Archeops was a balloon-borne instrument dedicated to measuring the Cosmic microwave background (CMB) temperature anisotropies.

[1] Namely, it consists of an open 3He-4He dilution cryostat cooling spiderweb-type bolometers at 100 mK; cold individual optics with horns at different temperature stages (0.1, 1.6, 10 K) and an off-axis Gregorian telescope.

Then, the upgraded instrument was launched three times from the Esrange base near Kiruna (Sweden) by the CNES during 2 consecutive Winter seasons (2001 and 2002).

Archeops has linked, for the first time and before WMAP, the large angular scales (previously measured by COBE) to the first acoustic peak region.

[2][3] From its results, inflation motivated cosmologies have been reinforced with a flat Universe (total energy density Ωtot = 1 within 3%).