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Glom
2009-Aug-25, 08:36 AM
Given the Space Shuttle is the only spacecraft capable of launching and returning an unpowered vessel, are the MPLMs going to the cornfield with the Space Shuttle?

slang
2009-Aug-25, 09:05 AM
MPLM (http://www.nasa.gov/mission_pages/station/structure/elements/mplm.html). I've wondered about that too, Glom. Is there any reason why one or two could not be left connected to ISS, as free office space?

Glom
2009-Aug-25, 11:01 AM
MPLM (http://www.nasa.gov/mission_pages/station/structure/elements/mplm.html). I've wondered about that too, Glom. Is there any reason why one or two could not be left connected to ISS, as free office space?

Good thought. Surely, there will be enough docking spaces once node 3 is added for an MPLM or two and for ATV and the Japanese one.

Larry Jacks
2009-Aug-25, 12:21 PM
It is a good question. I wonder if those modules were built with long term duration in mind. The 1980s LDEF experiment showed the harshness of the LEO environment on materials. Since the MLPMs were intended for short durations (typically less than 2 weeks), it's possible they weren't built to stay up there for years. Given how overbuilt just about everything for the ISS is, that probably isn't the case but that will likely be the determining factor.

slang
2009-Aug-25, 12:28 PM
There's a reference to some future plans on the Wikipedia article (http://en.wikipedia.org/wiki/Multi-Purpose_Logistics_Module#Permanent_Logistics_Modul e). Just add cooling and micro meteorite protection and slap it up there already! :)

Daggerstab
2009-Aug-25, 03:21 PM
Somewhat related question: Adding mass to the ISS increases the fuel expenses of re-boosting its orbit, doesn't it?

Antice
2009-Aug-25, 03:41 PM
It does. but it also increases the Kinetic energy of the station mass (Ke).
drag is a product of the stations Cross section, so whither it increases the overall re boost cost or not depends on where you add them to the station.
If you add mass without also increasing the cross section you end up increasing the stations Ke relative to the orbital velocity relative to earth. that means that the drag reduction in orbital speed is less than before. the drag has to bleed off more Ke per unit of orbital speedloss. in effect reboosts will need more fuel, but it will be longer between them.
The solar panels are the biggest contributor to cross section. therefore they have a glide mode used during night time to reduce the drag penalty. I.E. they are placed horizontally relative to earth to reduce drag when the sun is not available, or the stations energy needs are less than the full effect of the panels.

Glom
2009-Aug-25, 09:58 PM
It does. but it also increases the Kinetic energy of the station mass (Ke).
drag is a product of the stations Cross section, so whither it increases the overall re boost cost or not depends on where you add them to the station.
If you add mass without also increasing the cross section you end up increasing the stations Ke relative to the orbital velocity relative to earth. that means that the drag reduction in orbital speed is less than before. the drag has to bleed off more Ke per unit of orbital speedloss. in effect reboosts will need more fuel, but it will be longer between them.
The solar panels are the biggest contributor to cross section. therefore they have a glide mode used during night time to reduce the drag penalty. I.E. they are placed horizontally relative to earth to reduce drag when the sun is not available, or the stations energy needs are less than the full effect of the panels.

They should have used a fission reactor instead.

KaiYeves
2009-Aug-26, 01:38 AM
Thank you for explaining the acronym/initialism, Slang.

novaderrik
2009-Aug-26, 05:45 AM
They should have used a fission reactor instead.
the odds of them getting to launch a fission reactor that was going to be in earth orbit for a decade or more without a lot of protests and public outcry would be pretty low...

kucharek
2009-Aug-26, 05:52 AM
They should have used a fission reactor instead.
They are already busy enough with keeping the toilet running :)

ravens_cry
2009-Aug-26, 06:12 AM
the odds of them getting to launch a fission reactor that was going to be in earth orbit for a decade or more without a lot of protests and public outcry would be pretty low...
It's already been done (http://en.wikipedia.org/wiki/TOPAZ_nuclear_reactor). And even when one of the worst possible situations occurred, the breakup of Cosmos 954 (http://en.wikipedia.org/wiki/Cosmos_954) over northern Canada, the result weren't devastating. Probably les then an oil spill. Not pretty, but not exactly a reason to stop.
Nuclear power has risks, yes. Big ones. What else has risks? Strapping yourself to 2.6 million pounds of explosives as well as 1,622,000 pounds of cryogenic gases. Yet they light that match each time they launch the Space Shuttle.

JonClarke
2009-Aug-27, 10:48 AM
They should have used a fission reactor instead.

Why shoukld they use a less tested and less reliable technology with a great many safety issues in place of a highly reliable, well tested and extremely safe technology?

A reactor would either have to be placed at the end of a very long boom (at least 1 km), or have massive (tonnes) of shielding. It would require extensive cooling fins (maybe as large as the solar panels) to shed the ~1mW of excess heat. A reactor would also impose severe restrictions on approach angles by docking spacecraft.

Jon

kucharek
2009-Aug-27, 10:58 AM
It's already been done (http://en.wikipedia.org/wiki/TOPAZ_nuclear_reactor). And even when one of the worst possible situations occurred, the breakup of Cosmos 954 (http://en.wikipedia.org/wiki/Cosmos_954) over northern Canada, the result weren't devastating. Probably les then an oil spill. Not pretty, but not exactly a reason to stop.
Nuclear power has risks, yes. Big ones. What else has risks? Strapping yourself to 2.6 million pounds of explosives as well as 1,622,000 pounds of cryogenic gases. Yet they light that match each time they launch the Space Shuttle.

