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Juno sucks



 
 
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  #1  
Old May 29th 11, 07:14 PM posted to sci.space.policy
Anonymous Remailer (austria)
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Posts: 28
Default Juno sucks


http://www.spaceflightnow.com/news/n1105/29junosolar/

They should've powered it with an RTG, just like Cassini. The solar
cells on this billion dollar probe will only last three years at the
most, and severly limiting the probe's effectiveness during the mission
when its solar panels aren't viewed towards the sun. NASA and the DOE
have failed to restart plutonium production for RTG's resulting in
maimed and demasculated probes like Juno.

Cassini has now operated for almost 15 years on its nuclear power
source, the Voyagers for almost 35 years. Due to its nuclear power the
craft will be safer since it won't have to rely on batteries during
swingbys behind Saturn. There's a good chance these probes will operate
for quite some time still. Juno OTOH will wear out its solar panels in
a couple of years.

All in all, a waste of time, money and effort in my opinion.


  #2  
Old May 30th 11, 01:29 AM posted to sci.space.policy
Brian Thorn[_2_]
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Posts: 2,266
Default Juno sucks

On Sun, 29 May 2011 20:14:55 +0200 (CEST), "Anonymous Remailer
(austria)" wrote:


http://www.spaceflightnow.com/news/n1105/29junosolar/

They should've powered it with an RTG, just like Cassini.


No RTGs available due to plutonium processing shut down in the 1990s
and Russia's refusal to sell any more of their's. This was the only
way to do the mission without waiting 10 more years.

The solar
cells on this billion dollar probe will only last three years at the
most,


Which is about the fuel limit anyway.

Juno OTOH will wear out its solar panels in
a couple of years.


Juno is more or less replacing the Jupiter observations lost by the
crippled Galileo, which failed to open its High Gain Antenna and spent
most of its limited bandwidth on the Galilean satellites instead. As
such, it doesn't need a 10-year mission.

All in all, a waste of time, money and effort in my opinion.


The price was right. An RTG would probably have doubled the cost.

Brian
  #3  
Old May 30th 11, 04:26 AM posted to sci.space.policy
Bob Haller
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Posts: 3,197
Default Juno sucks

On May 30, 1:46*am, Pat Flannery wrote:
On 5/29/2011 10:14 AM, Anonymous Remailer (austria) wrote: NASA and the DOE

have failed to restart plutonium production for RTG's resulting in
maimed and demasculated probes like Juno.


Well, with a name like Juno, you shouldn't expect it to be male.
On the other hand, you might expect a certain deity to get really ****ed
if she thinks you just insulted her.
Keep an eye out for large serpents when you're sleeping tonight. ;-)

Pat


Thenlatest nasa probes appear very pricey and extremely complex.

I guess time will tell how well they work but I think the solar panel
idea was very dumb and should of never been approved.

RTGs not only power probes they help keep them warm very important at
such distances
  #4  
Old May 30th 11, 06:36 AM posted to sci.space.policy
Alan Erskine[_3_]
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Posts: 1,026
Default Juno sucks

On 30/05/2011 4:14 AM, Anonymous Remailer (austria) wrote:
http://www.spaceflightnow.com/news/n1105/29junosolar/

They should've powered it with an RTG, just like Cassini. The solar
cells on this billion dollar probe will only last three years at the
most, and severly limiting the probe's effectiveness during the mission
when its solar panels aren't viewed towards the sun. NASA and the DOE
have failed to restart plutonium production for RTG's resulting in
maimed and demasculated probes like Juno.

Cassini has now operated for almost 15 years on its nuclear power
source, the Voyagers for almost 35 years. Due to its nuclear power the
craft will be safer since it won't have to rely on batteries during
swingbys behind Saturn. There's a good chance these probes will operate
for quite some time still. Juno OTOH will wear out its solar panels in
a couple of years.

All in all, a waste of time, money and effort in my opinion.



Well, Mr anonymous, the mission is only scheduled to last for three
years; where do you get the information that the PV arrays will "burn
out" in a couple of years? The arrays on ISS (the space station) are
nothing special (just silicon) and will last for 10+ years and are
exposed to much more radiation than the Juno arrays.
  #5  
Old May 30th 11, 06:46 AM posted to sci.space.policy
Pat Flannery
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Posts: 18,465
Default Juno sucks

On 5/29/2011 10:14 AM, Anonymous Remailer (austria) wrote: NASA and the DOE
have failed to restart plutonium production for RTG's resulting in
maimed and demasculated probes like Juno.


