Researching maximum life span of the power supply of a small satellite.

[[email protected]]

For use in a private scientific project I'm researching how long a
small earth orbiting satellite will operate. The satellite's
electronics needs to generate for over 30 seconds 15 watts of power
each day.

I'm not scientific educated so please excuse me for saying stupid
things. The project is still in a hypothetical stage so don't be afraid
to tell it won't work.

I'm aiming at a life span of 100 years! Is this possible? For
engineering reasons I want to minimize the use of solar cells.

A good quality solar cell panel of 25 square centimeters (10 square
inches) will generate about 15 watts of energy. Solar cells have a
durability of some 40 years. But by light-induced degradation (LID) the
effectiveness of the cells will slowly degrade. Can this problem be
solved if you use a 3 times as big (75 square centimeters/ 30 square
inches) solar panel covered for 2/3 and shift this covering each 40
years to expose a new set of solar cells?

Other options are.

Extreme durable batteries
The longest shelf life of batteries are about 20 years.
(http://www.raytechcatalog.com/product_info/code-red-batteries-20-year-shelf-life-1-pair-142.html).
This is accomplished by keeping the electrolyte separate of the plates
until the battery is activated. Can this shelf life be expanded? By
lowering the temperature for example? How long will such a battery give
an amount of energy of a daily 15 watts over 30 seconds?

Fuel cells;
A fuel cell is also very durable. 40,000 hours for stationary
applications (wikipedia.org). 100 years*30 seconds = 305 hours. Or will
the electrolyte chemicals just like normal batteries degrade after a
few decades? The amounts of fuels like hydrogen and oxygen will be
quite a lot I think.

Atomic batteries:
Most satellites and space probes make use of nuclear. These batteries
are extremely durable. Even the Radioisotopic Thermoelectric Generator
of the space probe voyager 1 still makes some 300 watts ( at launch
date 1977 it generated 470 watts) after 29 years of use. But nuclear
devices are the least desirable choice of power supply for a small
satellite orbiting the earth. If the satellite burns up in the
atmosphere the nuclear elements will cause a very dangerous pollution.
However this is an example of a very small nickel-63 battery which will
give electrical energy for over some 50 years! The power specs (volt,
amperes, watts) are not given.
http://www.news.cornell.edu/releases/Oct02/cantilever.ws.html


I would be pleased by any comments!

Marcel

 

[Michael A. Terrell]

For use in a private scientific project I'm researching how long a
small earth orbiting satellite will operate. The satellite's
electronics needs to generate for over 30 seconds 15 watts of power
each day.

I'm not scientific educated so please excuse me for saying stupid
things. The project is still in a hypothetical stage so don't be afraid
to tell it won't work.

I'm aiming at a life span of 100 years! Is this possible? For
engineering reasons I want to minimize the use of solar cells.

A good quality solar cell panel of 25 square centimeters (10 square
inches) will generate about 15 watts of energy. Solar cells have a
durability of some 40 years. But by light-induced degradation (LID) the
effectiveness of the cells will slowly degrade. Can this problem be
solved if you use a 3 times as big (75 square centimeters/ 30 square
inches) solar panel covered for 2/3 and shift this covering each 40
years to expose a new set of solar cells?

Other options are.

Extreme durable batteries
The longest shelf life of batteries are about 20 years.
(http://www.raytechcatalog.com/product_info/code-red-batteries-20-year-shelf-life-1-pair-142.html).
This is accomplished by keeping the electrolyte separate of the plates
until the battery is activated. Can this shelf life be expanded? By
lowering the temperature for example? How long will such a battery give
an amount of energy of a daily 15 watts over 30 seconds?

Fuel cells;
A fuel cell is also very durable. 40,000 hours for stationary
applications (wikipedia.org). 100 years*30 seconds = 305 hours. Or will
the electrolyte chemicals just like normal batteries degrade after a
few decades? The amounts of fuels like hydrogen and oxygen will be
quite a lot I think.

Atomic batteries:
Most satellites and space probes make use of nuclear. These batteries
are extremely durable. Even the Radioisotopic Thermoelectric Generator
of the space probe voyager 1 still makes some 300 watts ( at launch
date 1977 it generated 470 watts) after 29 years of use. But nuclear
devices are the least desirable choice of power supply for a small
satellite orbiting the earth. If the satellite burns up in the
atmosphere the nuclear elements will cause a very dangerous pollution.
However this is an example of a very small nickel-63 battery which will
give electrical energy for over some 50 years! The power specs (volt,
amperes, watts) are not given.
http://www.news.cornell.edu/releases/Oct02/cantilever.ws.html

I would be pleased by any comments!

