Author Topic: DIRECT v2.0 - Thread 2  (Read 1356690 times)

Offline Kaputnik

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Re: DIRECT v2.0 - Thread 2
« Reply #3660 on: 12/26/2008 06:23 pm »
Actually, this is an interesting discussion. How far, and in what depth, should DIRECT plan?

I can see an argument in favour of keeping things simple: a single, simple message "Build a single vehicle which can reuse existing facilities, to save lots of money, and use some of that money to fly it often enough to offset any performance losses."

However I can also see the argument in favour of a more expansive approach- e.g. trying to get the space science crowd onboard with the promise of cheap heavy lift.
"I don't care what anything was DESIGNED to do, I care about what it CAN do"- Gene Kranz

Offline Fequalsma

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Re: DIRECT v2.0 - Thread 2
« Reply #3661 on: 12/26/2008 07:03 pm »
Chuck, Ross -

Did you ever use INTROS or a similar "NASA-approved" tool to size the J-232 EDS?  I would assume that the result would be heavier than a stage sized with the industry-provided tools you describe.  This would be an interesting comparison between the NASA- and industry-sized stages.  Also, did the system close with the heavier EDS?

F=ma

Offline marsavian

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Re: DIRECT v2.0 - Thread 2
« Reply #3662 on: 12/27/2008 01:15 am »
Is there an EDS backup option up DIRECT's sleeve? So that if/when NASA shoot down the numbers, you can fall back to something more robust. Even if that means accepting a performance hit.
In fact, IMHO, since the lunar mission requirements were essentially arbitary, there ought be nothing wrong with proposing a scaled down lunar mission if the cost is reduced appropriately. The whole point of DIRECT is about having a 'sweet spot' where we are tied into a certain performance level by the infrastructure and hardware that already exists. If that sweet spot can only support 3 men on the surface rather than four, but costs less than 75% as much, then what's the problem?

They can stretch the first stage tank and use 5-seg SRBs.
« Last Edit: 12/27/2008 11:27 am by marsavian »

Offline HIP2BSQRE

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Re: DIRECT v2.0 - Thread 2
« Reply #3663 on: 12/27/2008 02:58 am »
Actually, this is an interesting discussion. How far, and in what depth, should DIRECT plan?

I can see an argument in favour of keeping things simple: a single, simple message "Build a single vehicle which can reuse existing facilities, to save lots of money, and use some of that money to fly it often enough to offset any performance losses."

However I can also see the argument in favour of a more expansive approach- e.g. trying to get the space science crowd onboard with the promise of cheap heavy lift.

You have to remember that Direct is being addressed to differant audiances.  The Direct team has to be ready.  Direct will face techinical questions from NASA, but it has also got to answer the political questions eg workforce, cost, substainbility, how does it affect other stakeholders, etc.

Offline alexterrell

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Re: DIRECT v2.0 - Thread 2
« Reply #3664 on: 12/27/2008 10:40 am »
Is there an EDS backup option up DIRECT's sleeve? So that if/when NASA shoot down the numbers, you can fall back to something more robust. Even if that means accepting a performance hit.
In fact, IMHO, since the lunar mission requirements were essentially arbitary, there ought be nothing wrong with proposing a scaled down lunar mission if the cost is reduced appropriately.

But part of the attraction of DIRECT is that it can launch the currently planned hardware items like Orion and Altair, where as the Ares 1 can't.

Getting rid of Ares 1 and Ares V will be difficult for NASA, even if it's a no-brainer to everyone else. Getting rid of Orion will be an even harder sell.

Offline alexterrell

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Re: DIRECT v2.0 - Thread 2
« Reply #3665 on: 12/27/2008 10:51 am »
Keep in mind that the maximum number of Jupiter launches per year is limited, (16 to 22, IIRC?), without incurring huge additional infrastructure costs.  Better to use them for the big payloads that can't be easily sub-divided. Propellant can be.

Also, drastically increasing the flight rate of smaller launchers, and encouraging the development of new, cheaper launchers, can only reduce the cost to orbit for everyone else.

Do you have a reference which identifies the capacity constraints?

If NASA (Jupiter supply division) were a commercial organisation and someone (like NASA Exploration division) wanted to pay for 40 flights per year, could it be done? What might prevent it?

Increasing flight rates is the main argument for EELV (including Falcon) over DIRECTs. What would Spacex bid to deliver 300 tons per year to LEO over three years? What about 1,250 tons (a F9-H per week)? Or 9,000 tons (a daily F9-H launch).

