Author Topic: First manned mission to Phobos  (Read 6362 times)

Offline alexterrell

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First manned mission to Phobos
« on: 09/19/2009 10:14 PM »
EDIT: Apologies, this belongs in Exploration Alternatives. I've posted it there but can delete this message here.
====================================

Following a lot of discussion about Phobos, a potential exploration  scenario might include:
1. Robotic precursor missions, including sample return (Phobos Grunt), and testing of technologies.
2. Short stay mission departing from LEO: 30 to 60 days for a crew of 4-6 on the surface of Phobos.
3. Long stay mission departing from HEO: Establish permanent base on Phobos using large scale inflatables (http://forum.nasaspaceflight.com/index.php?topic=18759.0)
This focuses on part 2.

The mission is assembled in Low Earth Orbit. The crew stay in a Bigelow BA 330 module for 6-9 months out, 30-60 day stay, and 6-9 months return. Water is recycled in the service module.
The mission is launched using cryogenics. If available, a Jupiter Upper Stage with 175 tons of fuel will launch the stack to a Mars Transfer Orbit. Before Mars arrival, dehydrated waste is jettisoned. The mission uses aerocapture around Mars, and then a quick burn to meet with Phobos. The mission settle as Phobos, where crew spend 30-60 days doing a number of tasks:
•   Drilling in to Phobos and testing methods of regolith processing;
•   Testing water extraction and electrolysis equipment
•   Testing a storm shelter – inflating a 5m balloon under the regolith
•   Testing anchoring methods
•   Making observations of Mars – possible remote piloting surface vehicles

At the end of the stay, the crew leave behind the Phobos exploration module and return to Earth Transit (using storable propellants). The mission uses aerocapture around Earth to enter a highly elliptical orbit and then a high orbit. An Orion Capsule meets with the BA-330 to return the crew. The BA-330 and service module remains in orbit.

Total mass in LEO is just under 300 tons, of which 175 tons is cryogenic fuel. The storable fuel is 53 tons, and the payload 72 tons. So four Jupiter 232 launches or about 12 EELV launches, plus an Orion crew module (and another one to collect – or can it stay in orbit for 18 months.

Key components are:
Components   Mass      Notes
BA-330 module   23   tons   Source: Wikipedia
Service Module   10   tons   Incl solar panels, life support, water recycling
Return supplies   4   tons   
Heat shield   3   tons   
Return rocket   5   tons   
Phobos scientific module   10   tons   
Outbound supplies   5   tons   
LEO transfer rocket   12   tons   Based on Jupiter Upper Stage


Mass and Delta-V estimates are attached.

Is this doable for the mass?
Any new developments needed that are not in development?

It fits nicely with the Jupiter 246, given a 175 ton fuel capacity in the upper stage. But it would also work with the ULA EELV approach. There's no need for an Altair lander, but some novel ideas will be needed for testing.

Thoughts?
« Last Edit: 09/19/2009 10:24 PM by alexterrell »

Offline the_roche_lobe

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Re: First manned mission to Phobos
« Reply #1 on: 09/19/2009 10:48 PM »
+ Mars surface sample return? That mission has always seemed just too hard to do from Earth.

P

Offline simon-th

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Re: First manned mission to Phobos
« Reply #2 on: 09/20/2009 08:13 AM »
EDIT: Apologies, this belongs in Exploration Alternatives. I've posted it there but can delete this message here.
====================================

Following a lot of discussion about Phobos, a potential exploration  scenario might include:
1. Robotic precursor missions, including sample return (Phobos Grunt), and testing of technologies.
2. Short stay mission departing from LEO: 30 to 60 days for a crew of 4-6 on the surface of Phobos.
3. Long stay mission departing from HEO: Establish permanent base on Phobos using large scale inflatables (http://forum.nasaspaceflight.com/index.php?topic=18759.0)
This focuses on part 2.

