A near polar orbit station to act as transit point for lunar missions?

No doubt it is more "paper space plans" but would one even want to use
a space station in a near polar orbit as a transit point for a lunar
program?

http://perfscience.com/content/21464...rbital-station

rick jones
--
web2.0 n, the dot.com reunion tour...
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

"Rick Jones" wrote in message ...

No doubt it is more "paper space plans" but would one even want to use
a space station in a near polar orbit as a transit point for a lunar
program?

http://perfscience.com/content/21464...rbital-station

rick jones


I wouldn't hold my breath on this one. They talk big, but I don't think
economically they can pull this off.

Remember: http://en.wikipedia.org/wiki/Kliper

Or
http://en.wikipedia.org/wiki/Zarya_(spacecraft)

Or a dozen other projects.

When it comes to paper projects, they're as good as we are. ;-)



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

In article ,
says...

"Rick Jones" wrote in message ...

No doubt it is more "paper space plans" but would one even want to use
a space station in a near polar orbit as a transit point for a lunar
program?

http://perfscience.com/content/21464...rbital-station

rick jones


I wouldn't hold my breath on this one. They talk big, but I don't think
economically they can pull this off.

Remember: http://en.wikipedia.org/wiki/Kliper

Or
http://en.wikipedia.org/wiki/Zarya_(spacecraft)

Or a dozen other projects.

When it comes to paper projects, they're as good as we are. ;-)

Agreed. Russia plans a lot of things it can't afford to actually build.

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 19/11/14 01:03, Rick Jones wrote:
No doubt it is more "paper space plans" but would one even want to use
a space station in a near polar orbit as a transit point for a lunar
program?

http://perfscience.com/content/21464...rbital-station

rick jones

I would have thought that an equatorial orbit would be most useful for
lunar missions - it can be used for more secondary planetary missions,
launch windows come up every 90 minutes, TLI windows are plentiful, GTO
payloads are larger, and the orbital velocity provided by the rotation
of the earth is quite a plus when it comes to launching heavy payloads
from the ground - but an equatorial orbit requires a launch site on or
near the equator, which the Roosskies simply don't have.

No choice to go equatorial then, and near-polar has for the Russians the
advantage over near-equatorial that it covers most of the Earth,
especially northern Russia, giving earth-observation missions more
coverage (and being better for tourism "I can see my house down there");
and it has more TLI windows than a strictly polar orbit.


As for using a space station for a transit point, if you can do in-orbit
assembly then your orbital launchers can be smaller and thus cheaper;
the sweet spot there is probably about 10-20 tons LEO payload per
launch, with reasonable estimates of future total tonnage to LEO.

On-orbit assembly is a big advantage, and having a space station nearby
when you do it would help a lot more than it would hinder.

A'course, as the Russians already have 10-20 ton LEO launchers then if
they do do on-orbit assembly then they don't have to spend a gazillion
roubles developing a super-heavy for only a few missions.


If you already have a suitably-placed orbital station, using it for
on-orbit assembly of lunar missions would be a no-brainer - building one
just for that purpose, perhaps not so much, but if it has other purposes
as well..


Like others I doubt they'll get the financing, though breaking away from
the US collaboration on ISS might be sufficiently politically
advantageous (yes I know ESA, Japan, Canada and Brazil are in there too
- but it is widely seen as a US-Russian collaboration).

And ISS is only scheduled to last 'til 2020, and the russkies have said
they won't renew or extend that mission.

-- Peter Fairbrother

On Wednesday, November 19, 2014 2:03:25 PM UTC+13, Rick Jones wrote:
No doubt it is more "paper space plans" but would one even want to use
a space station in a near polar orbit as a transit point for a lunar
program?

http://perfscience.com/content/21464...rbital-station

rick jones
--
web2.0 n, the dot.com reunion tour...
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

A satellite in any orbital plane can transfer from Earth to Moon, and enter any orbital plane relative to the moon. This is shown with the Lunar Reconnaissance Orbiter (LRO) - which was launched into an orbit from Florida and entered a polar orbit around the moon.

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

As noted on Page 5 of this reference

http://babel.hathitrust.org/cgi/pt?i...iew=1up;seq=15

the inclination of the transfer orbit can vary from 0 to 180 degrees relative to the moon's path around the sun. So, its clearly possible to launch an object into a polar orbit around the Earth - from say New Zealand - and calculate a transfer orbit to the vicinity of the moon.

Of course these are minimum energy - free-return - trajectories. Other trajectories are possible if we allow more energy.

For example, a constant boost system that accelerates radially outward at two gees until sound speed is reached dropping back to one gee until an altitude of 100 km is reached. After which he vehicle then accelerates at 1 gee above local gravity - again radially outward until the moon rises above the Earth's horizon, then, you boost at 1 gee toward the moon, cancelling out the effect of gravity, directed toward the centre of the Earth.

For example, I am sitting at 43.533 degrees South Latitude and 172.674 degrees East Longitude on Thursday 20 November 17:12 NZT.

http://www.satellite-calculations.co...te/suncalc.htm

At this moment in time the Moon is 8.092 degrees above the Horizon since the moon is directly above a point on Earth located at 10.352 degrees South Latitude 84.449 degrees East Longitude

So, if I had a fusion powered rocket ship I could boost straight up at two gees for 26.6 seconds. I would achieve 260 m/sec (585 mph) and then cut back to one gee - to maintain that speed. I would maintain that speed for 384.6 seconds (6 minutes 24.6 seconds). I would then boost at an azimuth 263..5016 from North (relative to Earth's horizon) and 10.2883 degrees Elevation (again relative to Earth's horizon) at one gee - while boosting toward the Earth's centre (which changes with time) at nearly one gee - who's value falls off with distance from Earth's centre. This is achieved by properly orienting the thrust of the vehicle - and orienting the vehicle so we feel aboard the vehicle as if we're being accelerated at about 1.8 gees - falling off to nearly 1 gee in twenty minutes.

