O3b Networks has signed a contract with Thales Alenia Space for the construction of four satellites for its medium Earth orbit constellation.

O3b Network had previously signed a contract with Thales for the construction of eight satellites.

The first eight O3b satellites, which passed their critical design review in May 2011, are scheduled for launch in the first quarter of 2013 and are expected to offer services in the second quarter of that year.

The satellites will be positioned 8,000km above the Earth, four times nearer than geo-stationary satellites.

The Ka-band satellites will offer high-speed, low-cost, low-latency internet and telecommunications services in emerging markets.

The first eight O3b spacecraft will be launched aboard two European versions of Russia’s Soyuz rocket from Europe’s Guiana Space Centre spaceport in French Guiana.

O3b Networks is planning to enhance its capacity and guarantee greater service availability and reliability through the addition of the four extra satellites.