HEOS (Highly Eccentric Orbiting Satellite)
HEOS (Highly Eccentric Orbiting Satellite) 1 and 2 were ESRO (European Space Research Organisation) satellites that traveled in extremely elongated orbits in order to study the interplanetary magnetic field and solar and cosmic ray particles outside Earth's magnetosphere.
Nine scientific groups in five countries provided experiments for the HEOS 1 satellite. Under a December 30, 1966 memorandum of understanding and a March 8, 1967 contract with ESRO, the mission was the first cost-reimbursed NASA launch of a foreign scientific satellite.
HEOS 2, the second satellite in the series, continued the study of the interplanetary medium.
|spacecraft||launch vehicle||launch date||launch site||solar orbit||mass (kg)|
|HEOS 1||Delta E||Dec 5, 1968||Cape Canaveral||20,020 × 202,780 km × 60.5°||108|
|HEOS 2||Delta L||Jan 31, 1972||Vandenberg||405 × 240,164 km × 89.9°||123|