Another successful SpaceX launch and landing

Rick Jones explained on 7/22/2016 :
Snidely wrote:
Thursday, Rick Jones quipped:
If I recall past discussions correctly, that is some sort of
stiffening band/ring that is expected to detach sortly after
engine start-up.

I thought it looked like that sort of item, but I don't think I have
noticed it on previous flights. Thanks.

A bit of web searching "falcon 9 stiffening ring" turned-up:

http://www.spacex.com/news/2013/02/0...ght-1-pictures


Thanks again!

/dps

--
I have always been glad we weren't killed that night. I do not know
any particular reason, but I have always been glad.
_Roughing It_, Mark Twain

In article ,
says...

Jeff Findley wrote:

Certainly it would be possible to orbit fully fueled stages. But, the
issue you run into with that approach is a lot of extra engine mass when
you're talking about something like a Mars departure stage for a manned
mission if every stage delivered to orbit has its own engine.

You can avoid that problem by launching an upper stage then launching
fully fueled drop tanks to attach to the stage. But, once you start
down the path of launching fully fueled tanks, you're going to be
dealing with connecting plumbing and structures in LEO. If the fuel
and/or oxidizer is cryogenic, then add to that the desire to "top off"
the tanks before starting the mission. If topping off the tanks is
done, you're most of the way to the tech needed for an orbital fuel
depot.


All the refueling hardware doesn't ride free, either. You're going to
need lots of complicated plumbing, structure to attach the tanks (even
if only temporarily to transfer fuel if you don't use them as 'drop
tanks'), 'tug' engines of some kind to bring all your bits together,
docking sensors, etc, etc, etc.

I'm not convinced all that weighs less than the engine and you either

Fair enough. The thought is that much of this mass and complexity stays
with the fuel depot. As such, its mass doesn't really matter to the
missions launched from there. The other detail is that there may be
efficiencies to gain in terms of scale. Let's say we scale a reusable
first stage to be as large as is "practical" and compare two different
approaches to using it...

At the most extreme end of this scale, say a very large TSTO puts a
stretched, empty, 2nd stage into LEO to be refueled by a depot. This
orbited stage is sized to be big enough such that only one is needed for
an earth departure stage for a manned Mars mission. The size of that
stage (i.e. volume for fuel and oxidizer) will be far larger than the
size of a fully fueled (3rd stage) lofted by a TSTO with an identically
sized first stage. So, by launching fully fueled stages, you will
surely need more than one fully fueled 3rd stage for your manned Mars
departure.

In this case, it is the fully fueled stage approach which requires extra
structure to tie the needed stages together. The far larger stage which
reaches LEO empty needs only structure to attach it to the manned Mars
mission payload.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

On Saturday, July 23, 2016 at 9:02:24 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

In low Earth orbit, electromagnetic forces can be exploited with solar power, to modify the orbit of a satellite to achieve any plane change or effect rendezvous without any use of propellant.

https://www.researchgate.net/publica...ulsion_systems


If you've got a few decades, perhaps.




On Friday, July 22, 2016 at 9:51:49 AM UTC+12, Fred J. McCall wrote:
bob haller wrote:

fuel could be sent to orbit in tanks, powered by a railgun type launch run up the side of a high mountain...

Such a railgun could only launch to specific orbits which may not be
the ones where you need the fuel. However, regardless of that, any
method you have for putting fuel in tanks on orbit would work equally
well for putting fully fueled stages on orbit and you don't need all
the automated refueling systems.

Put the fueled stages where you want them when you want them there. I
don't see any case where that is not a net win over having to develop
all the on orbit refueling technology so that you can refuel spent
stages that may not even be where you need them to be.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw



Tethers have been flown in space since 1996. When a direct current is applied to a conductive tether, it exerts a Lorentz force against the Earth's magnetic field, and the tether exerts a force on the vehicle. It can be used either to accelerate or brake an orbiting spacecraft changing its orbit over a few days. Solar power is used to accelerate a vehicle. 10,000s of watts can be generated as well, when slowing a spacecraft.

In 2012, the company Star Technology and Research was awarded a $1.9 million contract to qualify a tether propulsion system for orbital debris removal.. Thrusts are on the order of 10 to 100 milligees. This is enough to impart 1 km/sec in 20 minutes to 200 minutes. That's less than three hours - far less than a decade!

