Bush Space Plan Unwise?

Sorry for being almost a week behind on this - I've been incommunicado.

Message: 2
Date: Fri, 05 Mar 2004 21:44:10 -0000
From: "George Perkins"
Subject: Re: Bush Space Plan Unwise?

[SNIP]

> Here's Mars Society's interpretation of Glenn's criticism of Bush's
> space plan:

> John Glenn Calls for "Direct to Mars" Plan
> March 5, 2004
> For further information about the Mars Society, visit our website at >
www.marssociety.org.

> In a speech delivered at Cape Canaveral, former astronaut and US
> Senator from Ohio John Glenn called for designing the new space
> initiative around "the direct to Mars" plan.

> John Glenn's comments were repoerted [sic] in Reuters wire story by
> Broward Liston, part of which is reproduced below.

> From Reuters:

> Glenn said he would support returning to the moon for research
> purposes, but urged the panel to seriously consider whether building
> habitable moon bases as a stepping stone to Mars was cost effective.

> "In effect you're making a Cape Canaveral out on the moon. It would
> be a smaller one, I'm sure, but it would be enormously complex,"
> Glenn said. "It just seems to me the direct-to-Mars (route) is the
> way to go."

> He warned NASA might "use up all our money on the moon and never get
> to Mars." One commission member, Neil de Grasse Tyson, an
> astrophysicist and director of the Hayden Planetarium in New York,
> called Glenn's testimony "refreshing in its candor."

> **** **** ****

> Glenn's comments about the need to avoid a massive Lunar diversion
> are right on the mark.

This is exactly the position you would expect Bob Zubrins pet martians
to take; Zubrin's books - and his scholarship and positions as advocated
in them - have, in this group, been criticized as intellectually
dishonest. His major fault seems to be the very human and
understandable failing of letting his desires dictate his beliefs; in
his eagerness to get a human footprint on Mars, he is willing to
dispense with anything which would seem to be a delay - even if that
means discarding prudence (establishing a permanent space-based
infrastructure) or intellectual honesty (the giant mirrors for an SPS
being utterly impossible in his estimation - but being part of his
design for martian terraforming). First and foremost, Zubrin (and, by
extension his Mars Society) is an ADVOCATE; he is trying to PUSH an idea
- it is a pursuit more akin to evangelism than to scholarly debate.
Data not favorable to his position is never mentioned - or sometimes
distorted.

> From the engineering point of view, the idea of launching Marsbound
> spacecraft from the Moon is utter nonsense. The reason why this is so
> is because rocket propulsion requirements to go from Low Earth Orbit
> (LEO) to the Moon and land are a delta V of 6 km/s, while it only
> requires 4.5 km/s of delta-V to go from LEO to Mars and land. So EVEN
> IF THE LUNAR CAPE CANAVERAL WERE ALREADY BUILT, and large supplies of
> rocket fuel were available right now, sitting in tanks on the lunar
> surface, and available FOR FREE, it would still make no sense for a
> Marsbound spacecraft to go to the Moon and refuel, as it would take
> more propellant in LEO to go to the Moon than it would to go straight
> to Mars.

Okay, here's an example of a distortion. These numbers seem familiar...
Ah, yes - here it is on page 98 in my copy of Zubrin's "Entering Space",
almost word for word. Trouble is, are these numbers accurate? For
reference, let me point you to
http://www.pma.caltech.edu/~chirata/deltav.html , which I found on my
first Google search for '"Delta V" Mars Moon'. I am sure other sources
are available. First, note the 'Apples to Oranges' comparison the
Delta-V for trips to and from each of the destinations are given FROM
LEO, as if all Mars bound craft launched from the moon would have to
burn 3.2 km/s to reach LEO before beginning its journey to mars! Zubrin
could have chosen to use the C3=0 earth orbit as the basis for his
comparison, but it would not have served his goal. The diagram on the
web page I have pointed you to is very helpful - and reveals this
fallacy in a very intuitive way. Doing the numbers, do they add up?
Well, from LEO to GTO to C3=0 to Lunar Orbit to Lunar surface is 2.5 +
0.7 + 0.7 + 1.6 = 5.5km/s; close enough that we can give Bob the benefit
of the doubt. And the trip from LEO to GTO to C3=0 to Mars Low Energy
Transfer Orbit to Mars C3=0 and beyond works out as 2.5 + 0.7 + 0.6 3.8km/s but note that this requires the use of aerobraking, making your
trip much slower or much deadlier - and one way. But what about leaving
from the moon? Let's see - Lunar Surface, to Lunar Orbit, to Earths
C3=0, to a similar Mars Low Energy Transfer Orbit is 1.6 + 0.7 + 0.6 2.9km/s.

> The "Lunar Cape Canaveral" is thus really a LUNAR TOLLBOOTH, which
> will cost decades of time and tens of billions of dollars to
> construct, and whose use, forced as a bureacratic [sic] imposition on
> Mars mission planners, would at least double the cost of Mars
> missions, assuming that any budget were available for Mars missions
> after the logistic burden costs required to support the Lunar
> Tollbooth itself are paid for.

I think here it is the "... decades of time ..." that Zubrin (and his
Mars Society) really hates; don't bother doing it right, just do it NOW.

> If you want to go to Mars, you need to go to Mars.

> An extensive disccusion [sic] on Mars mission designs that can
> actually achieve the goal of human Mars exploration will be held at
> the 7th International Mars Society Convention, Palmer House Hilton,
> Chicago, August 19-22, 2004. Registration is now open at
> www.marssociety.org.

> For further information about the Mars Society, visit our website at
> www.marssociety.org, or contact info@m....

Don't get me wrong, I like Bob Zubrin a lot - he has thought outside the
box on behalf of space at least once, and as an advocate for science
education and getting folks lined up behind a "Humanity Amongst the
Stars" vision, he's pretty good. But don't let him fool you - he can
blarney with the best of them, and his positions are carefully
constructed to support the irrational belief that everything in space
must be, always and only, Mars.