Re: Plutonium on Next Atlas V - Bad Idea?

On Tue, 16 Aug 2005 08:40:18 -0500, richard schumacher
<no-spam@xxxxxxxxxxx> wrote:

>By the way, how much plutonium did they finally get for the RTGs?
>Enough to undertake Kuiper belt object encounters?

I have been looking into your questions.

Half of the Plutonium-238 for New Horizons came from a DoE Los Alamos
nuclear weapons plant that closed in July 2004. A total of 36 of the
72 fuel units ordered had been left over from a spare RTG built
earlier for NASA's Cassini mission. When the lab shut down, it had 18
more units in the works.

This means that this probe will go ahead with a minimum of 61 fuel
units out of the maximum of 72. How many it actually has I cannot say,
when they may have been able to obtain extra from the Russians.

However, I can say that the full 72 fuel units can produce 200 watts
of electricity, where the 61 fuel units would produce 170 watts. And
this reduced configuration is what I guess they ended up with, which
means a change to their mission.

Some inside news is that instead of trying to cut back on the science
collection and storage, then they had been considering a plan to speed
up New Horizon's arrival at Pluto. This would bring arrival forwards
from the expected 2015 arrival at Pluto to about October 2014. They
can do this by sacrificing a very minor secondary experiment to
measure solar wind scintillation along the Earth-Pluto line with the
Radio Science Experiment (REX).

The point being is that every year they save in travel time equals
around an additional 5 watts in increased power at Pluto.

They also planned to reduce the primary data transmission from the
previous 5 months down to 46 days by using the maximum data
transmission rate available at Pluto. I guess that means that they
will need some extra large dishes on Earth to receive this high speed
data.

And so this explains exactly why New Horizons is using the Atlas V 551
configuration, when they intend to get out to Pluto as fast as
possible in order to have more energy available.

I sure hope that they put a speed dial on this launch, when New
Horizons could well become the fastest probe ever to be sent into the
outer solar system. It will pass the moon in under 9 hours and would
shoot by Jupiter just 13 months later.

Anyway, that is completely everything that I can find out about this
situation. Since I guess that they have to option to switch devices
off, then you should certainly see something from a KBO, if they
actually find one out there.

Cardman.
.

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