A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Space Science » Policy
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

Atlas5 vs Shuttle ( launch window)



 
 
Thread Tools Display Modes
  #1  
Old December 5th 15, 05:32 PM posted to sci.space.policy
Alain Fournier[_3_]
external usenet poster
 
Posts: 548
Default Atlas5 vs Shuttle ( launch window)

On 12/5/15 12:17 AM, JF Mezei wrote :
On 2015-12-04 20:50, Alain Fournier wrote:

relatively slowly. Then go to a LEO that isn't over the equator but
closer to the equator than the launch site.


So in this particular case, it is the second stage or even Cygnus that
has the added performance that gives a 30 minute window ?


I was responding to the question about geostationary satellites. In the
case of a rocket launch to ISS, the difference in orbital speeds at ISS
and at very low Earth orbit is not that big. Once in orbit, you do save
some by doing a plane change at apogee but not much.

In this case the plane change would be done in early launch phase. But
it doesn't do much of a difference where the added performance comes
from. If you do your plane change right after lift-off, your first stage
won't get your second stage quite as fast. This can be compensated by
having a more powerful first stage or by a more powerful second stage,
or some other stage.

Also, it isn't only a matter of how much power the rocket has. If you do
your plane change early in the launch phase you can run into aerodynamic
problems. One way that you could *theoretically* do the plane change is
to go due east right after launch, then when you are at the right plane
you go up, after what you resume your acceleration to achieve orbit. If
it wasn't for the atmosphere that wouldn't be too bad a way to do it
(not good, but not too bad). But since there is an atmosphere you can't
do that. The shuttle probably needed to stay further away from that
flight plan than Atlas 5 does. In other words, I think that the shuttle
had to go up higher before taking care of the plane change than Atlas 5
does.


Alain Fournier

  #2  
Old December 9th 15, 01:39 AM posted to sci.space.policy
Alain Fournier[_3_]
external usenet poster
 
Posts: 548
Default Atlas5 vs Shuttle ( launch window)

On 12/5/15 8:43 PM, JF Mezei wrote :
On 2015-12-05 11:32, Alain Fournier wrote:

problems. One way that you could *theoretically* do the plane change is
to go due east right after launch, then when you are at the right plane
you go up, after what you resume your acceleration to achieve orbit.



But in the case of ISS, when you launch late, the orbital plane is west
of you, so you don't want to launch east, you want to launch north to
intersect with orbital plane and then veer to 51°.


The problem with launching "north" is that there is something called
"land" on which your spent rockets (or possibly self desruct (aka range
safety) will result in debris falling on homes, cows and highways.


It seems they were skirting with that problem. There has been a sighting
of the fall of the booster in Halifax. So yes, they did launch quite
northward.

See:
http://www.cbc.ca/news/canada/nova-s...here-1.3354598


Alain Fournier

  #3  
Old December 11th 15, 12:36 AM posted to sci.space.policy
Dr J R Stockton[_195_]
external usenet poster
 
Posts: 27
Default Atlas5 vs Shuttle ( launch window)

In sci.space.policy message , Tue, 8 Dec
2015 19:39:12, Alain Fournier posted:


The problem with launching "north" is that there is something called
"land" on which your spent rockets (or possibly self desruct (aka range
safety) will result in debris falling on homes, cows and highways.


It seems they were skirting with that problem. There has been a
sighting of the fall of the booster in Halifax. So yes, they did launch
quite northward.


The Shuttle, when destined to ISS, launched roughly along but offshore
from the (American) East Coast.

One day, soon after effective sunset, I saw, from outer SW London, both
the Orbiter and its External Tank passing separately not far from
overhead and to the north of me; they must have crossed over populous
parts of North London, including where I lived as a young child with my
parents and with their parents, siblings, and other family nearby.

--
(c) John Stockton, nr London, UK. Mail via homepage. Turnpike v6.05 MIME.
Web - FAQqish topics, acronyms and links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
  #4  
Old December 11th 15, 02:22 AM posted to sci.space.policy
Alain Fournier[_3_]
external usenet poster
 
Posts: 548
Default Atlas5 vs Shuttle ( launch window)

On 12/10/15 6:36 PM, Dr J R Stockton wrote :
In sci.space.policy message , Tue, 8 Dec
2015 19:39:12, Alain Fournier posted:


The problem with launching "north" is that there is something called
"land" on which your spent rockets (or possibly self desruct (aka range
safety) will result in debris falling on homes, cows and highways.


