indroth

If you are saying all these are required, then I am, by definition, not alive because I don't have a girlfriend .

If we have figured out the specifics of what the mission needs to do, a requirements document would be the first step.

Unfortunately, 50 years from now robotics and automation will almost certainly have improved at a faster pace than human space flight, so it is likely that a manned mission will cost much more and be able to do much less. Rockets have hardly changed in the last 50 years, while computers are orders of magnitude smaller, lighter, faster and more energy efficient. Still, that doesn't mean it isn't worth discussing. Also, a manned mission is definitely more entertaining.

Have you seen this? It's not a tutorial, but it covers the important differences. https://docs.python.org/3/whatsnew/3.0.html

I haven't really looked through the details of your equations, but my first thought is that maybe you don't take into account that drag is dependent on surface velocity not orbital velocity. This will result in non-zero drag at zero surface velocity. Actually, how does that work in KSP? Is the atmosphere like a rigid shell so it is moving faster as you move higher up? Or is drag just proportional to the square of the surface velocity?

I usually strap on some extra small fuel tanks and use my launch engines to soften the landing. You don't need a TWR of more than 1, so you can turn on just a few for landing if necessary, although it may be optimal to turn on as many as possible so you have a short soft landing burn. Obviously, solids need to stay off until you launch. As an added bonus you can attach all the landing paraphernalia (parachutes, landing legs, girders etc). to these tanks so everything is dropped on launch.

Just make sure you keep in mind that this just works for a simple circuit with a resistance and diode in series. For anything more complicated, I would suggest a review of Kirchoff's Laws and Ohm's Law. That's cool. Maybe you can try to trigger a Soyuz style soft-landing rocket if you get the altitude thing working well. As an added bonus, you can get higher precision position data by combining sensor and GPS data.

What really matters for an LED is the current. LEDs need a minimum forward voltage and current to light up, but once they do the voltage drop across the LED remains roughly constant. This voltage is usually documented as the forward voltage drop in the LED data sheet. The data sheet will also tell you how much current should pass through the LED for normal operation. Given the forward voltage drop and current requirement, you can calculate what resistance you need quite easily. R = (Vpower - Vforward)/I R : Resistance Vpower : Power supply voltage (batteries or whatever) Vforward : Forward voltage drop across diode I : Current through circuit So for example assuming 2V forward voltage drop, 10mA current, 18V power, we have R = (18V - 2V)/10mA = 1.6 kOhms

The need to know things.

Shouldn't there be a v2 in there? Or am I missing something?

I would imagine the exact position would oscillate somewhat because the orbit isn't perfectly circular.

Anything less than 10 Jupiter radii has to cope with high levels of radiation. Radiation shielding may be less mass than the fuel and power required for a boost with a more distant assist though. Just having a Neptune flyby would be amazing considering there isn't even a plan for that.

So I just tried replicating my previous calculations and got a launch mass of 97 million kgs. Hooray for beer!

Let me try to get all this off the used post-its and miscellaneous scrap that I did it on. Not even sure it's correct, so maybe someone can confirm. But I should probably do some actual work at work today instead of this. One thing to keep in mind though is that the "tyranny of the rocket equation" is largely in relation to delta-v. Fuel mass is proportional to payload + engine + etc mass for any given delta-v and Isp.

Ideally, you would let yourself drop and then burn at full throttle at the right time to come to a stop on the ground. An approximation I find useful is if you are at 0 velocity at altitude h over the surface (that's radar altitude), start your burn at altitude h / TWR. You will actually reach 0 m/s before reaching the ground though, or sometimes you are moving so fast that you can't throttle up in time and crash. So take some extra delta-v and throttle up a little early.

Going off some of the performance numbers in previous posts, here's some rough numbers I calculated: Say we have a 3000kg payload mass (including power source and engines), 5N thrust, 5000s Isp, we try a solar escape trajectory with Jupiter assist so that we reach Sedna in 10 years. Assuming a hyperbolic trajectory with Pe around Jupiter orbit, this requires around 40km/s at Pe. Velocity with respect to the sun on arrival at Sedna will be around 36km/s. For Sedna capture, almost all of this will have to be burned off. That is about a 1 year burn using 3000 kg of propellant. New Horizons left Jupiter encounter with about 20km/s. If we assume a similar assist, an additional 20km/s delta-v needs to be added. With the now 6000 kg vehicle, that is an additional 1 year burn with 3000kg of propellant. So we have launch mass = 9 tonnes not including anything we need for the initial Jupiter intercept. For just a Sedna flyby, we only need 1500 kg of propellant to get to 40km/s leading to a total mass of 4.5 tonnes.

Except that this will not be a Hohmann transfer. That would take around 120 years. If you look at the New Horizons trajectory, you will see that it is almost a straight line to Pluto intercept after the Jupiter assist. This is much less than the acceleration due to the Sun's gravity even at Jupiter orbit, so this second 6 year estimate is probably way off. I haven't tried figuring out how the spiraling trajectory that you get by burning prograde works out though.

Yes, I suppose it is mostly a cost vs risk issue. Aiming for something that has the delta-v and TWR to land on Pluto may be the way to go. If it isn't good enough, we still have an impactor .

Not knowing the mass of Sedna makes anything beyond a flyby a difficult proposition at best. An impactor would be possible, and maybe orbit if there is lots of spare delta-v.

Too late this year, but maybe next year? http://www.smallsat.org/technical-program/workshop

If I am not mistaken, the SNR of N 1 minute exposures considering only read noise is worse than 1 N minute exposure by a factor of sqrt(N).

Yes, in fact an additional advantage of short exposures is that you don't saturate the image because of light pollution, so you can just stack the images and subtract the background out. The problem with short exposures is that every exposure adds readout noise which can be quite bad if you are using a relatively cheap camera (including low end DSLRs). However, it is definitely better to use shorter exposures if you don't have good tracking. The 4 minute thing was just to see how long I could make it. I am still trying to figure out my process.

That M82 picture I posted earlier in this thread, while not the best, was from a bunch of 4 minute untracked exposures, so a 30 minute exposure is probably not that hard with tracking. My tracker isn't ready yet though, so I may be mistaken. Edit: I did run it through a deconvolution algorithm though Also when I say untracked, I mean unguided. There was still open-loop tracking.

Cameras: http://www.diyspaceexploration.com/various-options-imaging-modules-cubesat-payload/