Space Shuttle Return To Flight

[Paratus]

Since return to flight still looks to be around mid-July, I though some of you might have questions about the Shuttle or ISS. I'm a flight controller for the ISS and wouldn't mind answering a few as time permits. (Crazy work hours and 2 young kids kinda puts a damper on posting at AT)

So if you have any post em here.


UPDATE 7/11
Launch Clock is running - currently scheduled for 3:51 p.m. EDT July 13.

UPDATE 7/12
Only risk for tomorrows launch is the weather.

UPDATE 7/13
Scrubbed for today due to a faulty sensor
Link

Well now I don't have to go in tonight.

UPDATE 7/22
Really looks like Tuesday 26th is the day. Launch will be around 9:30, if all goes well.
The launch time rolls back abot 23 minutes each day due to the vagaries of orbital mechanics.

UPDATE 7/26
Launch Day - 23 minutes on the official lauch clock (that does not include holds) so a little over an hour left to go. We'll see if the weather holds out.


- 9.00 minute hold


- Beautiful launch Great rocketcam footage

now I have to work the next 10 days.

UPDATE 7/30 FD-5
EVA1 is under way - got started a little late - The mission has been going well regardless of what you may have heard from the press. Shuttles are always "grounded" between flights until every anomaly from the previous flight has been understood with. If the next flight flies within 6 months I don't think many of the flight controllers will be suprised. There actually aren't that many good launch days left this year so we were expecting a delay anyway.

Discovery has seen a lot less tile hits than most other shuttles, so some the foam fixes worked. The large chunk that came off was from an area that was not changed since the last flight since they had little indications from previous flights that it was a problem. So I'm hopeful they can apply some the fixes used elsewhere to take care of it in a reasonable time frame.

 

[dmcowen674]

Originally posted by: Paratus
Since return to flight still looks to be around mid-July, I though some of you might have questions about the Shuttle or ISS. I'm a flight controller for the ISS and wouldn't mind answering a few as time permits. (Crazy work hours and 2 young kids kinda puts a damper on posting at AT)

So if you have any post em here.
Paratus

Thanks for the offer.

I've seen articles that there is no way the last of the Shuttle fleet (I would hardly call 3 orbiters a fleet) cannot get the remaining parts of the ISS up there.

Also kept hearing problems with Oxygen generator, has that been fixed?

 

[Armitage]

Cool!
How much emphasis do you put on Collision Avoidance (CA) analysis for ISS?
Do you do it in-house, or get it from Cheyenne Mt.?
Do you reserve any amount of dV for CA contingencies?

 

[Paratus]

Originally posted by: dmcowen674

Originally posted by: Paratus
Since return to flight still looks to be around mid-July, I though some of you might have questions about the Shuttle or ISS. I'm a flight controller for the ISS and wouldn't mind answering a few as time permits. (Crazy work hours and 2 young kids kinda puts a damper on posting at AT)

So if you have any post em here.
Paratus

Thanks for the offer.

I've seen articles that there is no way the last of the Shuttle fleet (I would hardly call 3 orbiters a fleet) cannot get the remaining parts of the ISS up there.

Also kept hearing problems with Oxygen generator, has that been fixed?

Well each one of the shuttles is capable of carrying any of the major payloads. So there is no reason technically that we can't finish the station. The question obviously is can we complete the ISS before our self-imposed 2010 deadline. Maybe, Maybe not. Depends on how well return to flight works out. We actually are only 8 flights from US Core complete or about two years once we start flying. The internation partner moduleswill take a lot of flights however.


I could tell you whether the Elektron (Russian built O2 generator) was working or not but by the time I did it would have changed. It's really finicky (sp?). But with the large internal volume the crew doesn't need it on 24-7. We actually have a lot of different sources of O2. The Russians have about 1-2 month supply of "candles" they can burn to release O2. (They aren't really candles but look a little like one and they give off O2 and a lot of heat in an exothermic reaction.) Plus they send up O2 tanks on each russian Progress resupply flight and we have several high pressure O2 tanks on the US side. So there's enough O2 for several months even with out the generator.

