Super Draco and ground operations.

[Adaptation]

Wikipedia notes that the super Draco uses nitrogen tetroxide / monomethyl hydrazine.  I know that the shuttle also had such fuel for thrusters but I was under the assumption that they depleted the propellant before they entered orbit but still men in bunny suits and lengthy procedures where applied before they would extricate the passengers. 

I would imagine more onerous precautions and restrictions would be placed on soft landing dragons as it they are burning the hydrazine in the atmosphere near the surface.

How large do you think the exclusion zone around the landing site would be? 

Would the dragon be prohibited from preforming non emergency landings under windy conditions to prevent the spread of hydrazine vapors. 

Are returning passengers going to be in space suits, would the suits they use provide protection from hydrazine or will they have to wait for the bunny guys give the all clear? 

When they test fire hydrazine engines what sorts of precautions are taken?

[Jim]

Bunny suits are for clean rooms and have nothing to with propellants.
SCAPE or PHE's are used for propellant ops.
And no, SCAPE or PHE's were not needed for nominal shuttle landings.  Only gas masks were worn by those tested the nearby environment before giving the all clear.

Shuttle did not completely empty its tanks nor will Dragon be able to since there will be a reserve at landing.  Hence precautions will have to taken

[Dudely]

It should also be noted that the fuel is the same as the one used by the regular draco thrusters. It just burns it 200x faster. So they are familiar with handling it already.

[AJA]

Shuttle did not completely empty its tanks nor will Dragon be able to since there will be a reserve at landing.

Can't they burn it off AFTER landing though? +X and -X to depletion, followed by +Y and -Y to depletion. Since you're firing only half your thrusters at any instant, you won't lift off.. and since you're firing opposite ones, you won't have any moment arms that might tip the capsule over.

What did they do with the shuttle reserves? Also, do the tanks need to be refurbished between flights? Were the shuttle's? (Given the much talked about corrosive nature of hypergols)

[Dudely]

Shuttle did not completely empty its tanks nor will Dragon be able to since there will be a reserve at landing.

Can't they burn it off AFTER landing though? +X and -X to depletion, followed by +Y and -Y to depletion. Since you're firing only half your thrusters at any instant, you won't lift off.. and since you're firing opposite ones, you won't have any moment arms that might tip the capsule over.

What did they do with the shuttle reserves? Also, do the tanks need to be refurbished between flights? Were the shuttle's? (Given the much talked about corrosive nature of hypergols)

Burning to depletion sounds a lot riskier than handling a bit of toxic fuel. Presumably they'd like to reuse them. The combustion instability that burning to depletion would cause would likely not help this endeavor.

[Roy_H]

I cannot believe they would use such dangerous chemicals near the ground. It would make much more sense to me if the Super Draco was methane/Lox but pressure fed instead of Raptor's staged combustion.

How reliable is the information? Is is just an assumption that the same fuel is used in the Super Draco as the standard Draco?

[docmordrid]

The Dracos and SuperDracos use the same tanks, and the Environmental Impact Statement for the pad abort test says the load is increased from 1290 kg to 1688 kg.

[docmordrid]

SpaceX Dragon CCiCAP landings: 'chutes & rockets:

[Roy_H]

Recent FAA Report cites NTO/MMH for crewed dragon.

From March 5th 2014. Page 8, 2nd paragraph:

http://www.faa.gov/about/office_org/headquarters_offices/ast/environmental/nepa_docs/review/launch/media/fonsi_dragon_pad_abort.pdf

Interesting reading but not conclusive. I am not a chemist, and I tried to find more information:

Monomethylhydrazine (MMH) CH₆N₂
Dinitrogen tetroxide (NTO) N₂O₄

Reaction products: H₂O, N₂, NO₂, N₂O₂, NO₃, HNO₃, HNO₂, OH, CO₂, O₂,
and to small extents  NO, CH₃NO, HNO, CH₄, H₂,
 
NO₂ poisoning symptoms - Eye redness, eye pain, eye burns, skin irritation, skin burns ...

N₂O₂, no info

NO₃ Nitrate toxicosis can occur through enterohepatic metabolism of nitrate to nitrite being an intermediate.[2] Nitrites oxidize the iron atoms in hemoglobin from ferrous iron (2+) to ferric iron (3+), rendering it unable to carry oxygen.[3] This process can lead to generalized lack of oxygen in organ tissue and a dangerous condition called methemoglobinemia.