The mission is assembled in Low Earth Orbit. The crew stay in a Bigelow BA 330 module for 6-9 months out, 30-60 day stay, and 6-9 months return. Water is recycled in the service module.
The mission is launched using cryogenics. If available, a Jupiter Upper Stage with 175 tons of fuel will launch the stack to a Mars Transfer Orbit. Before Mars arrival, dehydrated waste is jettisoned. The mission uses aerocapture around Mars, and then a quick burn to meet with Phobos. The mission settle as Phobos, where crew spend 30-60 days doing a number of tasks:
•   Drilling in to Phobos and testing methods of regolith processing;
•   Testing water extraction and electrolysis equipment
•   Testing a storm shelter – inflating a 5m balloon under the regolith
•   Testing anchoring methods
•   Making observations of Mars – possible remote piloting surface vehicles

At the end of the stay, the crew leave behind the Phobos exploration module and return to Earth Transit (using storable propellants). The mission uses aerocapture around Earth to enter a highly elliptical orbit and then a high orbit. An Orion Capsule meets with the BA-330 to return the crew. The BA-330 and service module remains in orbit.

Total mass in LEO is just under 300 tons, of which 175 tons is cryogenic fuel. The storable fuel is 53 tons, and the payload 72 tons. So four Jupiter 232 launches or about 12 EELV launches, plus an Orion crew module (and another one to collect – or can it stay in orbit for 18 months.

Key components are:
Components   Mass      Notes
BA-330 module   23   tons   Source: Wikipedia
Service Module   10   tons   Incl solar panels, life support, water recycling
Return supplies   4   tons   
Heat shield   3   tons   
Return rocket   5   tons   
Phobos scientific module   10   tons   
Outbound supplies   5   tons   
LEO transfer rocket   12   tons   Based on Jupiter Upper Stage


Mass and Delta-V estimates are attached.

Is this doable for the mass?
Any new developments needed that are not in development?

It fits nicely with the Jupiter 246, given a 175 ton fuel capacity in the upper stage. But it would also work with the ULA EELV approach. There's no need for an Altair lander, but some novel ideas will be needed for testing.

Thoughts?


Even with water recycling as currently done on the ISS, you have a 15-20kg per person requirement per day for supplies.

For a 4-crew to Phobos mission and an opposition class 500 mission, that adds up to at least 30mt. You calculate for 9mt.

Using Bigelow's large LEO hab module (that exists on paper only right now) also doesn't make any sense. You design your module to be as weighing as little as possilble. A BA330 is overkill in volume and doesn't provide the capabilities required for a Phobos mission, much less efficient GCR shielding. You also need to take your Orion with you, you need it for reentry on your way back.

For a reasonable Phobos mass budget for a opposition class 440 day mission to Phobos using chemical propulsion, look here http://www.astronautix.com/craft/phoion88.htm

Offline A_M_Swallow

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Re: First manned mission tinets o Phobos
« Reply #3 on: 09/20/2009 08:43 AM »
Using Bigelow's large LEO hab module (that exists on paper only right now) also doesn't make any sense. You design your module to be as weighing as little as possilble. A BA330 is overkill in volume and doesn't provide the capabilities required for a Phobos mission, much less efficient GCR shielding. You also need to take your Orion with you, you need it for reentry on your way back.

Too big a volume does not matter, we are not in an atmosphere.  The extra mass has an effect but fortunately it is mostly air at low density.

One of the advantages of returning to L1 or L2 is that the returning Transfer Vehicle can rendezvous with a waiting Earth lander (capsule).  The Orion never needs to leave Earth orbit.  That saves a significant amount of propellant.

The required thickness of GCR shielding does need determining.  Possibly by performing animal experiments at an L2 spacestation.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #4 on: 09/20/2009 08:59 AM »
Even with water recycling as currently done on the ISS, you have a 15-20kg per person requirement per day for supplies.

For a 4-crew to Phobos mission and an opposition class 500 mission, that adds up to at least 30mt. You calculate for 9mt.

Using Bigelow's large LEO hab module (that exists on paper only right now) also doesn't make any sense. You design your module to be as weighing as little as possilble. A BA330 is overkill in volume and doesn't provide the capabilities required for a Phobos mission, much less efficient GCR shielding. You also need to take your Orion with you, you need it for reentry on your way back.

For a reasonable Phobos mass budget for a opposition class 440 day mission to Phobos using chemical propulsion, look here http://www.astronautix.com/craft/phoion88.htm
Good points.

1. I thought a Bigelow might be overkill for 4 crew, but it's the only one on the drawing board. I suppose a simple polyethylene space capsule would be lighter.
2. Orion doesn't need to leave Earth Orbit. Return rendez-vous is in HEEO.
3. 15-20kg seems very high.
4. I would do a sample return as a seperate mission, seperate launch. But the return craft does a rendez-vous in Mars orbit. The 50kg of rocks are transferred over and put in a freezer. On that basis, the linked mass budget isn't applicable. Sending Phobos exploration module and return supplies ahead makes sense.

Offline simon-th

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Re: First manned mission tinets o Phobos
« Reply #5 on: 09/20/2009 09:00 AM »

Too big a volume does not matter, we are not in an atmosphere.  The extra mass has an effect but fortunately it is mostly air at low density.

1. The BA330 is not constructed to be a deep-space hab.
2. Why would you want to carry a 23mt hab all the way to Mars, if you really only need to develop a 5-10mt hab for that purpose? You design your hab for the mission you need it for, you don't use overly large and heavy structures for that purpose. It will cost you enormously mass-wise if you do so without gaining anything from it.

Quote
One of the advantages of returning to L1 or L2 is that the returning Transfer Vehicle can rendezvous with a waiting Earth lander (capsule).  The Orion never needs to leave Earth orbit.  That saves a significant amount of propellant.
True, but there is a delta-v penalty for you to go to EML-1/2 then to Mars orbit and then back to EML-1/2, instead of doing the TMI burn from LEO and do a direct descent with Orion on your way back.

The L1 and L2 approach is more complicated and also requires more mass lifted in total. It might be the way forward at some point in the future, but for a single Phobos mission, it doesn't make sense.

Quote
The required thickness of GCR shielding does need determining.  Possibly by performing animal experiments at an L2 spacestation.

No, we have a lot of data on GCR and there are countless papers on passive shielding for deep-space missions.

At solar minimum, any mission longer than about 150 days exceeds the maximum tolerable dose for astronauts if you go for minimum shielding (10g/cmē). That being said, a 500 day mission is only possible with GCR shielding of some kind, at least 30g/cmē - which of course can be provided by scientific equipment and polyethylene shielding. But the point is, the BA330 does not provide such shielding and also has an internal structure (mission equipment in the middle of the module instead of on the walls as in the ISS) that does not help.

To sum up, the BA330 is a. too large for the purpose and thus too heavy for the purpose, b. designed for LEO and not for deep-space and c. not idle from a GCR shielding point of view.

If Bigelow is successful with his inflatable habs in the next years, they might be one of the bidders for a deep-space transhabs. But a specific product  from items they advertise right now should not be used for a Phobos mission.

Offline simon-th

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Re: First manned mission to Phobos
« Reply #6 on: 09/20/2009 09:07 AM »

1. I thought a Bigelow might be overkill for 4 crew, but it's the only one on the drawing board. I suppose a simple polyethylene space capsule would be lighter.

Whatever the hab module will be, it will have to be specifically designed for deep space missions. Bigelow's company might bid for that contract and might come up with a solution, but currently they do not have a product that can or should be used for these missions. Polyethylene would be shielding material only, you still would have either a rigid outer shell (aluminium) or use an inflatable structure.

Quote
2. Orion doesn't need to leave Earth Orbit. Return rendez-vous is in HEEO.
How do you propose to do that? Do you want to do Earth aerocapture or propulsive capture? Both solutions require a lot of additional mass, more than just taking Orion with you - which also will have deep-space instrument that you can use during the mission.

Quote
3. 15-20kg seems very high.

Actually it's a low number. 24kg per person per day for basic life resources was e.g. mentioned by CSA a couple of years back: http://www.asc-csa.gc.ca/eng/educators/resources/ecosystem-edu.asp or more recently 30kg per person per day was mentioned in this 2008 article http://www.itwire.com/content/view/18103/1231/. And remember, if you want water recycling like you do it on the ISS, you need to take equipment for that purpose with you - which also has quite some mass.

« Last Edit: 09/20/2009 09:19 AM by simon-th »

Offline Archibald

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Re: First manned mission to Phobos
« Reply #7 on: 09/20/2009 09:28 AM »
solution: reduce your crew to two, just like zubrin "athena" :)
...you have been found guilty by the elders of the forum of a (imaginary) vendetta against Saint Elon - BLAAASPHEMER !

Offline simon-th

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Re: First manned mission to Phobos
« Reply #8 on: 09/20/2009 09:47 AM »
solution: reduce your crew to two, just like zubrin "athena" :)

I don't think that is really the best solution. People could then argue, "well why don't we eliminate another 2 people from the crew - that will save probably 90% in costs."

A crew of 4 is the minimum for a Mars orbital mission as far as I see it, except if you want to go all-out robotic.

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #9 on: 09/20/2009 10:29 AM »
The departure ship is assembled in LEO. You could take an Orion along to Mars if you can use it's heat sheild for Mars Aerocapture of the entire vessel - can you? It could also be used to provide extra living space (sleeps 2?).

If not, you leave it behind. For the return mission, you use aerocapture to put you into a HEEO. A small thrust at apogee would put you into a safe orbit (say 500,000km x 1,000km). The Orion would rendez-vous with you.

I originally dropped the Orion because the Bigelow provided so much volume, but if you go for a dedicated craft, it might look like an Orion with a very large Service Module. However, to use the heat shield for aero-capture, the "service module" needs to be at the other end.

I'll have a second go, with 2 missions:
1 for the humans
A second one for the Phobos Science module and a test Mars lander.

Offline A_M_Swallow

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Re: First manned mission tinets o Phobos
« Reply #10 on: 09/20/2009 11:31 AM »

1. The BA330 is not constructed to be a deep-space hab.
2. Why would you want to carry a 23mt hab all the way to Mars, if you really only need to develop a 5-10mt hab for that purpose? You design your hab for the mission you need it for, you don't use overly large and heavy structures for that purpose. It will cost you enormously mass-wise if you do so without gaining anything from it.

The Sundancer is a lighter hab than the BA330 and its prototype is due to fly within a couple of years.

The main advantage of using an existing hab is time.  What ever is used has a maximum development time of about 4 years.

The US Constitution requires President Obama's second term to end by January 2017.
Allowing 1 year for authorisation of a major project to go through Congress,
several months for the bidding process,
1 year for in-space testing and debugging
and 1 year for the inevitable delays
leaves 2017.1 -2009.9 -1 -0.5 -1 -1 = 3.7 years (approx)

That is about the same as the Ares I-X has taken, during the Credit Crunch this project is likely to have a smaller budget.

Quote
Quote
One of the advantages of returning to L1 or L2 is that the returning Transfer Vehicle can rendezvous with a waiting Earth lander (capsule).  The Orion never needs to leave Earth orbit.  That saves a significant amount of propellant.
True, but there is a delta-v penalty for you to go to EML-1/2 then to Mars orbit and then back to EML-1/2, instead of doing the TMI burn from LEO and do a direct descent with Orion on your way back.

The L1 and L2 approach is more complicated and also requires more mass lifted in total. It might be the way forward at some point in the future, but for a single Phobos mission, it doesn't make sense.

A high ISP LEO to EML-1/2 space tug would help.

One of the things demonstrated by Apollo is that space infrastructure has to be built and paid for by the high profile missions.  Apollo did not have a post-LEO spacestation or Moon base so we do not have them today.  Apollo did pay for launch complexes and a crawler which are still in use.  Without any infrastructure the second manned trip to Mars will be nearly as expensive as the first.

The prototype hab can be flight tested, including GCR radiation, at EML-2.  Post testing the hab could be reused as the living quarters of a L2 spacestation.

Quote
Quote
The required thickness of GCR shielding does need determining.  Possibly by performing animal experiments at an L2 spacestation.

No, we have a lot of data on GCR and there are countless papers on passive shielding for deep-space missions.

Low TRL, estimates exist but nothing has been experimentally tested for effectiveness in space.

Quote
At solar minimum, any mission longer than about 150 days exceeds the maximum tolerable dose for astronauts if you go for minimum shielding (10g/cmē). That being said, a 500 day mission is only possible with GCR shielding of some kind, at least 30g/cmē - which of course can be provided by scientific equipment and polyethylene shielding. But the point is, the BA330 does not provide such shielding and also has an internal structure (mission equipment in the middle of the module instead of on the walls as in the ISS) that does not help.

To sum up, the BA330 is a. too large for the purpose and thus too heavy for the purpose, b. designed for LEO and not for deep-space and c. not idle from a GCR shielding point of view.

If Bigelow is successful with his inflatable habs in the next years, they might be one of the bidders for a deep-space transhabs. But a specific product  from items they advertise right now should not be used for a Phobos mission.

I have no objection to a thicker skin on the Phobos spacecraft's hab.

Given the 4 year development timescale the rival long term contents of the spacecraft include Bigelow hotel systems, ISS systems and possibly the Orion life support systems.  p.s. or the RATS lunar systems.
« Last Edit: 09/20/2009 11:21 PM by A_M_Swallow »

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #11 on: 09/20/2009 05:05 PM »
Keeping the arbitrary limit of 175 tons of cryogenic departure fuel (because that's the Jupiter Upper Stage capacity, and it's arbitrary because we don't know what rocket will be used), it can be done if the Phobos Scientific module goes separately. 

So we now have:
Components      Mass   
Orion Module      9   tons
Service / Hab Module   16   tons
Return supplies      16   tons
Return rocket      5   tons
Outbound supplies   15   tons
LEO transfer rocket   12   tons
Return samples      1   tons

Basically, the increase in supplies takes up the weight saved by sending the Phobos Scientific module seperately.

Once in space, the Orion module turns around and docks with the service module / hab, so it's heat shield is facing out. The hab section is 3m diameter, 12m long unit providing 4 small sleeping bays, a toilet (Orion has a spare) and shower, a Mess area, and a Phobos access area. Around the hab module are service units and storable fuel for the return journey, to 4m in diameter. Around that is a layered impact shield.

So the crew have 85m3, plus 15m3 of the Orion. They'd better like each other.

The crew mission goes up in 4 Jupiter 246 missions. The science platform could use a J-130 or two EELVs.

Can the Orion's heat shield be used for aerocapture? It needs to kill 0.9km/s at Mars.

And, if we spin around the JUS for outbound artificial gravity, which way is up?

I would want to test the Mars lander to be used in the next stage, but the lander is so heavy that it only makes sense with ISRU. So it'll have to be tested above Earth.

In general, the mission is risky. If they lose oxygen or fuel, there's no return. I wonder whether it's better to skip Stage 2 and just send out a huge expedition ready to do ISRU and everything?

Offline Blackout

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Re: First manned mission to Phobos
« Reply #12 on: 09/20/2009 08:04 PM »
I have an alternate Reference Mission design for a manned Phobos Mission.  It is similar to what is proposed but simplified and instead of Jupiter, Ares V lite is assumed as the launch vehicle.

To my knowledge, the Delta-V required to go to Phobos is 20% less than the moon.  An Ares V Lite can throw 63mt at the moon, so I would assume it can throw about 70mt toward Phobos.

Since Orion will weigh about 25 tons, this allows the hab to weigh up to 45 tons.  Presumably the hab would be some kind of inflatable to save weight, additionally it would need some kind of propulsion to insert itself at Mars and then of course to get home.  Obviously cryogenics would not work so hypergolics for the hab propulsion module would be used.

With those assumptions, here is the plan:

Launch an Ares V lite with EDS only to max out fuel load. 

Launch second Ares V lite with Orion/Hab to meet up with EDS already in orbit.

EDS fires sending the stack to Mars on 6 month transit

Crew arrives and docks/lands on Phobos for 500 day say.

Crew heads back to earth, a few hours prior to arrival the Orion separates from hab and does a direct entry.

To add extra capability and saftey, Ariane V or EELVs can be used to launch cargo missions ahead of the manned stack to pre-position equipment and supplies.

Offline Patchouli

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Re: First manned mission tinets o Phobos
« Reply #13 on: 09/20/2009 08:16 PM »

Too big a volume does not matter, we are not in an atmosphere.  The extra mass has an effect but fortunately it is mostly air at low density.

1. The BA330 is not constructed to be a deep-space hab.
2. Why would you want to carry a 23mt hab all the way to Mars, if you really only need to develop a 5-10mt hab for that purpose? You design your hab for the mission you need it for, you don't use overly large and heavy structures for that purpose. It will cost you enormously mass-wise if you do so without gaining anything from it.

Quote
One of the advantages of returning to L1 or L2 is that the returning Transfer Vehicle can rendezvous with a waiting Earth lander (capsule).  The Orion never needs to leave Earth orbit.  That saves a significant amount of propellant.
True, but there is a delta-v penalty for you to go to EML-1/2 then to Mars orbit and then back to EML-1/2, instead of doing the TMI burn from LEO and do a direct descent with Orion on your way back.

The L1 and L2 approach is more complicated and also requires more mass lifted in total. It might be the way forward at some point in the future, but for a single Phobos mission, it doesn't make sense.

Quote
The required thickness of GCR shielding does need determining.  Possibly by performing animal experiments at an L2 spacestation.

No, we have a lot of data on GCR and there are countless papers on passive shielding for deep-space missions.

At solar minimum, any mission longer than about 150 days exceeds the maximum tolerable dose for astronauts if you go for minimum shielding (10g/cm²). That being said, a 500 day mission is only possible with GCR shielding of some kind, at least 30g/cm² - which of course can be provided by scientific equipment and polyethylene shielding. But the point is, the BA330 does not provide such shielding and also has an internal structure (mission equipment in the middle of the module instead of on the walls as in the ISS) that does not help.

To sum up, the BA330 is a. too large for the purpose and thus too heavy for the purpose, b. designed for LEO and not for deep-space and c. not idle from a GCR shielding point of view.

If Bigelow is successful with his inflatable habs in the next years, they might be one of the bidders for a deep-space transhabs. But a specific product  from items they advertise right now should not be used for a Phobos mission.

Modifying an existing hab such as Sundancer or a BA 330 would be a lot cheaper then anything you'll save on TMI propellant.
This is exactly what they planed back in the 60s by reusing skylab as habitation module.
Sometimes the lightest mission is not going to be the cheapest.
Payloads esp anything one off usually costs far more then the LV.
A 23T launch is only going to cost 90M to 180M double that if you want to send it to Mars.
R&D for a custom hab would be what a billion USD?

It's best to go ahead and deal with the extra mass so you get a more reliable vehicle and keep cabin fever at bay.
Besides I would not put a crew of four in anything smaller then 150 cubic meters for a mission of that duration.
Use the money saved on hab development for R&D on a mag shield ,inflatable aeroshell for aero-capture ,or a good space reactor.
 
It should be noted the Orion will not need a full service module since it's not performing any TEI burns.
The return vehicle also does not have to be an Orion depending on crew size a Dragon or Soyuz also can be used.
Though presently Dragon is the only vehicle with a storage life long enough for a Phobos mission barring use of advanced propulsion.
« Last Edit: 09/20/2009 08:28 PM by Patchouli »

Offline simon-th

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Re: First manned mission tinets o Phobos
« Reply #14 on: 09/20/2009 09:06 PM »
Modifying an existing hab such as Sundancer or a BA 330 would be a lot cheaper then anything you'll save on TMI propellant.
This is exactly what they planed back in the 60s by reusing skylab as habitation module.
Sometimes the lightest mission is not going to be the cheapest.
Payloads esp anything one off usually costs far more then the LV.
A 23T launch is only going to cost 90M to 180M double that if you want to send it to Mars.
R&D for a custom hab would be what a billion USD?

Again, the BA330 is not designed to be used as a deep-space hab. You would have to design a new module for it, that may or may not be a derivative of the BA330. But the BA330 as is, can't be used on a 500 day opposition class Phobos mission.

And we are not talking about just lifting 23mt. We are talking about a factor of about 4 or 5 in mass to LEO of that - due to requiring propellant for the EDS that lifts those 23mt to TMI + the propellant that lifts the propellant necessary to inject the 23mt into Mars orbit + the propellant that lifts the propellant that injects the propellant that is necessary for the burn from Mars orbit to an Earth trajectory back etc. etc. Every unnecessary mt in payload for your hab adds a LOT of mass you require in LEO, which adds a lot of cost.

Quote
It's best to go ahead and deal with the extra mass so you get a more reliable vehicle and keep cabin fever at bay.

No, I disagree. We know from Salyut that things like "cabin fever" are controllable and actually a non-issue for well trained astronauts/cosmonauts.

And again, the BA330 is not only overweight for the task, it's also not designed for the task and thus can't be used.

Quote
Besides I would not put a crew of four in anything smaller then 150 cubic meters for a mission of that duration.
On what do you base that? Salyut was 80mģ and perfectly fine for a crew of 3 for long duration missions.

Quote

It should be noted the Orion will not need a full service module since it's not performing any TEI burns.
It needs less propellant for sure. But it still needs the service module as is, due to the systems incorporated there.

Quote
Though presently Dragon is the only vehicle with a storage life long enough for a Phobos mission barring use of advanced propulsion.

Dragon's storage life is 0. It exists on paper only. Until it has had a successful test flight, we can't use it for any planning model.

Online Robotbeat

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Re: First manned mission to Phobos
« Reply #15 on: 09/20/2009 09:55 PM »
Orion has a storage life of zero. It exists on paper only. Until there a successful test flight, it can't be used for planning purposes.

The fact is that Dragon is closer than Orion is to a test flight. Success isn't guaranteed for either capsule.
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Offline Patchouli

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Re: First manned mission to Phobos
« Reply #16 on: 09/21/2009 02:01 AM »
Orion has a storage life of zero. It exists on paper only. Until there a successful test flight, it can't be used for planning purposes.

The fact is that Dragon is closer than Orion is to a test flight. Success isn't guaranteed for either capsule.

Agreed and Dragon should have several dragonlab flights before Orion even gets into Orbit.

It would be the only space vehicle tested for storage durations of over six months for your near term Phobos mission other then Soyuz.
it also should be noted Orion is designed for a six month max storage life as this meets all ISS and lunar mission requirements.
Mars going is likely bock II III or even Orion derived/follow on.

As for why a Sundancer it's the only western station module that is a 100% functional space vehicle plus you get 180M^3 of living space.
Consider 80M^3 enough then think of the extra volume as a bonus.
But on the subject of cabin fever The former Soviet Union did have some serious issues of it but they were able to control the situation.
It would be far worse of a problem away from Earth and real time communications so should not be underestimated.
On mass it's lighter then anything else even with added shielding and it's made of hydrogen rich materials due to it's composite construction.

A DOS station or ISS module would require much more shielding because it's hull is nearly useless for stopping GCR some even argue it's a liability.

It's also the only habitation module out there that comes in under 9MT.
http://en.wikipedia.org/wiki/Sundancer

You only other options a DOS station or highly modified ATV come in at 18 or 20MT.

A transhab derived hab just happens to be the winner here.
« Last Edit: 09/21/2009 02:18 AM by Patchouli »

Offline alexterrell

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Re: First manned mission to Phobos
« Reply #17 on: 09/21/2009 07:51 AM »
My second attempt above uses Orion, and the service module is rebuilt around the hab module to provide radiation shielding.

Inflatables save on volume but not weight, and you need the weight for protection. So I'd only consider inflatables if restricted to an EELV architechture.

The attached Excel assumes TMI burn in Low Earth Orbit.

If taking Orion to Mars, you'd want to use the heat shield and living space. Otherwise it's dead weight. I'd consider a halo-heatshield that goes over the Orion capsule to give a heatshield 10m wide. Then we can make the hab module shorter and wider - say 8m long and 5m internal width = 157m3. You could also put the Mars Manouevering Rockets around the Orion, in the heat-shield, so down is always down. (Though in this case the Earth Departure Vehicle (JUS), if used as an AG counter mass, needs to hook onto the other side once it's propellent is used).

I've baselined it on Jupiter. You could use Ares V but then there woudln't be any money left for Phobos missions.

I like Phobos because there's probably recoverable water there. But the main benefit of that is bringing it back to Earth Orbit to help with following missions. Manned Mars Mission 1 doesn't achieve that. It's testing only. Should we skip it, and proceed straight to Mission 2.

Mission 2 will be a lot bigger, crew of 12, Artificial Gravity, Nuclear Power, Phobos stay of 2-4 years. So a lot more expensive, because it won't yet use Phobos water. I'll put that down separately.

Offline Suzy

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Re: First manned mission to Phobos
« Reply #18 on: 09/25/2009 07:56 AM »
Regarding radiation shielding, there was a Russian article (NK 784) back in June about using polyethylene packaging with wet towels (reproduced below):

    22/05/2009/00:05 – Damp napkins will reduce the risk of adverse effects of space radiation

    A special screen, which will serve as additional protection against radiation for the crews of the ISS, should appear on board the Station in early 2010.

    “We have been successfully producing prototype draft-screen curtains and by the end of this year, the Rocket and Space Corporation Energiya specialists will put the product in a Progress cargo ship to be launched to the ISS in early 2010,” said Vyacheslav Shurshakov, Head of the Laboratory at the Institute of Biomedical Problems, part of the Russian Academy of Sciences, where the screen was developed.

    The screen is equipped with curtain-pockets, in which will be inserted plastic packaging with wet towels used for personal hygiene and cleaning crews of the station.

    The packaged napkins are impregnated with a material containing hydrogen, carbon and nitrogen, which effectively weaken the cosmic radiation, the scientist explained. Sensors are installed outside and inside the curtains to monitor radiation doses.

    Additional protection for the ISS crew is provided by securing three layers of polyethylene packaging with wet towels on the walls of the cabin which, in the opinion of scientists, will further reduce the risk of the adverse effects of space radiation.

    According to Shurshakova, the first results of the “Matryoshka”, «Матрешка» experiment on the ISS showed that the dose of radiation received by the vital organs decreases almost twice when you remove the person from the walls of the station to its center. “The Matryoshka-R with sensors installed on the ISS will allow us to test the effectiveness of the radiation protection provided by the sanitary napkins delivered to the Station,” he said.

    It is anticipated that the experimental screens will be fitted in the cabins of the ISS Service Module Zvezda. If the effectiveness of the new protection is confirmed, future orbital stations and interplanetary ships will be equipped with similar screens.

    The sanitary napkins can be used not only for radiation protection, but also to reduce noise in the cabin from constantly-operating machinery and devices, added the scientist.
« Last Edit: 09/25/2009 08:00 AM by Suzy »

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