Offline Mark S

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Re: DIRECT v2.0 - Thread 2
« Reply #3666 on: 12/27/2008 01:28 pm »
Is there an EDS backup option up DIRECT's sleeve? So that if/when NASA shoot down the numbers, you can fall back to something more robust. Even if that means accepting a performance hit.
In fact, IMHO, since the lunar mission requirements were essentially arbitary, there ought be nothing wrong with proposing a scaled down lunar mission if the cost is reduced appropriately.

But part of the attraction of DIRECT is that it can launch the currently planned hardware items like Orion and Altair, where as the Ares 1 can't.

Getting rid of Ares 1 and Ares V will be difficult for NASA, even if it's a no-brainer to everyone else. Getting rid of Orion will be an even harder sell.

No one wants to get rid of Orion.  In fact, one of the biggest criticisms of Ares-I is that its limited lift capacity has been adversely affecting development of Orion.  Switching launchers from Ares-I to Jupiter-120 will allow the Orion team to restore a lot of functionality that was dropped due to problems with Ares-I.  Little things like landing on land instead of in the ocean.

Mark S.

Offline Lancer525

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Re: DIRECT v2.0 - Thread 2
« Reply #3667 on: 12/27/2008 02:48 pm »

No one wants to get rid of Orion.  In fact, one of the biggest criticisms of Ares-I is that its limited lift capacity has been adversely affecting development of Orion.  Switching launchers from Ares-I to Jupiter-120 will allow the Orion team to restore a lot of functionality that was dropped due to problems with Ares-I.  Little things like landing on land instead of in the ocean.

 Given that Orion is pretty much the way to go, one would think that this argument alone would be the one that would tip the scales, so that means that there is some other reason, one the general public is unaware of, one that has been held closely, and one that if it got out, would cause serious problems, there has to be some other reason why limiting Orion is being permitted, and why there is such a push to "stay the course."

Haven't we learned anything over the last 8 years? 20 years? 30 years? 50 years?
"For some inexplicable reason, everyone seems to want to avoid simple schemes."   -John Houbolt

Offline TrueBlueWitt

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Re: DIRECT v2.0 - Thread 2
« Reply #3668 on: 12/27/2008 04:30 pm »
Is it just me.. or does this SSME based Ares V with smaller tank and 5-seg sound more and more like some early "heavy" variants of DIRECT?

For all those DIRECT "nay-sayers"(Griffin's groupies?) on this board..

How many real design issues with Ares/Orion(many that have forced NASA to change design direction.. for example: Base Heating)..  were brought up on this board as issues(by the DIRECT team).. and solutions already incorporated into DIRECT.. well before the issues were fully addressed by NASA?
« Last Edit: 12/27/2008 04:31 pm by TrueBlueWitt »

Offline kneecaps

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Re: DIRECT v2.0 - Thread 2
« Reply #3669 on: 12/27/2008 04:45 pm »
Is it just me.. or does this SSME based Ares V with smaller tank and 5-seg sound more and more like some early "heavy" variants of DIRECT?

For all those DIRECT "nay-sayers"(Griffin's groupies?) on this board..

How many real design issues with Ares/Orion(many that have forced NASA to change design direction.. for example: Base Heating)..  were brought up on this board as issues(by the DIRECT team).. and solutions already incorporated into DIRECT.. well before the issues were fully addressed by NASA?

It is taking on a more Direct-esq feel. However, hold your horses, it's a trade study at the moment, not a new baseline!
Allow subject to scream. In space no one will hear.

Offline TrueBlueWitt

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Re: DIRECT v2.0 - Thread 2
« Reply #3670 on: 12/27/2008 05:05 pm »
Is it just me.. or does this SSME based Ares V with smaller tank and 5-seg sound more and more like some early "heavy" variants of DIRECT?

For all those DIRECT "nay-sayers"(Griffin's groupies?) on this board..

How many real design issues with Ares/Orion(many that have forced NASA to change design direction.. for example: Base Heating)..  were brought up on this board as issues(by the DIRECT team).. and solutions already incorporated into DIRECT.. well before the issues were fully addressed by NASA?

It is taking on a more Direct-esq feel. However, hold your horses, it's a trade study at the moment, not a new baseline!

True enough.. although I can think of many other examples were DIRECT team addressed design issues in advance of NASA.

It was unclear from the article if they were also re-examining going back to 2 x J-2X for the Upper/EDS stage.  Seems that would definitely take some pressure off the massive Ares V "Core" and increase efficiency.

