A Penny into Orbit

[krrr]

I think Leo brought up the topic shortly before the long forgetting.<br /><br />What would a minimal launcher for a minimal nanosat look like?<br /><br />I'm thinking about an Explorer-like setup. A small (e.g. sounding) rocket climbs almost vertically and brings a 3- or 4-stage stack to an altitude of say 250 km. That stack is spin-stabilized. It separates and fires at the apex of the trajectory.<br /><br />Explorer used 11, 3 and 1 Sergeant rockets for the three kick stages. They had an ISP of 235 s, mass of 42 kg and empty mass of 21 kg. The satellite's mass (it remained attached to the upper stage) was 5 kg. <br /><br />Would it be possible to scale that down, e.g. to 4.2 kg/ 2.1 kg with a similar ISP?<br /><br />Also, what would the mass of a minimal, marginally useful nanosat be? With a small scientific payload and the ability to phone home (maybe literally)? <br /><br />

 

[CalliArcale]

Depends on what you mean by "marginally useful", probably. <img src="/images/icons/wink.gif" /> You can make use of surprisingly small nanosatellites. Heck, Vanguard was a pretty puny satellite. (It's still out there, actually, but it's long since dead.) I think it was about two feet long by eight inches wide, or thereabouts. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[mrmorris]

<font color="yellow">"Also, what would the mass of a minimal, marginally useful nanosat be? With a small scientific payload and the ability to phone home (maybe literally)? "</font><br /><br />The question is <b>way</b> too broad. <br /><br />Useful in what way?<br />Useful for how long?<br />Phone home how and how often?<br /><br />The answers to these questions have a HUGE impact on the size of the satellite. An X-band transmitter might be only a few ounces. Put that, a lithium-ion battery, and a minimal CCD camera into a coke can and put it into orbit. You now have a minimal nanosat with ~8 ounces of mass. It'll be able to take pictures (orientation on a take-what-you-get basis) and radio them back for a few hours/days. Is that useful to someone? Maybe. Not very useful for sure.<br /><br />Overall -- satellites are getting more and more capability crammed into a given mass. However -- it's still true that technology staying constant -- the lower the mass, the less capable the spacecraft. By the time you get down to a nanosat -- the satellites are generally short-lived and of limited capability. This is not to say they are <b>useless</b> by any means. But they are generally very focused on a specific purpose with a small number (or only one) of instruments.

 

[Leovinus]

As I recall, that thread was meant to answer the question: "How big a rocket is required to put a penny into orbit?"<br /><br />I was wondering if it was something an amateur could build. <div class="Discussion_UserSignature"> </div>

 

[krrr]

<blockquote><font class="small">In reply to:</font><hr /><p><br />The question is way too broad.<br /><br />Useful in what way?<br />Useful for how long?<br />Phone home how and how often? <br /><p><hr /></p></p></blockquote><br /><br />Agreed.<br /><br />Actually, I'm more interested in my first question: Is ist possible to build rocket stages with a mass of say 5 kg, empty-to-full ratio of 50% or less (and a decent ISP)?<br /><br />Possible application: A Mars sample return mission. Payload (on a 2- or 3-stage stack) would be a small container with maybe 200 g of Martian soil, together with a crude beacon. This would be picked up in Mars orbit by a larger spacecraft which would transfer the stuff to Earth.

 

[henryhallam]

SSTO on Mars is really pretty easy, additional stages would probably not be worth the extra complexity/failure modes. Single stage all the way from Mars surface to Earth surface is a bit trickier, especially when you have to transport the whole stack to Mars in the first place.

 

[holmec]

Hey, scalling it down. Good. I guess you can't get much more scalled down than putting a bullet in space. How big does the gun have to be?<br /><br />its all projectiles anyway. Wheather the projetile can transmit or recieve it doesn't matter. Its still a projetile.<br />From Sputnik to the ISS they are all projectiles.<br /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[holmec]

Not neccesarily. Perception could have stoped a project like this.<br /><br />Answering the question "Why?" would stop it. And what about if it hits the ISS or something. How would you like a law suit from Uncle Sam, lol. <br /><br />But it would be sooooo cool. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[tap_sa]

<font color="yellow">"Could a multi-stage solid-fueled rocket achieve orbit? "</font><br /><br />Could and has, OSC's Taurus for example. I'm positive that a small but determined bunch of skilled amateurs could put together a vehicle capable of delivering something like a one pound or kilogram to LEO. I bet the mental treshold is bigger than technical. It is as if getting to space still enjoys the 50s awe that it's only government's business. I'm pipedreaming of designing a nanolauncher, maybe even attempt to build one, but still many many books to read <img src="/images/icons/smile.gif" /> The difference to the 50s if that all essential information is readily available from places like Amazon to anybody, as is proper building materials plus electronics that von Brain & co probably couldn't even dream about.

