Author Topic: SpaceX Dragon Specs  (Read 54122 times)

Offline Jorge

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Re: SpaceX Dragon Specs
« Reply #20 on: 11/14/2008 12:15 am »

8 ) I'm 99% sure that's a passive CBM, which would be needed to go to the ISS.


This DragonLab is a non-ISS concept. Free flyer, but no go for ISS. No need for a berthing ring.


A berthing ring on the DragonLab would allow a manned Dragon to dock with the DragonLab.

Nope, CBMs are unsuitable for docking; they require a robotic arm to achieve the accuracy necessary to berth them.
JRF

Offline nacnud

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Re: SpaceX Dragon Specs
« Reply #21 on: 11/14/2008 12:31 am »
You could put such an arm in the Dragons trunk but why go to the trouble of a second Dragon launch when there are already people and an arm in orbit on the ISS.

Online A_M_Swallow

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Re: SpaceX Dragon Specs
« Reply #22 on: 11/14/2008 01:53 am »
You could put such an arm in the Dragons trunk but why go to the trouble of a second Dragon launch when there are already people and an arm in orbit on the ISS.

Using the ISS as a forward base sounds like a good idea.  However non-NASA people may have difficulties getting use of the ISS and its astronauts.

The experiments may need a different orbit from the ISS.  Possibilities include polar orbits, sun synchronous orbits and lunar orbits.

Two years is probably sufficient time for an ion thruster to fly the DragonLan to the Moon and back.  Once the equipment has been deployed the two capsules could disconnect.

Offline Jim

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Re: SpaceX Dragon Specs
« Reply #23 on: 11/14/2008 02:21 am »

The experiments may need a different orbit from the ISS.  Possibilities include polar orbits, sun synchronous orbits and lunar orbits.

Incorrect
Microgravity experiments, which Dragonlab is for, just need zero gravity, basically any orbit.

polar orbits and  sun synchronous orbits are for non microgravity missions, i.e. earth viewing and there are better spacecraft designs for that.
 
Same goes for lunar orbits.

There is no need for a pressurized compartment for polar orbits, sun synchronous orbits and lunar orbit missions.

Offline Jim

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Re: SpaceX Dragon Specs
« Reply #24 on: 11/14/2008 02:23 am »

Two launches may be cheaper that fully automating the equipment, particularly if the extra hardware has to be space certified. 

No it wouldn't and it has nothing to do with space certification..

Offline Antares

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Re: SpaceX Dragon Specs
« Reply #25 on: 11/14/2008 04:28 am »
Wow.  So many mines buried in the field today.

1) Jorge makes a good point about them being common BERTHING mechanisms.  I look at it as Active CBMs being REALLY expensive.

2) A disposable arm on the Dragon trunk?!?  Yeah, another economic unobtainium.

3) Jim, what's so wrong with putting people in polar orbit?  SpaceX customers might want to be the first people in a retrograde orbit.
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Offline HMXHMX

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Re: SpaceX Dragon Specs
« Reply #26 on: 11/14/2008 05:04 am »
There is a potential advantage in being in sunsync for microgravity missions if continuous power is need, and one doesn't want to rely on batteries due to weight or discharge issues, but that trade will be highly mission/payload dependent.

Polar orbits will have significantly higher radiation risks for human crews.  This is not to say they won't be flown (Apollo had high risks too), but it is something to keep in mind, especially in flare season.

Online A_M_Swallow

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Re: SpaceX Dragon Specs
« Reply #27 on: 11/14/2008 06:19 am »
There is no need for a pressurized compartment for polar orbits, sun synchronous orbits and lunar orbit missions.

Unless animal and plant experiments are being performed, they need a pressurized compartment.  Someone may wish to say determine how effective a new pill is at countering the effects of radiation and microgravity.  Different orbits have different radiation profiles.  The down mass facility permits post experiment inspection of the animals and plants.

Offline kevin-rf

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Re: SpaceX Dragon Specs
« Reply #28 on: 11/14/2008 12:11 pm »
3) Jim, what's so wrong with putting people in polar orbit?  SpaceX customers might want to be the first people in a retrograde orbit.

I'm sure you could sell Iran several one way retrograde dragon flights ;)

In all seriousness, if the cape becomes really busy spaceX might want to shift flights where the actual orbit doesn't matter (Tourism/Dragon Lab) to the west coast. That would mean a polar or retrograde orbit. More flights from the west coast would reduce the SpaceX fixed costs while opening up more east coast GTO flights slots.

Sun Synch flights on the terminator for power hungry material manufacturing experiments would be a plus.

(Yes jim, assuming they can get the flight rate up to more than two flights a year ;) ).
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Offline docmordrid

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Re: SpaceX Dragon Specs
« Reply #29 on: 11/16/2008 04:07 am »
Aren't Bigelow's module prototypes in polar orbit? What if his manned modules are likewise and Dragon ends up being one of the 'people movers'?  SpaceX does have Bigelow's Sundancer on their manifest.
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Offline hop

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Re: SpaceX Dragon Specs
« Reply #30 on: 11/16/2008 06:00 am »
Aren't Bigelow's module prototypes in polar orbit?
No. They are at relatively high inclinations (~64 deg according to wikipedia) but the orbit of the prototypes says little about the orbits of crewed modules. It was almost certainly driven by launcher/launch site, and that combinatio0n will not be used for either full sized modules or crew.

