Author Topic: General Falcon and Dragon discussion (Thread 15)  (Read 29027 times)

Online abaddon

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #20 on: 12/04/2018 02:06 pm »
I'm a little baffled why this is called a "breakthrough".  Surely the idea of a kick motor for the Heavy was as obvious to these professionals as it was to many of us arm-chair observers who have mused about this for some time now?

Maybe the breakthrough was: being able to even consider the Heavy due to Class C certification that came through recently?  Or maybe the STAR-48BV that @woods170 mentions?
« Last Edit: 12/04/2018 02:07 pm by abaddon »

Online LouScheffer

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #21 on: 12/04/2018 02:41 pm »
A Star-48 only adds a tiny bit of performance, so a Falcon Heavy alone could almost do the job.

A Star 48 has about 2114 kg mass, about 114 kg when done.  So assuming Clipper is 6 tonnes, as quoted, then at an ISP of 287, the Star-48 supplies 287*9.8*ln(8/6) = 809 m/s.

But the second stage performance is reduced by needing to boost the extra mass of the Star.  Assume that with no Star-48, the stack starts at 117t and ends at 11t.  But with the Star, it starts at 119t and ends at 13t.  At an ISP of 348, the extra mass then loses 348*9.8*(ln(117/11) - ln(119/13)) = 511 m/s.    So the net gain is only 809-511 = 298 m/s.

This is a pretty small faction of the 8000 m/s or so the second stage provides.  It's on the order of what a burn-to-depletion could provide, as opposed to a controlled shutdown.    But of course with a zillion dollar probe, they want to be sure they have the performance they need, not that it's merely likely.

It'll use the STAR-48BV variant which has an ISP of 292 (not 287), has a mass of 2164 kg when loaded and a mass of 138 kg when done (See the numbers for STAR-48BV in the NGIS Motor Catalog from June 2018).

So, the STAR-48BV will kick in a little more delta-V than you calculated.
Also, I suggest you try to refine your assumptions for FH stage 2 performance numbers a bit.
These changes, while sensible, make only trivial differences to the calculation.  For example, with a 6000 kg Clipper, the Star-48BV provides 292*9.8*l(8164/6138) = 816 m/s, just 8 m/s more than calculated above.

As far as stage 2 performance, thanks to the environmental impact statement for the abort test, page 2-6, we now know the second stage fuel load:
Quote
Stage 2 LOX: 168,100 pounds
Stage 2 RP-1: 65,000 pounds
That's 233,000 lb of propellant, or 106t.   So now the only unknown is the mass of the empty second stage + residuals.  I assumed 5t (4.5t empty + 500 kg residuals).   If we assume the second stage is lighter (4t for stage + residuals) then the benefit becomes slightly less ( 348*9.8*(l(116/10) - l(118/12)) = 563 m/s lost by second stage from increased payload).   If we assume the second stage is on the heavy end of estimates, at 6t for empty + residuals, then the loss is 348*9.8*(l(118/12) - l(120/14)) = 468 m/s.   

Basically, any plausable mass for the second stage yields the same results.  The Star adds about 800 m/s, but the extra payload on the second stage will eat at least half of that.  So the overall gain is small, <400 m/s or so.

Offline TorenAltair

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #22 on: 12/04/2018 02:57 pm »
Why do they no longer use larger kick stages like the STAR 62 or so? Should improve things a bit.

Offline hkultala

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #23 on: 12/04/2018 03:20 pm »
From the Ars article

Quote
The breakthrough referenced by Goldstein involved the addition of a Star 48 "kick stage" to the Falcon Heavy rocket, which would provide an extra boost of energy after the rocket's upper stage had fired. With this solid rocket motor kick stage, Goldstein said Clipper would need just a single Earth gravity assist and would not have to go into the inner Solar System for a Venus flyby.

"Nobody is saying we're not going on the SLS," Goldstein said. "But if by chance we don't, we don't have the challenge of the inner Solar System. This was a major development. This was a big deal for us."

A Star-48 only adds a tiny bit of performance, so a Falcon Heavy alone could almost do the job.

A Star 48 has about 2114 kg mass, about 114 kg when done.  So assuming Clipper is 6 tonnes, as quoted, then at an ISP of 287, the Star-48 supplies 287*9.8*ln(8/6) = 809 m/s.

