Why do people dislike developing an HLV?

[Fixerger]

Main question for HLV is the any PAYLOADS(except of few(?) telescopes) available for it? Why to build it?

 

[Urwumpe]

And also: Is in orbit assembly really a useless risky technology or maybe a basic technology for long-distance spaceflight, that needs to be practiced as good as possible to become routine?

 

[T.Neo]

Strangely, we can build serious houses with trucks, that can only transport a much smaller envelope. And it does not seem much easier to build complete houses in a factory far away and transport the houses to their location.

Payloads that require larger fairing sizes that cannot be split up will come up eventually (although such payloads would be very rare at best, it should be possible to split up even telescope mirrors). I don't know why it would be impossible to attach an "oversize load" fairing to a medium launcher, barring atmospheric effects.

If you assemble the spacecraft in orbit from standard modules, you can include improvements and fixes faster than in a monolithic spacecraft that is assembled for years on Earth and has huge R&D programs involved.

And such improvements and fixes cannot be implemented on a suitably configured payload back on Earth? Sounds more like dodgy engineering to me, something that would negatively affect smaller payloads as well.

The chance is higher to be hit by lightning while working on a house on Earth.

Is there a number behind this statement? And perhaps ones with more relevance, such as statistics for accidents in the SSPF?

The risk is there, but it is by such "measurements" not higher than the pure mathematical risk calculated by debris models for debris to pass through an astronaut sized area.

Debris is not the only danger during an EVA. It is a very risky activity in many regards. Nonetheless, it is certainly not an overly dangerous activity.

Cost should also be factored in, however.

 

[Urwumpe]

And such improvements and fixes cannot be implemented on a suitably configured payload back on Earth? Sounds more like dodgy engineering to me, something that would negatively affect smaller payloads as well.

No, really simple: If it is not modular already on Earth, installing new hardware/software/etc into it means massive changes and a complete new R&D package.

If it is already modular on Earth, you have to ask the question if it could also be assembled in space and if not, why.

It is a matter of interface definitions, managing side-effects, user interfaces and workflow... Short: You need to be very limited in your project requirements, if you can only launch it as one large piece, for example a large optical mirror. And that is a once in 100 years payload, especially since producing such mirrors would be better in microgravity.

---------- Post added at 04:16 PM ---------- Previous post was at 04:11 PM ----------

Is there a number behind this statement? And perhaps ones with more relevance, such as statistics for accidents in the SSPF?

I can cite you the exact number from a space debris lecture, it is calculated with ESA MASTER, the standard model for space debris predictions.

http://www.esa.int/esaMI/Space_Debris/SEMXP0WPXPF_0.html

Luckily, being a student has advantages... I also have a ESA MASTER version on my PC. :thumbup: Just in case you want to be more specific as "ISS orbit".

 

[T.Neo]

No, really simple: If it is not modular already on Earth, installing new hardware/software/etc into it means massive changes and a complete new R&D package.

If it is already modular on Earth, you have to ask the question if it could also be assembled in space and if not, why.

Not modular in an assembly sense, but modular in a design sense, so that sub-assemblies and systems can be reworked without major changes to the whole system.

If something is to be constructed on-orbit, it should be designed to be assembled with minimal work and as little direct human intervention as possible.

for example a large optical mirror. And that is a once in 100 years payload, especially since producing such mirrors would be better in microgravity.

Where is the infrastructure for producing a mirror in microgravity? At the current time we are far closer to having the technology for a heavy launcher, than we do for an orbital mirror manufacturing plant.

Shipping a mirror in segments would be cheaper. AFAIK this has been done on Earth, like your "building a house" analogy (spacecraft are not built of bricks, but a mirror is a mirror more or less).

I can cite you the exact number from a space debris lecture, it is calculated with ESA MASTER, the standard model for space debris predictions.

Not the number behind debris impacts, the number behind accidents in a facility such as the SSPF.

For that matter, what is the wage per hour for a SSPF worker, and the pay per hour of EVA for an astronaut?

 

[Urwumpe]

Not modular in an assembly sense, but modular in a design sense, so that sub-assemblies and systems can be reworked without major changes to the whole system.

