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Can Private Space Travel Take us to Mars?

Posted by: Senior Von Braun - Sun Dec 14, 2003 1:38 am
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Can Private Space Travel Take us to Mars? 
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Post    Posted on: Tue Mar 08, 2005 8:47 am
rpspeck wrote:
Actually I have been thinking of 2006 or 2007. It looks to me like the Falcon 1, plus a "Space Dev" motor like the one used on SpaceShipOne, could launch a midget on a one way trip to Mars.

rp I find it tough to agree with this. Falcon I is proposed to get 670 kg to LEO but that midget of yours is going to have to have negative weight in order to use a space dev motor to get to mars from there. That or divine intervention. Can you elaborate on some of the details?

DKH

I could not quickly find the mass of SS1, but WK was built to carry more than 3600 kg payloads, so any space dev motor using craft that is launchable on a falcon 1 to LEO is going to be a toy.

EDIT: Still can't find it but from memory I thought the mass of SS1 was somewhere between 2500 and 3000 kg.

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Post    Posted on: Tue Mar 08, 2005 11:21 am
In general for a martian trip it will be valid what I one day recently answered to Peter Campbell about the costs of a lunar trip:

1, Costs to get to earthian orbit +
2. costs to leave the earthian orbit for the other planet +
3. costs of orbital insertion around the other planet +
4. costs to levae that orbit for Earth +
5. costs to enter the earthian orbit +
6. costs to land on Earth.

The flight between leaving the one orbit and entering the other orbit doesn't cause any special spaceflight costs. They are reduced to nromal costs of living - food, water, clothing, waste. The costs of security will be investment into the vehicle mainly nad these are fixed costs regardless of the flight.

Additionaly or optionally the costs of landing at and launching from the other planet can be considered.

The largest portions will be the points 1, 2 and 5. If they are doubled it will be a conservative estimation of the costs.

The basics we will know as ssoon as a competitor has won the ASP. The costs of a Falcon I or a Falcon V-flight may be a first glance. But it may be valid regarding these two what is valid for Virgin Galactic's vehicles too - the goal will be a reduction down to far less ciost levels.



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Post    Posted on: Tue Mar 08, 2005 11:39 am
Dr_Keith_H, here is some info I think you're looking for.
http://www.astronautix.com/lvs/tierone.htm

"Burt Rutan's Tier One was the second manned reusable suborbital launch system (after the B-52/X-15). But it was developed privately at a small fraction of the cost. Payload: 400 kg. to a: 110 km suborbital trajectory. Apogee: 110 km. Total Mass: 7,700 kg. Core Diameter: 1.52 m. Span: 15.00 m. Boost Propulsion: Lox/Kerosene. Boost engine: J85-GE-5. Cruise Propulsion: N2O/Solid. Cruise engine: SpaceDev Hybrid. Cruise Thrust: 7,500 kgf. Guidance: Manual. Maximum speed: 5,300 kph. Minimum range: 65 km. Ceiling: 11,000 m. Development Cost $: 30.00 million. in 2004 average dollars. Launch Price $: 0.080 million. in 2004 price dollars. Total Number Built: 1. Cost comments: Privately-funded. "

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Post    Posted on: Tue Mar 08, 2005 12:48 pm
Thanks Sean, but I read down further on the page you link to (great!) that the total mass quote you cite seems to combine both WK and SS1 ... SS1 is down as 3600 kg (laden) and 1200 kg (unladen :wink: ) ... so I wasn't too far off. Here's the bit I saw ...

Quote:
Stage Number: 1. 1 x SpaceShipOne Gross Mass: 3,600 kg. Empty Mass: 1,200 kg. Thrust (vac): 7,500 kgf. Isp: 250 sec. Burn time: 80 sec. Diameter: 1.52 m. Span: 5.00 m. Propellants: N2O/Solid No Engines: 1. SpaceDev Hybrid Status: In production. Comments: Wing area 15 sq m.


I interpreted rp's ideas as a space-dev motor driven "to mars" stage as being the payload for a Falcon I ... which can only get 670 kg to LEO ... I figured (for a bunch of reasons) it could not weigh less than SS1.

DKH

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Post    Posted on: Tue Mar 08, 2005 1:44 pm
Ah yeah!, clearly I should have continued reading. No worries though, you found the necessary info.

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Post    Posted on: Tue Mar 08, 2005 3:05 pm
Hello, Dr_Keith_H, Sean Girling and rbspeck,

have I understood wrong something?

I didn't find in this thread the weight of SSO's motor but the weight of SSO as a whole only. So what is the weight of that hybrid motor? Is it less than 670 kilograms? If yes than it could be launched to orbit by the Falcon I.

rbspeck, I understand your post in the sense that a vehicle should be launched into earthian orbit that is equipped with SSO's hybrid motor and then that motor should get the vehicle escape velocity into the direction of Mars. Do I be in error? And do you imagine the whole second stage of Falcon I or a sufficient large portion of it to be the vehicle to be accelerated to Mars?



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Last edited by Ekkehard Augustin on Wed Mar 09, 2005 10:58 am, edited 1 time in total.



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Post    Posted on: Tue Mar 08, 2005 4:12 pm
Ekkehard Augustin wrote:
I didn't find in this thread the weight of SSO's motor but the weight of SSO as a whole only. So what is the weight of that hybrid motor? Is it less than 670 kilograms? If yes than it could be launched to orbit by the Falcon I.

Ekkehard, please do the damn math. Subtract laden from unladen and you get 2400 kg ... of fuel (mostly, perhaps this calculation fails to include the 400 kg of cargo mass) ... which by itself exceeds by a large margin the cargo capacity of Falcon I.

Now come up with an argument where you need less hybrid fuel than that to go from LEO to escape velocity.

DKH

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Post    Posted on: Tue Mar 08, 2005 4:39 pm
I do not understand this preoccupation with using SSO or anything connected with it for everything. :?:

Designs for an orbital craft are likely to be nothing like SSO as the requirements will be totally different. SSO was a brilliant design to accomplish the task of a sub-orbital flight and a variant of it will be used for the Virgin craft but it is extremely unlikely to be used as a basis for an orbital, lunar or Mars craft.

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Post    Posted on: Tue Mar 08, 2005 10:29 pm
Ekkehard Augustin wrote:
The flight between leaving the one orbit and entering the other orbit doesn't cause any special spaceflight costs. They are reduced to nromal costs of living - food, water, clothing, waste.
For a trip to Mars that takes many months, the cost of these items will be very high. You are wrong to dismiss this cost so easily.


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Post    Posted on: Wed Mar 09, 2005 10:57 am
Peter,

I don't dismiss them - it's a difference in the causes of the costs. Such differences are of major meaning to manage such a trip or project - they are impacting decisions and focusses to the real challenges, difficulties and negotiations.

The financial challenges of lunar or martian trips seem NOT to be the vehicles themselves or the propellent costs in the first line - that's what I said.

The challenges are food, water, clothing, waste - and these are costs caused by each trip at Earth too. This means that there are experiences and knowledges that could be used as basics - it is possible to leave it to normal trip-suppliers and -managers. There are ressources, methods, concepts already in use since long.

What I really have forgotten to list is artificial gravity or medical countermeasures to the absence of gravity at the martian trip.



Hello, Dr_Keith_H,

I may be misunderstanding "laden" and "unladen" - I took these words as "including passengers and/or cargo" and "without passengers and without cargo". This would mean the weight of SSO itself including the hybrid engine. I would be interested in the weight of the hybrid engine stand-alone instead.

It's not a proposal, suggestion or imagination of mine but only aquestion to fix if I am understanding rbspeck right or wrong because I am not sure concerning that. I hope for clarification by rbspeck. He has been speaking of the motor only - and he explicitly didn't speak of the SSO-motor itself but of a motor constructed and/or produced by SpaceDev LIKE that motor of SSO. rbspeck may be speaking of a modified motor - especially beacuse he is mentioning an unmanned sample return mission among others.



Andy Hill,

because of my last look into rbspeck's post - there may be a misunderstanding of it by several of us including me myself. He doesn't mention SSO itself but a motor made by SpaceDev only of that KIND that was used by SSO - a lighter or smaller version perhaps.



rbspeck,

what did you mean exactly?



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Post    Posted on: Wed Mar 09, 2005 11:35 am
Ekkehard Augustin wrote:
Hello, Dr_Keith_H,
I may be misunderstanding "laden" and "unladen" - I took these words as "including passengers and/or cargo" and "without passengers and without cargo". This would mean the weight of SSO itself including the hybrid engine. I would be interested in the weight of the hybrid engine stand-alone instead.

Hi Ekke, I mostly meant the difference in weight between a fueled and unfueled motor ... whatever form it took. I was trying to point out that even if you only took fuel up to LEO on a Falcon I ... it isn't enough to get ANYTHING to mars.

