to Mars and back

In a recent Brain Cox documentary, he produced a book from his childhood,
which predicted that there would be spaceliners travelling to and from
Mars in 2015.
Seems rather optimistic speculation.
We need rockets about 10 times as powerful, and about 1/000th the cost
of 20th century technology.

In article ,
says...

In a recent Brain Cox documentary, he produced a book from his childhood,
which predicted that there would be spaceliners travelling to and from
Mars in 2015.

So did most of the "space" books I read in the library in the 1970's
(books written either at the height of Apollo/Saturn or shortly
thereafter).

Seems rather optimistic speculation.

Not at all. What was optimistic was the assumption that NASA funding
would continue at the same level as it was during the height of
Apollo/Saturn development. That assumption was proven false.

We need rockets about 10 times as powerful, and about 1/000th the cost
of 20th century technology.

In terms of size, no, we don't. Saturn V would have been enough.
Falcon Heavy would be big enough too, given enough launches.

In terms of cost, I'm not sure we "need" three orders of magnitude in
cost reduction. Besides, we're well on our way to big cost reductions.
SpaceX is disrupting the industry with its low cost, and they've yet to
reuse a single first stage booster. Give them 5 to 10 years, and I'll
bet they'll demonstrate low enough launch costs for manned Mars missions
(if NASA would stop throwing billions down the SLS rat hole and instead
spend that money on actual Mars vehicles).

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On Sunday, February 22, 2015 at 10:48:08 PM UTC-5, Jeff Findley wrote:
In article ,
says...
Seems rather optimistic speculation.

Not at all. What was optimistic was the assumption that NASA funding
would continue at the same level as it was during the height of
Apollo/Saturn development. That assumption was proven false.

We need rockets about 10 times as powerful, and about 1/000th the cost
of 20th century technology.

In terms of size, no, we don't. Saturn V would have been enough.
Falcon Heavy would be big enough too, given enough launches.


Most Mars mission profiles from the 70's I recall, envisioned a nuclear upper stage. In the Saturn V configuration we're talking the 3rd stage, I believe.
Such technology was very close at hand in the early 70's but as you point out the funding had been cut off much earlier. Jeff, do you recall if there were other, pure chemical configurations based on Saturn V (either via fuel depot and/or multiple launches)? I keep remembering the timeline of ~1986 being tossed around as a "realistic" deadline for the first Saturn V derivative Mars missions. Of course that was all before we got the Space Truck fever!

In terms of cost, I'm not sure we "need" three orders of magnitude in
cost reduction. Besides, we're well on our way to big cost reductions.
SpaceX is disrupting the industry with its low cost, and they've yet to
reuse a single first stage booster. Give them 5 to 10 years, and I'll
bet they'll demonstrate low enough launch costs for manned Mars missions
(if NASA would stop throwing billions down the SLS rat hole and instead
spend that money on actual Mars vehicles).

Were that there were a way to convince Congresspeople that building Mars vehicles atop the soon to be existing commercial fleet would keep as many people employed as is building yet another redundant rocket.

And of course let's not forget the sheer cost of SLS operations. Which sets a very high barrier to entry for ANY mission that would attempt to leverage it.

Dave

In article ,
says...

On Sunday, February 22, 2015 at 10:48:08 PM UTC-5, Jeff Findley wrote:
In article ,
says...
Seems rather optimistic speculation.

Not at all. What was optimistic was the assumption that NASA funding
would continue at the same level as it was during the height of
Apollo/Saturn development. That assumption was proven false.

We need rockets about 10 times as powerful, and about 1/000th the cost
of 20th century technology.

In terms of size, no, we don't. Saturn V would have been enough.
Falcon Heavy would be big enough too, given enough launches.


Most Mars mission profiles from the 70's I recall, envisioned a nuclear upper stage. In the Saturn V configuration we're talking the 3rd stage, I believe.
Such technology was very close at hand in the early 70's but as you point out the funding had been cut off much earlier. Jeff, do you recall if there were other, pure chemical configurations based on Saturn V (either via fuel depot and/or multiple launches)? I keep remembering the timeline of ~1986 being tossed around as a "realistic" deadline for the first Saturn V derivative Mars missions. Of course that was all before we got the Space Truck fever!

