if photons in motion have mass and energy why don't they knock stuffover

See: http://www.weathernotebook.org/trans...000/05/18.html

A number of deep space probes have had solar reflector attitude control
panels. These use the photons to help stabilize or move the craft to a
new attitude using the photon momentum. There have been many proposals
over the years for solar sail propulsion for space probes.

You don't ordinarily see the effect because the pressures are very small
compared to pressures from even the most gentle breeze or air current.
But they ARE there.

wrote:

like little things like blades of grass or ants out of a tree

--
Don Stauffer in Minnesota

webpage- http://www.usfamily.net/web/stauffer

Don Stauffer wrote in message ...
A number of deep space probes have had solar reflector attitude control
panels. These use the photons to help stabilize or move the craft to a
new attitude using the photon momentum.

Um? A number of craft have had solar power panels. Which craft
have had solar reflector attitude control?

There have been many proposals
over the years for solar sail propulsion for space probes.

Proposals yes. Examples built, none.
Socks

[POSTED TO rec.photo.digital - REPLY ON USENET PLEASE]

In on 8 Apr 2004 10:13:14
-0700, wrote:

Don Stauffer wrote in message ...

A number of deep space probes have had solar reflector attitude control
panels. These use the photons to help stabilize or move the craft to a
new attitude using the photon momentum.

Um? A number of craft have had solar power panels. Which craft
have had solar reflector attitude control?

Mariner IV (the first Mars probe, which I worked on back in 1964) had solar
pressure vanes, mounted on the ends of each of the four solar panels, that
adjusted automatically when the attitude jets fired. After they found the
right balance, the need for attitude gas was so greatly reduced that the
spacecraft used only a fraction of the attitude gas that would have otherwise
been required. http://nssdc.gsfc.nasa.gov/nmc/tmp/1964-077A.html
http://home.earthlink.net/~nbrass1/mariner/miv.htm
http://home.earthlink.net/~nbrass1/mariner/mariner04.gif

The earlier Mariner II (the first Venus probe) had a solar sail, but it was
less effective than the four solar pressure vanes on Mariner IV.
http://nssdc.gsfc.nasa.gov/nmc/tmp/1962-041A.html

--
Best regards,
John Navas
[PLEASE NOTE: Ads belong *only* in rec.photo.marketplace.digital, as per
http://bobatkins.photo.net/info/charter.htm http://rpdfaq.50megs.com/]

In sci.astro wrote:
Don Stauffer wrote in message ...
A number of deep space probes have had solar reflector attitude control
panels. These use the photons to help stabilize or move the craft to a
new attitude using the photon momentum.

Um? A number of craft have had solar power panels. Which craft
have had solar reflector attitude control?

The solar panels on Mariner 10 were used for attitude control
via radiation pressure, by tilting them appropriately between
Mercury encounters. This conserved attitude-control gas and
helped give the third flyby. See
http://nssdc.gsfc.nasa.gov/database/...g?sc=1973-085A
http://www.fukuoka-edu.ac.jp/~kanami...ar/marin10.htm

This was possible because the solar panels had to be large enough to
deliver power not only at launch but during a Venus swingby, so
there was more tolerance for off-normal pointing. In fact, the
status report at
http://www.google.com/url?sa=U&start...estern.edu/M10
indicates that the controllers had to tilt the panels on some direction
anyway for thermal control after the first Mercury encounter.

Bill Keel

What is the one leaving solar system? Voyager, I believe it is. The
attitude control paddles are on the ends of the solar array panels.
These paddles are not the entire attitude control. If I remember right,
there are CMGs for primary, gas jets to desaturate wheel, and the solar
paddles. The paddles take some of the load off the CMGs, so they do not
approach saturation as often. There is a limited supply of gas, and
using it too often to unload CMGs would exhaust gas sooner.

Now, my memory is not as good as it should be, so maybe it was not
Voyager, but one of the later probes that went out to Jupiter and Saturn
(Mariner?). I know it was a deep space probe series, but it has been a
lot of years since I worked with it, so I am having a hard time
remembering its name. Anyway, it is one with four solar arrays, with a
paddle at end of each array. Clearly visible in pictures.

wrote:

Don Stauffer wrote in message ...
A number of deep space probes have had solar reflector attitude control
panels. These use the photons to help stabilize or move the craft to a
new attitude using the photon momentum.

Um? A number of craft have had solar power panels. Which craft
have had solar reflector attitude control?

There have been many proposals
over the years for solar sail propulsion for space probes.

Proposals yes. Examples built, none.
Socks

--
Don Stauffer in Minnesota

webpage- http://www.usfamily.net/web/stauffer

[POSTED TO rec.photo.digital - REPLY ON USENET PLEASE]

You're thinking of Mariner (Mars and Venus, as noted in my earlier post) --
Voyager has a different configuration. http://voyager.jpl.nasa.gov/

In on Fri, 09 Apr 2004 08:47:15 -0500, Don
Stauffer wrote:

What is the one leaving solar system? Voyager, I believe it is. The
attitude control paddles are on the ends of the solar array panels.
These paddles are not the entire attitude control. If I remember right,
there are CMGs for primary, gas jets to desaturate wheel, and the solar
paddles. The paddles take some of the load off the CMGs, so they do not
approach saturation as often. There is a limited supply of gas, and
using it too often to unload CMGs would exhaust gas sooner.

Now, my memory is not as good as it should be, so maybe it was not
Voyager, but one of the later probes that went out to Jupiter and Saturn
(Mariner?). I know it was a deep space probe series, but it has been a
lot of years since I worked with it, so I am having a hard time
remembering its name. Anyway, it is one with four solar arrays, with a
paddle at end of each array. Clearly visible in pictures.

wrote:

Don Stauffer wrote in message ...
A number of deep space probes have had solar reflector attitude control
panels. These use the photons to help stabilize or move the craft to a
new attitude using the photon momentum.

Um? A number of craft have had solar power panels. Which craft
have had solar reflector attitude control?

There have been many proposals
over the years for solar sail propulsion for space probes.

Proposals yes. Examples built, none.
Socks

--
Best regards,
John Navas
[PLEASE NOTE: Ads belong *only* in rec.photo.marketplace.digital, as per
http://bobatkins.photo.net/info/charter.htm http://rpdfaq.50megs.com/]