Quote:
It's not a proposal, suggestion or imagination of mine but only aquestion to fix if I am understanding rbspeck right or wrong because I am not sure concerning that. I hope for clarification by rbspeck. He has been speaking of the motor only - and he explicitly didn't speak of the SSO-motor itself but of a motor constructed and/or produced by SpaceDev LIKE that motor of SSO. rbspeck may be speaking of a modified motor - especially beacuse he is mentioning an unmanned sample return mission among others.

Well the reason that we aren't hearing from rpspeck on this one anymore is probably because he agrees that ... whatever the hell motor you use to get from earth orbit to mars ... Falcon I aint the beast to get the job into earth orbit, because it's payload capacity is too small. Which is the central thrust of my argument. I don't give a damn what kind of motor we are talking about, rp brought up the space-dev motor example so I just kept it focussed on that for simplicity.

DKH

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Post    Posted on: Wed Mar 09, 2005 11:53 am
All these posts may be a good reason to initiate a new thread in the Technology section perhaps - about the upper stage of the Falcon V to be equipped with a motor constructed by SpaceDev, enabled for a sample return mission and carrying sufficient propellent and lightweight.

The customers may be universities, scientific institutes, organizations like Mars Society and AMSAT.

This way SpaceX might be able to substitute the lost customer Bigelow Aerospace perhaps. SpaceX could delay the launch because the new virtual customer (virtual because it is a group of joint customers) will not have ready his concepts and equipment until Q2 2006.

...



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Last edited by Ekkehard Augustin on Thu Mar 10, 2005 7:49 am, edited 1 time in total.



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Post    Posted on: Wed Mar 09, 2005 8:21 pm
Thanks for the details about the SSO, I found no size details or masses in Scaled Composites online documents, and my estimates for mass is a bit low.

However, I had in mind the technology of the Space Dev motor rather than this exact design. These hybrids are rather adaptable, and a somewhat smaller motor would be no problem

LEO to Earth escape takes 3300 meters/sec Delta V, while Hohmann transfer to Mars “average orbit” (not the best case) only adds 400 meters/sec. Using the 250 sec vacuum ISP this 3700 m/s requires only 4.53 mass ratio. With 670 kg in LEO this leaves 148 kg on the way to Mars. The dead weight of a good liquid fuel motor system should be less than 10%. Use 48 kg (and remember that modest thrust, and small nozzle is adequate). Leaving 100 kg for “compact astronaut” and grub + small solar panels. How small can a human adult be who wants to do this – become the first person to set foot on Mars ? 40 kg? What do they need to survive for 260 days (given electrolysis for O2 regeneration)?

Note that with good small motors, a “near orbital” launch of the Falcon 1 would allow significantly greater payload, even after subtracting the added fuel for the final boost. I am not fixated on the SSO and am not particularly fond of Nitrous Oxide motors. However, they are a “proven “ technology, and I want to argue that human flight to Mars may be months – not years or decades – away.

WE, THE ENTREPRENEURS AND VISIONARIES, ARE NOT READY FOR IT!

I really like the Falcon 5, which by similar calculations can handle one full sized (or two compact) astronaut on a direct, one vehicle round trip to Mars. The hardware that remains to be developed can be built in a garage.


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Post    Posted on: Thu Mar 10, 2005 2:10 am
rpspeck wrote:
...148 kg on the way to Mars. The dead weight of a good liquid fuel motor system should be less than 10%. Use 48 kg (and remember that modest thrust, and small nozzle is adequate). Leaving 100 kg for “compact astronaut” and grub + small solar panels. How small can a human adult be who wants to do this – become the first person to set foot on Mars ? 40 kg? What do they need to survive for 260 days (given electrolysis for O2 regeneration)?
You are not really serious are you? A very small robotic probe maybe, but a manned vehicle that small? Get real!


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Post    Posted on: Thu Mar 10, 2005 3:11 am
I like your idea of a small robotic probe - it is time to show that private efforts can go into deep space.

But you miss my point about the human flights. Some people ARE serious about this kind of thing:

"Intrepid Voyagers : Stories of the World's Most Adventurous Sailors"
Alain Bombard, who tested his theories about surviving a shipwreck by crossing the Atlantic in a tiny sailing raft without taking food or water; You'll also find riveting accounts of: Hugo Vihlen's Atlantic crossing in the 6-foot April Fool.

Someone thinking far outside the box could be the first to walk on Mars! I am serious that a midget in a micro craft (probably more than 6 feet long) would have a shot at it. I concede that the Falcon 5 makes far more sense (with a one year delay?). I don't concede that a mega billion dollar NASA effort is worth waiting for (and I don't think one will ever happen).


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