Offline Mark S

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Re: DIRECT v2.0 - Thread 2
« Reply #3671 on: 12/27/2008 05:17 pm »

No one wants to get rid of Orion.  In fact, one of the biggest criticisms of Ares-I is that its limited lift capacity has been adversely affecting development of Orion.  Switching launchers from Ares-I to Jupiter-120 will allow the Orion team to restore a lot of functionality that was dropped due to problems with Ares-I.  Little things like landing on land instead of in the ocean.

 Given that Orion is pretty much the way to go, one would think that this argument alone would be the one that would tip the scales, so that means that there is some other reason, one the general public is unaware of, one that has been held closely, and one that if it got out, would cause serious problems, there has to be some other reason why limiting Orion is being permitted, and why there is such a push to "stay the course."

Haven't we learned anything over the last 8 years? 20 years? 30 years? 50 years?

Yeah, stay the course.  That's the ticket.  I hear the new president-elect is a big backer of "stay-the-course" strategies.  :)

And no, I would say that NASA management has not learned a flippin thing about listening to their engineers.  Especially since Dr. Griffin is the uber-engineer, and can out-engineer any of his underlings.

There is one thing I have been wondering about since NASA has reverted all the way back to Apollo-style splash-downs.  Is NASA going to pay the US Navy to fish its astronauts out of the ocean after every mission?  If so, how much is that going to cost, and will it be added to the mission cost numbers?  If not, then how much will it cost to maintain a fleet of Orion recovery tugs?

Have the dangers of an ocean spash-down been added to the Ares-I LOC numbers?  All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction.  Surely that would have an adverse affect on the safety ratings of the mission.  I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.

Mark S.
« Last Edit: 12/27/2008 05:25 pm by Mark S »

Offline clongton

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Re: DIRECT v2.0 - Thread 2
« Reply #3672 on: 12/27/2008 05:41 pm »

Have the dangers of an ocean spash-down been added to the Ares-I LOC numbers?  All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction.  Surely that would have an adverse affect on the safety ratings of the mission.  I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.

Mark S.

To the best of my knowledge, Ares-I LOM/LOC numbers do NOT include any spacecraft recovery events or milestones. IIRC, they are limited to the spacecraft launch. Someone please correct me if that is not right.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Mark S

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Re: DIRECT v2.0 - Thread 2
« Reply #3673 on: 12/27/2008 06:01 pm »

Have the dangers of an ocean spash-down been added to the Ares-I LOC numbers?  All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction.  Surely that would have an adverse affect on the safety ratings of the mission.  I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.

Mark S.

To the best of my knowledge, Ares-I LOM/LOC numbers do NOT include any spacecraft recovery events or milestones. IIRC, they are limited to the spacecraft launch. Someone please correct me if that is not right.

So, the Columbia accident should not count towards Shuttle LOC numbers, in that case.  Sure, the trigger event was during the launch, but they actually survived the launch, completed their science mission, and had left orbit.  Clearly, that line of logic does not hold up.

I would say that LOC/LOM numbers have to account for and include any possible loss while riding in, on, or around any NASA vehicle.  Once they are safely on board the Nimitz (or whatever), then NASA can be absolved of responsibility.

Didn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?

Mark S.
« Last Edit: 12/27/2008 06:05 pm by Mark S »

Offline Ben the Space Brit

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Re: DIRECT v2.0 - Thread 2
« Reply #3674 on: 12/27/2008 06:33 pm »
Didn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?

Yep, the second manned Mercury/Redstone.  I don't think it was ever established whether the LOV was caused by a crew error (Grissom hitting the 'hatch eject' lever too early) or by an equipment malfuction.  As the Liberty Bell 7 is at the bottom of a fairly deep ocean, I can't see it ever being resolved.
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Offline clongton

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Re: DIRECT v2.0 - Thread 2
« Reply #3675 on: 12/27/2008 06:35 pm »

Have the dangers of an ocean spash-down been added to the Ares-I LOC numbers?  All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction.  Surely that would have an adverse affect on the safety ratings of the mission.  I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.

Mark S.

To the best of my knowledge, Ares-I LOM/LOC numbers do NOT include any spacecraft recovery events or milestones. IIRC, they are limited to the spacecraft launch. Someone please correct me if that is not right.

So, the Columbia accident should not count towards Shuttle LOC numbers, in that case.  Sure, the trigger event was during the launch, but they actually survived the launch, completed their science mission, and had left orbit.  Clearly, that line of logic does not hold up.

