mc
short answer
essay
Prompt
[MANDATORY] Landsat β altitude, repeat, sensors, band cheat sheet.
Plain English answer (default view) β what you'd actually write on the test
**Landsat** is the granddaddy of Earth observation β running continuously since 1972, longer than any other civilian satellite series. It captures the whole Earth every **16 days** (or every 8 days now, with Landsat 8 + 9 working together) at moderate detail (30 m). The data is **free**, which is why it's the backbone of every long-term land-change study you've heard of: Amazon deforestation, glacier retreat, urban sprawl, agriculture monitoring. Modern sensors are **OLI-2** (visible/NIR/SWIR) and **TIRS-2** (thermal infrared).
π¬ Technical version / model bullets (revealed on click) β one bullet per line
Longest continuous EO record (1972βpresent, USGS / NASA). Orbit **705 km** (L4 onward), sun-synchronous, **16-day** repeat (L8 + L9 combined β 8-day). Modern sensors: **OLI-2** (9 bands @ 30 m, pan @ 15 m) + **TIRS-2** (2 thermal @ 100 m). Heritage TM/ETM+ numbering: 1 Blue, 2 Green, 3 Red, 4 NIR, 5 SWIR-1, 7 SWIR-2, 6 Thermal. NDVI: TM B4/B3 β OLI B5/B4 (numbering shifted by 1).
π‘ Mnemonic / memory aid (shown on hover)
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