Yes, that is modular. There are not different kinds of modular in engineering.

If something is to be constructed on-orbit, it should be designed to be assembled with minimal work and as little direct human intervention as possible.

That is always the case - it also applies to terrestrial building.

Where is the infrastructure for producing a mirror in microgravity? At the current time we are far closer to having the technology for a heavy launcher, than we do for an orbital mirror manufacturing plant.

We are at the current time also closer to build a steam train, than building a Warp drive. That kind of backwards orientation will not solve any problem.

Shipping a mirror in segments would be cheaper. AFAIK this has been done on Earth, like your "building a house" analogy (spacecraft are not built of bricks, but a mirror is a mirror more or less).

Yes, such mirrors also have the advantage of allowing adaptive optics.

Not the number behind debris impacts, the number behind accidents in a facility such as the SSPF.

Would be simpler if the number of accidents is published.

For that matter, what is the wage per hour for a SSPF worker, and the pay per hour of EVA for an astronaut?

Should be equivalent or even slightly cheaper, since military astronauts are paid slightly less than civilian ones, and civilian astronauts get paid only slightly more than engineers.

But then also include R&D and transportation costs into the equation. While you have a single launch, the costs for R&D and launch are much higher as well, usually even more than just the increase in payload mass.

 

[Sky Captain]

And also: Is in orbit assembly really a useless risky technology or maybe a basic technology for long-distance spaceflight, that needs to be practiced as good as possible to become routine?

In orbit assembly will be required anyway since even the Ares V could`t launch serious manned Mars mission in one go. Unless we build Nexus there will be no way around orbital assembly and mastering it is required for any serious deep space activities. I`m just trying to figure out what would be the most optimal size for a launcher so you would get decent flight rate and would`t limit yourself too much by launcher`s payload capacity and fairing size constraints.

 

[Urwumpe]

I would say, the optimal size will, economically, always approach the typical payload masses for the geostationary satellite market.

 

[T.Neo]

Yes, that is modular. There are not different kinds of modular in engineering.

LEGO is modular, and so is the ISS. Do they share technology?

We are at the current time also closer to build a steam train, than building a Warp drive. That kind of backwards orientation will not solve any problem.

Yes, such mirrors also have the advantage of allowing adaptive optics.

I never suggested that an HLV should be developed and constructed to launch a one in 100-year mirror, I was saying that such a mirror would not warrant an orbital construction facility.

From where does the 100 years figure originate?

Would be simpler if the number of accidents is published.

Indeed.

But then also include R&D and transportation costs into the equation. While you have a single launch, the costs for R&D and launch are much higher as well, usually even more than just the increase in payload mass.

There would also be associated costs for orbital assembly as well.

A lot of the associated costs are dependant on the exact engineering of the system.

I would say, the optimal size will, economically, always approach the typical payload masses for the geostationary satellite market.

Sure, as long as the geostationary satellite market is the most lucrative.

 

[Urwumpe]

From where does the 100 years figure originate?

I could also have used the saying "Once in a blue moon" and you would have asked me which definition of the blue moon I mean. Please relax and don't try to produce a flame-war.

Also the costs for on-orbit assembly will sure exist... but you can never tell exactly how high they are, before you try it. The pure assembly costs of the ISS had been pretty harmless so far, compared to developing an 400 ton HLV. And these costs would have to include EVAs.

Also docking is no longer the dangerous unknown technology, that it was in 1965. Today we already have reliable unmanned docking, as well as EVA tools that had been unthinkable in 1965.

 

[T.Neo]

Please relax and don't try to produce a flame-war.

:huh:

I could also have used the saying "Once in a blue moon" and you would have asked me which definition of the blue moon I mean.

It's important to note if one is using a figure of speech, to avoid confusion. "Once in 100 years" is mistakable for a real figure, "once in a blue moon" is not.

you can never tell exactly how high they are, before you try it.

At least a rough figure should be deducable by calculations beforehand though.

 

[Sky Captain]

I would say, the optimal size will, economically, always approach the typical payload masses for the geostationary satellite market.