I would reach the halfway point to the moon in 6260.8 seconds (1 hr 44 min 20.8 seconds). At this time I would flip over and slow at one gee - until I reached the vicinity of the moon. As I approached the moon, the thrust would rise to 1/6th gee over one gee as I approached the lunar surface at 3 hrs 28 minutes and 41.6 seconds into the flight.

Of course if I wanted to land at a spot other than the random point where the vector connecting my boost point above Earth to point where the vector intersects the surface of the Moon, I would adjust slightly the direction of the vector that slows the vehicle to arrive there.

All of which is easily calculable and easily put into a solid state machine - that controls four fusion rocket engines to create an automated interplanetary drone that travels anywhere in a reasonable period of time.

https://www.youtube.com/watch?v=4ErEBkj_3PY

http://www.astroviewer.com/index.php

Which could make for some great adventures

https://www.youtube.com/watch?v=L8eRzOYhLuw

In a 180 ton vehicle that looked something like this;

http://38.media.tumblr.com/6f14a3588...zo3_r1_250.gif

We can also look at Mars (or any planet, dwarf planet, moon)

http://www.wolframalpha.com/input/?i...earth+and+mars

and see that it would take only days of travel to get there at one gee.

Lithium-6 and Deuterium can be made into an efficient fusion engine. You drop a neutron into Lithium-6 and it causes it to fission forming Helium-4 and Tritium, releasing over 4 MeV of energy. This makes the Tritium energetic enough to fuse immediately with Deuterium easily meeting the Lawson criterion, forming another Helium-4 and giving the neutron back releasing over 17 MeV of energy! By placing sufficient Tungsten around the energetic neutron undergoes a W(n,2n) reaction multiplying the fusion energy.

Rockets with exhaust speeds of 23,300 km/sec (7.9% light speed) are achieved. This means that flight to the moon and back at one gee of a 180 tonne ship requires 1.9 tonnes of Lithium-6 Deuteride propellant.

To travel to Mars today (20 Nov 2014) requires boosting toward Mars for 1 day 21 hours 44 minutes 24.9 seconds - and then slowing for another 1 day 21 hours 44 minutes 24.9 seconds.

Adding 57.5 tonnes to a 180 tonne ship permits us to fly to Mars at one gee, land, and return - in 1 week 14 hours 57 minutes 39.6 seconds - plus whatever time spent on the Mars surface and its moons.

On Wednesday, November 19, 2014 11:32:50 PM UTC+13, Peter Fairbrother wrote:
On 19/11/14 01:03, Rick Jones wrote:
No doubt it is more "paper space plans" but would one even want to use
a space station in a near polar orbit as a transit point for a lunar
program?

http://perfscience.com/content/21464...rbital-station

rick jones

I would have thought that an equatorial orbit would be most useful for
lunar missions - it can be used for more secondary planetary missions,
launch windows come up every 90 minutes, TLI windows are plentiful, GTO
payloads are larger, and the orbital velocity provided by the rotation
of the earth is quite a plus when it comes to launching heavy payloads
from the ground - but an equatorial orbit requires a launch site on or
near the equator, which the Roosskies simply don't have.

No choice to go equatorial then, and near-polar has for the Russians the
advantage over near-equatorial that it covers most of the Earth,
especially northern Russia, giving earth-observation missions more
coverage (and being better for tourism "I can see my house down there");
and it has more TLI windows than a strictly polar orbit.


As for using a space station for a transit point, if you can do in-orbit
assembly then your orbital launchers can be smaller and thus cheaper;
the sweet spot there is probably about 10-20 tons LEO payload per
launch, with reasonable estimates of future total tonnage to LEO.

On-orbit assembly is a big advantage, and having a space station nearby
when you do it would help a lot more than it would hinder.

A'course, as the Russians already have 10-20 ton LEO launchers then if
they do do on-orbit assembly then they don't have to spend a gazillion
roubles developing a super-heavy for only a few missions.


If you already have a suitably-placed orbital station, using it for
on-orbit assembly of lunar missions would be a no-brainer - building one
just for that purpose, perhaps not so much, but if it has other purposes
as well..


Like others I doubt they'll get the financing, though breaking away from
the US collaboration on ISS might be sufficiently politically
advantageous (yes I know ESA, Japan, Canada and Brazil are in there too
- but it is widely seen as a US-Russian collaboration).

And ISS is only scheduled to last 'til 2020, and the russkies have said
they won't renew or extend that mission.

-- Peter Fairbrother

The equator is tilted to the ecliptic (the plane of the Earth's orbit around the Sun) and tilted to the plane of the moon's orbit, and the moon's equator is tilted to both of these as well. Here's a sketch that encodes all the angles;

http://www.psrd.hawaii.edu/WebImg/earmoon.gif

So, an equatorial orbit would be tilted 23.5 degrees to the ecliptic. The moon's orbit would be tilted 28.65 degrees from an equatorial orbit. The moon's equator is tilted 6.68 degrees to the plane of the moon's orbit and 1.13 degrees to the ecliptic.