PROBA is minisatellite technology demonstration mission in ESA's General Study Program with the objective to address issues of on-board operational autonomy of a generic platform. 
|Mission type||Experimental, Earth Observation|
|Mission duration||Elapsed: 21 years, 2 months, 20 days|
|Manufacturer||QinetiQ Space (previously Verhaert Space)|
|Launch mass||94 kg (207 lb)|
|Dry mass||94 kg (207 lb)|
|Dimensions||0.6 m × 0.6 m × 0.8 m (2 ft 0 in × 2 ft 0 in × 2 ft 7 in)|
|Start of mission|
|Launch date||04:53, 22 October 2001 (UTC)|
|Launch site||Sriharikota FLP|
|Perigee altitude||553 km (344 mi)|
|Apogee altitude||677 km (421 mi)|
|Epoch||22 October 2001 00:53:00 UTC|
PROBA (Project for On-Board Autonomy), renamed PROBA-1, is a Belgian satellite launched atop an Indian Polar Satellite Launch Vehicle by ISRO on 22 October 2001. The satellite was funded through the ESA's MicroSat program. This small (60×60×80 cm; 95 kg) boxlike system, with solar panel collectors on its surface, has remarkable image-making qualities. It hosts two Earth Observation instruments dubbed CHRIS and HRC. CHRIS is a hyperspectral system (200 narrow bands) that images at 17 m resolution, while HRC is a monochromatic camera that images visible light at 5 m resolution.
With an initial lifetime of one to two years, the satellite celebrated its 20th year of operations in 2021. On 9 March 2018, it surpassed ERS-2 as ESA's longest operated Earth observation mission of all time.
PROBA is also the name of the series of satellites starting with PROBA-1. The name is also used to refer to the bus of the satellites.
The second satellite in the PROBA series, PROBA-2, was launched on 2 November 2009 together with the SMOS satellite.
The third satellite to be launched was PROBA-V (PROBA-Vegetation), on 7 May 2013.
Further planned satellites in the PROBA series include the formation flying demonstration mission PROBA-3 and limb sounder ALTIUS.