TY  - RPRT
TI  - Problems of extremely long-duration missions in the inner solar system - Example Helios
AU  - Kehr, J.
AU  - Porsche, H.
AU  - Heftman, K.
PY  - 1979
UR  - https://ntrs.nasa.gov/citations/19790069296
ID  - 19790069296
ER  -