FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   PreferencesPreferences   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Forum index » Electronix » design
How To Ground a Space Vehicle?
Post new topic   Reply to topic Page 2 of 2 [20 Posts] View previous topic :: View next topic
Goto page:  Previous  1, 2
Author Message
Paul Hovnanian P.E.
electronics forum Guru


Joined: 29 Apr 2005
Posts: 583

PostPosted: Fri Jul 21, 2006 2:11 am    Post subject: Re: How To Ground a Space Vehicle? Reply with quote

Rich Grise wrote:
Quote:

On Thu, 20 Jul 2006 13:37:29 -0400, gfretwell wrote:

On Thu, 20 Jul 2006 16:42:10 +0200, "Meindert Sprang"
ms@NOJUNKcustomORSPAMware.nl> wrote:

Ok this is reasonable i thought the same but how can you keep the same
potential at the grid because there is a input for ex. sollar array.
and also how about electronic discharge.

When the space vehicle is a Faraday cage, you don't need ground to keep
discharges out. Inside, everything is ground.

Meindert

In a previous occupation I did a lot of work in lightning mitigation
on computer networks in Florida. The first thing we figured out is
there is no such thing as "ground". You can have a very extensive
grounding electrode system and 100 meters away another installation
with the same type electrode system might be fluxuating by dozens of
volts in a storm.
That brings you back to bonding. As long as everything is referenced
to a single bonding plane with a fat copper wire, those transients
bring you up and then back down. You don't care whether you are zero
volts or 1000 volts referenced to some hypothetical "ground". In the
case of your space craft you really only care about transients
generated on board and Mr Kirchoff says they will all reconcile
themselves on board. You just need to assure it happens over your
desired path. Whether you are a million volts above "ground" on some
distant planet is inconsequential.. An example, closer to earth, would
be a helicopter. They could be hundreds or thousands of volts "above
ground" cruising through the air but you don't know it until you drop
a steel cable to someone on the surface. They will get the snot
knocked out of them if they don't bond it first.

How do they moor a blimp? Use an insulating rope?

They drop a ground cable first. They do the same for an airplane (well,
not 'drop' but connect one to the airport grounding system).

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Error: Keyboard not attached. Press F1 to continue.
Back to top
Paul Hovnanian P.E.
electronics forum Guru


Joined: 29 Apr 2005
Posts: 583

PostPosted: Fri Jul 21, 2006 2:18 am    Post subject: Re: How To Ground a Space Vehicle? Reply with quote

Charlie Edmondson wrote:
Quote:

Michael A. Terrell wrote:

[snip]

Biggest problem I have heard about grounding problems have been to
possibility of attacting a 'cloud' of ionized particles of one polarity
or another. This is usually solved by outgassing a neutral stream of
both polarities to compensate...

I don't know about satellites, but aircraft have static bleeders. Little
metal points, that allow accumulated charge to discharge without
building up high voltages relative to the surrounding. The pointy ends
create very high E fields (for a given charge), causing the surrounding
air to break down at much lower charge levels. This keeps the RF from
the resulting discharge down to a minimum. Lots of little, low current
discharges instead of the occasional big buildup and then Bang!

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
The large print giveth and the small print taketh away.
-- Tom Waits
Back to top
Paul Hovnanian P.E.
electronics forum Guru


Joined: 29 Apr 2005
Posts: 583

PostPosted: Fri Jul 21, 2006 2:34 am    Post subject: Re: How To Ground a Space Vehicle? Reply with quote

martin griffith wrote:
Quote:

On 20 Jul 2006 15:43:40 -0700, in sci.electronics.design "John
O'Flaherty" <quiasmox@yahoo.com> wrote:


onurco wrote:
I have been thinking a while that how to ground a satellite or shuttle
at the vacuum environment. Can someone explain this? Extra resources
will be grateful thanks a lot.

The Earth itself is suspended in vacuum and isn't grounded to anything.
Just pretend the satellite is its own planet. However, now that you
brought up the question, I wonder if they get sparks when the shuttle
touches the space station.

well, it's all relative, where would the current go when they bonk
each other?

Same place charges go when you touch the leads of a charged cap
together.