Well, with a name like Juno, you shouldn't expect it to be male.
On the other hand, you might expect a certain deity to get really ****ed
if she thinks you just insulted her.
Keep an eye out for large serpents when you're sleeping tonight. ;-)

Pat
  #6  
Old May 30th 11, 07:48 AM posted to sci.space.policy
Pat Flannery
external usenet poster
 
Posts: 18,465
Default Juno sucks

On 5/29/2011 4:29 PM, Brian Thorn wrote:
On Sun, 29 May 2011 20:14:55 +0200 (CEST), "Anonymous Remailer
wrote:


http://www.spaceflightnow.com/news/n1105/29junosolar/

They should've powered it with an RTG, just like Cassini.


No RTGs available due to plutonium processing shut down in the 1990s
and Russia's refusal to sell any more of their's. This was the only
way to do the mission without waiting 10 more years.

The solar
cells on this billion dollar probe will only last three years at the
most,


Which is about the fuel limit anyway.

Juno OTOH will wear out its solar panels in
a couple of years.


Juno is more or less replacing the Jupiter observations lost by the
crippled Galileo, which failed to open its High Gain Antenna and spent
most of its limited bandwidth on the Galilean satellites instead. As
such, it doesn't need a 10-year mission.

All in all, a waste of time, money and effort in my opinion.


The price was right. An RTG would probably have doubled the cost.


They don't cost all that much, as they are pretty simple in design...
main cost is just the plutonium to power them:
http://en.wikipedia.org/wiki/Radiois...tric_generator
Plutonium goes for around 44,000 per gram, so it would take an awful lot
to double Juno's cost.
You want plutonium, go to the Japanese, who are burning it mixed with
U-235 as fuel in some of their reactors (that's also what we did with
the plutonium we got from Russia after the fall of the Soviet Union as
they destroyed a lot of their nuclear warheads).
The reactors GE sold the Japanese were a US design that produced
plutonium as part of normal operations that could be extracted from
their spent fuel rods, eliminating the US need for specialized breeder
reactors to make plutonium for our weapon's programs.
So unless they mixed it with U-235 and burned it in their reactors, to
the Japanese plutonium was simply a hazardous nuclear waste product that
had to be disposed of or stored somehow.
The whole "We're running out of plutonium for RTGs!" thing was BS by the
last Bush administration to try to restart US plutonium production for
new nuclear weapons.
Although space safety incidents with RTGs have been very few, the solar
power option removes the risk entirely, and with the continued
development of higher output solar arrays and lower power demand
electronics, the Juno approach becomes workable.

Pat


  #7  
Old May 30th 11, 01:48 PM posted to sci.space.policy
Bob Haller
external usenet poster
 
Posts: 3,197
Default Juno sucks

On May 30, 1:36*am, Alan Erskine wrote:
On 30/05/2011 4:14 AM, Anonymous Remailer (austria) wrote:





http://www.spaceflightnow.com/news/n1105/29junosolar/


They should've powered it with an RTG, just like Cassini. The solar
cells on this billion dollar probe will only last three years at the
most, and severly limiting the probe's effectiveness during the mission
when its solar panels aren't viewed towards the sun. NASA and the DOE
have failed to restart plutonium production for RTG's resulting in
maimed and demasculated probes like Juno.


Cassini has now operated for almost 15 years on its nuclear power
source, the Voyagers for almost 35 years. Due to its nuclear power the
craft will be safer since it won't have to rely on batteries during
swingbys behind Saturn. There's a good chance these probes will operate
for quite some time still. Juno OTOH will wear out its solar panels in
a couple of years.


All in all, a waste of time, money and effort in my opinion.


Well, Mr anonymous, the mission is only scheduled to last for three
years; where do you get the information that the PV arrays will "burn
out" in a couple of years? *The arrays on ISS (the space station) are
nothing special (just silicon) and will last for 10+ years and are
exposed to much more radiation than the Juno arrays.- Hide quoted text -

- Show quoted text -


no ISS is protected by the van allen belts, the station gets little
radiation for that reason.