We're currently working on a US regenerative O2 system to launch in the next couple of years as a backup.

 

[Paratus]

Originally posted by: Armitage
Cool!
How much emphasis do you put on Collision Avoidance (CA) analysis for ISS?
Do you do it in-house, or get it from Cheyenne Mt.?
Do you reserve any amount of dV for CA contingencies?

We talk to the guys at Cheyenne Mt. They let us know if anthing is coming our way. We then work with the Russian (they have the thrusters) to manuver out of the way.

For small stuff the US side has shielding that should protect the inner hull. But for particles bigger than that but smaller than radar can pick up we take our chances and handle it procedurely. We have patches and procedures in place for station leaks and in the worst case the crew will bail out in the Soyuz.

The russians always keep us above a minimum fuel level for reboosts and contingency manuvers so yes we have a reserve. The tanks get refueled from russian Progress flights.

 

[Armitage]

Originally posted by: Paratus

Originally posted by: Armitage
Cool!
How much emphasis do you put on Collision Avoidance (CA) analysis for ISS?
Do you do it in-house, or get it from Cheyenne Mt.?
Do you reserve any amount of dV for CA contingencies?

We talk to the guys at Cheyenne Mt. They let us know if anthing is coming our way. We then work with the Russian (they have the thrusters) to manuver out of the way.

For small stuff the US side has shielding that should protect the inner hull. But for particles bigger than that but smaller than radar can pick up we take our chances and handle it procedurely. We have patches and procedures in place for station leaks and in the worst case the crew will bail out in the Soyuz.

The russians always keep us above a minimum fuel level for reboosts and contingency manuvers so yes we have a reserve. The tanks get refueled from russian Progress flights.

Thanks
Is your manuever threshold strictly miss-distance based, or do you have probability of collision to work with as well? Last I heard, COMBO could only give you miss distance.

 

[Gibsons]

They aren't really candles but look a little like one and they give off O2 and a lot of heat in an exothermic reaction.

What reaction is this, do you know what they're made of?

 

[CycloWizard]

Not necessarily related, but what happened to the idea of the 'space plane' replacing the space shuttle? I read about this probably 10 years ago and haven't heard about it since then.

 

[Paratus]

Originally posted by: Armitage

Originally posted by: Paratus

Originally posted by: Armitage
Cool!
How much emphasis do you put on Collision Avoidance (CA) analysis for ISS?
Do you do it in-house, or get it from Cheyenne Mt.?
Do you reserve any amount of dV for CA contingencies?

We talk to the guys at Cheyenne Mt. They let us know if anthing is coming our way. We then work with the Russian (they have the thrusters) to manuver out of the way.

For small stuff the US side has shielding that should protect the inner hull. But for particles bigger than that but smaller than radar can pick up we take our chances and handle it procedurely. We have patches and procedures in place for station leaks and in the worst case the crew will bail out in the Soyuz.

The russians always keep us above a minimum fuel level for reboosts and contingency manuvers so yes we have a reserve. The tanks get refueled from russian Progress flights.

Thanks
Is your manuever threshold strictly miss-distance based, or do you have probability of collision to work with as well? Last I heard, COMBO could only give you miss distance.

As far as I know we only use miss distance but I'm a power guy not a trajectory officer.

 

[Paratus]

Originally posted by: Gibsons

They aren't really candles but look a little like one and they give off O2 and a lot of heat in an exothermic reaction.

What reaction is this, do you know what they're made of?

Not sure as I'm a power guy not a lifesupport guy.

 

[Paratus]

Originally posted by: CycloWizard
Not necessarily related, but what happened to the idea of the 'space plane' replacing the space shuttle? I read about this probably 10 years ago and haven't heard about it since then.

Well back around 88 to 90 they started work on the National Aerospace Plane. That one fell through because it was technically out of reach. Later they worked on the X-33 which was a sub-orbital test bed for a single stage to orbit vehicle that could dock at the ISS. It failed because they couldn't design and fabricate light enough composite fuel tanks without them rupturing. So most of the SSTO designs have fallen through.

