{"id":331182,"date":"2025-12-17T01:33:59","date_gmt":"2025-12-16T15:33:59","guid":{"rendered":"https:\/\/science.nasa.gov\/missions\/landsat\/whats-next-for-hls\/"},"modified":"2025-12-17T01:33:59","modified_gmt":"2025-12-16T15:33:59","slug":"whats-next-for-hls","status":"publish","type":"post","link":"https:\/\/www.vibewire.com.au\/?p=331182","title":{"rendered":"What\u2019s Next for HLS"},"content":{"rendered":"

Harmonized Landsat and Sentinel-2 PI Christopher Neigh shares milestones and a vision for the future<\/h4>\n

In 2025, the Harmonized Landsat and Sentinel-2 (HLS) program established itself as a cornerstone for global medium-resolution optical Earth observation and became one of NASA\u2019s most downloaded products. The seamless, analysis-ready dataset is free for anyone to use and download on NASA Earthdata: HLSL30v2.0<\/a> and HLSS30v2.0<\/a>. HLS version 2.0 (Ju et al., 2025<\/a>), released in July, represents a major advancement in algorithm sophistication and dataset completeness. The improved surface reflectance dataset now extends globally back to 2013 (excluding Antarctica) and integrates observations from Landsat 8\/9 and Sentinel-2A\/B\/C satellites, achieving an unprecedented median revisit interval of less than 1.6 days. This high frequency of observations transforms our ability to monitor Earth\u2019s changing surface.<\/p>\n

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\"Patches<\/a><\/figure>
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Patches of purple across Canada show where vegetation disturbances were detected in 2023.<\/div>\n
NASA\u2019s Earth Observatory\/Wanmei Liang<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n

June saw the first in-person HLS meeting between NASA headquarters, the Satellite Needs Working Group (SNWG)<\/a>, and representatives from NASA\u2019s Goddard Space Flight Center<\/a> and Marshall Space Flight Center<\/a>, representing enhanced coordination and strategic alignment. The HLS project also serves as a critical steppingstone for advancing collaboration between NASA and the European Space Agency (ESA).<\/p>\n

HLS\u2019s frequent revisit is one of its key values to data users. Zhou et al. (2025)<\/a> evaluated the cloud-free coverage of HLS V2.0 in 2022 and found that HLS data provided observations every 1.6 days at the global scale and 2.2 days in data-scarce tropical regions. This temporal resolution addresses one of the most persistent challenges in optical remote sensing: obtaining cloud-free observations for time-sensitive applications.<\/p>\n

HLS Impacts<\/h3>\n

Already, scientists are putting HLS to use for practical and scientific applications. Zhou et al. (2025)<\/a> evaluated the global consistency, reliability, and uncertainty of the newly-released suite of nine HLS vegetation indices<\/a>. This assessment provides the scientific community with confidence in using HLS-derived vegetation indices for agriculture, forestry, ecosystem monitoring, and more.<\/p>\n

Pickens et al. (2025)<\/a> unveiled a global land change monitoring system, DIST-ALERT, based on HLS data. DIST-ALERT highlights HLS\u2019s transformative impact on environmental monitoring, identifying new land change dynamics that are impossible to track with Landsat or Sentinel observations alone.<\/p>\n

Vision for the Future<\/h3>\n

The HLS program continues to evolve to deliver high-quality, reliable data to its expanding user base. Shi et al. (2026, under review in Remote Sensing of Environment<\/em>) developed Fmask version 5.0, employing a hybrid approach combining physical rules, machine learning, and deep learning for cloud masking. When released, this next-generation cloud detection algorithm will improve the accuracy and consistency of cloud\/cloud-shadow screening\u2014a critical component for maximizing usable observations in the HLS time series.<\/p>\n

Looking forward, the HLS vision encompasses:<\/p>\n