Flashcards

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Landsat 9 — launch date, altitude, sensors?

essential landsat

🚀 Launch: Sept 27, 2021
🛰️ Orbit
- Altitude: 705 km
- Sun-synchronous, 10 AM equator crossing
- 16-day repeat (8-day combined with Landsat 8)
📷 Sensors (the “-2” matches Landsat-9)
- OLI-2 — Operational Land Imager: 9 bands, 30 m VSWIR, 15 m pan
- TIRS-2 — Thermal Infrared Sensor: 2 thermal bands at 100 m
🎚️ Radiometric: 14-bit (vs 12-bit on L8, 8-bit on L5/7)

💡

705 km, 2021. OLI-2 + TIRS-2 (the '-2' matches Landsat-9). With L8 flying opposite, combined revisit ≈ 8 days.

landsat/landsat9-overview

Landsat TM — 7 bands and their resolutions?

essential landsat

TM has 7 spectral bands. All 30 m except thermal at 120 m.

🟦🟩🟥 Visible (30 m)
- Band 1 · Blue · 0.45–0.52 µm
- Band 2 · Green · 0.52–0.60 µm
- Band 3 · Red · 0.63–0.69 µm
🟪 Near-infrared (30 m)
- Band 4 · NIR · 0.76–0.90 µm
🟫 Shortwave infrared (30 m)
- Band 5 · SWIR-1 · 1.55–1.75 µm
- Band 7 · SWIR-2 · 2.08–2.35 µm
🔥 Thermal — coarser: 120 m
- Band 6 · Thermal IR · 10.4–12.5 µm

⚠️ Numbering oddity: 1-2-3-4-5-7-6. Band 7 was added later and squeezed in spectrally between 5 and 6 but numbered last.

💡

Bands 1-2-3-4-5-7-6. Yes, 7 before 6. All 30 m except thermal band 6 at 120 m. Watch for 'Band 4 = NIR' (on TM) vs 'Band 5 = NIR' (on OLI).

landsat/tm-bands

Landsat WRS-2 — path/row grid specs?

likely landsat

🌐 Grid size: 233 paths × 248 rows covering the globe
🧭 Numbering
- Paths numbered westward — Path 001 over eastern Greenland & S. America
- Rows numbered southward from 80°N — Row 60 ≈ equator
🛰️ Versions
- WRS-2 — Landsat 4–9 (16-day cycle, current)
- WRS-1 — Landsat 1–3 (251 paths, 18-day cycle, retired)

landsat/wrs2

Landsat 1–3 orbit — altitude + revisit?

maybe landsat

⚠️ Orbit was lowered to 705 km at Landsat 4 for better spatial resolution. That’s why later Landsats have 16-day revisit instead of 18.

landsat/l1-3-orbit

Landsat 7 ETM+ — what it added vs. TM?

maybe landsat

Two upgrades over the older TM:

🩶 New panchromatic band — 0.52–0.90 µm at 15 m
- Enables pan-sharpening (fuse 30 m MS with 15 m pan → 15 m color)
🔥 Thermal improved — 120 m → 60 m
Other VSWIR bands unchanged at 30 m

landsat/etm-pan

Landsat MSS band numbering — why does it differ across satellites?

maybe landsat

MSS flew on Landsat 1/2 and Landsat 4/5 — but the bands got renumbered. Same wavelengths, new numbers:

⚠️ MSS has no blue band — visible spectrum starts at green. That’s why MSS imagery can’t be made into natural-color composites.

landsat/mss-renumbering

Radiometric resolution bit depths?

maybe landsat

More bits → finer tonal detail in shadows + highlights.

landsat/radiometric-bits