Exploration using nano-sats.

[chriscdc]

Does anyone know how far away a 10kg satellite could be before you could no longer communicate with it? Must carry one piece of scientific equipment however.<br /><br />The reason I ask was because several months ago there was an article in the space review about a rocket builder who planned to build a nano-sat launcher. The twist though was that it would have a dV that could propel the satellite out of the solar system. <br /><br />Could it be possible to have a single communication satellite of that size that could then act as a relay for specific purpose built sats?

 

[tap_sa]

<font color="yellow">"Does anyone know how far away a 10kg satellite could be before you could no longer communicate with it?"</font><br /><br />I'd venture to guess that at least as far as Mars. The ability to power the sat with solar power only is a major limiting factor, 10kg is not enough to fit a RTG and still have payload left. Galileo communicated from Jupiter with only 20 watts and omnidirectional antenna. Mars is over three times closer so in theory you could communicate with order of magnitude less transmit power, two watts or so.<br /><br />Do you happen to have a link to the space review nanolauncher article, sounds interesting.

 

[chriscdc]

http://www.thespacereview.com/article/489/1<br /><br />http://www.microlaunchers.com/home.htm<br />I might have overstated the capability of the proposed system. Memories not as good as it used to be.<br /><br />This approach could encourage the development of standardised satellites. We can finally get around to flooding the solar system with cheap probes. Each probe would probably be identical apart from a single modular sensor.<br />Would it be more effective for each satellite to be able to be capable of communicating with earth or to have a specially designed module that would then communicate with the rest of the probes using cheaper shorter range radio/microwave/lasers?

 

[tap_sa]

1 lb to escape velocity with 1000lbs GLOW, and 50lbs with 10000lbs GLOW, quite reasonable estimations. I'd increase the initial vehicle size to 1 tonne GLOW and 1kg payload. Not because being a European metric nazi but because there's a standard for 1kg/1 liter sized satellites called Cubesat. There are already manufacturers who have experience building these small sats, all is needed is a easy and cheap way to launch them, just what this guy is up to.<br /><br /><font color="yellow">"Would it be more effective for each satellite to be able to be capable of communicating with earth or to have a specially designed module that would then communicate with the rest of the probes using cheaper shorter range radio/microwave/lasers?"</font><br /><br />Depends on various things; how far is the destination, what's the bandwith requirement, do you have easy access to powerful groundstation like DSN etc. Long distance, high bandwith and limited level of ground support might force you to have a special relay satellite with directional antenna. Send that with flotilla of science sats which have only simple low gain omnidirectional antenna capable of communicating high speed with the nearby relay sat. Should the relay fail then you need to beg NASA for some DSN time and/or scale down the bandwith.

 

[mlorrey]

Yes, there will be over 22 CubeSats launched this year alone. They are primarily being launched on converted ICBM launchers like Minotaur, Athena, Rokot, START, and Dneiper. CubeSat operators are paying $40,000.00 for their 1 kg payload, a hefty premium. If someone can offer a lower price, you would have the market.

 

[chriscdc]

The sort of mission that I see these being used for are non-invasive (no landings) missions to the asteroids.<br />If you make a standardised design of probe which can be built and launched for 10 to 20thousand dollars or so. Each probe will have a set amount of volume, mass and power that can accommadate a commercial or university built sensor. <br />There should be substantial advertising kudos attached eg an electronics compay can say that their camera took photos of an NEO up close. Perhaps one sat can be crashed into the asteroid and the swarm can then observe the chemicals released using mini-mass spectrometers etc.<br />If the cost can be kept down then there should be no reason why you can't send back up comunication sats. <br /><br />Will the small size make them particularly vulnerable to space radiation?

 

[annodomini2]

<blockquote><font class="small">In reply to:</font><hr /><p>"Does anyone know how far away a 10kg satellite could be before you could no longer communicate with it?"<br /><br />I'd venture to guess that at least as far as Mars. The ability to power the sat with solar power only is a major limiting factor, 10kg is not enough to fit a RTG and still have payload left. Galileo communicated from Jupiter with only 20 watts and omnidirectional antenna. Mars is over three times closer so in theory you could communicate with order of magnitude less transmit power, two watts or so.<br /><br />Do you happen to have a link to the space review nanolauncher article, sounds interesting.<p><hr /></p></p></blockquote><br /><br />Depends what communication method they are using, laser comms is becomming more prominent. <div class="Discussion_UserSignature"> </div>

 

[rocketman5000]

if you were sending satelittes in a swarm couldn't one of the satelittes (probes) be a dedicated comsat, with a directional antenna?

 

[mlorrey]

Yes, with star trackers, one nanosat could operate a maser link to Earth. Transmission is the only real problem with power. Reception of strong Earth signals is not an issue.<br /><br />Nanosats are not generally an issue in LEO. Their typical orbit leaves them with maximum lifetimes of 5-10 years. Besides that, trash removal is a potential profitable mission for nanosat OTVs. There are some really nice developments in diode pumped laser plasma thrusters that fit well in the nanosat architecture. Given their low cost, and the potential avoided costs of a small mass taking out a large LEO satellite, like ISS, a trash removal operator could bootstrap their business with nanosats.

