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#20
by
Ronsmytheiii
on 01 May, 2010 19:48
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Careful... not all the volume is dedicated to pressurized cargo - some have equipment in the pressurized volume - and some of that is lost on the hatch mechanism/opening swept volume and the "free space" (space for the astronauts to get inside and get the cargo out - hint: Progress has NO free space: you unload it from the top down...)
You may be interested in this old presentation from the early Cygnus design days. The actual "basic" PCM we ended up with is somewhere in between the "regular" and the "+" version in that presentation, with a total pressurized volume of 18.7 m3, and a useable cargo volume of about 12-13 m3. The "enhanced" version (to go with the liquid-second-stage Taurus II) has a whopping 19m3 of useable cargo volume (out of about 26m3 total pressurized vol).
Moral(s) of the story: a) Not all volume is pressurized and b) Not all pressurized volume is useable for cargo.
Do not pay too much attention to the spacecraft sketches - much has changed (single main engine, location of RCS jets, location of grapple fixture, etc. etc.) However, it is a curious insight into the design process... how much changes in less than two years!
Interesting mention of PCM+, if I had to guess I would imagine that is an enlarged version of the PCM when HESS comes along.
Also, why not have the Recoverable return module return racks as well? Seems like an asset NASA would want especially if a rack malfunctions and needs to be repaired on the ground rather than rebuild another and trash the previous one.
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#21
by
Jim
on 01 May, 2010 19:50
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Also, why not have the Recoverable return module return racks as well? Seems like an asset NASA would want especially if a rack malfunctions and needs to be repaired on the ground rather than rebuild another and trash the previous one.
They would only have to return a component of the rack and not the whole thing.
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#22
by
Robotbeat
on 02 May, 2010 07:44
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Will Cygnus be used for reboost?
No, wrong nominal attachment location (big moment arm wrt ISS center of mass.) Right now the only docking position in the U.S. side suitable for reboost has an APAS in it (Cygnus PCM uses a CBM)
Good question! Also, is a fuel-only cygnus possible, which can be used as a tug?
Yes, the SM was designed to be a self-standing spacecraft (power, comm, C&DH, RCS, star trackers, etc.)
And if you add a remote manipulator arm...
Hmmm... very interesting, antonioe... I read the presentation someone linked about using the Cygnus for servicing, and it mentioned refueling... How much fuel could a refueling Cygnus carry? 2 tons? 3 tons? Maybe more, if launched on a bigger launch vehicle? Sounds like an excellent bus for a tanker, or perhaps for picking up passive cargo in LEO and delivering them to a LEO depot or station. Could Cygnus be used as a tug for ULA's Payload Bay Fairing?
Also, the presentation mentioned attaching electric propulsion modules for end-of-life disposal of other satellites. Could such a module be added to Cygnus itself for boosting other payloads, perhaps with bigger solar arrays added to the Cygnus? Can Cygnus be used in deep space?
EDIT: Also, what's the on-orbit life of the Cygnus? Could it stay at GSO for years, servicing or deorbiting satellites on-demand?
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#23
by
Freddie
on 29 May, 2010 01:56
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#24
by
Freddie
on 29 May, 2010 02:08
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#25
by
simonth
on 29 May, 2010 07:50
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Orbital Sciences has issued its May 2010 progress update report for the Cygnus spacecraft. It can be read at http://www.orbital.com/CargoResupplyServices/.
I wonder why they say "up to 2000kg", if the actual design can hold 2700kg+.
Anyway, I hope the cargo demonstration flight won't slip much further than Q2 2011 and that NASA won't stand in the way of Orbital packing the demo mission full of (low cost) supplies, like water, clothing and packaged food.
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#26
by
Skyrocket
on 29 May, 2010 09:23
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Orbital Sciences has issued its May 2010 progress update report for the Cygnus spacecraft. It can be read at http://www.orbital.com/CargoResupplyServices/.
I wonder why they say "up to 2000kg", if the actual design can hold 2700kg+.
because they are speaking of the basic version, not the enhanced one. Please read in the August 2009 update:
The CDR included two Cygnus PCM configurations. A standard configuration will carry up to 2,000 kg of cargo for the ISS, and will be used in the COTS demonstration mission in 2011 and the first two missions under the Cargo Resupply Services (CRS) contract between 2011 and 2012. An enhanced configuration will carry up to 2,700 kg of cargo for CRS missions between 2013 and 2015.
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#27
by
Ben the Space Brit
on 29 May, 2010 16:41
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A hypothetical question: Are there any plans or suggestions that Cygnus may have an optional configuration like that of the HTV with a much smaller pressurised module and an unpressurised cargo rack?
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#28
by
hop
on 29 May, 2010 22:38
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A hypothetical question: Are there any plans or suggestions that Cygnus may have an optional configuration like that of the HTV with a much smaller pressurised module and an unpressurised cargo rack?
