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David A. Long investigated spectral parameters of rare oxygen isotopologues for atmospheric remote sensing. The molecular analysis distinguishes rotational angular momentum from total angular momentum and accounts for nuclear-spin restrictions on the allowed rotational levels.^[ref]

An Earth-centred orbit at relatively low altitude, commonly within roughly 2000 km of the surface. It supports frequent orbital revolutions and relatively fine spatial sampling for remote sensing.

An orbit passing near both geographic poles of its central body. Planetary rotation brings different longitudes beneath successive passes, useful for global remote sensing; one satellite still samples each location intermittently.

An operational spectral region often taken as about 1–2.5 micrometres in remote sensing, with convention-dependent boundaries. Water absorption makes suitable bands sensitive to leaf and surface moisture.

Solar Orbiter is an ESA-led spacecraft with strong NASA participation, launched in February 2020 to connect observations of the Sun with measurements of the solar wind. Its heliocentric orbit and gravity assists allow observations from different distances and increasing solar latitudes, rather than restricting every view to the plane from which Earth sees the Sun.^[ref]

Its ten instruments divide into six for remote sensing and four for sampling the surrounding environment. The remote sensing instruments observe emitted or scattered light from the Sun and its surroundings. The local instruments measure plasma, energetic particles, electric fields, magnetic fields and waves. A magnetometer and particle analysers therefore answer different questions from an image: one measures conditions at the spacecraft, while the other helps locate the remote source.^[ref]

A scientific comparison can ask whether a feature observed near the Sun is associated with a later change in the velocity distribution or composition of locally sampled particles. Identifying the connection requires accounting for the material's travel time and the changing geometry; simultaneous timestamps alone do not establish a common origin. The mission's combined apparatus makes such tests possible. A 2024 analysis, for example, separated proton and alpha particle populations in its solar wind data rather than representing all ions by one mean speed.^[ref]

Assignment of observations to categories using measured features and a statistical rule. In geological remote sensing, features can be multispectral pixel values or derived spectral reflectance ratios; known field samples provide training labels and independent observations assess errors. Classification boundaries need not coincide with lithological contacts when illumination or cover dominates the signal.