Landsat 9 简介
Landsat 9 是美国陆地卫星计划（Landsat）的第九颗卫星，2021年9月发射，为减少建造时间和观测数据的中断，Landsat 9 很大程度上是Landsat 8卫星的一个复制版。它携带由Ball Aerospace&Technologies公司建造的二代陆地成像仪（Operational Land Imager 2，OLI-2）和NASA戈达德航天飞行中心建造的二代热红外传感器（Thermal Infrared Sensor 2，TIRS-2）。
Status: Current, Prime Mission
Mission Category: Earth Systematic Missions Program, Inter-Agency Partnerships
Launch Date: September 27, 2021
Launch Location: Vandenberg Space Force Base
Designed Life: September 27, 2026
Launch Vehicle: United Launch Alliance (ULA) Atlas V rocket
Altitude:Distance from sea level. 705km
Inclination: 98.2°
Origination: NASA/USGS
Science Instruments: OLI-2; TIRS-2
OLI-2 build: Ball Aerospace & Technology Corp.
TIRS-2 build: NASA Goddard Space Flight Center
Spacecraft Provider:Northrop Grumman
Image Data: > 700 scenes per day
Orbit: near-polar, sun-synchronous at an altitude of 438 miles (705 km)
Spacecraft Speed: 16,760 mi/hr (26,972 km/hr),
Consumables: 10 years
Project Scientist(s): Jeff Masek
Deputy Project Scientist(s): Bruce Cook
Other Key Personnel: Dave Jarrett;Garik Gutman;Del Jenstrom
每天可以拍摄700多幅影像，近极地轨道使其约每16天覆盖全球，当Landsat 9 和Landsat 8 轨道联合，可以获得8天的分辨率。
Landsat 9 will replace Landsat 7 (launched in 1999), taking its place in orbit (8 days out of phase with Landsat 8). The combined Landsat 8 + Landsat 9 revisit time for data collection with be every 8 days, like it currently is for Landsat 8 + Landsat 7.
Both instruments have sensors with moderate spatial resolution—15 m (49 ft), 30 m (98 ft), and 100 m (328 ft) depending on spectral band—and the ability to detect a higher range in intensity than Landsat 8 (14-bit radiometric resolution vs. Landsat 8's 12-bit radiometric resolution).
OLI-2将捕获地球表面可见、近红外和短波红外波段的观测，辐射测量精度从Landsat8的12位量化提高到14位量化，并略微提高了总体信噪比。TIRS-2将通过两个波段测量地球表面的热红外辐射或热量，这两个波段的性能比Landsat8的热波段要好。尽管卫星有10年以上的消耗期，OLI-2和TIRS-2都只有5年的设计寿命。
Landsat 1-9 发射时间
Landsat 9 Bands
Landsat 8 和 Landsat 9 拥有11个光谱波段，分别通过 OLI/TIRS 和 OLI-2 / TIRS-2 仪器获取。
- 波段1可见（0.43-0.45μm）30m
- 波段2可见（0.450-0.51μm）30m
- 波段3可见（0.53-0.59μm）30m
- 波段4红色（0.64-0.67μm）30m
- 波段5近红外（0.85-0.88μm）30m
- 波段6 swir 1（1.57-1.65μm）30m
- 波段7 swir 2（2.11-2.29μm）30m
- 波段8全色（PAN）（0.50-0.68μm）15m
- 波段9卷云（1.36-1.38μm）30m
- 波段10 TIRS 1（10.6-11.19μm）100m
- 波段11 TIRS 2（11.5-12.51μm）100m
The Multispectral Scanner System (MSS) aboard Landsats 1–5 had four bands. The Thematic Mapper (TM) aboard Landsats 4 & 5 had seven bands. Landsat 7’s Enhanced Thematic Mapper Plus (ETM+) has 8 bands and Landsats 8 & 9 have 11 bands. The atmospheric transmission values for this graphic were calculated using MODTRAN for a summertime mid-latitude hazy atmosphere (circa 5 km visibility). - MSS(Landsats 1–5): 4 bands
- TM(Landsats 4 & 5): 7 bands
- ETM+(Landsats 7): 8 bands
- OLI/TIRS 和 OLI-2/TIRS-2(Landsats 8 & 9): 11 bands
截止Sept. 30, 2020每颗Landsat 卫星贡献至USGS Landsat data archive的数据量。 对于Landsats 4 和 5, 深色代表MSS(Multispectral Scanner System)数据，浅色代表TM（Thematic Mapper）数据
参考链接:
https://landsat.gsfc.nasa.gov/landsat-9 （有说介绍文档pdf下载）
Masek, Jeffrey G., Michael A. Wulder, Brian Markham, Joel McCorkel, Christopher J. Crawford, James Storey, and Del T. Jenstrom. 2020. "Landsat 9: Empowering open science and applications through continuity." Remote Sensing of Environment 248:111968. doi: https://doi.org/10.1016/j.rse.2020.111968.
https://landsat.gsfc.nasa.gov/landsat-9/landsat-9-overview
https://www.nasa.gov/content/landsat-9-instruments