William Mook wrote:

On Monday, July 25, 2016 at 11:26:20 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

Updated with slight corrections and clarifications of certain details;

My friend Keith Loftstrom ...


There's the 'detail' you need to correct. Loftstrom couldn't pick you
out of a lineup, you self-aggrandizing ****.


I see that you are resigned to believe whatever you like, but I know Keith, and he knows me. I'm sorry you can't see that.


Yeah, sure. And monkeys might fly out my butt.


--
"False words are not only evil in themselves, but they infect the
soul with evil."
-- Socrates

William Mook wrote:

I see that you are resigned to believe what you like, but I know Keith, and he knows me. I'm sorry you can't see that.


Yeah, sure. And monkeys might fly out my butt.

On Monday, July 25, 2016 at 11:24:05 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

On Sunday, July 24, 2016 at 12:36:45 AM UTC+12, Fred J. McCall wrote:
bob haller wrote:


Are you saying a railgun could launch a fuel tank fully fueled?


i believe so, a special fuel tank .......


Yeah, yours seems like a very 'special' scheme...

Bobbert, if you can launch a fuel tank you can launch a complete
stage. What you can't do is launch it to a desired orbital plane,
since your launch angle is fixed to a mountain. In fact, your
'special tank' is going to require engines anyway, else it's either
going into space forever or making one orbit and hitting the ground.


My friend Keith Loftstrom ...


I'd bet Loftstrom doesn't know you from Adam.


--
"False words are not only evil in themselves, but they infect the
soul with evil."
-- Socrates

William Mook wrote:

On Monday, July 25, 2016 at 11:25:11 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

My friend Keith Loftstrom ...


I'd bet Loftstrom doesn't know you from Adam.


I see that you are resigned to believe whatever you like, but I know Keith, and he knows me. I'm sorry you can't see that.


Yeah, sure. And monkeys might fly out my butt.


--
"False words are not only evil in themselves, but they infect the
soul with evil."
-- Socrates

William Mook wrote:

Since SpaceX intends to build colonies on Mars, it makes sense to look at the best way to achieve that. Using LOX/LNG rockets throughout requires far more launches than using a solar powered ion engine on orbit.

Landing on Diemos, and using water resources there, along with the solar power array, to execute many landings at many locations on the surface, during your stay on mars, is also beneficial early on.

So, for these reasons, what I say is perfectly germaine to this thread.


The thread was never about refueling AT MARS until you Mookjacked it
to push one of your constant loony ideas.

On Saturday, July 23, 2016 at 9:00:23 AM UTC+12, Fred J. McCall wrote:
Thank you for your non-answers, clearly demonstrating that you're just
Mookjacking the thread.

William Mook wrote:

On Friday, July 22, 2016 at 12:26:19 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

On Thursday, July 21, 2016 at 2:16:01 PM UTC+12, Greg (Strider) Moore wrote:
"Fred J. McCall" wrote in message
...

bob haller wrote:

i wonder if stages could be put in orbit, strapped together somehow, and
used to boost very large cargo runs to mars?

the boosters would need refueled. but their cost would be very low


There are those who disagree with me, but I've never seen the point of
refueling until we have a LOT more going on. Since you've got to
boost the fuel up anyway, why not just boost fully fueled stages?


Yeah... that's the part I can't figure out... what you really save here.
I'll admit I think it's an interesting idea, but not sure how it works
(besides the obvious logistical issues already mentioned.)


http://www.spacefuture.com/archive/t..._company.shtml

If Diemos has as much water as its low density suggests, the best place to set up a base for Mars exploration and development will likely be Diemos.


Non sequitur.

No, its relevant to a practical mission. Its you who obviously cannot see it.

Which part of "refueling spent stages in Earth orbit"
was it that took you to Mars?

Which part of having very high specific impulse stage on orbit is superior solution to having more low impulse propellant on orbit? This is part of the mission planning process and provides for a superior Mars mission cycle.

Getting propellant already present in Mars' orbit does the most to simplify mission planning for a Mars mission. Particularly if high specific impulse propulsion is available on orbit at Earth - as outlined in 1954. Today we use highly concentrating solar collectors in conjunction with hyper-efficient photovoltaics as described in my patents on the subject.

* * *
Refuelling on Mars
* * *

Let's consider a Falcon Heavy launching LNG/LOX propellant to refuel an upper stage that has a 3.3 km/sec exhaust velocity with the ability to make LNG/LOX on Mars after landing on Mars.

