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Scientific Chagrin. Mariner 5 accumulated and recorded so much data that at week's end it was still being played back and transmitted to Pasadena's Jet Propulsion Laboratory. From preliminary glimpses at Mariner's telemetry, JPL's scientists confirmed Venus 4's discovery of a halo or corona of hydrogen around Venus and agreed that the atmosphere is indeed "dense." They also reported that there had been some fluctuations in the magnetic field surrounding Mariner as it swung past Venus, but that this did not necessarily mean the detection of a Venusian magnetic field.
Although U.S. scientists were confident that Mariner's findings, when fully evaluated, would rival those of Venus 4 in importance, they were clearly chagrined at the Soviet success in sending an operational instrumented capsule through the atmosphere of another planet, years before the U.S. is scheduled even to attempt such a feat. Russia, they note, has already attempted 18 probes to Mars and Venus—compared with only five for the U.S.—and appears to be willing to pay the great costs of planetary exploration. Congress, on the other hand, has continuously snipped away at NASA's budget, leaving the U.S. only four planned planetary probes: a pair of Mars photographic flybys in 1969 and possibly a pair of Martian instrumented soft landings in 1975.