HNO₃ Nitric Acid classed as poison, symptoms Bluish colored lips and fingernails, choking, coughing up blood, dizziness ...

HNO₂ Nitrous Acid, no info

So somewhat inconclusive. I tried to arrange the reaction products in order of quantity and note that the first two, water and nitrogen, both benign, make up about 70%. I do find it strange that the FAA safety report on the Dragon Pad Abort test made no mention of any of these reaction products. It did acknowledge that MMH/NTO was loaded into tanks and precautions were taken, but when discussing exhaust fumes comparisons were made to the F9 and the implication was that the chemical make up was identical. This suggests to me that the Super Dracos run on RP1/LOX.

[Roy_H]

SpaceX Dragon CCiCAP landings: 'chutes & rockets:

Thanks for the video. OT but in most discussions I have read, people have insisted that the Dragon would land propulsively only and not use parachutes. This video clearly shows both being used, which makes a lot of sense to me. The obvious argument against is the precision of landing, to land accurately, the parachutes would have to be released long before final touchdown.

[docmordrid]

AIUI the chutes & rockets approach will be used initially while SpaceX evolves a totally propulsive landing.

And I have seen zero anout SuperDraco using RP-1/LOX. The only props I've seen mentioned by SpaceX have been the hypergolics, which store better in space and need no ignition system.

There was speculation 2 years ago about  NOFBx (a nitrous oxide + C2 hydrocarbon blend).  Most of that speculation was driven by a pic of Dragon on Firestar Technologies site.

[Lars_J]

So somewhat inconclusive. I tried to arrange the reaction products in order of quantity and note that the first two, water and nitrogen, both benign, make up about 70%. I do find it strange that the FAA safety report on the Dragon Pad Abort test made no mention of any of these reaction products. It did acknowledge that MMH/NTO was loaded into tanks and precautions were taken, but when discussing exhaust fumes comparisons were made to the F9 and the implication was that the chemical make up was identical. This suggests to me that the Super Dracos run on RP1/LOX.

You are incorrect.

[sublimemarsupial]

Recent FAA Report cites NTO/MMH for crewed dragon.

From March 5th 2014. Page 8, 2nd paragraph:

http://www.faa.gov/about/office_org/headquarters_offices/ast/environmental/nepa_docs/review/launch/media/fonsi_dragon_pad_abort.pdf

Interesting reading but not conclusive. I am not a chemist, and I tried to find more information:

Monomethylhydrazine (MMH) CH₆N₂
Dinitrogen tetroxide (NTO) N₂O₄

Reaction products: H₂O, N₂, NO₂, N₂O₂, NO₃, HNO₃, HNO₂, OH, CO₂, O₂,
and to small extents  NO, CH₃NO, HNO, CH₄, H₂,
 
NO₂ poisoning symptoms - Eye redness, eye pain, eye burns, skin irritation, skin burns ...

N₂O₂, no info

NO₃ Nitrate toxicosis can occur through enterohepatic metabolism of nitrate to nitrite being an intermediate.[2] Nitrites oxidize the iron atoms in hemoglobin from ferrous iron (2+) to ferric iron (3+), rendering it unable to carry oxygen.[3] This process can lead to generalized lack of oxygen in organ tissue and a dangerous condition called methemoglobinemia.

HNO₃ Nitric Acid classed as poison, symptoms Bluish colored lips and fingernails, choking, coughing up blood, dizziness ...

HNO₂ Nitrous Acid, no info

So somewhat inconclusive. I tried to arrange the reaction products in order of quantity and note that the first two, water and nitrogen, both benign, make up about 70%. I do find it strange that the FAA safety report on the Dragon Pad Abort test made no mention of any of these reaction products. It did acknowledge that MMH/NTO was loaded into tanks and precautions were taken, but when discussing exhaust fumes comparisons were made to the F9 and the implication was that the chemical make up was identical. This suggests to me that the Super Dracos run on RP1/LOX.

Superdraco is most definitely MMH-NTO, just like the regular Dracos.