The payload is 54,000 kg - with 20,000 kg Dragon capsule equipped with a landing on Mars and return to Mars orbit, and 34,000 kg inflatable Mission module similar to a B330 module, with long term life support.

We need a hyperbolic excess velocity at Earth of 4.5 km/sec. We need a hyperbolic excess velocity at Mars of 3.0 km/sec. We need a delta vee on orbit of 4.2 km/sec to fly to Mars. With a 3.3 km/sec this implies a propellant fraction of 72.0% - and with a 3.0% structure fraction, we have a payload fraction of 25.0%. So, with a 54,000 kg payload, that's a stage weight of 216,000 kg with 162,000 kg of propellant.

So, we need one Falcon Heavy launch to put up the vehicle, and three more Falcon Heavy Launches to put up the propellant. This propellant gets burned, and the Red Dragon separates and lands on Mars, whilst the mission module brakes into a Mars Synchronous orbit over the Dragon capsule landing site.

The Red Dragon uses sunlight to convert water into hydrogen and oxygen, and uses the hydrogen to gather carbon dioxide from the Martian atmosphere to make methane. The 20,000 kg payload must be accelerated to 3.56 km/sec. This means that the stage weight is 3x the payload and the propellant is 2x the payload. This is 40,000 kg of LOX/LNG that must be made from Martian resources. With a 3.21 to 1.00 Oxygen to Fuel mass ratio

http://www.dlr.de/Portaldata/55/Reso...5-0212prop.pdf

This means that we make 9,502 kg of methane and 30,499 kg of oxygen. The methane contains 2,375.3 kg of hydrogen and using the Sabatier process;

CO2 + 4 H2 -- CH4 + 2 H2O

requires 4,751 kg of hydrogen to make the required methane, since half the hydrogen goes back into water! Using process water reduces new water input

2 H2O + 2 H2O (process) = 4 H2O
4 H2O + energy -- 4 H2 + 2 O2

So, to make 4,751 kg of hydrogen requires 42,768 litres of water half of which is recycled. So, 21,384 litres of fresh water is required . 673.7 gigajoules of energy is required to make this propellant at a minimum.

With a 180 day stay time this is 3.75 GJ/day. With a 12 hour insolation and 510 W/m2 we require a large concentrator that tracks the Sun producing 16 peak megawatts reliably for 12 hours.

This boosts the lander to orbit where it docks with the mission module and returns to Earth.

Meanwhile, on orbit, the mission module makes its way to Diemos and refuels there. Leaving Mars requires a hyperbolic excess velocity of 3 km/sec and Mars' escape velocity is 5.03 km/sec. So, the total delta vee from the Surface is 5.9 km/sec and from Diemos 4.6 km/sec. This requires 108,000 kg of propellant, and a similar calculation can be done for Diemos. This requires a source of water and carbon be found on the tiny moon.

* * *
All Propellant
* * *

Alternatively, a dozen launches to orbit can be made to lift 108,000 kg of propellant to Mars, and another four launches to orbit can be made to lift 40,000 kg of propellant to Mars to deposit on the surface. This reduces the power requirements on Mars and improves reliability - at a tremendous cost in launches;

(1) - Mars vehicle 54,000 kg - lander + mission module
(2),(3),(4) 162,000 kg - departure propellant.
(5) - Mars orbit propellant (54,000 kg)
(6),(7),(8) 162,000 kg - departure propellant.
(9) - Mars orbit propellant (54,000 kg)
(10),(11),(12) - 162,000 kg - departure propellant.
(13) - Mars return propellant (and supplies) (40,000 kg + 14,000 kg supplies)
(14),(15),(16) - 162,000 kg - departure propellant.

For safety its best to have three mission vehicles, with spare capacity. So, we're talking 48 launches altogether. Another 2 launches for support, news and promotion.

At $60 million per launch, and $40 million per payload - that's $4.8 billion.

With hardware strewn across the inner solar system, and only the capsule recovered!

* * *

Now, compare this to the two launches required with the updated Sthulinger style mission described earlier! At $100 million per launch, a dozen vehicles are sent for $2.4 billion - half the cost - and ALL the hardware is FULLY REUSED with MULTIPLE LANDINGS FROM ORBIT over the period. We only need find water on Diemos or Phobos. If we do not, we can return to Earth, reuse the vehicles, and orbit the fuel for another $1.2 billion! We could also have a handful of landings from propellant brought along - regardless. So, we have one or two or three landings and return - from the one dozen vehicles - and a thorough root around Diemos and Phobos.

