Thursday, July 10, 2014

Space topics from Dr. Plata

Doug Plata recently suggested some possible space exploration topics. All of them are very interesting.

Dr. Plata has good ideas and invests a great deal of time and effort looking at them. He's involved in two excellent websites: LunarCOTS.com and CisLunarOne.com .

July and August is a slow period for the Ajo Copper News, the weekly newspaper my sister and I publish. Most people with money and good sense leave Ajo, Arizona for the summer months. Hopefully I will have time to examine some of Plata's topics in my blog over the next few months.

Here they are:

Partial vs full reusability
Falcon 9 has nine engines on the first stage and one engine on the second stage.  So, if only the first stage is reused, it would seem to me that 9/10 engines would be recovered.  That's got to be a huge reduction in launch cost right there, yes?  Just how much?  Certainly achieving even partial reusability would make SpaceX even more competitive that it already is.  If the Falcon Heavy were to be partially reusable, reusing the lateral boosters would mean only 18 out of 28 engines would be recovered unless the central core could be reused as well.

Propulsion service options
For a cis-lunar transportation system we most often think of fuel depots in LEO.  One problem with this is the need for fuel depots in multiple LEO planes with those depots being used only occasionally.  However, if propellant were coming from ice harvesting operations at the lunar poles, then conceivably an OTV could bring propellant into any LEO inclination just prior to a launch into that orbit from Earth.  However, in this scenario, do we even need LEO depots?  Why couldn't the OTV dock with the launched satellite and then use its own engines to boost the satellite to GTO or even GEO?  Do we need fuel depots or could propulsion service be enough?

Power options for lunar mining
Say you are wanting to do ice harvesting operations in a lunar polar permanently shadowed crater with the rim of such having a peak of eternal light (PEL).  Great, but there's still potentially kilometers of distance between the source of power and the ice harvesting operations site.  How to deal with that gap?  RTGs?  Laser beaming of power?  Drive a rover laying a cable down the side of the crater?  Hop the lander from the rim to the floor while draping a (superconducting) wire?  Or forget a solar panel farm at the PEL and crack the water at a fuel depot in orbit?  An interesting trade analysis.

Aerobraking
OTVs tend to be painted as broad, turtle-shaped craft.  But how do you launch and assemble such a thing?  Can aerobraking be done about as easily with a cylindrical-shaped OTV?  How about heat flaps popping out giving more surface area and control?  Necessary?  If one skims high enough in the atmosphere does one even need a heatshield?  What about using a lifting body form?

Travel times further out into the solar system
So if we develop the ability to safely send humans to Deimos, how much longer would it take to send them to Vesta, Ceres, and a Moon of Jupiter?
 
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ROCKETRY
Heavy Lift vs Single Stage vs Reusable vs Gun
Air launch
Partial vs Full reusability
Chemical versus liquid rockets

CIS-LUNAR TRANSPORTATION INFRASTRUCTURE
Propulsion service options
Power options for lunar mining
Aerobraking

ORBITAL DYNAMICS
The orbital dynamics of a Phobos vs Deimos vs surface mission

HUMAN FACTORS
Mass calculations of open-loop, vs closed chemical, vs ECLSS
How could an RP5 be provided?
How do the space radiation numbers compare between locations (i.e. LEO, free-space, lunar surface, Phobos, Mars?)
Animal studies
Partial gravity options

COLONIZATION
O'Neillian vs lunar colony - Where first?
Travel times further out into the solar system

3 comments:

JIm Baerg said...

Re: Aerobraking
http://selenianboondocks.com/category/mhd-aerobraking-and-tps/

has some information on the possibility of using a magnetic field to aerobrake in thinner air and reduce the heating of the spacecraft for the same deceleration rate.

Hollister David said...

Thanks Jim. Jon Goff has also been talking about magnetic braking on the NASAspaceflight forum. Very interesting stuff!

Standing Space said...

I've heard Doug Plata on the Space Show and I really like his ideas. Here are some spontaneous comments to the topics:

- PROPULSIONS SERVICE. I would think that the big potential market today is in GEO and they need recurring station keeping and thus refueling rather than tugging. But is it really sensible to service com sats? After 10 or so years they need to be replaced by newer technology anyway and its simpler to launch them with enough fuel for that lifetime.

- POWER OPTIONS. Maybe the Dragon of SpaceX can land solar panels on one place, then send a rover or hopper into the shadow? Or the Dragon itself could hop around. A variant of the Red Dragon concept. At least as a precursor. However, SpaceX seems little interested in the Moon. A challenge might be to construct equipment which work in the extreme cold of the shadow.

- OUTER SOLAR SYSTEM. Nuclear thermal rockets is the way to go. They could still need Lunar water as propulsion, and for other purposes.

OTHER IDEAS:
* Have you considered using water ice on the Moon as construction material? Melting it and then freezing it to any shape.

* The charged Lunar dust might be "vacuumed" by an electrically charged bumper at the front of any rover. Once removed along a route, it might take many many years for the dust to return.