Resources
RPS 60th: Transit IV-A Shareable

Launched on June 29, 1961, Transit IV-A was the first satellite to carry a radioisotope power system into space.
Transit IV-A conducted navigation trials and demonstrations, improved the understanding of the effects of ionospheric refraction on radio waves and increased knowledge of the earth's shape and gravitational field. Doppler data from this satellite confirmed that the equator of the earth is elliptical.
Credit
Credits: NASA/GRC