Awesome!

* * *

--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

On Tuesday, July 26, 2016 at 10:26:30 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

On Monday, July 25, 2016 at 11:26:20 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

Updated with slight corrections and clarifications of certain details;

My friend Keith Loftstrom ...


There's the 'detail' you need to correct. Loftstrom couldn't pick you
out of a lineup, you self-aggrandizing ****.


I see that you are resigned to believe whatever you like, but I know Keith, and he knows me. I'm sorry you can't see that.


Yeah, sure. And monkeys might fly out my butt.


--
"False words are not only evil in themselves, but they infect the
soul with evil."
-- Socrates

Interesting reply... lol.

https://www.youtube.com/watch?v=lPruGs4IyK4

On Tuesday, July 26, 2016 at 10:27:01 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

I see that you are resigned to believe what you like, but I know Keith, and he knows me. I'm sorry you can't see that.


Yeah, sure. And monkeys might fly out my butt.

On Monday, July 25, 2016 at 11:24:05 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

On Sunday, July 24, 2016 at 12:36:45 AM UTC+12, Fred J. McCall wrote:
bob haller wrote:


Are you saying a railgun could launch a fuel tank fully fueled?


i believe so, a special fuel tank .......


Yeah, yours seems like a very 'special' scheme...

Bobbert, if you can launch a fuel tank you can launch a complete
stage. What you can't do is launch it to a desired orbital plane,
since your launch angle is fixed to a mountain. In fact, your
'special tank' is going to require engines anyway, else it's either
going into space forever or making one orbit and hitting the ground.


My friend Keith Loftstrom ...


I'd bet Loftstrom doesn't know you from Adam.


--
"False words are not only evil in themselves, but they infect the
soul with evil."
-- Socrates

https://www.youtube.com/watch?v=lPruGs4IyK4

On Tuesday, July 26, 2016 at 10:30:47 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

Since SpaceX intends to build colonies on Mars, it makes sense to look at the best way to achieve that. Using LOX/LNG rockets throughout requires far more launches than using a solar powered ion engine on orbit.

Landing on Diemos, and using water resources there, along with the solar power array, to execute many landings at many locations on the surface, during your stay on mars, is also beneficial early on.

So, for these reasons, what I say is perfectly germaine to this thread.


The thread was never about refueling AT MARS until you Mookjacked it
to push one of your constant loony ideas.

The thread is about mission planning for a Mars trip. The ideas I relate are relevant to that. The ideas are not my ideas. They're ideas of the industry's best and brightest. They're ideas of friends of mine.

They are sane sensible and important to the problem being discussed in this thread. Anyone with an ounce of knowledge in the field, can see this.

Fact is, anyone who knows anything about mission planning knows that how you handle operations at your destination determines what you need on Earth at take off and on Earth orbit before departure.

John Houbolt proved that for Apollo and helpd America achieve the goal set by Kennedy for that programme.

Others like my friend Robert Zubrin have applied this to refueling on Mars to optimise mission performance for a Mars mission during his tenure at Lockheed.

Others have proposed similar approaches as well, involving extraction of water from Diemos to make propellant. This is what you're objecting to, which I've cited previously.

How you handle operations in lunar orbit determines the size of launcher you need
https://www.youtube.com/watch?v=9dQ6323HQ1U

How you handle operations on Mars' surface determines the size of launcher you need.
http://www.spacefuture.com/archive/t..._company.shtml

How you handle operations in Mars orbit, determines the size of launcher you need.
https://www.youtube.com/watch?v=NMZy2gxrF4g

Cooking water out of the rocks at Diemos.
http://www.spacefuture.com/archive/i..._company.2.gif

In addition to planning your mission efficiently as described above, all competent rocket scientists also know the benefit of high specific impulse low thrust, low power engines. The advantages of ion propulsion is well known and has been known early on. High specific impulse engines too favourably impact the size of the launcher you need to accomplish a mission to Mars and the cost of the mission.

Anyone familiar with the history of space exploration know ion engines have been looked at in detail by very competent folks like Ernst Sthulinger as far back as the 1950s.

I personally have had the great good fortune to meet Ernst when he gave a colloquim on the subject of Mars exploration back in the 1970s when I was an aerospace engineering student there. Ernst was good friends with Garvin vonEschen. Garvin taught me space propulsion engineering. A subject I aced as a graduate student at OSU.

https://www.youtube.com/watch?v=8vblN33OJCg

A landing on Diemos and Phobos to determine the availability of water there is an important detail for early Mars explorers.

