On Sunday, March 8, 2020 at 6:41:46 PM UTC-7, Scott Kozel wrote:


Even with the large gravity assists at Jupiter and Saturn, it took 9 years to
get to Uranus and 12 years to get to Neptune.

1977 launch, 1986 at Uranus, 1989 at Neptune.


Maybe nuclear propulsion can help:

"With congressional funding and industry support, nuclear thermal propulsion
technology is making progress for potential use on future NASA deep space
missions, although how it fits into the agency’s exploration architectures
remains uncertain.

The House Appropriations Committee approved May 22 a commerce, justice and
science (CJS) appropriations bill that offers $22.3 billion for NASA. That
funding includes $125 million for nuclear thermal propulsion development within
the agency’s space technology program, compared to an administration request for
no funding.

“The bill’s investment in nuclear thermal propulsion is critical as NASA works
towards the design of a flight demonstration by 2024,” said Rep. Robert Aderholt
(R-Ala.), ranking member of the CJS appropriations subcommittee, during that
subcommittee’s markup of the bill May 17. He offered similar comments in support
of that project at the full committee markup.

The $125 million comes on top of $100 million that Congress provided in 2019, of
which $70 million was earmarked for a flight demonstration by 2024. The report
accompanying the House bill makes no mention of a 2024 date for a flight
demonstration, but does call on NASA to develop “a multi-year plan that enables
a nuclear thermal propulsion demonstration, including the timeline associated
with the space demonstration, and a description of future missions and
propulsion and power systems enabled by this capability.”"

See:

https://spacenews.com/momentum-grows...al-propulsion/