Author Topic: Zubrin's Falcon Heavy Mars Mission  (Read 213988 times)

Offline ugordan

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #40 on: 05/14/2011 09:14 pm »
What's a "W/h" intended to mean?
Watt/hour.  Basic electricity term to determine power demand.

I think you mean Watt-hour (W·h).  Power divided by time doesn't make much sense. Power multiplied by time on the other hand is a measure of energy, which I assume is what you're thinking of.

Offline Downix

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #41 on: 05/14/2011 09:32 pm »

Who needs the shuttle when we have ISS? Why not use capsules to ISS on the cheap and space walk from ISS to do on orbit assembly? That way we don't have to pay to launch an entire on orbit assembly platform in the shape of shuttle when we have one that sits up in space and cost us $100 billion.

Lets use the ISS!
You'd have to increase the side of the ISS crew in order to turn it into an assembly location, plus the arm does not have a long enough reach as it is, so you would need to expand the ISS a bit to handle this kind of role.  Not saying it can't be done, but do understand that it will need more work for this.

Incidentally, utilizing a 70mT launch vehicle with a larger payload size (J-130 w/ 8m shroud) would enable a two-HLV, three-EELV scenario, further reducing the cost to both develop and deploy.

This has gotten me thinking a bit for a mission for AJAX, with the existing budget.  Time to number crunch.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline pathfinder_01

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #42 on: 05/14/2011 10:20 pm »
You'd have to increase the side of the ISS crew in order to turn it into an assembly location, plus the arm does not have a long enough reach as it is, so you would need to expand the ISS a bit to handle this kind of role.  Not saying it can't be done, but do understand that it will need more work for this.


Depends on which arm you are talking about. The ESA robot arm planed to be added next year can inch worm from attachment point to attachment point. The larger Canada arm can too. Just put attachment points on the Craft and it could in theory go there...plus the craft itself may have a robot arm.

A mars ship's hab module could also function as shelter for the crew that is assembling the spacecraft.   

Big work but not that huge. It also does not need to be totally assemebled just assembled enough that it can function on it own's when undocked.
« Last Edit: 05/14/2011 10:26 pm by pathfinder_01 »

Offline sanman

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #43 on: 05/14/2011 10:27 pm »
What about something like Russia's plan to set up a robotic base on the Moon? How about adapting that idea for Mars, so that a series of robot missions are sent there, building up a robotic infrastructure that could be re-purposed for supporting humans who would be sent at some later date.

That way, once humans arrive, they can simply plug into that infrastructure, which could comfortably support them indefinitely, should unforeseen events prevent the return portion of their journey.

So this type of approach would allow one-way-to-stay as a fallback position, if the planned return leg of the mission didn't work out for whatever reason.

I'd like to see humans start living on Mars as soon as possible, to make it part of our future. As for finding out whether life once existed on Mars, that's about making Mars part of our past, and it's of lesser importance to me. The sooner people start living on Mars, the sooner we can start turning it towards our ends.

Offline Ralph Buttigieg

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #44 on: 05/14/2011 10:36 pm »
G'day,

Regarding the risk and the worth of the project.

It depends are people being sent or people deciding to go?

There are two type of explorers, contract and private.

Contract explorers are what current professional astronauts are. An organisation such as NASA has a mission for them then send them out. They are hired employees. That means NASA has certain responsibilities regarding their safety and the success of the project. They can not afford to send anyone unless they are sure of a very high success rate. My understanding is that American OH&S regulation wouldn't allow human Mars missions because of the radiation risk alone.

 Private exploration is a different matter. There successful explorers assess the risk and take counter measures to reduce them to a level which *they* find acceptable. Then they go. Think of Frenchwoman Raphaela Le Gouvello who has crossed by wind surf the Atlantic, Pacific and Indian Oceans  or the two Aussie lads who Kayaked the Tasman.

The great think about the Zubrin/Dragon mission is that it reduce costs to a level were jut maybe private mission could be done. At the very least it brings that day closer.

ta

Ralph

Offline pathfinder_01

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #45 on: 05/14/2011 10:44 pm »
Private exploration is a different matter. There successful explorers assess the risk and take counter measures to reduce them to a level which *they* find acceptable. Then they go. Think of Frenchwoman Raphaela Le Gouvello who has crossed by wind surf the Atlantic, Pacific and Indian Oceans  or the two Aussie lads who Kayaked the Tasman.

The great think about the Zubrin/Dragon mission is that it reduce costs to a level were jut maybe private mission could be done. At the very least it brings that day closer.

ta

Ralph

Yeap that is one benefit to commercial space. It enables this kind of thing.

Offline HIP2BSQRE

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #46 on: 05/14/2011 11:48 pm »
Before this dissolves into a debate of technology.. and I thoroughly admit to having started that debate.. I have to say I would much rather hear people's opinions on the quotes.  Zubrin doesn't get up on stage or write for the newspapers to convince the technical audience.  In fact, I'm not terribly sure I've ever heard Zubrin say much to convince the technical audience. 

As I see it, his argument is simple: risk to astronaut life, be it immediate mission failure risk or long term health risk, is worth it to go to Mars.. and he typically goes on to say that the possibility of finding life is the best reason to go to Mars, with eventual colonization being a distant second.

How do you feel about that?  Is his "right stuff" mentality correct?  Is NASA way too cautious these days?  Or is he just shouting into the wind?

(for anyone who cares, my personal belief is that NASA will never do another mission with the level of risk of Apollo 8.. and their biggest fear is that another set of astronauts will some day die and the entirety of HSF will be shut down.  Whether or not you think that is good or bad is irrelevant, it's the way it is, deal with it.)


NASA is risk adverse.  But guess what--the West would not be won if we were risk adverse.  People climb mountain--everest.  How many die each year???

Offline Adaptation

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #47 on: 05/15/2011 06:42 am »
Your array would loose 5% of it's total capability every 3 weeks.

brb calling Hubble team to find out how they still get pictures with the infinitesimal amount of power they have after considering radiation decay.

  Take that over two 6 month trips.  Figure out your power need, then work backwards and double it in case circuits are broken in between cells. 

Yep hayabusa sure lost half its power from broken circuits.

Let us do the math.  I will assume that this is a low-capacity 2-person mars mission, with a Dragon and an Almaz-sized/capability module with a propultion system which is chemical, not electric in order to reduce the power demands.  Almaz consumed 8500W/h, and Dragon's demands appear to be closer to 1500W/h, so let us get an aim-point of 10kW total demand after 12 months of exposure to solar radiation.

Holy donuts batman Almaz needed just 8500 watt hours of energy to run for a year.  Forget solar all together I can get that in about 500 lbs of lead acid batteries. 

  What has been found is, per solar incident, solar panels decay at the rate of 2%.  During active periods (and we're entering into one right now), there are between 200-250 of these incidents per year.  So, let us calculate, 10kW, growing by 2% each time over 250 times, gives us  1484.13 kW.  Doubling that, we will need roughly 3MW of power in order to guarantee survival for return.
I thought you already mentioned this as the radiation decay of 5% per three weeks.  Also didn't we double because of all the circuit that will be destroyed from space magic. 

Each panel of the ISS generates 246kW of power, so we would need 6 of them to guarantee power supply.  When you take this with the weight of the panels, four of them with the truss needed to support them at 14mT.  Adding 50% more would result in 21mT.
Yeay ten year old tech getting 20 W/kg that must be the pinnacle of solar development... Just checked, you can get arrays around ten times the power density of that these days.

Offline rklaehn

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #48 on: 05/15/2011 07:38 am »
What has been found is, per solar incident, solar panels decay at the rate of 2%.  During active periods (and we're entering into one right now), there are between 200-250 of these incidents per year.  So, let us calculate, 10kW, growing by 2% each time over 250 times, gives us  1484.13 kW.  Doubling that, we will need roughly 3MW of power in order to guarantee survival for return.  Each panel of the ISS generates 246kW of power, so we would need 6 of them to guarantee power supply.  When you take this with the weight of the panels, four of them with the truss needed to support them at 14mT.  Adding 50% more would result in 21mT.

These numbers do not make any sense. GEO comsats are mostly outside the earth magnetic field, so they get the full brunt of all "solar events". Yet they manage with a loss of power of <30% over the typical lifetime of 15 years. If you use the same kind of cells on a mars mission, your power loss due to radiation would be almost negible for a 900 day mars mission.

Online docmordrid

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #49 on: 05/15/2011 08:17 am »
Just what kind of solar cells are we talking about here?

Different types of solar cells have different degrees of radiation hardness,  and some newer types are pretty darned hard vs. older ones. p-n? Ga nitride? InGa nitride? InGaP/GaAs/Ge triple-junction? ???

Without specifying solar cell type comparing satellite A to space station B or telescope C isn't very helpful.
« Last Edit: 05/15/2011 08:35 am by docmordrid »
DM

Offline Nathan

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #50 on: 05/15/2011 08:48 am »
Zubrin is preparing to talk in deal on this subject on 22nd according to the mars society website so we will get details then.
I expect the landing system will use supersonic retro propulsion.
The mission is less risky is a complete set of vehicle copies are sent ahead.
Zubrin is the most innovative and inspirational thinker on the subject of mars - out thinking NASA consistently. Case for mars laid out the first realistic method of running a mars program. I respect the man. I look forward to hearing the details of this architecture.

Given finite cash, if we want to go to Mars then we should go to Mars.

Offline QuantumG

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #51 on: 05/15/2011 08:54 am »
Don't be too disappointed if the "details" are nothing more than hobbyist level analysis that you might read on someone's blog *cough*.

Human spaceflight is basically just LARPing now.

Offline alexw

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #52 on: 05/15/2011 09:27 am »
What's a "W/h" intended to mean?
Watt/hour.  Basic electricity term to determine power demand.
I think you mean Watt-hour (W·h).  Power divided by time doesn't make much sense. Power multiplied by time on the other hand is a measure of energy, which I assume is what you're thinking of.
    Indeed. I'm afraid it's a case of "You keep using that word. I do not think it means what you think it means."

     Actually, it is mildly amusing to try to think of situations where W/h -- some form of power acceleration -- would be a sensible unit. Perhaps the slow ramping up of (say) a hydroelectric dam to meet shifting grid demand.

     -Alex

Offline alexw

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #53 on: 05/15/2011 09:36 am »
What has been found is, per solar incident, solar panels decay at the rate of 2%.  During active periods (and we're entering into one right now), there are between 200-250 of these incidents per year.  So, let us calculate, 10kW, growing by 2% each time over 250 times, gives us  1484.13 kW.  Doubling that, we will need roughly 3MW of power in order to guarantee survival for return.  Each panel of the ISS generates 246kW of power, so we would need 6 of them to guarantee power supply.  When you take this with the weight of the panels, four of them with the truss needed to support them at 14mT.  Adding 50% more would result in 21mT.
These numbers do not make any sense. GEO comsats are mostly outside the earth magnetic field, so they get the full brunt of all "solar events". Yet they manage with a loss of power of <30% over the typical lifetime of 15 years. If you use the same kind of cells on a mars mission, your power loss due to radiation would be almost negible for a 900 day mars mission.
   Yeah. 0.98^250 = 0.0064. Surely existing Mars orbiters are not down to much less than 1% of their rated power. How much worse for poor MESSENGER?
    -Alex

Offline A_M_Swallow

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #54 on: 05/15/2011 10:38 am »
{snip}
     Actually, it is mildly amusing to try to think of situations where W/h -- some form of power acceleration -- would be a sensible unit. Perhaps the slow ramping up of (say) a hydroelectric dam to meet shifting grid demand.

The power output of solar power stations changes throughout the day as the angle to the sun changes.

Offline A_M_Swallow

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #55 on: 05/15/2011 10:41 am »
Just what kind of solar cells are we talking about here?

Different types of solar cells have different degrees of radiation hardness,  and some newer types are pretty darned hard vs. older ones. p-n? Ga nitride? InGa nitride? InGaP/GaAs/Ge triple-junction? ???

Without specifying solar cell type comparing satellite A to space station B or telescope C isn't very helpful.

Solar cells do not have a monopoly on generating electricity from sun light.  Mirrors concentrating light onto Stirling engines can also be used.  Solar dynamic systems are intrinsically radiation hard.

Offline sanman

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #56 on: 05/15/2011 12:12 pm »
Why do we have to rush to send a man, if we can just send better robots that could learn the same stuff more cheaply?

Offline Nathan

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #57 on: 05/15/2011 12:13 pm »
Don't be too disappointed if the "details" are nothing more than hobbyist level analysis that you might read on someone's blog *cough*.


NASA can't even get to that level. I have a great deal of respect for the man and his passion for the cause.
Given finite cash, if we want to go to Mars then we should go to Mars.

Offline QuantumG

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #58 on: 05/15/2011 12:15 pm »
Why do we have to rush to send a man, if we can just send better robots that could learn the same stuff more cheaply?

There's at least two other threads going with that topic, please don't add to it here.

Human spaceflight is basically just LARPing now.

Offline pathfinder_01

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Re: Zubrin's Falcon Heavy Mars Mission
« Reply #59 on: 05/15/2011 02:18 pm »
Don't be too disappointed if the "details" are nothing more than hobbyist level analysis that you might read on someone's blog *cough*.


NASA can't even get to that level. I have a great deal of respect for the man and his passion for the cause.

That is becuase there hasn't been enough development to see what is and is not possible and what is and is not needed.  FH may lower the price to space but it can't fix the technology issuses.

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