Offline kkattula

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Re: SpaceX Dragon Specs
« Reply #31 on: 11/16/2008 01:21 pm »
IIRC, Bigelow want to use a 41 deg inclination orbit. This gives safer abort options for launch from the Cape, passes over the same ground track every 24 hours for daily launch & landing opportunities, and gives a view of their high latitude homelands for the most likely customers.

Offline edkyle99

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Re: SpaceX Dragon Specs
« Reply #32 on: 11/16/2008 03:53 pm »
what's so wrong with putting people in polar orbit?  SpaceX customers might want to be the first people in a retrograde orbit.

There may be two reasons you don't see people launched to polar orbit.  The first reason is that polar orbits require more launch energy (delta-v), which means either more powerful, expensive rockets or smaller, less-capable spacecraft.  The second reason may be that space travelers would be exposed to more radiation in a polar orbit. 

See, for example,

http://books.nap.edu/openbook.php?record_id=9725&page=7

http://74.125.95.104/search?q=cache:dSqXGSoh0D0J:www.cosis.net/abstracts/COSPAR02/01686/COSPAR02-A-01686.pdf+radiation+in+polar+orbit&hl=en&ct=clnk&cd=3&gl=us&client=firefox-a

http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA204598

Etc.

 - Ed Kyle
« Last Edit: 11/16/2008 03:56 pm by edkyle99 »

Offline Ronsmytheiii

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Re: SpaceX Dragon Specs
« Reply #33 on: 11/16/2008 04:01 pm »
IIRC, Bigelow want to use a 41 deg inclination orbit. This gives safer abort options for launch from the Cape, passes over the same ground track every 24 hours for daily launch & landing opportunities, and gives a view of their high latitude homelands for the most likely customers.

Of course at 41 degrees Bigelow cannot use any Russian vehicles or spacecraft except maybe from Kouru.

Offline nomadd22

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Re: SpaceX Dragon Specs
« Reply #34 on: 11/16/2008 05:20 pm »

The experiments may need a different orbit from the ISS.  Possibilities include polar orbits, sun synchronous orbits and lunar orbits.

Incorrect
Microgravity experiments, which Dragonlab is for, just need zero gravity, basically any orbit.

polar orbits and  sun synchronous orbits are for non microgravity missions, i.e. earth viewing and there are better spacecraft designs for that.
 
Same goes for lunar orbits.

There is no need for a pressurized compartment for polar orbits, sun synchronous orbits and lunar orbit missions.

 Then why do they advertise "Sensors/apertures up to 3.5 m (138 in) dia."? And remote sensing mission would likely need a high inclination or polar orbit.

Offline Jim

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Re: SpaceX Dragon Specs
« Reply #35 on: 11/16/2008 05:28 pm »

 Then why do they advertise "Sensors/apertures up to 3.5 m (138 in) dia."? And remote sensing mission would likely need a high inclination or polar orbit.

They may advertise the capability but there are many other better buses for these type missions

Offline Patchouli

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Re: SpaceX Dragon Specs
« Reply #36 on: 11/16/2008 06:30 pm »
One thing to keep in mind F9 is somewhat over powered for the task of launching Dragon.
So missions to other orbits such as polar orbits may be possible and economic.
Dragon has a GLOW around 8000Kg while F9 can lift 12,000kg.
I think the only people who complained when Bigelow wanted to use a 450 mile orbit for their station was space adventures because Soyuz could not fly that high.

Offline William Barton

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Re: SpaceX Dragon Specs
« Reply #37 on: 11/16/2008 07:15 pm »

 Then why do they advertise "Sensors/apertures up to 3.5 m (138 in) dia."? And remote sensing mission would likely need a high inclination or polar orbit.

They may advertise the capability but there are many other better buses for these type missions

I think it's safe to say they're advertising what they're advertising because that's what they expect to have, and nothing to do with what's best for what mission. As well ask why the Good Humor truck advertises ice cream...

Online A_M_Swallow

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Re: SpaceX Dragon Specs
« Reply #38 on: 11/16/2008 10:33 pm »

 Then why do they advertise "Sensors/apertures up to 3.5 m (138 in) dia."? And remote sensing mission would likely need a high inclination or polar orbit.

They may advertise the capability but there are many other better buses for these type missions

That is something for you to put in the trade study, in say 3 or 4 years time, when some NASA project is looking for a cheap bus.  The total cost includes the launch vehicle.

Offline Jim

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Re: SpaceX Dragon Specs
« Reply #39 on: 11/16/2008 10:50 pm »

That is something for you to put in the trade study, in say 3 or 4 years time, when some NASA project is looking for a cheap bus.  The total cost includes the launch vehicle.

No, it doesn't enter the equation.  Spacecraft and launch vehicle procurements are kept separate.  If a NASA project is looking for a cheap bus, it will do it and will not include the launch vehicle.  NASA has been burned by all in one contracts

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