It seems they were skirting with that problem. There has been a
sighting of the fall of the booster in Halifax. So yes, they did launch
quite northward.


The Shuttle, when destined to ISS, launched roughly along but offshore
from the (American) East Coast.

One day, soon after effective sunset, I saw, from outer SW London, both
the Orbiter and its External Tank passing separately not far from
overhead and to the north of me; they must have crossed over populous
parts of North London, including where I lived as a young child with my
parents and with their parents, siblings, and other family nearby.


Obviously they have to accept to fly over populated areas after some
time. I wonder what is considered to be safe. Maybe the launcher is
considered to be high enough once over Nova Scotia to go over populated
areas. Does anyone know who decides what is safe in that regard and what
are the guidelines?


Alain Fournier

  #5  
Old December 13th 15, 12:15 AM posted to sci.space.policy
Dr J R Stockton[_195_]
external usenet poster
 
Posts: 27
Default Atlas5 vs Shuttle ( launch window)

In sci.space.policy message
web.com, Thu, 10 Dec 2015 20:13:37, JF Mezei jfmezei.spamnot@vaxinatio
n.ca posted:

On 2015-12-10 18:36, Dr J R Stockton wrote:

One day, soon after effective sunset, I saw, from outer SW London, both
the Orbiter and its External Tank passing separately not far from
overhead and to the north of me; they must have crossed over populous
parts of North London, including where I lived as a young child with my
parents and with their parents, siblings, and other family nearby.



By the time it flies over England, the orbiter and the tank are orbital.
No "range safety" (aka self destruct) risk and no risk of major
malfunction causing debris to fall.


Agreed to that, as written. But a failure to complete the desired
acceleration earlier, at the final stage of SSME-powered flight would
lead to failure to quite achieve orbit, with re-entry along some part of
the intended track. The probability of anything coming down along the
UK portion of that track was non-zero, but small.


--
(c) John Stockton, nr London, UK. Mail via homepage. Turnpike v6.05 MIME.
Web - FAQqish topics, acronyms and links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
  #6  
Old December 13th 15, 12:35 AM posted to sci.space.policy
Dr J R Stockton[_195_]
external usenet poster
 
Posts: 27
Default Atlas5 vs Shuttle ( launch window)

In sci.space.policy message , Thu, 10 Dec
2015 20:22:05, Alain Fournier posted:

On 12/10/15 6:36 PM, Dr J R Stockton wrote :
In sci.space.policy message , Tue, 8 Dec
2015 19:39:12, Alain Fournier posted:


The problem with launching "north" is that there is something called
"land" on which your spent rockets (or possibly self desruct (aka range
safety) will result in debris falling on homes, cows and highways.

It seems they were skirting with that problem. There has been a
sighting of the fall of the booster in Halifax. So yes, they did launch
quite northward.


The Shuttle, when destined to ISS, launched roughly along but offshore
from the (American) East Coast.

One day, soon after effective sunset, I saw, from outer SW London, both
the Orbiter and its External Tank passing separately not far from
overhead and to the north of me; they must have crossed over populous
parts of North London, including where I lived as a young child with my
parents and with their parents, siblings, and other family nearby.


Obviously they have to accept to fly over populated areas after some
time. I wonder what is considered to be safe. Maybe the launcher is
considered to be high enough once over Nova Scotia to go over populated
areas. Does anyone know who decides what is safe in that regard and
what are the guidelines?



(1) Nova Scotia is not part of the USA.
(2) Testing with a piece of string and a rather small globe appears to
demonstrate that a great circle from any part of the Florida peninsula
to any part of England does not cross any part of Canada. It might
cross Saint Pierre et Miquelon, but one from CCAFS to London would not
do so.
(3) Can Google Maps or another such tool show great circle paths? It
shows an air route London, United Kingdom to Melbourne, FL, USA - which
seems to miss Canada by too much to be a Great Circle.

--
(c) John Stockton, Surrey, UK. Turnpike v6.05 MIME.
Merlyn Web Site - FAQish topics, acronyms, & links.


  #7  
Old December 13th 15, 02:10 AM posted to sci.space.policy
Alain Fournier[_3_]
external usenet poster
 
Posts: 548
Default Atlas5 vs Shuttle ( launch window)

On 12/12/15 6:35 PM, Dr J R Stockton wrote :
In sci.space.policy message , Thu, 10 Dec
2015 20:22:05, Alain Fournier posted:

On 12/10/15 6:36 PM, Dr J R Stockton wrote :
In sci.space.policy message , Tue, 8 Dec
2015 19:39:12, Alain Fournier posted:


The problem with launching "north" is that there is something called
"land" on which your spent rockets (or possibly self desruct (aka range
safety) will result in debris falling on homes, cows and highways.