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
"The day Microsoft makes something that doesn't suck is probably the day
they start making vacuum cleaners" - Ernst Jan Plugge
Back to top
onurco
electronics forum beginner


Joined: 18 Feb 2006
Posts: 5

PostPosted: Fri Jul 21, 2006 8:59 am    Post subject: Re: How To Ground a Space Vehicle? Reply with quote

Paul Hovnanian P.E. yazdi:
Quote:
Charlie Edmondson wrote:

Michael A. Terrell wrote:

[snip]

Biggest problem I have heard about grounding problems have been to
possibility of attacting a 'cloud' of ionized particles of one polarity
or another. This is usually solved by outgassing a neutral stream of
both polarities to compensate...

I don't know about satellites, but aircraft have static bleeders. Little
metal points, that allow accumulated charge to discharge without
building up high voltages relative to the surrounding. The pointy ends
create very high E fields (for a given charge), causing the surrounding
air to break down at much lower charge levels. This keeps the RF from
the resulting discharge down to a minimum. Lots of little, low current
discharges instead of the occasional big buildup and then Bang!

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
The large print giveth and the small print taketh away.
-- Tom Waits


There lots of people with a disgusting sense of humor but i see they
don't know a thing about esd and the importance of grounding.I have
started my first post with the sentence "I have been thinking", I have
been thinking because because i am writing a report about spacecraft
harness design,limitations etc. you idiots( not the one who tried to
help me).

So as you see from the paul's answer:Some of you have said that
satellite is a faraday cage but aircrafts are also faraday cage and i
have known that they were using the chasis of the aircraft paul has
extended the subject. I have found a document of space craft and they
are using two level composite material with keeping them at the
different potentials( it is like you have said bonding.) and assign to
a ground point at the craft surface and at the launching station they
connect a blockhouse and ground the craft.
Back to top
onurco
electronics forum beginner


Joined: 18 Feb 2006
Posts: 5

PostPosted: Fri Jul 21, 2006 11:07 am    Post subject: Re: How To Ground a Space Vehicle? Reply with quote

John O'Flaherty yazdi:
Quote:
onurco wrote:
I have been thinking a while that how to ground a satellite or shuttle
at the vacuum environment. Can someone explain this? Extra resources
will be grateful thanks a lot.

The Earth itself is suspended in vacuum and isn't grounded to anything.
Just pretend the satellite is its own planet. However, now that you
brought up the question, I wonder if they get sparks when the shuttle
touches the space station.
--
john

If you charge the very small areas(the most given example is the nail
head) with a great amount of charge , very small volume of air around
that surface will become conductor and you can't keep your charges at
that small area so it doesn't matter you want it or not that area will
be discharged .this is one of the ideas at the medium that contains
air that is why i said vacuum you can't do the same at the space.i have
nothing to do with the charge balance of a system.
Back to top
Google

Back to top
Display posts from previous:   
Post new topic   Reply to topic Page 2 of 2 [20 Posts] Goto page:  Previous  1, 2
View previous topic :: View next topic
The time now is Fri Nov 24, 2017 7:23 am | All times are GMT
Forum index » Electronix » design
Jump to:  

Similar Topics
Topic Author Forum Replies Last Post
No new posts Removing ground planes under small capacitors Joel Kolstad design 6 Tue Jul 18, 2006 3:08 am
No new posts ground wire extension (anti-static ground) toronado455 Repair 5 Sun Jul 16, 2006 6:53 pm
No new posts Danger of high voltage ground short in ESD protection sch... nicklaforge@gmail.com Basics 4 Wed Jul 12, 2006 1:37 am
No new posts Force-feedback on steering wheel of a vehicle mike design 6 Mon Jul 03, 2006 2:58 am
No new posts Via to ground for microstrip design in ADS steve cad 0 Fri Jun 16, 2006 6:48 pm

Copyright © 2004-2005 DeniX Solutions SRL
Other DeniX Solutions sites: Unix/Linux blog |  Unix/Linux documentation |  Unix/Linux forums |  Medicine forum |  Science forum  |  Send and track newsletters


Powered by phpBB © 2001, 2005 phpBB Group