Research Discussion: Japan's Solar Sail

Japan's Solar Sail
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Hagar
2010-07-22 16:42:48 EST
http://www.space.com/news/solar-sail-exploration-hailed-100721.html

This gives rise to some serious questions. First off, the acceleration,
once the sail is unfurled, must be at snail's pace. So, let's say you
get all the way to Saturn and you want to stop for a look-see. Now
you need chemical thrusters to slow you down again and to
maneuver the neighborhood. So now you decide to go on to Pluto,
but the light from the Sun is so weak that it takes a month of
Sundays to reach any kind of speed. So you finally get there,
and once again have to rely on chemical rockets to slow down and hang a
u-turn. What about the trip home ??? Entirely by chemical
means. Even though it sounds like the "green" thing to do, the
cost to effect ratio is at best marginal. Seems Ion Propulsion
would be the preferred method to boogey in outer space.



Rex
2010-07-23 03:00:22 EST
Hagar wrote:
> http://www.space.com/news/solar-sail-exploration-hailed-100721.html
>
> This gives rise to some serious questions. First off, the acceleration,
> once the sail is unfurled, must be at snail's pace. So, let's say you
> get all the way to Saturn and you want to stop for a look-see. Now
> you need chemical thrusters to slow you down again and to
> maneuver the neighborhood. So now you decide to go on to Pluto,
> but the light from the Sun is so weak that it takes a month of
> Sundays to reach any kind of speed. So you finally get there,
> and once again have to rely on chemical rockets to slow down and hang a
> u-turn. What about the trip home ??? Entirely by chemical
> means. Even though it sounds like the "green" thing to do, the
> cost to effect ratio is at best marginal. Seems Ion Propulsion
> would be the preferred method to boogey in outer space.
>
>

The acceleration is slow, but constant. Over a period of time it will
develop massive velocity compared to conventional rockets. Steering and
slowing down will be a problem as you say.



-------------------------------------
Piracy is a victimless crime, like punching someone in the dark.
-- .sig of Solignac Julien
-------------------------------------

HVAC
2010-07-23 07:42:01 EST

"Hagar" <hagen@sahm.name> wrote in message
news:NIydnaG9EufUMNXRnZ2dnUVZ_qWdnZ2d@giganews.com...
> http://www.space.com/news/solar-sail-exploration-hailed-100721.html
>
> This gives rise to some serious questions. First off, the acceleration,
> once the sail is unfurled, must be at snail's pace. So, let's say you
> get all the way to Saturn and you want to stop for a look-see. Now
> you need chemical thrusters to slow you down again and to
> maneuver the neighborhood. So now you decide to go on to Pluto,
> but the light from the Sun is so weak that it takes a month of
> Sundays to reach any kind of speed. So you finally get there,
> and once again have to rely on chemical rockets to slow down and hang a
> u-turn. What about the trip home ??? Entirely by chemical
> means. Even though it sounds like the "green" thing to do, the
> cost to effect ratio is at best marginal. Seems Ion Propulsion
> would be the preferred method to boogey in outer space.


Why not both?

Also, a solar sail can be 'tacked' to change course
much as a sailboat on Earth does.



Bert
2010-07-23 07:48:36 EST
On Jul 23, 3:00 am, Rex <rexdudeREMOVEANDREVERSEDOM...@liam.ur> wrote:
> Hagar wrote:
> >http://www.space.com/news/solar-sail-exploration-hailed-100721.html
>
> > This gives rise to some serious questions.  First off, the acceleration,
> > once the sail is unfurled, must be at snail's pace.  So, let's say you
> > get all the way to Saturn and you want to stop for a look-see. Now
> > you need chemical thrusters to slow you down again and to
> > maneuver the neighborhood.  So now you decide to go on to Pluto,
> > but the light from the Sun is so weak that it takes a month of
> > Sundays to reach any kind of speed.  So you finally get there,
> > and once again have to rely on chemical rockets to slow down and hang a
> > u-turn.  What about the trip home ??? Entirely by chemical
> > means.  Even though it sounds like the "green" thing to do, the
> > cost to effect ratio is at best marginal. Seems Ion Propulsion
> > would be the preferred method to boogey in outer space.
>
> The acceleration is slow, but constant. Over a period of time it will
> develop massive velocity compared to conventional rockets. Steering and
> slowing down will be a problem as you say.
>
> -------------------------------------
> Piracy is a victimless crime, like punching someone in the dark.
> -- .sig of Solignac Julien
> -------------------------------------- Hide quoted text -
>
> - Show quoted text -

To much time going to waste waiting for it to get up in speed. Might
be good for robot space ships. Best to keep in mind the further from
the Sun the weaker the push. Want green energy best to go with
"slingshot effect" Did we not slingshot Voyager spacecraft to reach
far away Neptune. Gravity on paper can bring a spaceship easily up to
73% of c What future spacemen need to do is find the nearest neutron
star,and by slinging around it they can travel the galaxy. TreBert

U*@t-online.de
2010-07-23 07:58:10 EST
On Fri, 23 Jul 2010 07:42:01 -0400, "HVAC" <mr.hvac@gmail.com> wrote:

>Why not both?
>
>Also, a solar sail can be 'tacked' to change course
>much as a sailboat on Earth does.

