Pluto Flyby

Pluto Flyby

Is the 2006 Pluto mission dead?

Or is a scaled down version still possible for that launch
window?

Does anyone have any good links or references on more
recent developments?

Remus wrote:

Pluto Flyby

Is the 2006 Pluto mission dead?

Or is a scaled down version still possible for that launch
window?

Does anyone have any good links or references on more
recent developments?

Try: http://www.jpl.nasa.gov/missions/future_missions.cfm
http://www.jpl.nasa.gov/missions/proposed_missions.cfm
http://www.jpl.nasa.gov/missions/index.cfm

Sam Wormley wrote:

Remus wrote:

Pluto Flyby

Is the 2006 Pluto mission dead?

Or is a scaled down version still possible for that launch
window?

Does anyone have any good links or references on more
recent developments?


Try: http://www.jpl.nasa.gov/missions/future_missions.cfm
http://www.jpl.nasa.gov/missions/proposed_missions.cfm
http://www.jpl.nasa.gov/missions/index.cfm

Also try http://www.boulder.swri.edu/pkb/ and http://pluto.jhuapl.edu/

--


Alex R. Blackwell
University of Hawaii

"Remus" wrote in message
om...
Pluto Flyby

Is the 2006 Pluto mission dead?

No, although it may slip to 2007 because of delays in assembly of the RTG
for the mission.

Or is a scaled down version still possible for that launch
window?

Yes, if the Los Alamos folks can deliver enough plutonium for the RTG. I
think I read that a reduced mission would need 170 watts, versus 220 watts
for the full mission. The team is also looking at methods of conserving
power during the outbound leg.

-Kim-

Kim Keller wrote:

Yes, if the Los Alamos folks can deliver enough plutonium for the RTG. I
think I read that a reduced mission would need 170 watts, versus 220 watts
for the full mission. The team is also looking at methods of conserving
power during the outbound leg.

True. And contrary to the recent Space.com story, which New Horizons
team members told me contains several factual errors, the NH team is
*not* considering any cutback in spacecraft capabilities or data
storage. They are considering a faster trajectory, which the NH team
believes could save at least 1 year on travel time. Specifically, this
option entails a relaxation in the July arrival constraint to an "any
month" constraint. The July arrival constraint was driven by a fairly
arcane secondary science calibration objective (i.e., measuring solar
wind scintillation along the Earth-Pluto line with the Radio Science
Experiment [REX]). If that constraint is relaxed, then arrival at
Pluto/Charon will occur, in the worst case, during October 2014. The NH
team also feels they can telescope the primary data transmission from 5
months down to 46 days by utilizing the maximum data transmission rate
available at Pluto. All of these options could result in 1 year
savings in travel time, which translates into ~5 W increase in power for
every year saved in transit.

The NH team is also considering options for more efficient operational
procedures to reduce power demand (e.g., disabling *excess* memory
storage not needed for science data. This is possible since the memory
allocation for the critical encounter sequence is many times the minimal
requirement).

--


Alex R. Blackwell
University of Hawaii

"Alex R. Blackwell" wrote

Kim Keller wrote:

The team is also looking at methods of conserving
power during the outbound leg.


The NH team is also considering options for more efficient operational
procedures to reduce power demand (e.g., disabling *excess* memory
storage not needed for science data.

I'm missing something here. Cutting travel time down to have
more power at Pluto makes sense (the plutonium is decaying all
the time), but what's the point of reducing power demand? The
RTG is not going to be depleted any faster by increased electrical
load.

Or do they just want to be able to use as much of the available
power for data transmission at Pluto as possible?

On 27 Aug 2004 07:10:06 -0700, (Allen Thomson) wrote,
in part:

Or do they just want to be able to use as much of the available
power for data transmission at Pluto as possible?

I would suspect that. The spacecraft doesn't have much to remember on
the way out.

John Savard
http://home.ecn.ab.ca/~jsavard/index.html

In article ,
Allen Thomson wrote:
The NH team is also considering options for more efficient operational
procedures to reduce power demand (e.g., disabling *excess* memory
storage not needed for science data.

I'm missing something here. Cutting travel time down to have
more power at Pluto makes sense (the plutonium is decaying all
the time), but what's the point of reducing power demand? The
RTG is not going to be depleted any faster by increased electrical
load.

However, if you can reduce the demands at encounter time, you don't need
as much power out of the RTG.

Also, a more subtle point: electrical issues *can* affect RTG life,
because the bulk of the decline in power output is not from the decay of
the Pu-238 -- it has a half-life of nearly a century -- but from the
accumulation of radiation damage in the semiconductor thermoelectric
elements. You can't change the plutonium's decay rate, but anything you
can do that will make the converters run cooler will extend their life,
because the damage rate is quite sensitive to temperature. There have
been several concepts for fiddling with RTG operating parameters to run
them less efficiently but cooler at times when power demand is low. (I
don't know if NH is using any of them; I know they were looked at
seriously for CRAF.)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In sci.space.policy Henry Spencer wrote:

Also, a more subtle point: electrical issues *can* affect RTG life,
because the bulk of the decline in power output is not from the decay of
the Pu-238 -- it has a half-life of nearly a century -- but from the
accumulation of radiation damage in the semiconductor thermoelectric
elements. You can't change the plutonium's decay rate, but anything you
can do that will make the converters run cooler will extend their life,
because the damage rate is quite sensitive to temperature. There have
been several concepts for fiddling with RTG operating parameters to run
them less efficiently but cooler at times when power demand is low. (I
don't know if NH is using any of them; I know they were looked at
seriously for CRAF.)

Couldn't you just replace them with spares?

--
Sander

+++ Out of cheese error +++

Henry Spencer wrote:
... the bulk of the decline in power output is not from the decay of
the Pu-238 -- it has a half-life of nearly a century -- but from the
accumulation of radiation damage in the semiconductor thermoelectric
elements.

Isn't the radiation entirely alpha particles, which are easy to block?
Why don't they just put a thin shield between the radiation source
and the thermocouples? It's not like it would cause any less heat to
come out.
--
Keith F. Lynch - http://keithlynch.net/
Please see http://keithlynch.net/email.html before emailing me.