 

[CalliArcale]

Pegasus is solid-fueled too, although since it arguably uses a Lockheed Tristar airliner as a first stage, it might not count. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[tap_sa]

<font color="yellow">"it arguably uses a Lockheed Tristar airliner as a first stage"</font><br /><br />...or B-52, and some model of Pegasus has hydrazine-fueled 4th stage (5th if the airplane is included). That's why I chose Taurus, no ambiguities. <br /><br />Edit: Couple more all-solid orbital LVs; US Scout and Brazillian VLS. Latter had a horrible accident couple years ago, somehow the rocket ignited while people were still doing launch-prep on it, 21 dead.

 

[spacefire]

assuming you get permsission to launch something as useless as a penny in orbit (though maybe electronics that can trasmit a powerful enough signal to be picked up from Earth can be put in a penny with today's technology): I don't think a solid rocket would do it, burn times and specific impulse are too small. Possibly a hybrid rocket, like the one on SS1. I'd like to make it more challenging and say it has to be single stage and reusable-i.e. it can return to Earth in one piece. I do believe it would still be something amateurs can build. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[henryhallam]

<i> Possibly a hybrid rocket, like the one on SS1. I'd like to make it more challenging and say it has to be single stage and reusable-i.e. it can return to Earth in one piece. I do believe it would still be something amateurs can build.</i><br /><br />SSTO <b>requires</b> very high Isp, basically the only option is LOX/LH2.<br /><br />To build a reusable, orbital, single-stage liquid fuel rocket with high enough mass fraction - no matter how light the payload - is so far out of the reach of amateurs that you might as well try for a DIY manned moonshot.<br /> <br />Recoverable SSTO has never even been done by professionals.

 

[tap_sa]

<font color="yellow">"assuming you get permsission to launch"</font><br /><br />I'd bypass any red tape by choosing benevolent civil disobedience for the greater good of mankind, ie. <i>screw permissions</i>. Just take all precautions to ensure that it would be practically impossible to do any harm to either earthlings or any existing space assets up there, ISS being the most important. I'd choose some remote launch site, coast of Kenya maybe, aim for 100nm/185km LEO and ignite when ISS is just passing over you. There's nobody else at 100nm because orbits that low last just a few weeks tops.<br /><br />Another option would be to work with some banana country's government to get some sort of permission, convince them that if they let you operate relatively freely there might be a stream of smallpayload customers visiting that country in the future.<br /><br />Anyway, anything but wrestling with FAA/ASOC, operating from US soil would be pretty much no-no.<br /><br /><font color="yellow">"something as useless as a penny in orbit"</font><br /><br />You can squeeze a lot into a penny but making a rocket that takes <i>just</i> a penny would be impractical. Because of atmospheric drag and state of manufacturing tools there's a certain practical minimum size for a rocket. A nice initial target payload would be the basic SI unit one kilogram, there are already manufacturers of nanosatellites in that size.<br /><br /><font color="yellow">"I don't think a solid rocket would do it, burn times and specific impulse are too small. Possibly a hybrid rocket, like the one on SS1."</font><br /><br />SS1 hybrid's I_sp isn't any higher than average solids, and as you can see above there has already been all-solid orbital vehicles.<br /><br /><font color="yellow">"I'd like to make it more challenging and say it has to be single stage and reusable-i.e. it can return to Earth in one piece. I do believe it would still be something amateurs can build."</font>

 

[mrmorris]

<font color="yellow">"Another option would be to work with some banana country's government "</font><br /><br />Work with Equador. Set up your launch pad at the top of Mount Chimborazo. The summit of Chimoborazo constitutes the furthest point from the center of the Earth because of the high elevation, the location of the mountain at the equator and the oblateness of the Earth. To my knowledge, here is no ground-launch location that will make it easier for your mini-booster to achieve orbit. <br /><br />Now, actually *getting* your booster and launch facilities to the top of MC in the first place... is another matter entirely. <img src="/images/icons/smile.gif" />

 

[nacnud]

Why not avoid the whole turbo pumb problem, flometrics seem to have an interesting pressure fed design.