But the second stage performance is reduced by needing to boost the extra mass of the Star.  Assume that with no Star-48, the stack starts at 117t and ends at 11t.  But with the Star, it starts at 119t and ends at 13t.  At an ISP of 348, the extra mass then loses 348*9.8*(ln(117/11) - ln(119/13)) = 511 m/s.    So the net gain is only 809-511 = 298 m/s.

This is a pretty small faction of the 8000 m/s or so the second stage provides.  It's on the order of what a burn-to-depletion could provide, as opposed to a controlled shutdown.    But of course with a zillion dollar probe, they want to be sure they have the performance they need, not that it's merely likely.

"Small fraction" of delta-v difference can mean HUGE difference in overall performance requirements, because of the logarithmics on the rocket equation.

One should NEVER compare "fractions" of delta-v. Always calculate the absolute difference, or the pythagoran difference.

« Last Edit: 12/04/2018 03:20 pm by hkultala »

Offline envy887

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #24 on: 12/04/2018 06:00 pm »
A Star-48 only adds a tiny bit of performance, so a Falcon Heavy alone could almost do the job.

A Star 48 has about 2114 kg mass, about 114 kg when done.  So assuming Clipper is 6 tonnes, as quoted, then at an ISP of 287, the Star-48 supplies 287*9.8*ln(8/6) = 809 m/s.

But the second stage performance is reduced by needing to boost the extra mass of the Star.  Assume that with no Star-48, the stack starts at 117t and ends at 11t.  But with the Star, it starts at 119t and ends at 13t.  At an ISP of 348, the extra mass then loses 348*9.8*(ln(117/11) - ln(119/13)) = 511 m/s.    So the net gain is only 809-511 = 298 m/s.

This is a pretty small faction of the 8000 m/s or so the second stage provides.  It's on the order of what a burn-to-depletion could provide, as opposed to a controlled shutdown.    But of course with a zillion dollar probe, they want to be sure they have the performance they need, not that it's merely likely.

It'll use the STAR-48BV variant which has an ISP of 292 (not 287), has a mass of 2164 kg when loaded and a mass of 138 kg when done (See the numbers for STAR-48BV in the NGIS Motor Catalog from June 2018).

So, the STAR-48BV will kick in a little more delta-V than you calculated.
Also, I suggest you try to refine your assumptions for FH stage 2 performance numbers a bit.
These changes, while sensible, make only trivial differences to the calculation.  For example, with a 6000 kg Clipper, the Star-48BV provides 292*9.8*l(8164/6138) = 816 m/s, just 8 m/s more than calculated above.

As far as stage 2 performance, thanks to the environmental impact statement for the abort test, page 2-6, we now know the second stage fuel load:
Quote
Stage 2 LOX: 168,100 pounds
Stage 2 RP-1: 65,000 pounds
That's 233,000 lb of propellant, or 106t.   So now the only unknown is the mass of the empty second stage + residuals.  I assumed 5t (4.5t empty + 500 kg residuals).   If we assume the second stage is lighter (4t for stage + residuals) then the benefit becomes slightly less ( 348*9.8*(l(116/10) - l(118/12)) = 563 m/s lost by second stage from increased payload).   If we assume the second stage is on the heavy end of estimates, at 6t for empty + residuals, then the loss is 348*9.8*(l(118/12) - l(120/14)) = 468 m/s.   

Basically, any plausable mass for the second stage yields the same results.  The Star adds about 800 m/s, but the extra payload on the second stage will eat at least half of that.  So the overall gain is small, <400 m/s or so.

How many kg of payload does it add to a c3 of 85?

Per LSP, FH can lift 8230 kg to a c3 of 30, and 1810 kg to a c3 of 85.
« Last Edit: 12/04/2018 06:07 pm by envy887 »

Offline Negan

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #25 on: 12/04/2018 06:22 pm »
On a totally other note, any estimates on what a Dragon 2 trunk costs?

Offline woods170

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #26 on: 12/04/2018 06:28 pm »
A Star-48 only adds a tiny bit of performance, so a Falcon Heavy alone could almost do the job.