 

[rocketman5000]

I was thinking all nsats in the swarm would receive the earth signals and the com nsat would be the only one with long distance high datarate tranmission capabilities. Using this method would free up all transmission bandwidth of the comsat to be sending signals back to Earth as well as reduce the power needed. I would envision the entire mass of the comsat to be taken up by solar panels and trasmitter. Hopefully the communications dish and fuel tanks being built into the structure of the sat to make it as light weight as possible. This would trade off the functionality of the satelitte for higher transmission capabilities. Ie. it might not be able to point the dish at earth, solar panels at the sun and be firing thrusters in the correct direction all at the same time. <br /><br />does anyone know if there are reaction wheels developed for nanosats or do most nsats rely on thrusters?

 

[tap_sa]

<font color="yellow">"CubeSat operators are paying $40,000.00 for their 1 kg payload, a hefty premium. If someone can offer a lower price, you would have the market."</font><br /><br />I bet there would be a good market even with $40,000 pricetag for <i>dedicated</i> CubeSat launches. The launchers you listed are in the Falcon I class costing millions per launch while putting hundreds kilos to orbit. The CubeSats always have to wait and piggyback a suitable bigger satellite launch.<br /><br />Can a complete orbital vehicle be made for $40k? I believe it can. The empty launcher would weigh around 50kg/110lbs, a person could carry it. Initial R&D might be prohibitely high for purely commercial venture, but bunch of determined amateurs/professionals looking for extreme hobby could pull it off.<br /><br />

 

[mlorrey]

There are reaction wheels being produced in university lab setting by MEMS processes.

 

[nspace]

"Can a complete orbital vehicle be made for $40k? I believe it can. The empty launcher would weigh around 50kg/110lbs, a person could carry it. Initial R&D might be prohibitely high for purely commercial venture, but bunch of determined amateurs/professionals looking for extreme hobby could pull it off. "<br /><br />Launch site cost and 3rd party insurance are always neglected by rocket enthusiast. Also any guided rocket must be fitted with a qualified flight termination system (FTS). An attempt to source one of these for less than $10K would be optimistic. I was once quoted around USD$45K to use Andoya Rocket Range ( Norway ) for a small PEO launcher, this did not include 3rd party insurance. Try sourcing a USD$50million pubic liabillity policy for less than $50K. These factors do not scale in a linear factor along with launch vehicle size, so you would wind up with a small cheap rocket with huge operational cost.<br /><br />Perhaps an air launched platform would lower these cost but still it cost thousands of dollars per hr to keep a large aircraft in the air also..<br /><br />The actual launch vehicle segment is probably only a 3rd of the total cost of a space launch service. Having being involved in several space launch ventures, I can safely say its just not viable to hedge a business on dedicated launch to LEO for 1kg.<br /><br />From all my figures the base point for a viable system is around 100kg.<br /><br />Hope this helps.<br /><br />J Griffiths

 

[j05h]

You can buy a $40,000 with Dnepr launch, but we already saw what can result. Dnepr and Volna have both been distractions to US private space monies, I'd rather pay a little more for Soyuz (if they'd fly nanos). I like the idea of a microlauncher for the nanosats. Could a hybrid lower stage and small cryo 2nd stage work?<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[nspace]

"I like the idea of a microlauncher for the nanosats. Could a hybrid lower stage and small cryo 2nd stage work?<br /><br />Josh"<br /><br />Okay personally I believe the most straight foward small launcher could be based on a self pressurizing liquid rocket. Hydrogen peroxide would be the ideal choice for oxydizer, based on storability and compatabillity with polyethylene. Fuels would be either Propane, Ethane or Propylene which have vapour pressures in the 120 to 300psi range at room temp" Propellant tanks would be low cost glass filament wound over roto molded polyethylene liners. A movable intertank would serve to seperate the propellants while also allowing the fuel to pressurize the peroxide.<br /><br />To minimise risk and complexity only 2 stages would be used which creates just 1 seperation event. I would propably use a common motor and cluster 4 or 5 in the first stage and one with a much larger expansion ratio. This would minimise the cost of propulsion development in line with low cost R&D program. A motor of around 2000lbs thrust is well within the abillites of the experimental comunity, and would allow GLOW in the predicted range for 10 to 15KG to LEO.<br /><br />Hybrids are still an low effeciency technology and present a technical risk to a "cheap" sat launcher project. New wax based fuels may address this, but a small LV program should avoid pathfinder technologies.<br /><br />So we have a fairly cheap launch vehicle strcuture and propulsion, how about guidence ccontrol and navigation? Here is where we come undone. So far the cheapest low drift (inertial mesurment unit) IMU suitable for LV use I can find is in the USD$7 to 10K range. Now you can get some amazing computing power now for mere hundreds so flight computer is not an issue, nor is telemetry with all the new developments in spread spectrum data modems. But you can expect a NASA range qualified FTS will break the budget.<br /><br />How could said launcher be built ... Well I would say the only way