 

[tap_sa]

<font color="yellow">"Now, actually *getting* your booster and launch facilities to the top of MC in the first place... is another matter entirely."</font><br /><br />It's a nano-launcher, remember <img src="/images/icons/wink.gif" /> Empty weight somewhere between 50-100kg, strong man could carry it like a log on a shoulder, followed by trail of carriers with fuel and LOX-dewars in their backpacks... but maybe not to Mnt Chimborazo. It's a nice place but, like you pointed out, getting there is too much. ASA travels lightly but not that light, we tow the launcher with Silverado so no road, no go. I bet there's some sort of national park around Chimborazo so anything but a rich tourist there would get an evil eye from the Equadorian government, despite any bribery efforts.<br /><br />There's a 4509m Mount Wilhelm in Papua New Guinea. I'd prefer the pacific ocean in the immediate east over Colombia, Peru or Brazil to recieve the fiery failures. (ASA has no delusions over getting everything right from the start!) I bet especially Brazil with it's own active space program would get restless and pull some international policy crap if another country nearby would suddenly shoot rockets over (and maybe into) it.

 

[tap_sa]

Yep, Flometric's pistonless design looks very promising. Other options are a pistonpump (like XCOR's) or conventional pressure fed. I'd prefer the pistonless because it has potential to scale well and offer interesting fuel options (gelled etc) in the future.

 

[mrmorris]

<font color="yellow">"...strong man could carry it like a log on a shoulder, followed by trail of carriers with fuel and LOX-dewars in their backpacks... "</font><br /><br />For some reason I get this image of you, wielding a machete and leading a pack of native bearers trudging up a tree and vine-laden slope. Suddenly a ululating cry rings out of the jungle. You turn to the wide-eyed bearers and ask 'What was that?" Replies bearer #1: 'That Tarzan -- <b>King</b> of Chimborazo'. <img src="/images/icons/smile.gif" />

 

[spacefire]

<font color="yellow">SSTO requires very high Isp, basically the only option is LOX/LH2. </font><br /><br />you are right, for now. But hybrid rocket technology is advancing.<br />from spacedev's website.<br />"The Isp of a LOX/HTPB hybrid motor is comparable to solid propellant motors and LOX/kerosene rocket boosters. The propellant mass fraction of a hybrid motor is typically 20% to 30% less than these competing systems. However, new developments in hybrid motor fuels and oxidizer injection techniques show great promise for closing the gap on mass fraction"<br /><br />I admit that I rushed when I said SSTO could be achieved by amateurs. Still, it would be a worthy goal for anyone. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[henryhallam]

Solids or hybrids can never have Isp in the 300-400 range due fundamental physical and chemical reasons (they all use large molecules)

 

[spacefire]

what about better mixing, maybe the fuel grain being honeycombed to increase the contact surface with the N2O?<br /><br /> <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[henryhallam]

No luck - that would allow greater thrust and perhaps slightly better efficiency, but the limiting factor is the chemistry itself.<br /><br />Only hydrogen and oxygen combine the two features of high energy density (hydrogen is the best possible fuel, and LOX is beaten only by ozone and other ridiculous oxidisers) and low molecular weight of the products (water, and a substantial amount of hydrogen gas due to more H2 being used than is needed to react with the O2).<br /><br />As you know, a rocket works by accelerating "reaction mass" in the opposite direction to the way you want to go. You can get greater acceleration by either throwing out more total mass, or accelerating it to a greater velocity.<br /><br />Obviously the greater the energy density of the propellant combination, the more energy is released that can be transferred to kinetic energy in the reaction mass.<br /><br />However, the molecular mass of the reaction mass is very important too (this is how much each molecule weighs).<br /><br />If you want to speed up your rocket by a certain change in velocity (delta-V), you can either shoot out a small amount of mass at a high velocity, or a larger mass at reduced velocity. The kinetic energy required is proportional to mass * (velocity^2), while the impule your rocket gets is proportional to (mass * velocity). You would think that this means it is better to use larger masses at low velocities, because you save on energy. BUT this means you have to lug up a greater mass of fuel, so although you get the same impulse, the rocket weighs more which means less delta-V.<br />The maths works out that the lighter the fuel, the better.<br /><br />If you like I can try to give an example with some numbers - some parts are a bit counterintuitive, but it's all definitely true!

 

[spacefire]

thanks, I know about rockets, but not about hybrid rockets. i thought the ISP would be better than for a liquid combination but I guess I was wrong. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[henryhallam]

Even the most capable hybrids, using LOX as the oxidiser, struggle to get an Isp of greater than about 280 seconds. I think the SS1 engine is around 250s.