New Mars Forums

Official discussion forum of The Mars Society and MarsNews.com

You are not logged in.

Announcement

Announcement: This forum is accepting new registrations by emailing newmarsmember * gmail.com become a registered member. Read the Recruiting expertise for NewMars Forum topic in Meta New Mars for other information for this process.

#76 2008-03-10 05:54:43

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Design Reference Mission 5.0

Remember NASA currently pays at least 10 times what any task is worth.

This is not true. Sure, government procurement for highly customized systems is expensive but that's because there's no market. When a free market appears for human spaceflight in the future, as it has in the aircraft business, then competition, better technology, economies of scale and large numbers of suppliers will drive costs down. Only then will costs go down to small fractions of what they are today, but currently the costs are what they are. Why doesn't NASA procure equivalent products for a tenth of the price, because they don't exist!

NASA is inefficient, it's not in the business of producing products, it does exploration and cutting edge research. That tends to be high risk, messy and wasteful. Things are better in the space probe world, there are more systems, more suppliers and more customers. So the cost of unmanned spacecraft has been falling. Only the US, Russia and China have human spaceflight capability today. If it was easy and cheap to do many more countries and even private organizations would be doing it. ESA dropped out of building its own capability (Hermes) because it was too expensive. This is the situation currently after 45 years of human spaceflight development.


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

Offline

#77 2008-03-10 10:38:45

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,934
Website

Re: Design Reference Mission 5.0

Remember NASA currently pays at least 10 times what any task is worth.

This is not true.

It is true. Every time I tried to prepare a bid for NASA, after adding padding for unexpected cost overruns and a reasonable profit margin, the price ended up between 8% and10% of what Boeing and Lockheed-Martin charge. Remember United Space Alliance is a 50:50 joint venture between those two, so I lump that allinace in as well.

I'll give you one specific example. NASA posted an opportunity through their bidding process, but the contract was through United Space Alliance. They wanted to replace a 1988 vintage computer with a new one, a used for a diagnostic workstation workstation for the shuttle orbiter. The announcement of opportunity said they expected an emulator for the old computer because that model computer isn't made any more. But they're wrong, that model computer just went through a major upgrade at one point, and that new one is still current. Applying 17 years updates to the software would have taken me 3 to 6 months, including testing. To provide all the NASA reports, I would have had to hire a technical writer. I am skilled with computer hardware as well; I already found the suppliers for the hardware and could assemble it myself. The bid expected a team of 10 to 12 people to take 12 months to write the emulator. In the end they would still have 1988 vintage software running on a 1988 operating system. I happen to have certification as an expert on that 1988 operating system, but try finding others who do. According to United Space Alliance, I was the only one who wanted to upgrade to a new model of the same computer. I didn't get the bid because United Space Alliance (not NASA) didn't want to work with a non-American contractor; I'm Canadian. They led me along just to get my ideas, but had no intention of even letting me bid. But notice the result, one full-time and one part-time worker would take 3 to 6 months, budget for 9 months to leave room for overruns, verses 10 to 12 people taking 12 months. That's how the 10 times cost padding happens.

I'll give you another example. When looking at building a new analogue spacesuit for FMARS, I asked the manufacturer of joint seals for the real spacesuit how much they cost. A waist seal costs $50,000 and each wrist seal costs $20,000. Obviously way too expensive for an analogue, but this raised the question why NASA pays that much. I know a couple machining companies who could make those parts for less than 1/10 the price, even at a quantity of only 10 sets (seals for 10 suits). They're used to smaller parts that cost tens of dollars each, even for small quantities. Large parts like this would cost hundreds. Adding the bearings and air-tight seals would be an expensive job, but for them expensive would be several hundred or at most single-digit thousands dollar price. That means less than 1/10th the price. I have asked before, if NASA holds the patent then give me the blueprints and I'll have one of these other companies make a copy. If NASA doesn't, then has the patent expred by now?