Will you be sailing to the moon some day,
on a sunny, sunny day in May?

C.

Bert
2010-07-23 08:50:18 EST
On Jul 23, 7:58 am, UseNetO...@t-online.de wrote:
> On Fri, 23 Jul 2010 07:42:01 -0400, "HVAC" <mr.h...@gmail.com> wrote:
> >Why not both?
>
> >Also, a solar sail can be 'tacked' to change course
> >much as a sailboat on Earth does.
>
> Will you be sailing to the moon some day,
> on a sunny, sunny day in May?
>
> C.


Bert
2010-07-23 08:51:56 EST
On Jul 23, 7:58 am, UseNetO...@t-online.de wrote:
> On Fri, 23 Jul 2010 07:42:01 -0400, "HVAC" <mr.h...@gmail.com> wrote:
> >Why not both?
>
> >Also, a solar sail can be 'tacked' to change course
> >much as a sailboat on Earth does.
>
> Will you be sailing to the moon some day,
> on a sunny, sunny day in May?
>
> C.

How do you tack with the push of photons? The world would like to
know TreBert

HVAC
2010-07-23 09:27:17 EST

"bert" <herbertglazier79@msn.com> wrote in message
news:3ea2eb32-735a-4e83-a946-9b1c0f3b6de8@i31g2000yqm.googlegroups.com...
On Jul 23, 7:58 am, UseNetO...@t-online.de wrote:
> On Fri, 23 Jul 2010 07:42:01 -0400, "HVAC" <mr.h...@gmail.com> wrote:
> >Why not both?
>
> >Also, a solar sail can be 'tacked' to change course
> >much as a sailboat on Earth does.

How do you tack with the push of photons? The world would like to
know TreBert
~~~~~~~~~~~~~~~~~~~~~~~~~~


Well, it's a sail. And much as sails on Earth are
angled, or 'tacked' against the wind, so too can
sails using the solar wind be 'tacked' to change
course. On a solar sail this 'tacking' is done by
changing the propeties of some parts of the sail
so they are less affected by the push of the solar
wind. In this manner, course corrections can be
effected.



--
None of you seem to understand. I'm not locked in
here with you....You're locked in here with ME!



Hagar
2010-07-23 09:53:50 EST

"HVAC" <mr.hvac@gmail.com> wrote in message
news:i2bv68$fpl$1@hvac.motzarella.org...
>
> "Hagar" <hagen@sahm.name> wrote in message
> news:NIydnaG9EufUMNXRnZ2dnUVZ_qWdnZ2d@giganews.com...
>> http://www.space.com/news/solar-sail-exploration-hailed-100721.html
>>
>> This gives rise to some serious questions. First off, the acceleration,
>> once the sail is unfurled, must be at snail's pace. So, let's say you
>> get all the way to Saturn and you want to stop for a look-see. Now
>> you need chemical thrusters to slow you down again and to
>> maneuver the neighborhood. So now you decide to go on to Pluto,
>> but the light from the Sun is so weak that it takes a month of
>> Sundays to reach any kind of speed. So you finally get there,
>> and once again have to rely on chemical rockets to slow down and hang a
>> u-turn. What about the trip home ??? Entirely by chemical
>> means. Even though it sounds like the "green" thing to do, the
>> cost to effect ratio is at best marginal. Seems Ion Propulsion
>> would be the preferred method to boogey in outer space.
>
>
> Why not both?
>
> Also, a solar sail can be 'tacked' to change course
> much as a sailboat on Earth does.
>

This you'll have to explain ... with a sail boat, the wind blows from
one direction, but the keel of the boat and the resistance of the
water forces the boat to "tack" at an angle, up to 45 degrees from
the wind direction. In space, there is no equivalent to that
water/keel resistance ... so how would tacking in space work ???



HVAC
2010-07-23 10:17:55 EST

"Hagar" <hagen@sahm.name> wrote in message
news:dPCdnRz22JhtA9TRnZ2dnUVZ_rydnZ2d@giganews.com...
>
> This you'll have to explain ... with a sail boat, the wind blows from
> one direction, but the keel of the boat and the resistance of the
> water forces the boat to "tack" at an angle, up to 45 degrees from
> the wind direction. In space, there is no equivalent to that
> water/keel resistance ... so how would tacking in space work ???
>

Well, it's a sail. And much as sails on Earth are
angled, or 'tacked' against the wind, so too can
sails using the solar wind be 'tacked' to change
course. On a solar sail this 'tacking' is done by
changing the propeties of some parts of the sail
so they are less affected by the push of the solar
wind. In this manner, course corrections can be
effected.


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