Author Topic: Throwing and Catching in Space  (Read 2947 times)

Offline Salvapatos

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Throwing and Catching in Space
« on: 10/25/2012 06:11 AM »
The attached document outlines a kind of a space sling which perhaps one day could be used to throw objects from one orbit to another orbit and catch them there.
There are two versions of the document. First I wrote the German one which I then tried to translate  to English.

The idea is based on the physical law that changing the location of something does not necessarily mean that energy has to be spent in the viewed system. One can extend the boundary of the system so that the sum of all energy forms stays constant. Unfortunately in most techniques the remaining energy turns out to become waste heat. Everywhere where you can store and recover the energy without transforming it to waste heat this energy is saved.

Roughly speaking the proposed space sling stores the kinetic energy from approaching flying objects and gives the energy back by sending objects on the journey.

I wonder if the ideas has conceptual mistakes.
Also notes about other mistakes (e.g. translation) are welcome.
« Last Edit: 10/25/2012 06:32 AM by Salvapatos »

Offline KristianAndresen

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Re: Throwing and Catching in Space
« Reply #1 on: 10/25/2012 03:12 PM »
Your document doesn't have very many references to existing designs. Have you seen spacetethers.com, for instance?

Offline muomega0

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Re: Throwing and Catching in Space
« Reply #2 on: 10/25/2012 03:45 PM »
Concept discussed here:  Sling Me to the Moon  and several other locations.

Conceptually ready?

--A capture mechanism was demonstrated in a ground test bed.

--Flywheels have no components or technology issues to prevent raising the TRL (just need $)

- So that leaves the tether, mechanisms, and rest of the integrated assembly.

How to get started?

Perhaps start with ISS reboost or inclination change over two years, then incrementally move toward the higher tether load applications. 

Reboost of a LEO ZBO depot may be another first step.

Offline Salvapatos

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Re: Throwing and Catching in Space
« Reply #3 on: 10/26/2012 06:04 AM »
Thank you KristianAndresen and muomega0!
I have found a lot of concepts but apparently not all the relevant ones.
It seems to me that there is still a lot of stuff to read and learn from.

What I was missing on the found concepts so far is the feature of storing the energy from a catch and reusing it for a throw with negligible influence on the trajectory or orbit of the sling.
This could only be achieved by building the sling very much heavier than the objects to be caught an thrown.
It seems that was the intention of “... to bulk up the tether” in Sling me to the Moon.
« Last Edit: 10/26/2012 06:52 AM by Salvapatos »

Offline KelvinZero

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Re: Throwing and Catching in Space
« Reply #4 on: 10/26/2012 07:40 AM »
Im not quite sure what you mean.. how do you avoid a heavy counterweight? Throwing and catching at the same time?

You can apparently actually "charge up" your tether system by moving mass downhill from the moon to earth btw, so bulking up your tether with a counterweight might not be as expensive as you think, at least in terms of propulsion needed. The counterweight could just be a bucket that is filled with regolith delivered by the tether system itself. (The moon tether system can actually pick up and drop off cargo directly from/to the lunar surface.)
http://en.wikipedia.org/wiki/Momentum_exchange_tether#Cislunar_transportation_system

Offline muomega0

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Re: Throwing and Catching in Space
« Reply #5 on: 10/26/2012 01:56 PM »
Im not quite sure what you mean.. how do you avoid a heavy counterweight? Throwing and catching at the same time?

You can apparently actually "charge up" your tether system by moving mass downhill from the moon to earth btw, so bulking up your tether with a counterweight might not be as expensive as you think, at least in terms of propulsion needed. The counterweight could just be a bucket that is filled with regolith delivered by the tether system itself. (The moon tether system can actually pick up and drop off cargo directly from/to the lunar surface.)
http://en.wikipedia.org/wiki/Momentum_exchange_tether#Cislunar_transportation_system

The ~ mass required is in Chris's article.

Quote
With a mass some six to ten times that of its payload, it will ‘pay’ itself off after 6-10 uses, since a typical Moon mission has to carry an equal amount of fuel to the payload it wants to send to the Moon. Engineers anticipate that the tether system will be able to recharge quickly enough to support monthly trips to the Moon.

The video may be on L2 only:  Here is the youtube link:
 

To fund HLV engine development programs, *All* worked stopped on tethers

Could this system reduce the ISRU launch costs?

So even < 1M/year for the key component development was not deemed important.

Offline KelvinZero

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Re: Throwing and Catching in Space
« Reply #6 on: 10/26/2012 10:03 PM »
The ~ mass required is in Chris's article.

Hi muomega0, looks cool and I definitely would have liked to have seen what tech development could have been done if Obama's budget had not been overridden by congress's SLS.

My comment was directed at Salvapatos who might be saying they had a new idea not mentioned elsewhere.

Online QuantumG

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Re: Throwing and Catching in Space
« Reply #7 on: 10/26/2012 11:02 PM »
Actually, all the technology roadmaps released by the Office of the Chief Technologist had tethers pointedly missing.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline KelvinZero

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Re: Throwing and Catching in Space
« Reply #8 on: 10/27/2012 04:28 AM »
Actually, all the technology roadmaps released by the Office of the Chief Technologist had tethers pointedly missing.
Pointedly? Not quite sure what you are implying.

Offline Salvapatos

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Re: Throwing and Catching in Space
« Reply #9 on: 10/27/2012 10:35 AM »
Sorry, I haven't found the right web pages to see the relevant information before.
Actually this forum I just discovered short time before I completed the document.
I knew tethers.com but I did not know spacetethers.com and the plenty of sites you forum users are familiar with.
I do admit that I was or I still am ignorant.
I also have to admit that many expressions and abbreviations users here use I don't understand. E.g. I don't know what TRL means.

I thought tethers.com was the most relevant site for this kind of transportation.
And here I was wondering why they would rely on electrodynamic tether propulsion for the Momentum Exchange Space Tethers. I thought storing and restoring the kinetic energy of the payloads as rotational energy of the sling was more universal because it would work everywhere where no magnetic field is available.
At this time I did not have the information I have now or I did not understand all of it.
Your answers have pointed me to the right directions. Thank you!
« Last Edit: 10/27/2012 10:38 AM by Salvapatos »

Offline A_M_Swallow

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Re: Throwing and Catching in Space
« Reply #10 on: 10/27/2012 09:28 PM »
{snip}
I also have to admit that many expressions and abbreviations users here use I don't understand. E.g. I don't know what TRL means.
{snip}

It is a bad engineering practice to assume 100% efficiency.  The designer has to add something to deal with the inefficiency.

TRL = Technology Readiness Level.
This is a simple way of showing if the device exists and whether or not it has been tested in space.
http://en.wikipedia.org/wiki/Technology_readiness_level