See this video of a Superdraco test (there is an M1D test first, then the superdraco test at 1:00 or so):

You can see the characteristic red MMH plume at 1:03 or so. For comparison check out the Bantam engine (which is also MMH-NTO) here:

[hrissan]

Recent FAA Report cites NTO/MMH for crewed dragon.

From March 5th 2014. Page 8, 2nd paragraph:

http://www.faa.gov/about/office_org/headquarters_offices/ast/environmental/nepa_docs/review/launch/media/fonsi_dragon_pad_abort.pdf

Interesting reading but not conclusive. I am not a chemist, and I tried to find more information:

Monomethylhydrazine (MMH) CH₆N₂
Dinitrogen tetroxide (NTO) N₂O₄

Reaction products: H₂O, N₂, NO₂, N₂O₂, NO₃, HNO₃, HNO₂, OH, CO₂, O₂,
and to small extents  NO, CH₃NO, HNO, CH₄, H₂,
 
NO₂ poisoning symptoms - Eye redness, eye pain, eye burns, skin irritation, skin burns ...

N₂O₂, no info

NO₃ Nitrate toxicosis can occur through enterohepatic metabolism of nitrate to nitrite being an intermediate.[2] Nitrites oxidize the iron atoms in hemoglobin from ferrous iron (2+) to ferric iron (3+), rendering it unable to carry oxygen.[3] This process can lead to generalized lack of oxygen in organ tissue and a dangerous condition called methemoglobinemia.

HNO₃ Nitric Acid classed as poison, symptoms Bluish colored lips and fingernails, choking, coughing up blood, dizziness ...

HNO₂ Nitrous Acid, no info

So somewhat inconclusive. I tried to arrange the reaction products in order of quantity and note that the first two, water and nitrogen, both benign, make up about 70%. I do find it strange that the FAA safety report on the Dragon Pad Abort test made no mention of any of these reaction products. It did acknowledge that MMH/NTO was loaded into tanks and precautions were taken, but when discussing exhaust fumes comparisons were made to the F9 and the implication was that the chemical make up was identical. This suggests to me that the Super Dracos run on RP1/LOX.

Just imagine how much of this stuff is released when the Proton rocket is launched! Ye, it's dangerous, but I bet the pad workers get less per year poisoning than workers on an average chemical plant...

And SuperDracos are abort engines, they are not going to be used every time, everyone hopes they will never be actually used after the pair of tests.

[Jim]

So somewhat inconclusive. I tried to arrange the reaction products in order of quantity and note that the first two, water and nitrogen, both benign, make up about 70%. I do find it strange that the FAA safety report on the Dragon Pad Abort test made no mention of any of these reaction products. It did acknowledge that MMH/NTO was loaded into tanks and precautions were taken, but when discussing exhaust fumes comparisons were made to the F9 and the implication was that the chemical make up was identical. This suggests to me that the Super Dracos run on RP1/LOX.

Just bad documentation.

[sublimemarsupial]

And SuperDracos are abort engines, they are not going to be used every time, everyone hopes they will never be actually used after the pair of tests.

Dragon also will use them for propulsive landing, so they'll be used on every flight regardless of whether there is an abort.

[hrissan]

And SuperDracos are abort engines, they are not going to be used every time, everyone hopes they will never be actually used after the pair of tests.

Dragon also will use them for propulsive landing, so they'll be used on every flight regardless of whether there is an abort.

Good point... Forgot about landing.

Looked through russian papers regarding Proton exhaust... They claim that the Proton exhaust is a bit less toxic than Soyuz's. And they both are much less toxic than shuttle's SRBs exhaust...

[butters]

It should be noted that, in addition to NTO/MMH thrusters, Shuttle also had hydrazine monopropellant APUs for hydraulic power and an ammonia boiler for cooling. Both of these systems remained active after wheel stop and contributed to the precautions taken by the SCAPE crew.

Dragon wouldn't *intentionally* release hazardous substances after landing, however it will take a few minutes at least for the SuperDraco exhaust to dissipate after landing, and there may be some risk of anomalous propellant leakage, both of which may require monitoring before passenger egress.

Because Dragon will be landing on a fairly precise target, it may be feasible to install monitoring equipment at the landing pad if that helps to streamline operations.