I would say that LOC/LOM numbers have to account for and include any possible loss while riding in, on, or around any NASA vehicle.  Once they are safely on board the Nimitz (or whatever), then NASA can be absolved of responsibility.

Didn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?

Mark S.

Being fair, there is a very big difference between Launch Vehicle LOM/LOC numbers and Mission LOM/LOC numbers. While there are certain launch events that can have an affect on the Mission numbers, as in Columbia, typically the Launch Vehicle numbers do not include Mission numbers but are considered and quoted separately. Launching the spacecraft is the job of the launch vehicle. The mission after orbital insertion is generally not affected by the launch vehicle. That's why the mission numbers are quoted separately from the launch event.

The falacy in this particular case (Orion/Ares vs. Orion/Jupiter) is the current design of Orion has been severly compromised by the performance limitations of Ares-I, making the spacecraft much less safe than it would have been otherwise. It is not UN-safe, it is LESS-safe. That does NOT include resulting spacecraft performance shortfalls, only safety considerations; things like lacking mmod protection, reduced survival time in the water after splashdown, and single fault tolerant systems vs. dual fault tolerant.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline clongton

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Re: DIRECT v2.0 - Thread 2
« Reply #3676 on: 12/27/2008 06:39 pm »
Didn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?

Yep, the second manned Mercury/Redstone.  I don't think it was ever established whether the LOV was caused by a crew error (Grissom hitting the 'hatch eject' lever too early) or by an equipment malfunction.  As the Liberty Bell 7 is at the bottom of a fairly deep ocean, I can't see it ever being resolved.

Liberty Bell 7 was raised from the ocean floor on July 20, 1999. It was then proven that the hatch was blown by an as-yet unresolved system malfunction, but they definitely demonstrated that Gus did NOT blow the hatch; it was caused by equipment malfunction. To the best of my knowledge, they have never specifically identified the root cause, but pilot interaction was eliminated. All his controls were still in the 'Locked Disable' position. Once activated, they cannot be put back. Gus did not do it.

Here's a link to the story: http://www.space.com/missionlaunches/missions/liberty_bell_000617.html
« Last Edit: 12/27/2008 06:42 pm by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Jorge

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Re: DIRECT v2.0 - Thread 2
« Reply #3677 on: 12/27/2008 06:40 pm »
Didn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?

Yep, the second manned Mercury/Redstone.  I don't think it was ever established whether the LOV was caused by a crew error (Grissom hitting the 'hatch eject' lever too early) or by an equipment malfuction.  As the Liberty Bell 7 is at the bottom of a fairly deep ocean, I can't see it ever being resolved.

Never underestimate the ingenuity of the Kansas Cosmosphere.

http://www.space.com/missionlaunches/missions/liberty_bell_000617.html

Edit: Chuck beat me to it...
« Last Edit: 12/27/2008 06:40 pm by Jorge »
JRF

Offline Jorge

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Re: DIRECT v2.0 - Thread 2
« Reply #3678 on: 12/27/2008 06:45 pm »

Have the dangers of an ocean spash-down been added to the Ares-I LOC numbers?  All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction.  Surely that would have an adverse affect on the safety ratings of the mission.  I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.

Mark S.

To the best of my knowledge, Ares-I LOM/LOC numbers do NOT include any spacecraft recovery events or milestones. IIRC, they are limited to the spacecraft launch. Someone please correct me if that is not right.

So, the Columbia accident should not count towards Shuttle LOC numbers, in that case.

It unquestionably does count, because "Shuttle" is defined as the complete system: orbiter+ET+SRBs. The only controversy is which subsystem: ET or orbiter. The ET routinely violated debris requirements; the orbiter TPS was designed for the required debris environment rather than that actual debris environment.

Quote
Sure, the trigger event was during the launch, but they actually survived the launch, completed their science mission, and had left orbit.  Clearly, that line of logic does not hold up.

Strawman logic rarely holds up.
JRF

Offline Jim

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Re: DIRECT v2.0 - Thread 2
« Reply #3679 on: 12/27/2008 06:55 pm »
The only controversy is which subsystem: ET or orbiter. The ET routinely violated debris requirements; the orbiter TPS was designed for the required debris environment rather than that actual debris environment.


As far as ET debris requirements, they were/are unreasonable (all LV's shed debris).  It comes down to the ET ET debris requirements crutching a bad selection of the orbiter TPS.

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