Well, that would mean something in 20 - 30 ton LEO payload range like EELV`s or proposed Falcon 9 heavy. While a Moon missions and base building and supply could be done if propellant depots are employed what about mission to Mars or missions to asteorid belt? Is there any study of how a manned Mars mission with surface visit could be done employing only EELV class launch vehicles?

 

[T.Neo]

Is there any study of how a manned Mars mission with surface visit could be done employing only EELV class launch vehicles?

There are several. See Mars for Less.

There is even an Orbiter addon for it, AFAIK.

 

[PhantomCruiser]

We interrupt this program... but there is such thing as a "blue moon", two full moons in the same month... Now back to our regularly scheduled arguments...

Kidding, kidding, this is some pretty good stuff. From a dumb 'ol wrench turner point of view, I like the regular schedule of medium lift vehicles. The government worker in me wants the heavy lifter (honestly though it'd be a work project, not cost effective, but a means of putting people to work).
In either case, the plan still has to be reviewed, negotiated and completely screwed up by the Congress before anything gets built.

 

[Urwumpe]

Kidding, kidding, this is some pretty good stuff. From a dumb 'ol wrench turner point of view, I like the regular schedule of medium lift vehicles. The government worker in me wants the heavy lifter (honestly though it'd be a work project, not cost effective, but a means of putting people to work).

I would rather see them employed building spacecraft parts and medium launchers "like sausages" (RIP Sergej)

Or ideally "go work in space".

In either case, the plan still has to be reviewed, negotiated and completely screwed up by the Congress before anything gets built.

That is what parliaments are for. :rofl:

 

[PhantomCruiser]

I would rather see them employed building spacecraft parts and medium launchers "like sausages"...

Same here; plus you get a better bang for the buck due to an increased launch schedule.
Regarding construction in LEO, I think something resembling a Descarte could be built "on orbit" with little difficulty considering what we've already done on the ISS. You'd mentioned automated docking, the Russians have got that tech in the bag, ESA's done it too.
The engineers would have a field day with a project like that, don't you think?

 

[Urwumpe]

You'd mentioned automated docking, the Russians have got that tech in the bag, ESA's done it too.

Japan as well, while no automatic docking, getting the HTV to the ISS for being grappled by the robot arm is only slightly simpler.

The USA failed their attempts for that so far, but the USA also didn't try very hard yet.

The engineers would have a field day with a project like that, don't you think?

Sure, especially if this means that they can finally do something new every year, and not do the same in different flavors.

 

[T.Neo]

I would rather see them employed building spacecraft parts and medium launchers "like sausages" (RIP Sergej)

I think economies of scale impede medium launchers as well, to a degree- from what I can gather a medium launcher can expect 4-5 launches per year. It's like an AK-47; they can be mass produced in several countries for retail prices on the order of hundreds of dollars, but making a single unit would be hugely prohibitive. Even making a few per year would be prohibitive, and an AK-47 is far less involved than a launch vehicle.

Me, I'd like to see 100 ton launchers going up every month, but that obviously won't happen till we have geostationary communications satellites that are the size of cities. :lol:

 

[AirSimming]

I think that the HLV proposal might become a Constellation replacement: epic fail. Without cooperation and commercialization, NASA certainly won't go anywhere again, manned, if not pumping uselessly much budget into it. They fail sustainable programs one after another obviously. NASA gets 3 billion USD for development of that HLV. Maybe they manage to clean the floor inside the VAB with that money, one time.

They are also talking about a reduced version of Orion as a life boat for ISS crews. How do they get a reduced version of Orion into LEO?

I think what NASA really needs is a less expensive structure and cheap and reliable access to LEO first, before aiming to the Moon, near earth asteroids, moons of Mars and Mars (did I miss a goal?).

 

[Sky Captain]

I think economies of scale impede medium launchers as well, to a degree- from what I can gather a medium launcher can expect 4-5 launches per year.

That is if only space program is commercial satellite launches. If EELV`s are used to support Moon and NEO`s missions flight rate would go up probably to several dozen launches per year which should bring price of each individual launch down.