El gráfico muestra la nave espacial Sentinel-6 Michael Freilich.
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ESPACIO

Misión Sentinel-6A Michael Freilich

By Duncan Mil

October 19, 2020 - November 10, 2020 - Dos naves espaciales Sentinel-6 suministrarán mediciones en escala de centímetros del aumento del nivel del mar. Ambas naves gemelas – Sentinel-6A y Sentinel-6B – llevarán nuevos y poderosos radares altímetros Poseidon-4

Sentinel-6A bears the name Dr Michael Freilich -- a tireless advocate for advancing satellite measurements of the ocean -- and is the sixth mission of the European Copernicus Earth observation programme.

Sentinel-6A Michael Freilich will launch atop a SpaceX Falcon-9 rocket from Vandenberg Air Force Base at 06:31GMT (11:31PST) on November 10. Sentinel-6B will launch in 2025.

Since the early 1990s, satellite altimeters have revolutionised our understanding of sea-level change -- one of the principal concerns linked to climate change.

The Poseidon-4 radar altimeter, developed by Airbus Defence and Space, has an accuracy of 3 centimetres (1.2 inches) from low Earth orbit, about 1,330km (830 miles).

Poseidon-4 bounces radar pulses off the sea surface and measures the time it takes the signals to return to the satellite.

A microwave radiometer corrects so-called “wet-path delay” -- errors caused by water vapour in the atmosphere. The round-trip travel time calculates the distance between the spacecraft and the ocean surface.

Sentinel-6 carries a suite of instruments for Precise Orbit Determination or POD. One Doppler Orbit Radio positioning system (DORIS), a laser retro-reflector and star trackers locate the position of the satellite in orbit.

The combination of altimeter distance and Sentinel’s exact location in space, determine the height of the sea surface relative to the centre of the Earth.

During the last 25 years, the Copernicus programme has measured a global mean sea level increase of 3.3mm/year and a total global increase since 1993 of about 9.4cm (3.7 inches).

PUBLISHED: 19/10/2020; STORY: Graphic News
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