A Star 48 has about 2114 kg mass, about 114 kg when done.  So assuming Clipper is 6 tonnes, as quoted, then at an ISP of 287, the Star-48 supplies 287*9.8*ln(8/6) = 809 m/s.

But the second stage performance is reduced by needing to boost the extra mass of the Star.  Assume that with no Star-48, the stack starts at 117t and ends at 11t.  But with the Star, it starts at 119t and ends at 13t.  At an ISP of 348, the extra mass then loses 348*9.8*(ln(117/11) - ln(119/13)) = 511 m/s.    So the net gain is only 809-511 = 298 m/s.

This is a pretty small faction of the 8000 m/s or so the second stage provides.  It's on the order of what a burn-to-depletion could provide, as opposed to a controlled shutdown.    But of course with a zillion dollar probe, they want to be sure they have the performance they need, not that it's merely likely.

It'll use the STAR-48BV variant which has an ISP of 292 (not 287), has a mass of 2164 kg when loaded and a mass of 138 kg when done (See the numbers for STAR-48BV in the NGIS Motor Catalog from June 2018).

So, the STAR-48BV will kick in a little more delta-V than you calculated.
Also, I suggest you try to refine your assumptions for FH stage 2 performance numbers a bit.
These changes, while sensible, make only trivial differences to the calculation.  For example, with a 6000 kg Clipper, the Star-48BV provides 292*9.8*l(8164/6138) = 816 m/s, just 8 m/s more than calculated above.

Yes, that's why I said "a little more".

Offline GreenShrike

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #27 on: 12/04/2018 06:34 pm »
Why do they no longer use larger kick stages like the STAR 62 or so? Should improve things a bit.

Lou's always fun -- he shows how to do the math. You don't even need a fancy calculator -- just copy/paste the equations into Google and you'll get the answer.  ;-)


From the NGIS catalog, a STAR 63D has an ISP of ~283s, a starting mass of ~3.5t and a burnout mass of ~230kg.

So with a 6000kg Clipper, the STAR 63D provides:

283*9.8*ln((6+3.5)/(6+0.23)) = 1170m/s

The second stage, on the other hand, loses:

348*9.8*(ln((111+6)/(5+6)) - ln((111+6+3.5)/(5+6+3.5))) = 840m/s

For a whopping net of 330m/s.

So you're looking at a <50m/s gain at a cost of a kick stage almost twice the size of a STAR 48 (and over half the mass of the payload)

Oh, and the STAR 63D doesn't provide thrust vector control (TVC) -- going from a STAR 48B to a 48BV adds 20-odd kilos, so if Clipper needs a kick with TVC, the benefit will be even lower.
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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #28 on: 12/04/2018 06:41 pm »
Why do they no longer use larger kick stages like the STAR 62 or so? Should improve things a bit.

Lou's always fun -- he shows how to do the math. You don't even need a fancy calculator -- just copy/paste the equations into Google and you'll get the answer.  ;-)


From the NGIS catalog, a STAR 63D has an ISP of ~283s, a starting mass of ~3.5t and a burnout mass of ~230kg.

So with a 6000kg Clipper, the STAR 63D provides:

283*9.8*ln((6+3.5)/(6+0.23)) = 1170m/s

The second stage, on the other hand, loses:

348*9.8*(ln((111+6)/(5+6)) - ln((111+6+3.5)/(5+6+3.5))) = 840m/s

For a whopping net of 330m/s.

So you're looking at a <50m/s gain at a cost of a kick stage almost twice the size of a STAR 48 (and over half the mass of the payload)

Oh, and the STAR 63D doesn't provide thrust vector control (TVC) -- going from a STAR 48B to a 48BV adds 20-odd kilos, so if Clipper needs a kick with TVC, the benefit will be even lower.


This.
The reason for STAR-48BV is the TVC system. A regular STAR-48 is spin stabilized, which requires the payload to de-spin after separation.
Europa Clipper is not designed to be inserted into orbit by spin-stabilized kick-stage. So, hence the need for TVC on the kick-stage. And that pretty much is how they got to STAR-48BV.

Offline GreenShrike

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #29 on: 12/04/2018 07:14 pm »
How many kg of payload does it add to a c3 of 85?