Here is the delta vee budgets;

https://en.wikipedia.org/wiki/Delta-...lar_System.svg

From LEO to Mars Transfer is 3.8 km/sec. From Mars Transfer to Diemos surface is 1.2 km/sec. A total delta vee of 5.0 km/sec. To transfer from Diemos to Mars atmosphere requires 1.4 km/sec and to return to Diemos requires 5.5 km/sec.

Here's the specification on Stulhinger's 1954 atomic powered ion ship, using a variant of the same nuclear reactor that was used aboard the SSN-571, equipped with a large radiator for the closed Brayton cycle engine it powered;

Payload: 136,000 kg (299,000 lb). Thrust: 490 N (110 lbf). Gross mass: 660,000 kg (1,450,000 lb). Unfuelled mass: 328,000 kg (723,000 lb). Specific impulse: 8,200 s. Height: 46.00 m (150.00 ft).

Now,

(1) since lightweight inflatable solar concentrators with high intensity hyper efficient photovoltaics, have greater specific power density than 1950s era nuclear reactors, and

(2) since the size of these concentrators is about the same as the radiator area of the nuclear reactor proposed by Stulhinger originally, and

(3) since performance and thrust to weight of modern micro-scale ion engines are superior to that of the 1950s (credited in part to Sthulinger's continuing work on the problem of ion engines throughout his career), and

(4) since computing performance is leagues ahead of the 1950s, and

(5) since micro-scale life support and power management, is vastly superior than anything in 1950s, and

(6) since materials available today outclasses anything available in the 1950s,

we can do vastly better than proposed in Sthulinger's original 1954 study.

In fact by the 1970s, Sthulinger in personal conversations with me and my propulsion engineering class, said then he could drop the size of his system proposed in 1950s by a factor of 6. First by reducing the crew from a crew of 20 to a crew of 6 and reduce weight by a factor of 6 - to 110,000 kg - small enough to be launched by a single Saturn V using the advances achieved during Apollo!

Nearly half of this was the Mars Excursion Module

http://www.astronautix.com/m/mem.html

Here the ion propelled mother ship moves from LEO to LMO and lands a Mars Excursion Module on Mars while the mother ship remains on orbit. The Mars Excursion Module then returns to LMO connects with the mother ship and flies to reconnoiter Diemos and Phobos.

Getting rid of the Mars Excursion Module, and using a rocket belt and wingsuit combination to land on Mars and return to Mars orbit,

https://goo.gl/DhujNG

So, we take the 110 tonne mass of Stulhinger's later configurations, and remove 49 tonnes of payload attributed to the Mars Excursion Module, and replace it with a 9 tonne Dragon capsule for Earth return and emergency escape. We end up with 70 tonnes. We add 6 half tonne rocket belts that let a single person land on Mars and return to Mars orbit. We now have the need to put up basically TWO Falcon Heavy launches.

We use a BA330 inflatable module, and a Dragon capsule, in combination with advanced ion propulsion and very high power photovoltaics

http://www.nasa.gov/centers/glenn/about/fs21grc.html

http://www.google.com/patents/US20050051205

This lets us send 6 people to Mars and return them with a brief visit to the Martian surface. We also equip them with the ability to extract water from the rocks of Diemos and Phobos, and make hydrogen and oxygen via electrolysis using the solar energy system that powers the ion engine. This lets us refuel the ion engine and the rocket belts. We can drop a quarter tonne one way to the Mars surface, using these rocket belts as drones. This is plenty to stay for long periods of time on the Martian surface.

So, two flights of a Falcon Heavy - one with a Dragon Capsule and BA 330 inflatable module, and supplies for six people up to two years. Another an ion engine and solar power array, propellant, including propellant for six rocket belts that can deorbit land on the surface drop a payload and return. They can also take an astronaut with limited supplies to the Martian surface and return them to Mars orbit.

This ship flies to Mars, enters Mars orbit, and executes a landing on the surface of Mars for four of the six with two units in reserve. (an empty rocket belt flown from Mars orbit with extra fuel can recover two astronauts from the Martian surface).

