The payload "stack" for Vega's second mission from French Guiana has been completed and is ready for installation on the lightweight launch vehicle at the Spaceport.

This milestone completes the integration of all three payloads to be orbited on the May 2 mission, and underscores the capabilities of Arianespace's latest launcher family member to accommodate a variety of satellite passengers.

The payload stack begins with Vietnam's 120-kg. VNREDSat-1 and the 1.3-kg. ESTCube-1 Estonian student nanosatellite, which are positioned inside a dispenser container system called Vespa. Installed atop the Vespa dispenser is Proba-V, a 160-kg. spacecraft for the European Space Agency (ESA).

To complete the integration process, the payload stack was encapsulated inside Vega's payload fairing - readying it for transfer from the S5 preparation facility to the Spaceport's ZLV launch site.

The May 2 flight - which follows Vega's qualification mission in February 2012 - marks the debut of Europe's VERTA (Vega Research and Technology Accompaniment) program - which is to demonstrate the light-lift vehicle's flexibility and versatility. At a planned minimum of two launches annually, this ESA program will allow the smooth transition of Vega into Arianespace's commercial operations.

After its deployment by Vega on the upcoming flight, Proba-V will begin the satellite's mission of mapping land cover and vegetation growth across the Earth every two days. The miniaturized ESA satellite is to provide data for the instrument's worldwide scientific user community and service providers once its in-orbit commissioning is completed.

Proba-V was produced by prime contractor QinetiQ Space Belgium and carries a new, advanced version of the Vegetation instrument - the latest in a series already deployed on France's full-sized Spot-4 and Spot-5 satellites, which have been observing the planet since 1998 after their launches by Arianespace.

The Astrium-built VNREDSat-1 will support the Vietnamese government's initiative to create an infrastructure enabling better studies of climate change effects, improving predictions for natural disasters and optimizing the country's natural resource management. It was built on behalf of the Vietnam Academy of Science and Technology.

ESTCube-1 is to test electric solar wind sail technologies and help establish an Estonian infrastructure for future space projects. This satellite was produced in a collaboration of students from Tartu University, Estonian Aviation Academy, Tallinn University of Technology and University of Life Sciences - and developed in conjunction with the Finnish Meteorological Institute and the German Space Center (DLR).

Once in orbit, ESTCube-1 will deploy a small conductive tether which is to be electrically charged to 500 Volts using electron guns contained within the 10 x 10 x 10-cm. cubesat.