Marcel

How do you plan on keeping a satellite in orbit for 100 years?

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Bob Myers]

How do you plan on keeping a satellite in orbit for 100 years?

Well, the Moon's been in orbit a good deal longer than that,
so it DOES appear to be possible...

Supplying electrical power to the thing, reliably, over that sort
of time span does appear to be a real challenge, though. I
would think it would have to be some sort of nuclear source,
specifically designed for extremely long-duration operation.
Might also be possible to do something via thermoelectric
generation, too, I guess...

Bob M.

 

[[email protected]]

How do you plan on keeping a satellite in orbit for 100 years?

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Isn't Vanguard 1 still in orbit? I recall seeing predictions that it
would stay up for over 200 years.

 

[Michael A. Terrell]

Well, the Moon's been in orbit a good deal longer than that,
so it DOES appear to be possible...

Supplying electrical power to the thing, reliably, over that sort
of time span does appear to be a real challenge, though. I
would think it would have to be some sort of nuclear source,
specifically designed for extremely long-duration operation.
Might also be possible to do something via thermoelectric
generation, too, I guess...

Bob M.

He didn't say he was building a moon, or putting a satellite into a
Lagrangian point so the question remains, how is he going to keep it in
place for 100 years?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

Isn't Vanguard 1 still in orbit? I recall seeing predictions that it
would stay up for over 200 years.

http://en.wikipedia.org/wiki/Vanguard_1 is a dead bird that weighs
almost nothing and had no real long life payload. The prediction was
much longer, but they found out they were wrong. What good does it do
to put a piece of space junk up that can't do something useful?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Rich Grise]

http://en.wikipedia.org/wiki/Vanguard_1 is a dead bird that weighs
almost nothing and had no real long life payload. The prediction was
much longer, but they found out they were wrong. What good does it do
to put a piece of space junk up that can't do something useful?

The point was, it's still up there. When you're in orbit, you're in
orbit. LEO decays because of air resistance from skimming the atmosphere,
but you could stay in HEO practically indefinitely - how long do they
expect the phone and cable TV satellites to stay in place?

Thanks,
Rich

 

[Jonathan Kirwan]

For use in a private scientific project I'm researching how long a
small earth orbiting satellite will operate. The satellite's
electronics needs to generate for over 30 seconds 15 watts of power
each day.

I'm not scientific educated so please excuse me for saying stupid
things. The project is still in a hypothetical stage so don't be afraid
to tell it won't work.

I'm aiming at a life span of 100 years! Is this possible? For
engineering reasons I want to minimize the use of solar cells.

A good quality solar cell panel of 25 square centimeters (10 square
inches) will generate about 15 watts of energy. Solar cells have a
durability of some 40 years. But by light-induced degradation (LID) the
effectiveness of the cells will slowly degrade. Can this problem be
solved if you use a 3 times as big (75 square centimeters/ 30 square
inches) solar panel covered for 2/3 and shift this covering each 40
years to expose a new set of solar cells?

Other options are.

Extreme durable batteries
The longest shelf life of batteries are about 20 years.
(http://www.raytechcatalog.com/product_info/code-red-batteries-20-year-shelf-life-1-pair-142.html).
This is accomplished by keeping the electrolyte separate of the plates
until the battery is activated. Can this shelf life be expanded? By
lowering the temperature for example? How long will such a battery give
an amount of energy of a daily 15 watts over 30 seconds?

Fuel cells;
A fuel cell is also very durable. 40,000 hours for stationary
applications (wikipedia.org). 100 years*30 seconds = 305 hours. Or will
the electrolyte chemicals just like normal batteries degrade after a
few decades? The amounts of fuels like hydrogen and oxygen will be
quite a lot I think.

Atomic batteries:
Most satellites and space probes make use of nuclear. These batteries
are extremely durable. Even the Radioisotopic Thermoelectric Generator
of the space probe voyager 1 still makes some 300 watts ( at launch
date 1977 it generated 470 watts) after 29 years of use. But nuclear
devices are the least desirable choice of power supply for a small
satellite orbiting the earth. If the satellite burns up in the
atmosphere the nuclear elements will cause a very dangerous pollution.
However this is an example of a very small nickel-63 battery which will
give electrical energy for over some 50 years! The power specs (volt,
amperes, watts) are not given.
http://www.news.cornell.edu/releases/Oct02/cantilever.ws.html

I would be pleased by any comments!