The initial plan had unpressurized and pressurized variants. ISTR NASA has requested only the pressurized variant for early flights, where the initial plans had a mix fairly early on. All of this has been covered in the various Cygnus/Torus/Orbital threads.
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#29
by
Ronsmytheiii
on 04 Jun, 2010 19:14
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Just to let people know, I will be traveling to Wallops/Mars this weekend for an open house, most updates will be in L2 but I will drop a few nuggets here, and if anyone want to pose a question let me know.
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#30
by
Ronsmytheiii
on 23 Jun, 2010 02:46
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a Quick question for Dr Elias or anyone who might have the ability to answer, will there be a possibility to add or move the existing grapple fixture for SSRMS to the PCM+ ? It might save the ISSP some headaches for a few years as seen by a L2 document.
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#31
by
sdsds
on 02 Jul, 2010 03:52
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The current Cygnus fact sheet (©2010 Orbital Sciences Corporation. FS006_08g) does not provide dimensions (other than volume) for the Pressurized Cargo Module. Yet those must now be set, as the manufacturing pathfinder article is well into production. Are length and diameter values available from some source other than the fact sheet?
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#32
by
Freddie
on 02 Jul, 2010 06:46
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#33
by
Space Pete
on 08 Jul, 2010 17:32
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Here's a great article about Cygnus being assembled by Thales Alenia Space (TAS) in Torino, Italy.
BBC News'/Jonathan Amos' "Spaceman" Blog: "The private spaceships taking shape in Torino".
www.bbc.co.uk/blogs/thereporters/jonathanamos/2010/07/cygnus.shtmlThe article refers to a "37-inch hatch, specially developed by TAS". I thought Cygnus is going to use the CBM hatch (which is 50-inches in diameter)?
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#34
by
Ronsmytheiii
on 08 Jul, 2010 19:15
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Here's a great article about Cygnus being assembled by Thales Alenia Space (TAS) in Torino, Italy.
BBC News'/Jonathan Amos' "Spaceman" Blog: "The private spaceships taking shape in Torino".
www.bbc.co.uk/blogs/thereporters/jonathanamos/2010/07/cygnus.shtml
The article refers to a "37-inch hatch, specially developed by TAS". I thought Cygnus is going to use the CBM hatch (which is 50-inches in diameter)?
What I find hilarious is how the article goes to great lengths to show how much more sophisticated ATV is from its "American cousin" That may be true technically, but Cygnus is more robust operationally (Ie can lift racks, berth to multiple ports) for less cost.technology, isnt that a good thing?
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#35
by
sdsds
on 09 Jul, 2010 04:31
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Here's a great article about Cygnus being assembled by Thales Alenia Space (TAS) in Torino, Italy.
BBC News'/Jonathan Amos' "Spaceman" Blog: "The private spaceships taking shape in Torino".
www.bbc.co.uk/blogs/thereporters/jonathanamos/2010/07/cygnus.shtml
The article refers to a "37-inch hatch, specially developed by TAS". I thought Cygnus is going to use the CBM hatch (which is 50-inches in diameter)?
In the audio clip right near the end of the article Walter Cugno (programme manager on Cygnus at TAS) describes this a bit. Short synopsis: no ISPRs, so no need for 50 in. hatch.
It's apparently still compatible with CBM, though. The vacuum seal must be out at the circular perimeter rather than the square hatch?
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#36
by
pippin
on 09 Jul, 2010 07:53
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What I find hilarious is how the article goes to great lengths to show how much more sophisticated ATV is from its "American cousin" That may be true technically, but Cygnus is more robust operationally (Ie can lift racks, berth to multiple ports) for less cost.technology, isnt that a good thing?
Bla bla to explain why you are spending so much more (tax) money on ATV. People could compare apples to oranges and ask why Cygnus is cheaper.
You can't really compare the two since they are built to completely different requirements.
ATV has a smaller hatch because it docks on the Russian side but that gives it reboost capability, can make it dock autonomously and allows it to deliver fuel.
Both do what they were designed to do (well, Cygnus WILL hopefully do what it is being designed to do). Is an iPhone more advanced than, say, a Dell notebook? Or the other way around?
ISS is an international cooperation. You have a set of overall functions that have to be available to operate it but not every system (supply vehicle in this case) needs to fulfill all of them.
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#37
by
edkyle99
on 09 Jul, 2010 13:36
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What I find hilarious is how the article goes to great lengths to show how much more sophisticated ATV is from its "American cousin"
How is it "American" if it is being built in Italy?
- Ed Kyle
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#38
by
kevin-rf
on 09 Jul, 2010 13:45
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Who paid for it?
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#39
by
Jim
on 09 Jul, 2010 14:17
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What I find hilarious is how the article goes to great lengths to show how much more sophisticated ATV is from its "American cousin"
How is it "American" if it is being built in Italy?
- Ed Kyle
Only the shell is Italian, the service module is the spacecraft and US. Especially, since it can be used with an unpressurized logistics carrier.