thirty meter telescope in the infrared."
The meeting was hosted by KIAA and co-organized by Herczeg, Ho, and Xue, with support from KIAA staff and PhD student Changhao Chen.
