Probe propulsion question

[rybanis]

I origninally asked this question awhile back, but now cannot find what thread it was in!<br /><br />My question was: Are space probe propulsion systems custom built for each probe? Or, is there some method of standardization?<br /><br />I've been rather interested as of late with all this talk of the 27 minute long MRO burn tomorrow. <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

Yes, though outside of some common mono and bipropellant vernier thrusters, most others are produced on rather a short order basis, or with very short production runs.<br /><br />Hopefully once the nanosat movement really gets going, and the MEMS components for nanosats enter the market, we'll start to see some real production rates as producing nanosats becomes something of an expensive hobby.

 

[mikejz]

That actually is my personal dream: To design and build my own nanosat. <img src="/images/icons/smile.gif" />

 

[propforce]

<font color="yellow">That actually is my personal dream: To design and build my own nanosat. </font><br /><br />The tough part is paying for a launch though.... But if you team up with a local university, maybe you can get it to qualified as secondary payloads on NASA and EELV launches <img src="/images/icons/smile.gif" /><br /> <div class="Discussion_UserSignature"> </div>

 

[willpittenger]

Back before Challenger, NASA had a program where you could fill a container that got power in orbit but no other interaction. The container would just sit in the cargo bay and return to Earth. Does NASA still fly those containers? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[mikejz]

Actually I'm currrently working on my masters degree, and the University I am attending has a small-satellite project (UF). <br /><br />Of course I'm getting a business degree, have no enginnering or CS background, and see myself either going on to law school or taking a position with a Big-Four accounting firm<br /><br />I'm sure I would contribute a lot to that the group of engineering students putting it together <img src="/images/icons/smile.gif" />

 

[propforce]

There you go. <br />I can just see your capstone project for your business degree "Nano satellite kit for every do-it-yourself scientists: a business plan for a space start-up company, mikejz space products". <br /><br /><img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[henryhallam]

<font color="yellow">Does NASA still fly those containers?</font><br /><br />The "get away specials" / "hitchhiker" programs have been cancelled unfortunately, I think after STS-107 though it could have been shortly beforehand. They were quite successful and popular but presumably now all the upmass is needed for Station components and supplies.

 

[mlorrey]

Currently, CubeSats, which are 1 kg, are launched on Russian ICBMs with other cubesats, at a price of $40,000 per cube. As this is more than ten times higher than the actual russian price/kg, I suspect that cubesat.org is raking in a hefty profit to fund their activities (they have 22 cubesats scheduled for launch this year, which is earning them about $770,000).<br /><br />Seeing this as a potential market, I have calculated that my X-106 launcher could launch over 450 CubeSats at a time, if the back seat and its passenger were removed to save mass. At a price of only $5,000 per cube, this would earn me over $2.25 million per flight. At $10,000 per cube, that would be $4.5 million per flight.<br /><br />So, who wants a Personal Satellite?

 

[egom]

Well, first you need to prove that you can fly the plane/ship and put something to space. After that I am sure that you will be able to bring the money in. UCrrently it seems that the smaller the sattelite is, the more it costs per pound.<br /><br />EgoM

 

[mlorrey]

Sure, but this is where Moore's Law comes in: every 18 months, the space for a given number of transistors falls by half. MEMS technology is applying this to designs for satellite components, including flywheels, plasma thrusters, gyroscopes, transponders, you name it. <br /><br />This means, for a given nanosat design today, you can realistically design one half the mass with the same capabilities a year and a half from now, and so on and so on. Personal Satellites become realistically affordable due to miniaturization. Put enough in orbit with wi-fi capabilities or a similar laser based networking protocol, and anybody on earth could keep in touch with their Personal Satellite via the orbiting packet network, thus evading corporate and national firewalls that censor, control, and spy on the people.

 

[willpittenger]

<blockquote><font class="small">In reply to:</font><hr /><p>Put enough in orbit with wi-fi capabilities or a similar laser based networking protocol, and anybody on earth could keep in touch with their Personal Satellite via the orbiting packet network<p><hr /></p></p></blockquote><br />Until the satellites collide. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[willpittenger]

Not if there is "enough in orbit". <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[mlorrey]

Actually will, according to the numbers developed by Teledesic, 400-500 satellites in LEO in a common network could provide 100% coverage to something like 95% of the earth's surface.<br /><br />The real marketing question is: how many people could afford a personal satellite, and how many would want to buy one given x level of performance?<br /><br />There are already over 100,000 objects between 1-5 cm diameter in earth orbit. There are thousands of satellites in orbit. A responsibly designed nano-sat will have protocols to deorbit the sat when it reaches a critical fuel level for its diode laser plasma thruster, or, if given the size of the market, there appears a refueling capacity in orbit, to maneuver to the local refuelling station. Most current satellites launched are equipped with deorbit capability. As for collisions, while hitting OTHER objects might be a problem, given that all nanosats in the same packet network would have routers timing signal time between each sat, collision avoidance algorithms would be an inherent part of their programming.

 

[mikejz]

Actually, the small sat program at my school is designed to test the idea of a de-orbiting via an inflatable ballute.<br /><br />http://ufsmallsat.com/<br /><br />The biggest issue with LEO for comm sats, is that the bandwidth seems so minor for the coverage area vs. ground based alternatives.

 

[tap_sa]

<font color="yellow">"idea of a de-orbiting via an inflatable ballute."</font><br /><br />Interesting! Hope you have great success with that project. I like the idea of as many as possible having a chance to send their cheap cubesats into space, but currently most of them seem to end up in relatively high, sun-synchronous orbit. AFAIK the natural decay rate from that height is quite low. I'd much rather see the cubesats at much lower orbits, where drag would automatically deorbit them within weeks or months.<br /><br />Why are most of the cubesats placed into (polar) s-s orbit, does anyone know? Is it a communication issue, lack of worldwide cheap tracking/comms so the s-s orbit guarantees that the little sat passes over you on regular basis? <br /><br />edit: About 'everybody' sending their personal satellite, would they all really need to be in individual orbits? Cluster them together. Fly 400-500 'racks' to cover the globe as mlorrey pointed out, and let invididuals to rent rackspace for their 1U, 2U, 3U etc. 'satellites'. Rack provides energy, comms etc. common utilities.

 

[mlorrey]

two reasons: sun synchronous orbit allows satellite overpass of the base station at the same time every day, and the primary launchers being used are converted Russian ICBMs at launch sites that serve polar/ss orbits.<br /><br />Deorbiting a piece of equipment that likely cost someone or team of someones a large chunk of their savings is not cost effective. Decay rates seem to last 2-9 years depending on solar flare activity. Check this chart pulled from a scandinavian nanosat project.<br /><br />You are correct that clustering would be more effective from a facilities point of view, but putting up a proven system, such as Mod Progress M, is much more expensive per server than the cubesat approach. One would have to build their own server farm sat from scratch. This may become feasible once a real market as been established for such quantities, but at this point there isn't the demand to justify such a capital investment.

 

[tap_sa]

Thanks for the chart! They seem to come down much faster than I expected. Thought they are dense enough to stay at nearly 600km altitude for at least a decade or several. Vanguard I is still up there since 1958, granted it's apogee is much higher.

 

[mlorrey]

Yeah, an eccentric orbit has longer life because the drag it encounters at perigee doesn't change perigee altitude, it changes apogee altitude, so over time apogee will drop lower and lower til it reaches a circular orbit, then the real decay starts.

 

[frasercain]

Yes, though outside of some common mono and bipropellant vernier thrusters, most others are produced on rather a short order basis, or with very short production runs. <br /><br />Hopefully once the nanosat movement really gets going, and the MEMS components for nanosats enter the market, we'll start to see some real production rates as producing nanosats becomes something of an expensive hobby.