What have you already studied in this area? My first reaction is to
tell you that it's not going to just be about electronics. As I
gather it now, orbit stability near Earth is on the order of 12-15
years, today. So, 100 years? What will be the placement of the
satellite? Around Earth? At what altitude? Elsewhere? Where? What
do you know about what already limits the duration of existing
systems?

Some quick thoughts:

(1) Orbit stability and maintenance. 12 year dormancy seems doable,
but excessively long durations in orbit will probably require an
active system to keep it there -- assuming Earth centered orbit.
(2) Radiation. The van Allen belts have high energy protons in a
fairly narrow stretching zone and high energy electrons in a much more
diffuse and broad zone. In addition, there are various high energy
particles (mostly in the proton/helium size but some fairly big ones,
too) and photons (X-rays and beyond) to deal with. Single events and
long term degradation results. Not just in the electronics, but
affecting sensors, solar cell surfaces, and various optical properties
among others, etc. 100 years poses a serious problem here.
(3) Heat dissipation. You are in space and all of the energy that
impinges on the craft heats it. You must dissipate that energy in
some fashion. The usual approach (and this applies in spades to solar
panels) is to take into integrate the absorption over wavelength and
to maximize the emissivity of the material at the wavelength that most
of the longwave radiation away will take place at, given the estimated
stability temperature. The shape of your satellite will bear on its
own absorption. But as an example I'm aware of, a rotating cylinder
in space at Earth's distance from the sun having an absorption close
to "1" at the important wavelengths the sun emits (this means visible,
and it is almost by design that solar panels will be close to this)
and an emissivity close to "1" at the 10-15 micron band (I think this
is appropriate) will stabilize at about 300K in space here. One of
the reasons why space-based solar panels need a thicker layer of oxide
(quartz) on their surface is exactly because this layer has a very
high emissivity in the important emission band of 10-15 microns, if
memory serves. That is needed.

A friend of mine (physicist) was hired to consider the issues of
ionized particles as it relates to keeping a satellite in space for 30
years. He remains one of the very few recognized experts in thermal
issues in space, in fact. But even struggling for 30 years wasn't at
all a trivial exercise.

Some thoughts on the electronics parts and detailing some of the
environment issues is found here:

http://www.atmel.com/dyn/resources/prod_documents/doc4170.pdf

and here:

"The space radiation environment for electronics," Stassinopoulos,
E.G. Raymond, J.P., NASA, Goddard Space Flight Center, Greenbelt,
MD, Proceedings of the IEEE, Publication Date: Nov 1988, Volume: 76,
Issue: 11, On page(s): 1423-1442.

For starters. But you should contact NASA and ESA and JPL to see what
you can glean from them. I'm sure there are also peer-reviewed papers
in various science publications on this subject to be found, as well.
A lot of it may be considered proprietary, but much of the funding in
the US comes from the military R&D budget (the vast bulk of it) and
some of that may be declassified over time, too. And commercial
companies making electronic components, those having a presence in
this area and accepting funding to develop parts for space systems,
may be able to help a lot, too.

I'm not knowledgeable on this subject, but those are some of the
things that come to mind right away.

Jon

 

[Jonathan Kirwan]

(1) Orbit stability and maintenance. 12 year dormancy seems doable,
but excessively long durations in orbit will probably require an
active system to keep it there -- assuming Earth centered orbit.

By this, I mean at some desired place. If all you care about is a
piece of metal somewhere, but don't care where, then I suppose longer
times can be readily achieved without active systems.

Jon

 

[[email protected]]

http://en.wikipedia.org/wiki/Vanguard_1 is a dead bird that weighs
almost nothing and had no real long life payload. The prediction was
much longer, but they found out they were wrong. What good does it do
to put a piece of space junk up that can't do something useful?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

First, that was not your original question, so you are trying to change
the argument.

Second, are you suggesting that we no longer have the capability to put
something up as high as Vanguard 1? I think we now have the ability to
easily match and exceed that altitude. My guess is that the satellites
in the Clarke belt have orbital lifetimes much longer than 200 years.

 

[Michael A. Terrell]

First, that was not your original question, so you are trying to change
the argument.