Per LSP, FH can lift 8230 kg to a c3 of 30, and 1810 kg to a c3 of 85.

A STAR 48BV doesn't, AFAICT. **

Given:

Payload 1.81t
STAR 48BV ISP 292s
STAR 48BV Mi 2.169t
STAR 48BV Mf .138t

The STAR would provide:

292*9.8*ln((1.81+2.169)/(1.81+0.138)) = ~2043m/s

However, the second stage loses:

348*9.8*(ln((111+1.81)/(5+1.81)) - ln((111+1.81+2.169)/(5+6+2.169))) = ~2184m/s

So you're looking at negative returns.


--------

**Edit -- Should actually be:

348*9.8*(ln((111+1.81)/(5+1.81)) - ln((111+1.81+2.169)/(5+1.81+2.169))) = 878m/s

For a positive return of 2043 - 878 = 1165m/s.


So apparently there are disadvantages to just plugging numbers into Google. ;-)

Ironically, I put together a spreadsheet for the below calc, but didn't bother going back to verify the above. <sigh>

--------

OTOH, if you drop the kick stage to a STAR 37GV...

Payload 1.81t
STAR 37GV ISP 293s
STAR 37GV Mi 1.087t
STAR 37GV Mf 0.104t

293*9.8*ln((1.81+1.087)/(1.81+0.104)) = ~1190m/s
348*9.8*(ln((111+1.81)/(5+1.81)) - ln((111+1.81+1.087)/(5+1.81+1.087))) = ~472m/s
1190 - 472 = 718m/s

...you get a decent amount of excess delta-V, so this kick stage is viable.


Upping the payload to 2.75t (chosen after some playing with figures ;-) ) gets you a kick of:

293*9.8*ln((2.75+1.087)/(2.75+0.104)) = ~849m/s

while sapping from the S2 (as compared against the 1.81t reference payload):

348*9.8*(ln((111+1.81)/(5+1.81)) - ln((111+2.75+1.087)/(5+2.75+1.087))) = ~827m/s

849 - 827 = 22m/s

So... maybe something a little under an additional tonne of payload?
« Last Edit: 12/05/2018 03:29 pm by GreenShrike »
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Online ncb1397

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #30 on: 12/04/2018 08:40 pm »
How many kg of payload does it add to a c3 of 85?

Per LSP, FH can lift 8230 kg to a c3 of 30, and 1810 kg to a c3 of 85.

A STAR 48BV doesn't, AFAICT.

Given:

Payload 1.81t
STAR 48BV ISP 292s
STAR 48BV Mi 2.169t
STAR 48BV Mf .138t

The STAR would provide:

292*9.8*ln((1.81+2.169)/(1.81+0.138)) = ~2043m/s

However, the second stage loses:

348*9.8*(ln((111+1.81)/(5+1.81)) - ln((111+1.81+2.169)/(5+6+2.169))) = ~2184m/s

So you're looking at negative returns.


Think there is an error in your math. Using Space Launch Reports estimates for the Falcon 9 stages[1]and Star 48 BV numbers above, I get a net positive effect of ~1 km/s for a 1.81 t payload (no throttle down on heavy, core stages stage nearly at the same time).

My work: https://docs.google.com/spreadsheets/d/1XOKLBwm_0IOSWe7KZtz-NOxOGpIVd0alH36YOX2T2zo/edit?usp=sharing

[1]http://www.spacelaunchreport.com/falcon9ft.html

As far as what that means in terms of kilograms to a C3. The total stack delta v without the kick stage at 1810 kg matches total stack delta v with the kick stage at about 3040 kg.

But I think Jupiter direct is more like a C3 of 80, not 85 (at least if you optimize launch timing for lower C3). Which according to the LSP performance query, Falcon Heavy can do 2195 kg to. That should mean about 3,340 kg with a Star 48 BV stage as that is about where stack delta v without the kick stage and 2195 kg of payload matches with it.
« Last Edit: 12/04/2018 09:22 pm by ncb1397 »

Offline 192

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #31 on: 12/04/2018 10:11 pm »
How many kg of payload does it add to a c3 of 85?

Per LSP, FH can lift 8230 kg to a c3 of 30, and 1810 kg to a c3 of 85.