It seems they were skirting with that problem. There has been a
sighting of the fall of the booster in Halifax. So yes, they did launch
quite northward.

The Shuttle, when destined to ISS, launched roughly along but offshore
from the (American) East Coast.

One day, soon after effective sunset, I saw, from outer SW London, both
the Orbiter and its External Tank passing separately not far from
overhead and to the north of me; they must have crossed over populous
parts of North London, including where I lived as a young child with my
parents and with their parents, siblings, and other family nearby.


Obviously they have to accept to fly over populated areas after some
time. I wonder what is considered to be safe. Maybe the launcher is
considered to be high enough once over Nova Scotia to go over populated
areas. Does anyone know who decides what is safe in that regard and
what are the guidelines?



(1) Nova Scotia is not part of the USA.


Yes, I think that is an important point (from NASA's perspective).

(2) Testing with a piece of string and a rather small globe appears to
demonstrate that a great circle from any part of the Florida peninsula
to any part of England does not cross any part of Canada. It might
cross Saint Pierre et Miquelon, but one from CCAFS to London would not
do so.


I think you are either misplacing St-Pierre et Miquelon or the limits of
Canada. If it goes over St-Pierre et Miquelon, it will go over
Newfoundland which is part of Canada.

(3) Can Google Maps or another such tool show great circle paths? It
shows an air route London, United Kingdom to Melbourne, FL, USA - which
seems to miss Canada by too much to be a Great Circle.


We aren't really talking of a rocket following a Great Circle here. We
are talking of a rocket launching late in its launch window that has to
do a plane change to get to the orbit of ISS. Early in launch it goes
more northward and then turns a little eastward to do the plane change.
After having completed the plane change, the trajectory still isn't
really a Great Circle, it is a Great Circle that is slipping westward as
Earth rotates. But if you find an app or web site that can overlay Great
Circles over a map, I would like to see that. If you find an app or web
site that can overlay orbital paths on a map it is even better.


Alain Fournier

  #8  
Old December 13th 15, 04:06 PM posted to sci.space.policy
Alain Fournier[_3_]
external usenet poster
 
Posts: 548
Default Atlas5 vs Shuttle ( launch window)

On 12/12/15 10:05 PM, JF Mezei wrote :

Circles over a map, I would like to see that. If you find an app or web
site that can overlay orbital paths on a map it is even better.



Designed for flying but could be of use.

http://gc.kls2.com/

(from there you can go to newer version of it).


If you enter MCO-LHR (Orlando to London) you get a good great circle.
London is at 51.5 which is pretty good approximation of the ISS orbit,
but not clear if this represents the highest latitude in that path.

Here is an example on the new interface:

http://www.gcmap.com/mapui?P=MCO-LHR...SU=kts&RS=best


Thank you JF.


Alain Fournier

  #9  
Old December 15th 15, 09:30 PM posted to sci.space.policy
Dr J R Stockton[_195_]
external usenet poster
 
Posts: 27
Default Atlas5 vs Shuttle ( launch window)

In sci.space.policy message , Sat, 12 Dec
2015 20:10:23, Alain Fournier posted:


(2) Testing with a piece of string and a rather small globe appears to
demonstrate that a great circle from any part of the Florida peninsula
to any part of England does not cross any part of Canada. It might
cross Saint Pierre et Miquelon, but one from CCAFS to London would not
do so.


I think you are either misplacing St-Pierre et Miquelon or the limits
of Canada. If it goes over St-Pierre et Miquelon, it will go over
Newfoundland which is part of Canada.


Agreed. My globe is too little to handle well the case of a territory
so small with a name so long.

--
(c) John Stockton, Surrey, UK. Turnpike v6.05 MIME.
Merlyn Web Site - FAQish topics, acronyms, & links.


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
NASA moves Shuttle return to flight later into launch window Jacques van Oene News 0 July 16th 05 09:24 AM
NASA sets new Space Shuttle launch planning window Jacques van Oene Space Shuttle 0 October 30th 04 09:20 AM
NASA sets new Space Shuttle launch planning window Jacques van Oene Space Station 0 October 30th 04 09:20 AM
NASA sets new Space Shuttle launch planning window Jacques van Oene News 0 October 30th 04 09:20 AM


All times are GMT +1. The time now is 10:30 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.