NASA is moving towards more cutting edge complex probes. Either they
will do great

Or we will watch multiple high profile faiures that will put mre nails
in nasas coffin
  #8  
Old May 30th 11, 04:16 PM posted to sci.space.policy
Brian Thorn[_2_]
external usenet poster
 
Posts: 2,266
Default Juno sucks

On Sun, 29 May 2011 22:48:17 -0800, Pat Flannery
wrote:


The price was right. An RTG would probably have doubled the cost.


They don't cost all that much, as they are pretty simple in design...
main cost is just the plutonium to power them:
http://en.wikipedia.org/wiki/Radiois...tric_generator
Plutonium goes for around 44,000 per gram, so it would take an awful lot
to double Juno's cost.


It is far from just the cost of the RTG (which is not nearly as cheap
as you suggest), it is also the mountain of paperwork, safety studies,
and environmental impact studies that has to accompany one.

The simple fact remains that RTG power would have pushed Juno out of
its budget range and would have delayed Juno several years farther
down the road (which would have driven up costs even more.)

Who is to blame for the lack of RTG supplies is irrelevant. We don't
have the plutonium and wouldn't have had any until years after Juno's
original 2010 launch date. RTG was not an option for Juno.

Brian
  #9  
Old May 30th 11, 04:27 PM posted to sci.space.policy
Brian Thorn[_2_]
external usenet poster
 
Posts: 2,266
Default Juno sucks

On Mon, 30 May 2011 15:36:33 +1000, Alan Erskine
wrote:

Well, Mr anonymous, the mission is only scheduled to last for three
years; where do you get the information that the PV arrays will "burn
out" in a couple of years? The arrays on ISS (the space station) are
nothing special (just silicon) and will last for 10+ years and are
exposed to much more radiation than the Juno arrays.


No, Mr. Remailer is absolutely correct about the radiation, he just
leapt to the wrong conclusion that the solar arrays will be the cause
of death.

"The mass of the titanium walls provides a radiation shelter where all
of the spacecraft avionics are housed. 'All the sensors are outside,'
Gasparrini says. 'But as much of the critical avionics [as possible]
is sandwiched in the vault. [Exterior equipment] is as hard as it
could reasonably be within cost constraints. It's expected that after
30 orbits you've pretty much taken your radiation beating, and you're
not going to survive much longer."

Aviation Week
March 21, 2011
  #10  
Old May 30th 11, 07:30 PM posted to sci.space.policy
Nomen Nescio
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Posts: 307
Default Juno sucks

"Alan Erskine" wrote in message
ond.com...
On 30/05/2011 4:14 AM, Anonymous Remailer (austria) wrote:
http://www.spaceflightnow.com/news/n1105/29junosolar/

They should've powered it with an RTG, just like Cassini. The solar
cells on this billion dollar probe will only last three years at the
most, and severly limiting the probe's effectiveness during the

mission
when its solar panels aren't viewed towards the sun. NASA and the DOE
have failed to restart plutonium production for RTG's resulting in
maimed and demasculated probes like Juno.

Cassini has now operated for almost 15 years on its nuclear power
source, the Voyagers for almost 35 years. Due to its nuclear power

the
craft will be safer since it won't have to rely on batteries during
swingbys behind Saturn. There's a good chance these probes will

operate
for quite some time still. Juno OTOH will wear out its solar panels

in
a couple of years.

All in all, a waste of time, money and effort in my opinion.



Well, Mr anonymous, the mission is only scheduled to last for three
years; where do you get the information that the PV arrays will "burn
out" in a couple of years? The arrays on ISS (the space station) are
nothing special (just silicon) and will last for 10+ years and are
exposed to much more radiation than the Juno arrays.


I should rephrase that: the power systems on the probe will wear out,
mainly the batteries. RTG powered probes can keep working for decades
even though their design life was only a couple of years. Cassini's
main mission was projected to be a mere three years IIRC. It's still
going strong and still revealing mysteries about Jupiter and its moons.
Its longevity has been a real boon for planetary science.

Juno will probably work for the intended mission duration, but I doubt
it will last long after that. That makes it expensive IMHO.


 




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