Offline

#78 2008-03-10 11:14:19

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Design Reference Mission 5.0

Thanks for the detailed reply, real examples are worth a lot of blah blah. Yes the real world is like this, commercial companies and government agencies alike. It seems to get worse the larger the organization. On the other hand big companies can cut deals smaller ones can't and they can afford specialists and consultants. Parkinson tends to rule, decisions on spending hundreds of millions are sometimes made quicker than ones involving hundreds because everyone has something to say about that new computer or coffee machine but very few people have the knowledge to question a big contract. This factor of ten may apply to a few cases, but it's false to say it applies at every level. If you want to see real waste check out what happens inside ESA, it's estimated that there's at least a 30% overhead because of the multi cultural cooperations, distributed work sites and associated bureaucracy. Add to that another big number to account for the mandatory work sharing between partner states.


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

Offline

#79 2008-03-10 14:37:05

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,934
Website

Re: Design Reference Mission 5.0

Real hard concrete data that illistrates the issue, and you dismiss it as "blah blah". Typical, you don't like the conclusion so just ignore the data. Then you go on to say "So and so is worse than me so what I'm doing is somehow Ok!" Since when has that excuse ever worked?

Offline

#80 2008-03-10 14:53:46

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Design Reference Mission 5.0

No RobertDyck. Read it again. It was a compliment to you for giving real examples not a dismissal of them - ok the phrasing was a bit clumsy. The point about ESA is that it can be worse and similar things probably happen with NASA's international projects.


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

Offline

#81 2008-03-13 06:09:17

Swoosh
Member
From: Australia
Registered: 2008-01-28
Posts: 33

Re: Design Reference Mission 5.0

I think the worst bit about DRM5 is that it seems NASA is doing nothing but planning for decades on end. We've gone from the 90 day report, to the reworked MarsDirect, through a few more incarnations of the DRM, and now they've basically taken a carbon-copy of the ESA's ludicrous mission architecture and swapped Energias for Ares-Vs (which, to be fair, makes the mission slightly less crackpot). There is absolutely no prospect of any action being taken in the forseeable future which might make this, or any other Mars architecture, the slightest bit closer to realisation. What a shame.

Offline

#82 2008-03-13 06:29:40

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Design Reference Mission 5.0

NASA can only make outline plans right now and do studies, it doesn't have the budget to start development. DRM 5.0 is a big step forward over earlier schemes because human Mars exploration was approved in the 2005 Space Act. It's also based on hardware that is in development right now. Unless more funding is appropriated, NASA has to wait until the 2020s before it can afford development of the MTV, NTR and lander. However it will have Ares V and Orion/Ares I operational and the lunar Outpost. BTW DRM 5.0 is based on DRM 3.0 not ESA's Aurora architecture.

In the meantime the robotic work continues with Phoenix about to land, MSL in development, the 2013 orbiter being competed, and planning for MSO in 2016 and MSR in 2018 and 2020.

With more funding everything can happen sooner. Get Australia to contribute to the Mars program instead of just whinging about it.


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

Offline

#83 2008-03-13 08:11:03

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Design Reference Mission 5.0

BTW DRM 5.0 is based on DRM 3.0 not ESA's Aurora architecture... With more funding everything can happen sooner. Get Australia to contribute to the Mars program instead of just whinging about it.

Yes, the new plan is a take-off on DRM-III, redesigned for safer landing, improved provision for a future base/hopper system, and trading NTR for more Ares-V launches.

If the Aussies donated a billion to NASA annually, NASA could shave YEARS off getting to Mars.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

Offline

#84 2008-03-13 09:05:34

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,934
Website

Re: Design Reference Mission 5.0

There are a few enabling technologies they could work on right now. I keep hearing about the need to study the effects of human exposure to zero gravity, or the need to develop a closed loop life support system. So much work has been done on both these areas that they're practically done!

First zero-G. The effects have been studied through Mercury, Gemini, Apollo, Skylab, Mir, and ISS. The Russians have studied it too. It's been studied to death. Shannon Lucent spent 6 months on Mir, she walked off the shuttle. The effects on her body were exactly what was predicted. If you want to study zero-G any further you have to conduct a new experiment, simply putting astronauts in orbit and conducting a medical exam will not learn anything that hasn't already been learned. To put it another way, repeating the same experiment over and over again will not lean anything new. They could fly the centrifuge module to test the effects of partial gravity, including lunar or Mars gravity, but beyond that there is nothing new they can learn. But they cancelled the ISS centrifuge accommodation module. If they want to study the effects of Mars gravity, restore that module.

Second, life support. The Russian life support system is based on electrolysis of water. Let's look at human metabolism of carbohydrates, it's a lot simpler than protein. Monosaccharides have the chemical formula C6H12O6, when cellular respiration breaks that down it follows the formula:
6 O2 + C6H12O6 -> 6 CO2 + 6 H2O
So that means half of the oxygen astronauts breathe becomes incorporated into water. The other half goes into carbon dioxide. Half of the oxygen in carbon dioxide comes from cabin oxygen, the other half comes from oxygen molecules in dry carbohydrate from food. So a system that recycles water and uses electrolysis to generate oxygen only recycles half the oxygen astronauts breathe. They have to ship water up to feed the electrolysis tank. Water can be shipped in a simple bag, not a heavy pressure vessel like oxygen, so the total launch weight is lower. But still that means ISS is dependant on resupply from Earth.

A Sabatier reactor takes half the CO2 removed from cabin air, and all the hydrogen to form methane and water.
CO2 + 4 H2 -> CH4 + 2 H2O
This generates enough water to feed the electrolysis tank. Instead of dumping all the hydrogen and CO2 into space, this system dumps methane and the other half of CO2 into space. If everything operates with 100% efficiency it will close the loop. However, nothing ever operates with 100% efficiency. For example, removing CO2 from cabin air is done with a reusable sorbent; a material that either absorbs or adsorbs CO2. Every so often with the sorbent gets full, they stop the fans that blow cabin air through the sorbent chamber, seal off the chamber and pump air out, then open the chamber to space and bake out the CO2. But they can't ever pump all cabin air out, they will loose some air with each cycle. When they dump methane into space they try to ensure all water is recovered, but there will still be some moisture evaporated in it.

NASA intends to fly a equipment that does all this in Node 3. They also intend to fly improved water recycling. The Russian system uses reverse osmosis filters to recover water from the cabin dehumidifier and the urine collection tube. The cabin dehumidifier will recover sweat and breath, as well as any evaporated water from washing. The Russian module doesn't make any attempt to recover wash water or moisture from feces. Russia was going to fly a vacuum desiccator toilet but NASA thought the plumbing was too complicated. The new equipment on Node 3 is supposed to have water recycling that also uses reverse osmosis to filter water from a dehumidifier and urine collection tube, but will also recover wash water. The Johnson Space Center did some work on an incinerator toilet and filtering the moisture recovered from that, they could use an electro-resistive oven to bake it dry, but I don't know if they developed any flight hardware. This again raises the question of how to replenish recycling losses.

The solution is a couple simple pieces of technology. First tell the Russians to send up their vacuum recycling toilet. Launch Node 3 with a toilet that bakes feces and routes moisture through the urine collection filtration system for further purification. We can see which toilet works better by testing them both in space.

The third and final piece of technology is something they have prepared as flight hardware but for another purpose: direct CO2 electrolysis. This was going to fly to Mars as the ISPP Precursor experiment, to generate oxygen from Mars atmosphere. But as life support, it can generate oxygen from the half of CO2 that would otherwise be dumped in space. Direct CO2 electrolysis only converts CO2 into O2 and CO, and only 80% of the CO2 is converted, so it isn't all that efficient. While a Sabatier rector / water electrolysis system recovers all oxygen from CO2, direct CO2 electrolysis only recovers 40%. Furthermore per kilogram of oxygen it takes 3 times as much power. This may appear to be an inefficient technology, however it can recover oxygen without use of hydrogen. All the hydrogen from electrolysis is sent to the Sabatier reactor. Remember the source of oxygen in the half of CO2 that would be dumped in space came from dry carbohydrate in food, so while the Sabatier/water electrolysis system recycles oxygen, direct CO2 electrolysis would replenish oxygen that is sourced from dry and dehydrated food. Furthermore, if the recycling system is sufficiently tight that oxygen generated from direct CO2 electrolysis is more than enough, you could dial up CO2 electrolysis and dial down water electrolysis. This would let some of the hydrogen from food remain in the system to replenish water losses as well, instead of being dumped in space as methane. The water electrolysis tank links oxygen and water recycling systems. So as long as recycling systems are efficient enough, direct CO2 electrolysis would replenish all losses.

All this hardware could be flown on ISS today. This would demonstrate in space the life support system for a long-term mission to the Moon or Mars.

Another technology is a spacesuit. The Mark 3 hard suit currently being tested is fine for the Moon, but not good enough for Mars. We need an MCP suit.

An alternative to zero-G is artificial gravity by rotation. The trick is manoeuvring while rotating in tethered flight. This can be developed and tested by connecting a Russian Soyuz spacecraft to a spent Progress cargo module filled with garbage. Or connect an Orion command and service module to a European ATV. Either way, move away from ISS, connect the two spacecraft by a tether, rotate to Mars gravity, then change orbit just a little. The orbital manoeuvre doesn't have to be great, just enough to prove you can. Testing in Earth orbit with a re-entry capsule means if something goes wrong you can cut the tether and drop back to Earth. The cargo module would be spent anyway and destined to burn up in the atmosphere, so no loss. It's a lot safer to test in Earth orbit than enroute to Mars.

NASA does have the budget to do all this work now.

Offline

#85 2008-03-17 02:27:04

Michael Bloxham
Member
From: Auckland, New Zealand
Registered: 2002-03-31
Posts: 426

Re: Design Reference Mission 5.0

Good work, Robert. I seem to recall that VSE, when it was first announced, called for the remainder of ISS research to be directed more towards human life support systems and the like (to support future manned exploration efforts). How much more do we know about this? What sort of new technologies might be tested there before it is retired?


- Mike,  Member of the [b][url=http://cleanslate.editboard.com]Clean Slate Society[/url][/b]

Offline

#86 2008-03-17 06:53:38

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,433

Re: Design Reference Mission 5.0

Here is a starter page less the centrifuge that no longer is going up...
http://www.isset.org/nasa/tss/aerospace … ch2_2.html

It is from this orginal one http://aerospacescholars.jsc.nasa.gov/H … ss/5/4.cfm

Of course Breathing easy is one step http://science.nasa.gov/headlines/y2000/ast13nov_1.htm

Of course each trip up there as well as while a crew stays for long periods of time there are always on going work http://www.spacedaily.com/news/iss-science-03a.html

Lots more can be found here as weel as many more places http://spaceflightsystems.grc.nasa.gov/ … SResearch/


Then there is the student learning level http://iss.cet.edu/lifescience/default.xml

Offline

#87 2008-03-17 07:36:49

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Design Reference Mission 5.0

An alternative to zero-G is artificial gravity by rotation. The trick is manoeuvring while rotating in tethered flight. This can be developed and tested by connecting a Russian Soyuz spacecraft to a spent Progress cargo module filled with garbage. Or connect an Orion command and service module to a European ATV. Either way, move away from ISS, connect the two spacecraft by a tether, rotate to Mars gravity, then change orbit just a little. The orbital manoeuvre doesn't have to be great, just enough to prove you can. Testing in Earth orbit with a re-entry capsule means if something goes wrong you can cut the tether and drop back to Earth. The cargo module would be spent anyway and destined to burn up in the atmosphere, so no loss. It's a lot safer to test in Earth orbit than enroute to Mars.

NASA does have the budget to do all this work now.

If artificial gravity is to be used on long duration voyages, it must be proven before a crew can rely on it to mitigate the risk of expose to zero g. Centrifuge experiments in LEO such as Mars gravity biosatellite would be far cheaper and would provide the first data points for Martian gravity exposure. Results from this type of experiment  could then be used to establish the parameters for human tests. From all these results a design can be made. There are some indications that a combination of diet, exercise and medications may be sufficient, this approach would certainly be far cheaper than building a rotating spacecraft.

Previous long discussion on this subject:

Long duration Human space missions - Can we survive them?


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

Offline

#88 2008-03-17 08:28:54

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,433

Re: Design Reference Mission 5.0

Also see the old translife threads  as well and thanks for the newer thread as I will post to it as well.

Offline

#89 2008-03-17 22:41:15

Michael Bloxham
Member
From: Auckland, New Zealand
Registered: 2002-03-31
Posts: 426

Re: Design Reference Mission 5.0

There are some indications that a combination of diet, exercise and medications may be sufficient, this approach would certainly be far cheaper than building a rotating spacecraft.

Cheaper perhaps, but far less effective.

Edit: Thanks again for the links, SpaceNut!


- Mike,  Member of the [b][url=http://cleanslate.editboard.com]Clean Slate Society[/url][/b]

Offline

#90 2008-03-18 02:10:38

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Design Reference Mission 5.0

Cheaper perhaps, but far less effective.

Based on what evidence? There's a lot of experience and data from crews using diet, exercise and medications, and there's continuing research into the underlying mechanisms aimed at improving these methods. There is no data whatsoever on artificial gravity. Wishful thinking is not enough.


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

Offline

#91 2008-03-18 22:38:27

Michael Bloxham
Member
From: Auckland, New Zealand
Registered: 2002-03-31
Posts: 426

Re: Design Reference Mission 5.0

cIclops, this is not wishful thinking; it is common sense. Strict adherence to scientific method is not a complete substitute for reason.


- Mike,  Member of the [b][url=http://cleanslate.editboard.com]Clean Slate Society[/url][/b]

Offline

#92 2008-03-19 02:19:00

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Design Reference Mission 5.0

cIclops, this is not wishful thinking; it is common sense. Strict adherence to scientific method is not a complete substitute for reason.

The scientific method relies on reason, however, it is insufficient. Experimental data is vital and necessary to ensure the health and survival of people in an environment that is outside the realm of common sense. Assumptions that may work well enough in everyday life are very risky in extreme situations.


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

Offline

#93 2008-03-20 00:16:13

Michael Bloxham
Member
From: Auckland, New Zealand
Registered: 2002-03-31
Posts: 426

Re: Design Reference Mission 5.0

I'm pretty sure the human body can't tell the difference between gravity created naturally or artificially. Physically, they are both identical. Unless your talking about short radius arms. But for sufficiently long radii; I'm pretty sure the body will find it indistinguishable from natural gravity.


- Mike,  Member of the [b][url=http://cleanslate.editboard.com]Clean Slate Society[/url][/b]

Offline

#94 2008-03-20 04:30:02

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Design Reference Mission 5.0

I'm pretty sure the human body can't tell the difference between gravity created naturally or artificially. Physically, they are both identical. Unless your talking about short radius arms. But for sufficiently long radii; I'm pretty sure the body will find it indistinguishable from natural gravity.

Being 'pretty sure' is not good enough when the lives of the first expedition are at risk and probably the entire program. Even a radius of rotation of 100m will cause gradients in the artificial field, the effect of this on humans over an extended time are completely unknown. If artificial gravity doesn't work then redesigning the MTV will be cause long delays and be very expensive.


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

Offline

#95 2008-03-20 06:47:07

Dayton Kitchens
Member
From: Norphlet, Arkansas
Registered: 2005-12-13
Posts: 183

Re: Design Reference Mission 5.0

Building a spacecraft that spins around a common axis tethered to a rocket booster isn't a big deal.

And I say why bother with years of experiments when you can get all the information you need just by launching your Mars mission in the first place.

I will never understand this obsession with reducing risks for a manned Mars program when all these steps at best produce just marginal improvements in safety.

Offline

#96 2008-03-20 08:44:03

Commodore
Member
From: Upstate NY, USA
Registered: 2004-07-25
Posts: 1,021

Re: Design Reference Mission 5.0

Who wants to be the one to go to Congress with the tether idea?

You'll be about as popular as Rumsfield.


"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane

Offline

#97 2008-03-20 08:57:15

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,934
Website

Re: Design Reference Mission 5.0

Who wants to be the one to go to Congress with the tether idea?

You'll be about as popular as Rumsfield.

Why? Considering it would make the spacecraft much, much, smaller and cheaper while at the same time aleviating the risk of medical problems from zero-G on the long mission to Mars; why would it be unpopular?

And I say why bother with years of experiments when you can get all the information you need just by launching your Mars mission in the first place.

I will never understand this obsession with reducing risks for a manned Mars program when all these steps at best produce just marginal improvements in safety.

Uh, I agree that NASA is going in circles, not getting anywhere. However, every Apollo mission other than Apollo 17 had a problem. They incrementally tested to find problems and solve them before someong got killed. As it was, 3 astronauts were killed in the Apollo 1 fire, and the Apollo 13 astronauts were almost killed. A mission to Mars is 26 months round trip, and you can't get back to Earth early. Something as simple as a tether test in Earth orbit with a small Russian spacecraft would be prudent.

Offline

#98 2008-03-20 10:44:26

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Design Reference Mission 5.0

A tether-for-gravity system really isn't that complicated, and would be a pretty easy addition to a Mars vehicle design. The EDS stage will probably already have thrusters, just increase their fuel tankage a little and add power/control/telemetry links to them via the tether cable. A simple shape charge or explosive bolt cutting mechanism... It really won't cost that much.

In fact, such a system doesn't even need space testing short of the Mars ship I bet, the cable doesn't care if you are pulling on it in space or on the ground in a vacuum chamber, its all the same to it. Hit it with heat/radiation/derbies in said chamber to test it if you really have to.

Anyway, thats a good thought from Robert that equipment won't have to be zero-G rated if the ship isn't going to be in zero-G for any length of time, however in the event of trouble I think the vehicle should be able to operate sans-gravity and should be tested likewise.

The main troubles with a tether system are that you can't use it after you cut the EDS stage loose, which unfortunately you have to do in order to aerobrake, and it you can't readily dock with a spinning vehicle (eg docking with lander).

It would also complicate rocket braking maneuvers dramatically, to the point where you would probably want to cut the EDS loose before such a burn.

So, spinning works great for MarsDirect or DRM-3, but not so good for DRM-5, since the former two fly directly from Earth to Mars atmospheric entry, and the return vehicles don't spin until after the crew has boarded. In DRM-5, the same vehicle is used for the outbound and inbound leg of the trip, so the ship has to slow to Mars orbit, exchange crew with the lander at least once, and then return to Earth.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

Offline

#99 2008-03-20 13:58:25

Commodore
Member
From: Upstate NY, USA
Registered: 2004-07-25
Posts: 1,021

Re: Design Reference Mission 5.0

Who wants to be the one to go to Congress with the tether idea?

You'll be about as popular as Rumsfield.

Why? Considering it would make the spacecraft much, much, smaller and cheaper while at the same time aleviating the risk of medical problems from zero-G on the long mission to Mars; why would it be unpopular?

Making a multi-billion $ mission and several lives contingent on spinning billions of dollars worth of hardware on a string will not pass the BS test of those unfamiliar with the physics (ie: legislators).

Though having said that, the best reason for opposing a tether, aside from being unable to aerobrake, or dock with anything, or perform mid course corrections, or having it work on the way home, is it completely misses the point of manned interplanetary flight, which is simulate Earth-like ecosystems and to reproduce them at your destinations. Interplanetary space itself is a destination. Using a tether so you can cram a crew in a tin can to eat MRE's for 6 months doesn't do that.


"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane

Offline

#100 2008-03-20 14:12:39

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: Design Reference Mission 5.0

It would also complicate rocket braking maneuvers dramatically, to the point where you would probably want to cut the EDS loose before such a burn.

It complicates many things including mid course correction burns, communications and orientation of the storm shelter. Working around all these complications will add mass and risk to the mission.


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

Offline

Board footer

Powered by FluxBB