Note that even with a nuclear upper stage, you still needed a lot of LH2
to "fuel" it, so the cryogenic storage problem would still need to be
solved (at least to the point of "good enough") with nuclear.

When you look at those sorts of details, nuclear wasn't really "needed".
It was part of the "everything and the kitchen sink" R&D that came with
Apollo/Saturn's blank checks.

Either a nuclear upper stage or cryogenic fuel depots could have been
used with conventional LOX/LH2 engines (J-2 wasn't a bad engine for its
time and had upgrade potential, just as the F-1 was being upgraded to
the F-1A).

In terms of cost, I'm not sure we "need" three orders of magnitude in
cost reduction. Besides, we're well on our way to big cost reductions.
SpaceX is disrupting the industry with its low cost, and they've yet to
reuse a single first stage booster. Give them 5 to 10 years, and I'll
bet they'll demonstrate low enough launch costs for manned Mars missions
(if NASA would stop throwing billions down the SLS rat hole and instead
spend that money on actual Mars vehicles).

Were that there were a way to convince Congresspeople that building Mars vehicles atop the soon to be existing commercial fleet would keep as many people employed as is building yet another redundant rocket.

And of course let's not forget the sheer cost of SLS operations. Which sets a very high barrier to entry for ANY mission that would attempt to leverage it.

The biggest barrier to putting men on Mars is the myth that "heavy
lift", in the form of a very large expendable vehicle, is needed. What
is needed is low cost launches measured in cost per kg to LEO. Falcon
Heavy with reusable booster and core first stage is a step in the right
direction.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On Monday, February 23, 2015 at 6:35:01 PM UTC-5, Jeff Findley wrote:
In article ,
david.l.spain says...

On Sunday, February 22, 2015 at 10:48:08 PM UTC-5, Jeff Findley wrote:
In article ,
pedro1492 says...
Seems rather optimistic speculation.

Not at all. What was optimistic was the assumption that NASA funding
would continue at the same level as it was during the height of
Apollo/Saturn development. That assumption was proven false.

We need rockets about 10 times as powerful, and about 1/000th the cost
of 20th century technology.

In terms of size, no, we don't. Saturn V would have been enough.
Falcon Heavy would be big enough too, given enough launches.


Most Mars mission profiles from the 70's I recall, envisioned a nuclear upper stage. In the Saturn V configuration we're talking the 3rd stage, I believe.
Such technology was very close at hand in the early 70's but as you point out the funding had been cut off much earlier. Jeff, do you recall if there were other, pure chemical configurations based on Saturn V (either via fuel depot and/or multiple launches)? I keep remembering the timeline of ~1986 being tossed around as a "realistic" deadline for the first Saturn V derivative Mars missions. Of course that was all before we got the Space Truck fever!

Note that even with a nuclear upper stage, you still needed a lot of LH2
to "fuel" it, so the cryogenic storage problem would still need to be
solved (at least to the point of "good enough") with nuclear.

When you look at those sorts of details, nuclear wasn't really "needed".
It was part of the "everything and the kitchen sink" R&D that came with
Apollo/Saturn's blank checks.

Either a nuclear upper stage or cryogenic fuel depots could have been
used with conventional LOX/LH2 engines (J-2 wasn't a bad engine for its
time and had upgrade potential, just as the F-1 was being upgraded to
the F-1A).


Sorry to revive an old thread, but upon reflection and re-reading this some time later I realize what I remembered was a configuration of "assembled-in-orbit" cluster of Saturn V 3rd stages all feeding their own nuclear engine. I suppose in this configuration the 3rd stage was significantly modified to hold only LH2 or mostly LH2 with significantly reduced O2 tanks for air and water (with H2+O fuel cell combination?) for the trans hab module that sat on top of the core this cluster.

Dave

wrote in message
...

In a recent Brain Cox documentary, he produced a book from his childhood,
which predicted that there would be spaceliners travelling to and from
Mars in 2015.
Seems rather optimistic speculation.
We need rockets about 10 times as powerful, and about 1/000th the cost
of 20th century technology.


"Powerful" isn't the real issue. Efficiency is.

