Author Topic: Raising ISS orbit with (super) Draco thrust  (Read 9302 times)

Offline rubtest

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Raising ISS orbit with (super) Draco thrust
« on: 05/28/2012 02:46 am »
first congratulation for NASA and Spacex for the nicest present
to all the space follower folk. We all dream about moon and mars ...

OK, around 2014  the last ATV mission will fly to the station.
The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.
Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?
If it makes sense  , NASA can leave maybe  a dedicated dragon ( a used one ) on nadir 2 to be used as backup  for Orbit raising.
 current thrust numbers that I have picked up :
http://www.spaceref.com/iss/elements/sm.html
 Zwezda : 2 large thrusters each 3070 N +
               2x16 130 N attitude  thrusters
 Draco    : 18 Thrusters 400 N each but I think only 4 are
                oriented for forward pushing movement
 Superdraco : 67000 N per thruster ( but probably larger fueling needs)
congratulation for NASA and especially Spacex for the nicest present
to all the believers folk




Offline Jorge

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #1 on: 05/28/2012 02:52 am »
first congratulation for NASA and Spacex for the nicest present
to all the space follower folk. We all dream about moon and mars ...

OK, around 2014  the last ATV mission will fly to the station.
The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.
Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?
If it makes sense  , NASA can leave maybe  a dedicated dragon ( a used one ) on nadir 2 to be used as backup  for Orbit raising.

Node 2 nadir is a crappy location for reboost, due to the large moment arm.

What's wrong with Zvezda/Progress?
JRF

Offline FinalFrontier

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #2 on: 05/28/2012 02:54 am »
first congratulation for NASA and Spacex for the nicest present
to all the space follower folk. We all dream about moon and mars ...

OK, around 2014  the last ATV mission will fly to the station.
The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.
Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?
If it makes sense  , NASA can leave maybe  a dedicated dragon ( a used one ) on nadir 2 to be used as backup  for Orbit raising.

Node 2 nadir is a crappy location for reboost, due to the large moment arm.

What's wrong with Zvezda/Progress?

I suppose the notion that Zvezda is aging and progress has and may fail again in the future.

Sort of brings up the UCM, ICM, PDR module debate again....

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Offline rubtest

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #3 on: 05/28/2012 03:04 am »


What's wrong with Zvezda/Progress?

yes , Nadir 2 is a poor position for massive thrust ( I think also of
thrust contamination residues problem in this port area )
Zwezda + Progress are good and reliable, but are also single point of failure for several station essential functions.
having  a dragon can provide  a Backup for orbit changes

Offline Jorge

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #4 on: 05/28/2012 03:06 am »
first congratulation for NASA and Spacex for the nicest present
to all the space follower folk. We all dream about moon and mars ...

OK, around 2014  the last ATV mission will fly to the station.
The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.
Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?
If it makes sense  , NASA can leave maybe  a dedicated dragon ( a used one ) on nadir 2 to be used as backup  for Orbit raising.

Node 2 nadir is a crappy location for reboost, due to the large moment arm.

What's wrong with Zvezda/Progress?

I suppose the notion that Zvezda is aging and progress has and may fail again in the future.

Post-shuttle, ISS has been boosted to an orbit that could easily survive a Progress stand-down of at least a year, perhaps much longer. So the failure of an individual Progress is not an issue.
JRF

Offline sanman

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #5 on: 05/28/2012 03:07 am »
Why couldn't Dragon be modified to attach where Progress does, to do the same kind of boosting using SuperDracos?

Offline Jorge

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #6 on: 05/28/2012 03:11 am »
Why couldn't Dragon be modified to attach where Progress does, to do the same kind of boosting using SuperDracos?

Crew Dragon could. Would need a Russian probe-and-drogue mechanism, plus possibly additional LIDAR reflectors on the aft end of Zvezda.

Who's going to pay for it, and under what circumstance would this be cheaper than simply launching another Progress?
JRF

Offline FinalFrontier

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #7 on: 05/28/2012 03:12 am »
Why couldn't Dragon be modified to attach where Progress does, to do the same kind of boosting using SuperDracos?

There is literally no reason to do this. Dragon is designed for use with the U.S. segment modifying it for use with the Russian segment would be totally unnecessary and expensive.
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Offline FinalFrontier

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #8 on: 05/28/2012 03:13 am »
first congratulation for NASA and Spacex for the nicest present
to all the space follower folk. We all dream about moon and mars ...

OK, around 2014  the last ATV mission will fly to the station.
The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.
Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?
If it makes sense  , NASA can leave maybe  a dedicated dragon ( a used one ) on nadir 2 to be used as backup  for Orbit raising.

Node 2 nadir is a crappy location for reboost, due to the large moment arm.

What's wrong with Zvezda/Progress?

I suppose the notion that Zvezda is aging and progress has and may fail again in the future.

Post-shuttle, ISS has been boosted to an orbit that could easily survive a Progress stand-down of at least a year, perhaps much longer. So the failure of an individual Progress is not an issue.

True but zvezda is still aging. Without progress what if its engines fail?

I guess that is the argument being put forward here anyway. I did say "the notion is" I don't agree with it myself.
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Offline Jorge

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #9 on: 05/28/2012 03:19 am »
first congratulation for NASA and Spacex for the nicest present
to all the space follower folk. We all dream about moon and mars ...

OK, around 2014  the last ATV mission will fly to the station.
The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.
Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?
If it makes sense  , NASA can leave maybe  a dedicated dragon ( a used one ) on nadir 2 to be used as backup  for Orbit raising.

Node 2 nadir is a crappy location for reboost, due to the large moment arm.

What's wrong with Zvezda/Progress?

I suppose the notion that Zvezda is aging and progress has and may fail again in the future.

Post-shuttle, ISS has been boosted to an orbit that could easily survive a Progress stand-down of at least a year, perhaps much longer. So the failure of an individual Progress is not an issue.

True but zvezda is still aging. Without progress what if its engines fail?

That's why Zvezda has two engines. And if Zvezda has a serious propulsion failure upstream of the engines, ISS is doomed anyway since Zvezda is the sole source of CMG desaturation for attitude control.

Quote
I guess that is the argument being put forward here anyway. I did say "the notion is" I don't agree with it myself.

Fair enough.
JRF

Offline rubtest

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #10 on: 05/28/2012 03:30 am »
[quote author=FinalFrontier
True but zvezda is still aging. Without progress what if its engines fail?

I guess that is the argument being put forward here anyway. I did say "the notion is" I don't agree with it myself.
[/quote]

I was actually interested to hear if the thrust of the current Draco engines from a dragon can influence at all the orbit of the ISS ?
is it at all feasible from the american segment ?

all the Orbit raising vehicles till now were docked to the ZWEZDA port ( Progress , ATV) in the russian segment.

if it is somehow feasible , NASA can prepare a detailed  emergency procedure "how to do it"  in case of a need, maybe test it once.
and have a plan "B" in the hand.

Offline Jorge

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #11 on: 05/28/2012 03:35 am »
Quote from: FinalFrontier
True but zvezda is still aging. Without progress what if its engines fail?

I guess that is the argument being put forward here anyway. I did say "the notion is" I don't agree with it myself.

I was actually interested to hear if the thrust of the current Draco engines from a dragon can influence at all the orbit of the ISS ?
is it at all feasible from the american segment ?

It is not a matter of thrust. The shuttle performed reboost of ISS using the vernier RCS thrusters, which have about one-fourth the thrust of the Dracos.

Quote
all the Orbit raising vehicles till now were docked to the ZWEZDA port ( Progress , ATV) in the russian segment.

Not true. The shuttle did it while docked to PMA-2 on the US segment. But what they have in common is that the thrust was directed axially, though the CG of the station.

Quote
if it is somehow feasible , NASA can prepare a detailed  emergency procedure "how to do it"  in case of a need, maybe test it once.
and have a plan "B" in the hand.


It is not feasible for reboost to be performed from either of the Node 2 radial ports, either nadir or zenith. Only axial. Cargo Dragon will never berth to the axial ports, only radial. So only crew Dragon (or some other vehicle docked to the axial port) can perform reboost.
« Last Edit: 05/28/2012 03:35 am by Jorge »
JRF

Offline FinalFrontier

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #12 on: 05/28/2012 03:43 am »
Short answer, it will never be done with a cargo dragon.
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Offline QuantumG

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #13 on: 05/28/2012 03:54 am »
Didn't Bill Gerstenmaier say they don't need much reboost anymore? Maybe I'm misremembering that.. he was probably talking about maneuvering to avoid debris.
Human spaceflight is basically just LARPing now.

Offline FinalFrontier

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #14 on: 05/28/2012 04:07 am »
Didn't Bill Gerstenmaier say they don't need much reboost anymore? Maybe I'm misremembering that.. he was probably talking about maneuvering to avoid debris.


I believe he said they have needed less then expected in something like the last two years due to lessened solar drag (because of lower solar activity not including this year of course) and because ISS was raised to a higher orbit following STS retirement.


Don't have the quote on hand so, pardon the irony, "don't quote me"  :-X
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Offline Jorge

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #15 on: 05/28/2012 04:09 am »
Didn't Bill Gerstenmaier say they don't need much reboost anymore? Maybe I'm misremembering that.. he was probably talking about maneuvering to avoid debris.


More for drag. Drag decreases exponentially with altitude. The ATV reboosts have put ISS at an altitude where drag is much lower and reboosts for altitude maintenance are much less frequent. But the debris environment is actually worse because the lack of drag causes the debris to decay more slowly, too.
JRF

Offline FinalFrontier

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #16 on: 05/28/2012 04:23 am »
first congratulation for NASA and Spacex for the nicest present
to all the space follower folk. We all dream about moon and mars ...

OK, around 2014  the last ATV mission will fly to the station.
The only orbit raising possibility for ISS stays the good old Zwezda with refueling via Progress flights.
Can the dragon with some extra fueling modifications use the draco thrusters to raise ISS orbit ?
If it makes sense  , NASA can leave maybe  a dedicated dragon ( a used one ) on nadir 2 to be used as backup  for Orbit raising.

Node 2 nadir is a crappy location for reboost, due to the large moment arm.

What's wrong with Zvezda/Progress?

I suppose the notion that Zvezda is aging and progress has and may fail again in the future.

Post-shuttle, ISS has been boosted to an orbit that could easily survive a Progress stand-down of at least a year, perhaps much longer. So the failure of an individual Progress is not an issue.

True but zvezda is still aging. Without progress what if its engines fail?

That's why Zvezda has two engines. And if Zvezda has a serious propulsion failure upstream of the engines, ISS is doomed anyway since Zvezda is the sole source of CMG desaturation for attitude control.

Quote
I guess that is the argument being put forward here anyway. I did say "the notion is" I don't agree with it myself.

Fair enough.

Agreed but going to play devils advocate one more time.

Remember this? :

1. http://www.msnbc.msn.com/id/28998876/ns/technology_and_science-space/t/shaking-space-station-rattles-nasa/#.T8L81NVSRyI


And this?

2. http://www.thespacereview.com/article/619/1


Hence, I can see why there would be a desire to have a backup to Zvezda (besides Visiting Vehicles) but that brings up the ICM/USCM ect debates again and is beyond the scope of this thread (as dragon is a visiting vehicle).
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Offline Jorge

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #17 on: 05/28/2012 04:27 am »
Hence, I can see why there would be a desire to have a backup to Zvezda (besides Visiting Vehicles) but that brings up the ICM/USCM ect debates again and is beyond the scope of this thread (as dragon is a visiting vehicle).

Right. You can posit Zvezda to be a vulnerability all you want, but you can't posit Dragon as the solution unless you intend to have one up there all the time.
JRF

Offline FinalFrontier

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #18 on: 05/28/2012 04:33 am »
Hence, I can see why there would be a desire to have a backup to Zvezda (besides Visiting Vehicles) but that brings up the ICM/USCM ect debates again and is beyond the scope of this thread (as dragon is a visiting vehicle).

Right. You can posit Zvezda to be a vulnerability all you want, but you can't posit Dragon as the solution unless you intend to have one up there all the time.

Correct. And it won't ever be its not designed to be, its designed to be  a visiting vehicle and the only version that could preform adjustment is going to be one docked to PMA 2 and there is only one PMA 2 hence it will always be a visiting vehicle not a permanent attachment acting as control backup to the SM.


In any event it might be time to start a new thread regarding things like PDR,ICM,  USCM and node 4 or some of the other "u.s. control module" options that have been discussed over the years once again, considering this thread caused me to start thinking about long term Zvezda issues again.

« Last Edit: 05/28/2012 04:35 am by FinalFrontier »
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Offline sanman

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Re: Raising ISS orbit with (super) Draco thrust
« Reply #19 on: 05/28/2012 04:36 am »
Why couldn't Dragon be modified to attach where Progress does, to do the same kind of boosting using SuperDracos?

There is literally no reason to do this. Dragon is designed for use with the U.S. segment modifying it for use with the Russian segment would be totally unnecessary and expensive.

Well, then there should be universal docking point where anything can attach to do a station boost. Then the station can always get boosted in a pinch, if Progress or whatever else has been delayed/suspended/etc.

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