A STAR 48BV doesn't, AFAICT.

Given:

Payload 1.81t
STAR 48BV ISP 292s
STAR 48BV Mi 2.169t
STAR 48BV Mf .138t

The STAR would provide:

292*9.8*ln((1.81+2.169)/(1.81+0.138)) = ~2043m/s

However, the second stage loses:

348*9.8*(ln((111+1.81)/(5+1.81)) - ln((111+1.81+2.169)/(5+6+2.169))) = ~2184m/s

So you're looking at negative returns.


Think there is an error in your math.

I think the final 6 in that equation should be a 1.81 (perhaps confused the theoretical c3 of 85 payload with Europa Clipper's nominal mass), payload shouldn't lose mass while second stage is burning. That gives a loss of ~ 878 m/s for a net gain of  ~ 1165 m/s

Online LouScheffer

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #32 on: 12/04/2018 11:14 pm »
It's not obvious to me why they need the Star-48 at all, if they are doing an Earth flyby.  Suppose they use a Juno-like strategy - Earth launch, deep space maneuver (DSM), Earth flyby, Jupiter.  According to the Ames trajectory browser, for launches in the 2020s, this requires a C3 of slightly less than 30 km^2/sec^2, and a deep space maneuver of about 7-800 m/s.    Juno used a similar trajectory with C3 = 31 and dV (deep space) of 730 m/s.

Now suppose a direct to Jupiter mission masses 6000 kg.  With the EEJ trajectory, you'll need enough extra fuel so that after the DSM the mass is 6000 kg.  How much extra fuel is needed?  For ISP=312 (as Juno), an 800 m/s manuever takes a mass ratio of exp(800/(312*9.8)) = 1.30.  So Clipper would need to start the DSM at 6000*1.30 = 7800 kg, finish at 6000 kg, then coast to Jupiter.

From the NASA LSP launch charts, FH expendable can put 8000 kg to a C3 of 30 km^2/sec^2, so this should be feasible.   All Clipper should need is larger tanks and it's ready to go.

So I can't see where using the Star-48 near Earth makes any sense.  If Clipper has enough dV for a DSM, it's not needed.  If not, then the place where they need the extra dV is in deep space.   So maybe they add a 2000 kg Star to a 6000 kg Clipper, then launch on a EEJ trajectory with Falcon Heavy.  Then the Star-48 performs the Deep Space Maneuver a year or so later.  It's just about the right size (800 m/s), so surely the trajectory can be adjusted to allow this.

The main question would seem to be whether the Star-48 is qualified to fire when fairly cold and after a year in space.  It would also explain why this was not an obvious solution.

 

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #33 on: 12/05/2018 12:09 am »
This discussion has been fascinating - I even understand some of the math! But seriously; can I assume that all iterations of Europa Clipper launched on Falcon Heavy would need a fully expendable FH, even with 1x Earth flyby?
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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #34 on: 12/05/2018 12:22 am »
Why do they no longer use larger kick stages like the STAR 62 or so? Should improve things a bit.

Lou's always fun -- he shows how to do the math. You don't even need a fancy calculator -- just copy/paste the equations into Google and you'll get the answer.  ;-)


From the NGIS catalog, a STAR 63D has an ISP of ~283s, a starting mass of ~3.5t and a burnout mass of ~230kg.

So with a 6000kg Clipper, the STAR 63D provides:

283*9.8*ln((6+3.5)/(6+0.23)) = 1170m/s

The second stage, on the other hand, loses:

348*9.8*(ln((111+6)/(5+6)) - ln((111+6+3.5)/(5+6+3.5))) = 840m/s

For a whopping net of 330m/s.

So you're looking at a <50m/s gain at a cost of a kick stage almost twice the size of a STAR 48 (and over half the mass of the payload)

Oh, and the STAR 63D doesn't provide thrust vector control (TVC) -- going from a STAR 48B to a 48BV adds 20-odd kilos, so if Clipper needs a kick with TVC, the benefit will be even lower.