Once that is achieved, the remaining time is spent on Mars orbit, exploring Diemos and Phobos. The main experiment here is to extract water and from that hydrogen and oxygen, to refuel the rocket belts! Success with this mission, permits all crew members to rotate to the Martian surface during the remainder of their stay, and to deposit supplies on the Mars surface for extended surface stays.

When the system returns, it enters LEO and the astronauts return via the Dragon Capsule. While on orbit, it operates as a space station. It requires only a single resupply mission of a Falcon Heavy to return to Mars. The solar power unit can also double as an experimental system to process materials on orbit and to beam power to test rigs on Earth.

People like my friend Jordin Kare have even helped organise companies to make laser power beaming a reality;

http://lasermotive.com

Eight launches of the Falcon Heavy permits four ships to be placed on orbit and allow 24 people to fly to Mars. The failure of any one system, allows the other three to support all 24 with reduced rations. 28 rocket belts across four ships provides a rather comprehensive capacity to explore the Martian surface extensively even if only for one visit per belt, with sufficient backup for rescue attempts.

Private Missions

Sixteen of the 24 persons could be selected from qualified persons who wish to pay for a trip to Mars and enter the history books. At a cost of $100 million each, $1.6 billion could be earned. This is enough to pay for the entire programme -built upon eight launches initially of a reusable ship.

https://spaceflightnow.com/2016/03/3...or-40-million/

Eight launches at $40 million each is $320 million. 80 tonnes per ship at $2 million per tonne is $160 million per ship. Times four ships is $640 million. A total cost of $960 million.

Earning $1.6 billion every 2.15 years gives us an average APR of 26.8% !!

Can it be sold?

In 2015, there was a record of 1,826 people who had over $1 billion in cash.. This icluded a record 290 newcomers with 71 from China, 57 from the US, 28 from India and Germany with 23. People under 40 had 46 join the list. A record of 197 women were on the list. The average net worth of the listed came in at US$3.86 billion.

Added together, the total net worth for 2015's billionaires was US$7.05 trillion.

Now, at a cost of $100 million out of $3.86 billion is 2.6% of their average net worth. A total of 16 out of 1826 is a market penetration of 0.9% . An achieveable figure. Typical market penetration is 3.4% to 5.9% for an ad campaigns. Leveraging a successful first mission to Mars, this could become a steady revenue generator for SpaceX.



On Saturday, July 23, 2016 at 9:00:23 AM UTC+12, Fred J. McCall wrote:
Thank you for your non-answers, clearly demonstrating that you're just
Mookjacking the thread.

William Mook wrote:

On Friday, July 22, 2016 at 12:26:19 AM UTC+12, Fred J. McCall wrote:
William Mook wrote:

On Thursday, July 21, 2016 at 2:16:01 PM UTC+12, Greg (Strider) Moore wrote:
"Fred J. McCall" wrote in message
...

bob haller wrote:

i wonder if stages could be put in orbit, strapped together somehow, and
used to boost very large cargo runs to mars?

the boosters would need refueled. but their cost would be very low


There are those who disagree with me, but I've never seen the point of
refueling until we have a LOT more going on. Since you've got to
boost the fuel up anyway, why not just boost fully fueled stages?


Yeah... that's the part I can't figure out... what you really save here.
I'll admit I think it's an interesting idea, but not sure how it works
(besides the obvious logistical issues already mentioned.)


http://www.spacefuture.com/archive/t..._company.shtml

If Diemos has as much water as its low density suggests, the best place to set up a base for Mars exploration and development will likely be Diemos.


Non sequitur.

No, its relevant to a practical mission. Its you who obviously cannot see it.

Which part of "refueling spent stages in Earth orbit"
was it that took you to Mars?

Which part of having very high specific impulse stage on orbit is superior solution to having more low impulse propellant on orbit? This is part of the mission planning process and provides for a superior Mars mission cycle.

Getting propellant already present in Mars' orbit does the most to simplify mission planning for a Mars mission. Particularly if high specific impulse propulsion is available on orbit at Earth - as outlined in 1954. Today we use highly concentrating solar collectors in conjunction with hyper-efficient photovoltaics as described in my patents on the subject.

* * *
Refuelling on Mars
* * *

Let's consider a Falcon Heavy launching LNG/LOX propellant to refuel an upper stage that has a 3.3 km/sec exhaust velocity with the ability to make LNG/LOX on Mars after landing on Mars.

The payload is 54,000 kg - with 20,000 kg Dragon capsule equipped with a landing on Mars and return to Mars orbit, and 34,000 kg inflatable Mission module similar to a B330 module, with long term life support.

