Author Topic: Antares to sun-synchronous orbit  (Read 4508 times)

Offline Kim Keller

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Offline MP99

Re: Antares to sun-synchronous orbit
« Reply #1 on: 08/26/2014 08:07 PM »
Quote
Among the details to be settled is...

Surprised the article doesn't clarify how close / far this would put flights from overflying anyone / anything. (Orbital would have clarified this for themselves as one of the first considerations.)

cheers, Martin

Offline Lars_J

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Re: Antares to sun-synchronous orbit
« Reply #2 on: 08/26/2014 09:24 PM »
Isn't that a 98 degree inclination? Would this require a dog-leg maneuver to get around Kitty Hawk and Cape Hatteras?

Offline edkyle99

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Re: Antares to sun-synchronous orbit
« Reply #3 on: 08/27/2014 02:26 AM »
Isn't that a 98 degree inclination? Would this require a dog-leg maneuver to get around Kitty Hawk and Cape Hatteras?
Dog legs for sure.  The most southern launch azimuth from Wallops is something like 160 degrees from north (would provide a 60 deg inclination if flown without dog leg).  The North Carolina Outer Banks are the "restricting landmass for southern launch azimuths", according to NASA.  It will cost an Antares 131 about one-third of its SSO potential compared to a launch from, say, Kodiak, but that still leaves 3 tonnes to 400 km, which is better than a Delta 7420 from Vandenberg.  A coup if it works, to launch both to ISS and SSO, and maybe even GTO, from one launch pad.  Note that this assumes use of the optional Bi-Propellant Third Stage, which this announcement seems to hint is going to be developed.

 - Ed Kyle
« Last Edit: 08/27/2014 03:57 AM by edkyle99 »

Offline sdsds

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Re: Antares to sun-synchronous orbit
« Reply #4 on: 08/27/2014 03:01 AM »
Is the assumption that a dog-leg maneuver is exo-atmospheric? If the structure can withstand the aerodynamic forces isn't there also the option of doing the dog-leg early, i.e. well before max-q?
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Offline edkyle99

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Re: Antares to sun-synchronous orbit
« Reply #5 on: 08/27/2014 03:11 AM »
Is the assumption that a dog-leg maneuver is exo-atmospheric? If the structure can withstand the aerodynamic forces isn't there also the option of doing the dog-leg early, i.e. well before max-q?
My guess is that it will only involve yawing during exo-atmospheric upper stage flight, which comes after a several minute coast after first stage burnout, since the first stage has to drop safely off of the coastline.  Note that the IIP would probably pass over part of Cuba and then probably Panama before entering the Pacific Ocean. 

 - Ed Kyle
« Last Edit: 08/27/2014 03:18 AM by edkyle99 »

Offline Lars_J

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Re: Antares to sun-synchronous orbit
« Reply #6 on: 08/27/2014 03:34 AM »
Isn't that a 98 degree inclination? Would this require a dog-leg maneuver to get around Kitty Hawk and Cape Hatteras?
Dog legs for sure.  The most southern launch azimuth from Wallops is something like 160 degrees from north (would provide a 60 deg inclination if flown without dog leg).  The North Carolina Outer Banks are the "restricting landmass for southern launch azimuths", according to NASA.  It will cost an Antares 131 about one-third of its SSO potential compared to a launch from, say, Kodiak, but that still leaves 3 tonnes to 400 km, which is better than a Delta 7420.  A coup if it works, to launch both to ISS and SSO, and maybe even GTO, from one launch pad.

So a dog-leg trajecory like this, then? (my annotated screencap from Google Earth)

But the potential overflight issues for this kind of launch might make the Texas Boca Chica location look easy by comparison.
« Last Edit: 08/27/2014 03:36 AM by Lars_J »

Offline edkyle99

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Re: Antares to sun-synchronous orbit
« Reply #7 on: 08/27/2014 03:51 AM »
So a dog-leg trajecory like this, then? (my annotated screencap from Google Earth)
Something like that, though swinging a bit further east, maybe crossing the eastern third of Cuba and passing above the center of Panama.

 - Ed Kyle
« Last Edit: 08/27/2014 03:55 AM by edkyle99 »

Offline edkyle99

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Re: Antares to sun-synchronous orbit
« Reply #8 on: 08/28/2014 03:30 AM »
But the potential overflight issues for this kind of launch ...
Guantanamo Bay and Panama Canal overflight? Think they'd complain? :)
Cuba probably would complain, but a precedent of sorts was already set when a few polar orbit missions were flown from Cape Canaveral during the early 1960s.  One failed, with rocket parts falling on eastern Cuba.  Wallops Island is further from Cuba than the Cape.  Only the smaller upper stages and payload would overfly Cuba. 

A bigger concern would likely be the Bahamas.  Trajectories would likely be driven east to avoid populated areas. 

 - Ed Kyle
« Last Edit: 08/28/2014 03:36 AM by edkyle99 »

Offline kevin-rf

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Re: Antares to sun-synchronous orbit
« Reply #9 on: 08/28/2014 11:46 AM »

Only the smaller upper stages and payload would overfly Cuba. 
Other than those "smaller" upper stages and payloads are most likely larger than the Thor's that overflew Cuba.

btw. There once was a short thread that listed all the Cape Polar launches... http://forum.nasaspaceflight.com/index.php?topic=14778.0
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Offline edkyle99

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Re: Antares to sun-synchronous orbit
« Reply #10 on: 08/28/2014 03:12 PM »

Only the smaller upper stages and payload would overfly Cuba. 
Other than those "smaller" upper stages and payloads are most likely larger than the Thor's that overflew Cuba.

btw. There once was a short thread that listed all the Cape Polar launches... http://forum.nasaspaceflight.com/index.php?topic=14778.0
It is all a matter of statistical chance, I suppose.  The first stage will burn out and separate even before Antares passes the Outer Banks of North Carolina.  The second stage will complete its burn off the coast of Florida, before the ground track even reaches the Bahamas region.  If the second stage failed to start it, along with the first stage, would fall short of the Bahamas.  Once ignited and accelerating, it would take probably 25 seconds or less for the IIP to cross Cuba.  Those will be long seconds for the RSO and for certain government officials.

 - Ed Kyle
« Last Edit: 08/28/2014 03:22 PM by edkyle99 »

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