As for cost, we're getting there. SpaceX is really changing the
environment.
--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

In article ,
says...

wrote in message
...

In a recent Brain Cox documentary, he produced a book from his childhood,
which predicted that there would be spaceliners travelling to and from
Mars in 2015.
Seems rather optimistic speculation.
We need rockets about 10 times as powerful, and about 1/000th the cost
of 20th century technology.


"Powerful" isn't the real issue. Efficiency is.

I'll agree if "efficiency" is defined as cost per kg to LEO. SpaceX has
proven that "efficient" engines, at least in terms of ISP, are
absolutely not needed to deliver satellites to LEO, geosynch transfer
orbit, and even beyond (recent Goresat launch).

As for cost, we're getting there. SpaceX is really changing the
environment.

They're introducing disruptive business practices. Technology, not so
much. Nothing they're doing is "new tech".

Jeff

--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

"Jeff Findley" wrote in message
...

In article ,
says...

wrote in message
...

In a recent Brain Cox documentary, he produced a book from his
childhood,
which predicted that there would be spaceliners travelling to and from
Mars in 2015.
Seems rather optimistic speculation.
We need rockets about 10 times as powerful, and about 1/000th the cost
of 20th century technology.


"Powerful" isn't the real issue. Efficiency is.

I'll agree if "efficiency" is defined as cost per kg to LEO. SpaceX has
proven that "efficient" engines, at least in terms of ISP, are
absolutely not needed to deliver satellites to LEO, geosynch transfer
orbit, and even beyond (recent Goresat launch).

Actually I was thinking more along the lines of also things like using
upsized ion or hall thrusters for slow but efficient movement of cargo
there.

But you're right. It's not about higher ISP or higher thrust, but cost per
pound ultimately. If I can lift 2x as much mass as you for the same cost, I
"win".


As for cost, we're getting there. SpaceX is really changing the
environment.

They're introducing disruptive business practices. Technology, not so
much. Nothing they're doing is "new tech".

Mostly. I mean landing and re-use is arguably "new tech".

But yeah, as I saw, I expect SpaceX to do far more to get us to Mars than
SLS ever will.



Jeff


--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

In article ,
says...

"Jeff Findley" wrote in message
...

In article ,
says...

wrote in message
...

In a recent Brain Cox documentary, he produced a book from his
childhood,
which predicted that there would be spaceliners travelling to and from
Mars in 2015.
Seems rather optimistic speculation.
We need rockets about 10 times as powerful, and about 1/000th the cost
of 20th century technology.


"Powerful" isn't the real issue. Efficiency is.

I'll agree if "efficiency" is defined as cost per kg to LEO. SpaceX has
proven that "efficient" engines, at least in terms of ISP, are
absolutely not needed to deliver satellites to LEO, geosynch transfer
orbit, and even beyond (recent Goresat launch).

Actually I was thinking more along the lines of also things like using
upsized ion or hall thrusters for slow but efficient movement of cargo
there.

But you're right. It's not about higher ISP or higher thrust, but cost per
pound ultimately. If I can lift 2x as much mass as you for the same cost, I
"win".


As for cost, we're getting there. SpaceX is really changing the
environment.

They're introducing disruptive business practices. Technology, not so
much. Nothing they're doing is "new tech".

Mostly. I mean landing and re-use is arguably "new tech".

DC-X proved VTVL was viable for cryogenic, liquid fueled, rocket powered
vehicle decades ago. So, VTVL for a first stage is not really "new
tech". It's just that the dinosaurs at the time didn't want to continue
funding for that path. Instead, NASA "proved" we didn't have the tech
for affordable reusable spaceflight by picking a VTHL lifting body
design to try next. They completely ignored the successes of DC-X and
****ed away about $1 billion on a program that never flew a single
flight.

The fact is, we've had the tech for VTVL for a long time, but have not
had the right management to execute using that tech.

But yeah, as I saw, I expect SpaceX to do far more to get us to Mars than
SLS ever will.

No doubt. SLS excels at spending tens of billions of dollars with
little to nothing to show for it. SpaceX developed and flew the
original Falcon 9 for less than a single billion dollars.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer