Although the Halley's Comet retrograde orbit and high inclination made it difficult to send a space probe to it, the 1986 apparition gave scientists the opportunity to study the comet closely and several probes were launched to do so. The Soviet Vega 1 probe began returning images of Halley on 4 March 1986, captured the first-ever image of its nucleus, and made its flyby on 6 March. It was followed by the Vega 2 probe, making its flyby on 9 March. On 14 March, the "Giotto" space probe, launched by the European Space Agency, made the closest pass of the comet's nucleus. There also were two Japanese probes, "Suisei" and "Sakigake". Unofficially, the numerous probes became known as the Halley Armada.