Bad example. You compare a risk to the public with a personal risk.

Tuckerfan
2009-Aug-28, 07:22 PM
An answer to your question. (http://news.bbc.co.uk/2/hi/science/nature/8226309.stm)
Mrs Di Pippo also said Esa was close to an agreement with the Americans on adding an extra European "room" to the International Space Station.

The intention is to leave one of the Multi-Purpose Logistics Modules (MPLMs) at the ISS.

The Italian-built MPLMs are the large cylindrical "packing boxes" put in a shuttle's payload bay when the orbiter flies logistics missions to the orbiting platform. They hold about 7-10 tonnes of supplies.

Once in orbit, the pressurised module is picked up by the shuttle's robotic arm and attached to a station docking port. The astronauts then unload its contents.

Normally, the MPLMs return home immediately with the shuttle, but with the orbiter fleet's retirement, the intention now is to leave the module known as Raffaello in space to provide extra volume.

slang
2009-Aug-28, 08:06 PM
Awesome. Thanks, Tuckerfan.

mugaliens
2009-Aug-29, 09:51 PM
A reactor would either have to be placed at the end of a very long boom (at least 1 km), or have massive (tonnes) of shielding. It would require extensive cooling fins (maybe as large as the solar panels) to shed the ~1mW of excess heat. A reactor would also impose severe restrictions on approach angles by docking spacecraft.

Jon

Hi, Jon. Nuclear reactors used for power generation range in size from a button (nuclear battery) in which the radiation causes flourescing in an adjacent substance, creating light which in turn powers a photovoltaic, to those capable of powering several cities. Diablo Canyon, for example, produces 2,200 MW to supply electricity to more than 2.2 million people.

SNAP-10A, a 30 kW unit launched in 1965, was the first nuclear reactor launched and flight tested by the United States. It's still up there, in a 700 NM orbit, and will remain there for about 4,000 years.

Cassini's radioisotope thermoelectric generator (http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator) (RTG) is powered by plutonium decay.

slang
2009-Sep-05, 05:03 PM
Universe Today (http://www.universetoday.com/2009/09/04/additional-lab-to-be-added-to-iss/):


Apparently the International Space Station is going to get bigger. According to an article on Flight Global, NASA and the Italian Space Agency (ASI) are preparing to sign an agreement to add another laboratory to the ISS by using a modified multipurpose logistics module (Raffaello) during the final Space Shuttle mission. It will be attached in September 2010 during Endeavour's STS-133 mission. The idea had originally been rejected, but earlier this year ISS program manager Michael Suffredini said using an MPLM for an additional module was being reconsidered.

JonClarke
2009-Sep-06, 04:19 AM
Hi, Jon. Nuclear reactors used for power generation range in size from a button (nuclear battery) in which the radiation causes flourescing in an adjacent substance, creating light which in turn powers a photovoltaic, to those capable of powering several cities. Diablo Canyon, for example, produces 2,200 MW to supply electricity to more than 2.2 million people.

SNAP-10A, a 30 kW unit launched in 1965, was the first nuclear reactor launched and flight tested by the United States. It's still up there, in a 700 NM orbit, and will remain there for about 4,000 years.

Cassini's radioisotope thermoelectric generator (http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator) (RTG) is powered by plutonium decay.

You can't really compare RTGs and reactors, they are quite different in concept. One supplies heat through radioactive decay, the other through controlled fission. RTGs are trypically ood for less than 1 kW of power, reactors i8n pri8nciple can supply mWs, although none that big have ever been flown.

SNAP-10A (the first reactor in space) was rated at 30 kW thermal, its electrical power output was only 500 W. the Russian reactors (at least three different designs as I recall) were up to about 12 kW electrical. But that is still only a 10th of the power output of the ISS's solar arrays.

RTGs are escellent for certain types of missions, and fission reactors have lots of potential for others.

But for a space station in LEO it isn't a good idea, for reasons I have already ennumerated.

Jon

Nicolas
2009-Sep-06, 11:44 AM
SI nitpick:

mW = milliwatt; MW = megawatt.

JonClarke
2009-Sep-06, 12:33 PM
SI nitpick:

mW = milliwatt; MW = megawatt.

Thanks!

mugaliens
2009-Sep-06, 08:18 PM
Somewhat related question: Adding mass to the ISS increases the fuel expenses of re-boosting its orbit, doesn't it?

Yes, as well as frontal area interacting with the uppermost atmospheric drag which is degrading its orbit. If they were all in a line, like a freight train, the additional atmospheric drag would be minimal and would reduce the decay, but the energy required to boost it back would remain proportional to it's mass.

Antice
2009-Sep-06, 08:55 PM
I do not think that single MLPM will add significant amounts to the overall drag of ISS. those whopping big solar panels are a gigantic brake when they are deployed in the vertical to catch the dawn. (several dawns a day even :) )

KaiYeves
2009-Sep-07, 01:20 AM
(several dawns a day even )
16, to be exact.

slang
2009-Dec-07, 11:28 AM
Spaceflight Now: Logistics module to be modified for new mission (http://spaceflightnow.com/news/n0912/06pmm/)


NASA and the Italian Space Agency are planning to strip the Leonardo cargo module of unnecessary parts and beef up shielding to equip the barrel-shaped spacecraft for a permanent stay at the International Space Station.
[...]
The new module is called the Permanent Multipurpose Module, or PMM.

Engineers are modifying the module as part of an agreement with the Italian Space Agency, which provided the Leonardo, Raffaelo and Donatello logistics carriers to NASA.