 

[Armitage]

Originally posted by: Paratus

Originally posted by: Armitage

Originally posted by: Paratus

Originally posted by: Armitage
Cool!
How much emphasis do you put on Collision Avoidance (CA) analysis for ISS?
Do you do it in-house, or get it from Cheyenne Mt.?
Do you reserve any amount of dV for CA contingencies?

We talk to the guys at Cheyenne Mt. They let us know if anthing is coming our way. We then work with the Russian (they have the thrusters) to manuver out of the way.

For small stuff the US side has shielding that should protect the inner hull. But for particles bigger than that but smaller than radar can pick up we take our chances and handle it procedurely. We have patches and procedures in place for station leaks and in the worst case the crew will bail out in the Soyuz.

The russians always keep us above a minimum fuel level for reboosts and contingency manuvers so yes we have a reserve. The tanks get refueled from russian Progress flights.

Thanks
Is your manuever threshold strictly miss-distance based, or do you have probability of collision to work with as well? Last I heard, COMBO could only give you miss distance.

As far as I know we only use miss distance but I'm a power guy not a trajectory officer.

Ok - just curious. In general, miss distance alone isn't a good predictor of collision risk. I know the miss distance bounds that you use are conservative enough - I've seen some papers on it. But taking a probability based approach may reduce your manuever rate for stuff that comes inside the box.

Do you have any idea how often you manuever based on collision threats?

 

[Paratus]

It's not very often. Maybe 1-3 times a year, if that. I think I've been on console when one was coming up maybe twice in the last two years.

You sound like you've got a bit of orbital debris knowledge yourself.

 

[Armitage]

Originally posted by: Paratus
It's not very often. Maybe 1-3 times a year, if that. I think I've been on console when one was coming up maybe twice in the last two years.

Wow, that's less then I expected, though I haven't done much work in LEO.

You sound like you've got a bit of orbital debris knowledge yourself.

Yea, I've done quite a bit of it. Though more collision avoidance then orbital debris - ie., I'm more interested in anything that might run into anything else - not so interested in what the debris population itself looks like. We do have some people that look at it from the longer term/bigger picture side as well.

It's been kind of a banner year in the field so far - two new on-orbit collisions identified, though one is historical (1991). Brings the total to 3.

I've been working on an algorithm to do the screening much faster then anybody can do it right now (AFAIK). It looks like you've got a close one coming up Wed. morning 😉

 

[Paratus]

Interesting sounds like it I'll have some good uses. Any chance they might use it for RTF. I know they are going to be watching orbital debris like a hawk once the shuttle is back in use.

 

[Armitage]

Originally posted by: Paratus
Interesting sounds like it I'll have some good uses. Any chance they might use it for RTF. I know they are going to be watching orbital debris like a hawk once the shuttle is back in use.

Not right away. It's still very beta & needs alot of V&V. We've had some discussions with some NASA folks, but not in manned arena.

The space surveillance community is incredibly political - it's very difficult to get a foot in the door with something like this. And you have to because they have the good data. TLE data is crap for this sort of thing.

Interesting bit inspired by the shuttle - I'm considering setting up my algorithm to screen for conjunctions a few days in the past as well as in the future - that might have detected the separation of the piece of debris from Columbia prior to reentry. Assuming they had generated an elset on it right away instead of after the fact :disgust:

 

[Paratus]

Originally posted by: Armitage

Originally posted by: Paratus
Interesting sounds like it I'll have some good uses. Any chance they might use it for RTF. I know they are going to be watching orbital debris like a hawk once the shuttle is back in use.

Not right away. It's still very beta & needs alot of V&V. We've had some discussions with some NASA folks, but not in manned arena.

The space surveillance community is incredibly political - it's very difficult to get a foot in the door with something like this. And you have to because they have the good data. TLE data is crap for this sort of thing.