This.
The reason for STAR-48BV is the TVC system. A regular STAR-48 is spin stabilized, which requires the payload to de-spin after separation.
Europa Clipper is not designed to be inserted into orbit by spin-stabilized kick-stage. So, hence the need for TVC on the kick-stage. And that pretty much is how they got to STAR-48BV.
There's a version of STAR-63 that has TVC. It has been tested (on the ground, at least).
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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #35 on: 12/05/2018 02:09 am »
This discussion has been fascinating - I even understand some of the math! But seriously; can I assume that all iterations of Europa Clipper launched on Falcon Heavy would need a fully expendable FH, even with 1x Earth flyby?
Yes, you need an expendable FH to get the performance needed.   From the NASA plot, FH recoverable (and I'm pretty sure this is still expending the center core, just recovering the two sides) can push 6000 kg to a C3 of about 5.  But for ANY trajectory to Jupiter, you need a C3 of at least 6-7 (since you need to reach some other planet to do a fly by, and Venus is the closest at C3 of 6-7 km^2/sec^2).   So not only can a FH recoverable not do the Earth-flyby trajectory, it can't do ANY trajectory to Jupiter with a 6000 kg payload.

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #36 on: 12/05/2018 12:00 pm »
ncb, you are assuming a 1.81 mT payload vs. Lou is using a 6mT payload. Which one is it?

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #37 on: 12/05/2018 12:36 pm »
ncb, you are assuming a 1.81 mT payload vs. Lou is using a 6mT payload. Which one is it?
From this JPL newsletter, the absolute maximum mass is 6001 kg.  A few hundred kg are being held in the project manager's reserve to solve unforseen issues.  So 5.8-6t will be the loaded launch mass.

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #38 on: 12/05/2018 02:07 pm »
A SPACEX DELIVERY CAPSULE MAY BE CONTAMINATING THE ISS

SARAH SCOLES SCIENCE 12.05.1807:00 AM

IN FEBRUARY 2017, a SpaceX Falcon 9 rocket lifted through low clouds, pushing a Dragon capsule toward orbit. Among the spare parts and food, an important piece of scientific cargo, called SAGE III, rumbled upward. Once installed on the International Space Station, SAGE would peer back and measure ozone molecules and aerosols in Earth’s atmosphere. Its older siblings (SAGEs I and II) had revealed both the growth of the gaping ozone hole and, after humans decided to stop spraying Freon everywhere, its subsequent recovery.

This third kid, then, had a lot to live up to. Like its environmentally conscious predecessors, SAGE III is super sensitive. Because it needs unpolluted conditions to operate optimally, it includes contamination sensors that keep an eye on whether and how its environment might be messing up its measurements. Those sensors soon came in handy: When the next three Dragons docked at the Space Station, over the following months, SAGE experienced unexplained spikes in contamination. Something on these Dragons was outgassing—releasing molecules beyond the expected, and perhaps the acceptable, levels. And those molecules were sticking to SAGE.

Outgassing, in earthly terms, is what makes a new car smell like a new car. “There are volatile chemicals in those new materials that migrate through the material to the surface," says Alan Tribble, author of Fundamentals of Contamination Control. You’re smelling escaped seat ingredients, in other words.

Outgassing also builds up as a greasy film on the inside of your new car’s windows—or the outside of your space station. This grime is mostly a problem for instruments that measure light, but it can also reduce solar panels’ efficiency and can make surfaces hotter than they’re supposed to be. To avoid all that, engineers build Space Station additions and satellites in clean rooms, use only prequalified materials, bake out contaminants before launch, and set strict limits on how much proverbial new-car smell a craft can release. “It’s an intense process and considered extremely critical,” says Meg Abraham of the Aerospace Corporation, which consults on a number of space projects. “Everyone thinks about this.”

https://www.wired.com/story/a-spacex-delivery-capsule-may-be-contaminating-the-iss/

Offline Brovane

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Re: General Falcon and Dragon discussion (Thread 15)
« Reply #39 on: 12/05/2018 02:23 pm »
To bad the story about out-gassing on the Dragon hadn't been known a couple of days earlier.  Would like to have seen the response to questions on this from NASA and SpaceX at the CRS-16 press conference. 
"Look at that! If anybody ever said, "you'll be sitting in a spacecraft naked with a 134-pound backpack on your knees charging it", I'd have said "Aw, get serious". - John Young - Apollo-16

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