Second, are you suggesting that we no longer have the capability to put
something up as high as Vanguard 1? I think we now have the ability to
easily match and exceed that altitude. My guess is that the satellites
in the Clarke belt have orbital lifetimes much longer than 200 years.

I give up. Guess all you want to. I no longer give a damn. I made
no suggestions whatsoever, but if they ever offer a one way trip to the
moon I'll make sure to put your name on the list of those I want to make
the trip.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[[email protected]]

Geeeee... I'm really overwhelmed by all these extensive replies. Thanks
a lot, all of you!!

But my main issue is the power supply for over 100 years. The orbit
maintenance is at this stage of later concern.

Will solar cells degrade by LID (light-induced degradation) if you
don't expose them to the solar light?

I can choose to have 3 small solar panels and expose each of them for
40 years so I can make at least 100 years.

Marcel

 

[Bob Masta]

For use in a private scientific project I'm researching how long a
small earth orbiting satellite will operate. The satellite's
electronics needs to generate for over 30 seconds 15 watts of power
each day.

I'm not scientific educated so please excuse me for saying stupid
things. The project is still in a hypothetical stage so don't be afraid
to tell it won't work.

I'm aiming at a life span of 100 years! Is this possible? For
engineering reasons I want to minimize the use of solar cells.

<snip>

What about tether systems? The idea is that you have a really
long cable stretched between 2 satellites. The cable passing
through the Earth's magnetic field generates current. David
Gerrold mentions this in the Aug 8 PC Magazine, and notes that
there is a satellite launched last year called the Tether Physics
and Survivability Experiment.

It would seem that there would be no parts to wear out or
be consumed, so orbital stability would be the main issue.

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

[Sjouke Burry]

Geeeee... I'm really overwhelmed by all these extensive replies. Thanks
a lot, all of you!!

But my main issue is the power supply for over 100 years. The orbit
maintenance is at this stage of later concern.

Will solar cells degrade by LID (light-induced degradation) if you
don't expose them to the solar light?

I can choose to have 3 small solar panels and expose each of them for
40 years so I can make at least 100 years.

Marcel

That might work,but 40 years??.

For storage: have you considered mechanical
storage, as in a clock spring? A robust
motor/generator/spring could have a very long
life in space,and can store a lot of
energy.
Also, if the spring completely unwinds,
that would be the signal,to switch solar
panels.

 

[Bob Myers]

Now, placing anything in a higher orbit requires more fuel.
Redundant systems add weight, which requires more fuel. The extra lift
raises the cost of the launch. He hasn't addressed any of the other
problems and seems to have no real plans in place. Three sets of solar
panels? Ok, what happens when the on board batteries die? Is there any
current power technology that will last 100 years? On the other end,
how is he going to track and control the bird for 100 years? The whole
plan sounds like the numbers were picked out of thin air, or with darts
and a dart board where he added up the total points to select his goal.

Well, I looked at the original request more as a thought
experiment rather than part of a serious project to actually
put a bird into orbit with an expected usable life of 100+ years.
Fun to think about, but hardly something we're going to see
done by a private group of hobbyists like the OSCAR stuff
was.

Bob M,

 

[[email protected]]

what is DD214???

And what is the biggest problem (energy, orbit maintenance etc. etc.)
to realize this project with the current state of technology?

Sorry, I don't want to be rude.

Marcel

 

[Rich Grise]

what is DD214???

It's a piece of paper that they issue to members of the US armed
forces when they finish their enlistment and go home.

It basically says, "<person> was in the US <armed force> and received
an <honorable/general/undesirable/bad conduct/dishonorable> discharge."

I re-upped in the USAF for a second term in 1973, after I'd gotten out
from my first 4 years - Vietnam was in full swing, and they were
offering thousands of dollars for a re-up bonus, if you re-upped within
3 months of your discharge date. So, I went and re-upped, but by the
time they had adjusted their records, they had already issued me my
Honorable Discharge from the first four year term. Then, after I finished
my second 4 years, in about 1975 or 76, the US had lost miserably in
Vietnam and we were being invited to leave Southeast Asia, so I got out
again, and they gave me another Honorable Discharge. I'm sure I've got a
DD214 or two on record somewhere, but so what? I've got Two Honorable
Discharges! They're all foil-embossed, and calligrahied, and everything. ;-)

Cheers!
Rich