Interesting bit inspired by the shuttle - I'm considering setting up my algorithm to screen for conjunctions a few days in the past as well as in the future - that might have detected the separation of the piece of debris from Columbia prior to reentry. Assuming they had generated an elset on it right away instead of after the fact :disgust:

Great idea!

 

[Armitage]

Originally posted by: Armitage

Originally posted by: Paratus
It's not very often. Maybe 1-3 times a year, if that. I think I've been on console when one was coming up maybe twice in the last two years.

Wow, that's less then I expected, though I haven't done much work in LEO.

You sound like you've got a bit of orbital debris knowledge yourself.

Yea, I've done quite a bit of it. Though more collision avoidance then orbital debris - ie., I'm more interested in anything that might run into anything else - not so interested in what the debris population itself looks like. We do have some people that look at it from the longer term/bigger picture side as well.

It's been kind of a banner year in the field so far - two new on-orbit collisions identified, though one is historical (1991). Brings the total to 3.

I've been working on an algorithm to do the screening much faster then anybody can do it right now (AFAIK). It looks like you've got a close one coming up Wed. morning 😉

Nevermind - it went away with newer data.

 

[Paratus]

Updated First Post

 

[everman]

I have a question since you say that you are a "power guy". Regarding the fuel cells used on the shuttle, have there been many significant advances made in that area in the past few years, and are any new things comming in the near future? I recently read that GM has made great advances in that area, hopefully bringing hydrogen fuel cell powered vehicles in the next 15yrs.

Thanks, it's always nice to talk to someone on the inside 🙂

 

[Paratus]

Originally posted by: everman
I have a question since you say that you are a "power guy". Regarding the fuel cells used on the shuttle, have there been many significant advances made in that area in the past few years, and are any new things comming in the near future? I recently read that GM has made great advances in that area, hopefully bringing hydrogen fuel cell powered vehicles in the next 15yrs.

Thanks, it's always nice to talk to someone on the inside 🙂

Launch scrubbed see top



Well I'm more of a Solar Array guy since I work power on the station but as far as I know there have only been incremental imporvements made to the shuttle fuel cells.

Remember making any changes to any system on board the shuttle is a major hassle so they try not to do it. I know they were looking into long duration fuel cells a few years ago, but in this case long duration means long duration before over haul and maintenance.

 

[The Boston Dangler]

What kind of deflection does a solar panel produce with temp changes? Are the roll-up type of panels used, or the rigid panels?

Is it likely a tether will be used any time soon. I'm referring to the 13 mile long American/Italian tether deployed from a shuttle years ago. It made so much juice, it cooked.

 

[Paratus]

Originally posted by: The Boston Dangler
What kind of deflection does a solar panel produce with temp changes? Are the roll-up type of panels used, or the rigid panels?

Is it likely a tether will be used any time soon. I'm referring to the 13 mile long American/Italian tether deployed from a shuttle years ago. It made so much juice, it cooked.

Sorry about just getting back to you,

It's funny that you should ask that as we have Boeing (our engineering support folks) analyzing that right now. We expect at assembly complete that the tips could flex several feet.

Currently we proceduraly avoid shadowing 1 longeron (4 of them run the length of the mast) for long periods of time to prevent buckling due to the uneven forces. If we're rotating then it's not a problem because the shadowing is relatively short.

The panels fold up from about 120 feet to around 6 inches.

We have no current plans to fly a tether again because other things have priority right now (not that it wouldn't be a good idea to try again). Money and shuttle flights are tight right now.

Hope that helps! 🙂

 

[unipidity]

Doesnt a tether just use KE already generated, ie a power converter, not a source? In which case is it going to be vastly more efficient of simple than a fuel cell?

 

[Armitage]

Originally posted by: unipidity
Doesnt a tether just use KE already generated, ie a power converter, not a source?

Yes, anyt energy you get from a tether comes out of your orbital energy.

In which case is it going to be vastly more efficient of simple than a fuel cell?

Tether dynamics are pretty freaky and there is alot of concern about them in the debris community.