ACHIEVING, ASSESSING AND EXPLOITING THE ERS-1 2 TANDEM ORBIT CONFIGURATION/

Although the ERS-1 spacecraft, launched on 17 July 1991, had exceeded its specified nominal lifetime when ERS-2 was launched by an Ariane-4 on 21 April 1995, it continues to function very successfully and, than ks to the decision by the contributing ESA Member States to extend ERS -1 operations beyond the end of the ERS-2 Commissioning Phase, the 'ta ndem mission' has become a reality, Both spacecraft are currently orbi ting the Earth in almost the same orbital plane, with a spacing betwee n them of about one third of an orbital period.