Hongtu-1

{{Short description|Commercial X-band interferometric synthetic aperture radar}}

{{Use dmy dates|date=May 2023}}{{Use American English|date=May 2023}}

{{Infobox space program

| name = Hongtu

| image =

| caption =

| country = {{PRC}}

| organization = China Academy of Space Technology (CAST)

| purpose = Earth observation, reconnaissance

| status = Active

| firstflight = 30 March 2023

| lastflight = 16 December 2024

| successes = 12

| failures = 0

| launchsite = TSLC

| launcher = Long March 2D, Long March 2C

| native_name_a = 宏图

| native_name_r = Hóngtú

}}

The Hongtu-1 ({{Zh|s=宏图一号}}), known commonly by its English-language name PIESAT-1 and infrequently as Nuwa-1, is a Chinese commercial X-band interferometric synthetic aperture radar (InSAR) satellite constellation performing Earth observation missions in Sun-synchronous orbit.{{Cite web |last=Jones |first=Andrew |date=31 March 2023 |title=China launches 4 InSAR satellites and new Yaogan reconnaissance sat |url=https://spacenews.com/china-launches-4-insar-satellites-and-new-yaogan-reconnaissance-sat/ |access-date= |website=SpaceNews |language=en-US}}{{Cite tweet|number=1641556554922045441|user=planet4589|title=China's SAST launched a CZ-2D at 1050 UTC Mar 30 placing four radar satellites in a 497 x 512 km x 97.4 deg, 18:00 LTDN sun-sync orbit. The CZ-2D second stage appears to have made a controlled deorbit soon after deploying the satellites.|author=Jonathan McDowell|author-link=Jonathan McDowell|date=30 March 2023}} Hongtu-1 satellites are intended to map global non-polar regions at a scale of 1:50,000 meters to produce high-precision digital surface models (DSM), likely fulfilling both commercial, scientific, and military reconnaissance tasks.{{Cite web |title=PIESAT - About Us |url=https://www.piesat.cn/cn/ |website=PIESAT}}

The constellation is designed around a hub-and-spoke architecture with three auxiliary (or 'spoke') satellites collecting and a single master (or 'hub') satellite transmitting collected data and receiving instructions for the accompanying auxiliary satellites. Operating in a close formation, these co-orbiting satellites utilize inter-satellite communication to maintain stable and precision synchronization. According to the developer of Hongtu-1 satellites, GalaxySpace, the master satellite weights approximately 320 kilograms and a single auxiliary satellite weights approximately 270 kilograms.{{citation needed|date=May 2023}}

File:30MAR2023 Launch of Hongtu-1 Satellites.png

Hongtu-1 satellites are domestically produced by GalaxySpace, a Beijing-based private satellite developer, for PIESAT Information Technology Co. Ltd. and launched by China Great Wall Industry Corporation (CGWIC), a subsidiary of China Aerospace Science and Technology Corporation (CASC) on a Long March 2D rocket provided by CASC's Shanghai Academy of Spaceflight Technology (SAST).{{Cite web |date=31 March 2023 |title=CGWIC Successfully Launches PIESAT-1-A-01 and PIESAT-1-B-01~03 satellites by LM-2D Launch Vehicle |url=http://www.cgwic.com.cn/News/2023/20230331.html |website=China Great Wall Industry Corporation}} PIESAT has publicly announced their goal to deploy 38 satellites in the constellation, 28 of which are synthetic aperture radar (SAR) alongside 10 optical imaging satellites including panchromatic and multispectral sensors.{{Cite tweet|number=1605926934311043072|user=CNSpaceflight|title=PIESAT 航天宏图 plans to build a 38-satellite constellation: Nuwa-1, including 28 SARs and 10 optical imaging satellites. The first 4, named PIESAT-1, are planned to be launched on March 30 2023|date=22 December 2022}} The first launch of PIESAT-1 (Hongtu-1) satellites took place at Taiyuan Satellite Launch Center (TSLC) in China's Shanxi Province on 30 March 2023.{{Cite video |url=https://www.youtube.com/watch?v=lScMkgf4ihw&ab_channel=%E4%B8%AD%E5%9B%BD%E6%96%B0%E9%97%BB%E7%A4%BE |title=中国成功发射宏图一号01组卫星 |date=30 March 2023 |type=Television production |language=zh |publisher=China News Service |trans-title=China successfully launches Hongtu-1 Group 01 satellites}}