We need a hyperbolic excess velocity at Earth of 4.5 km/sec. We need a hyperbolic excess velocity at Mars of 3.0 km/sec. We need a delta vee on orbit of 4.2 km/sec to fly to Mars. With a 3.3 km/sec this implies a propellant fraction of 72.0% - and with a 3.0% structure fraction, we have a payload fraction of 25.0%. So, with a 54,000 kg payload, that's a stage weight of 216,000 kg with 162,000 kg of propellant.

So, we need one Falcon Heavy launch to put up the vehicle, and three more Falcon Heavy Launches to put up the propellant. This propellant gets burned, and the Red Dragon separates and lands on Mars, whilst the mission module brakes into a Mars Synchronous orbit over the Dragon capsule landing site.

The Red Dragon uses sunlight to convert water into hydrogen and oxygen, and uses the hydrogen to gather carbon dioxide from the Martian atmosphere to make methane. The 20,000 kg payload must be accelerated to 3.56 km/sec. This means that the stage weight is 3x the payload and the propellant is 2x the payload. This is 40,000 kg of LOX/LNG that must be made from Martian resources. With a 3.21 to 1.00 Oxygen to Fuel mass ratio

http://www.dlr.de/Portaldata/55/Reso...5-0212prop.pdf

This means that we make 9,502 kg of methane and 30,499 kg of oxygen. The methane contains 2,375.3 kg of hydrogen and using the Sabatier process;

CO2 + 4 H2 -- CH4 + 2 H2O

requires 4,751 kg of hydrogen to make the required methane, since half the hydrogen goes back into water! Using process water reduces new water input

2 H2O + 2 H2O (process) = 4 H2O
4 H2O + energy -- 4 H2 + 2 O2

So, to make 4,751 kg of hydrogen requires 42,768 litres of water half of which is recycled. So, 21,384 litres of fresh water is required . 673..7 gigajoules of energy is required to make this propellant at a minimum.

With a 180 day stay time this is 3.75 GJ/day. With a 12 hour insolation and 510 W/m2 we require a large concentrator that tracks the Sun producing 16 peak megawatts reliably for 12 hours.

This boosts the lander to orbit where it docks with the mission module and returns to Earth.

Meanwhile, on orbit, the mission module makes its way to Diemos and refuels there. Leaving Mars requires a hyperbolic excess velocity of 3 km/sec and Mars' escape velocity is 5.03 km/sec. So, the total delta vee from the Surface is 5.9 km/sec and from Diemos 4.6 km/sec. This requires 108,000 kg of propellant, and a similar calculation can be done for Diemos. This requires a source of water and carbon be found on the tiny moon.

* * *
All Propellant
* * *

Alternatively, a dozen launches to orbit can be made to lift 108,000 kg of propellant to Mars, and another four launches to orbit can be made to lift 40,000 kg of propellant to Mars to deposit on the surface. This reduces the power requirements on Mars and improves reliability - at a tremendous cost in launches;

(1) - Mars vehicle 54,000 kg - lander + mission module
(2),(3),(4) 162,000 kg - departure propellant.
(5) - Mars orbit propellant (54,000 kg)
(6),(7),(8) 162,000 kg - departure propellant.
(9) - Mars orbit propellant (54,000 kg)
(10),(11),(12) - 162,000 kg - departure propellant.
(13) - Mars return propellant (and supplies) (40,000 kg + 14,000 kg supplies)
(14),(15),(16) - 162,000 kg - departure propellant.

For safety its best to have three mission vehicles, with spare capacity. So, we're talking 48 launches altogether. Another 2 launches for support, news and promotion.

At $60 million per launch, and $40 million per payload - that's $4.8 billion.

With hardware strewn across the inner solar system, and only the capsule recovered!

* * *

Now, compare this to the two launches required with the updated Sthulinger style mission described earlier! At $100 million per launch, a dozen vehicles are sent for $2.4 billion - half the cost - and ALL the hardware is FULLY REUSED with MULTIPLE LANDINGS FROM ORBIT over the period. We only need find water on Diemos or Phobos. If we do not, we can return to Earth, reuse the vehicles, and orbit the fuel for another $1.2 billion! We could also have a handful of landings from propellant brought along - regardless. So, we have one or two or three landings and return - from the one dozen vehicles - and a thorough root around Diemos and Phobos.

Awesome!

* * *

--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn