Hypography X Prize Entry

[Roadam]

Units of mass and weight are confused in most nonscientific language. People commonly use kilograms as a unit of weight, when they should use Newtons. In the peculiar English/American system, pounds are both a unit of mass and force - units used only for mass in this system are very obscure – the slug (1 pound = 1 slug * 1 foot/second/second) and the blob (1 pound = 1 blob * 1 inch/second/second) – all the more reason, IMHO, not to use this weird old system if you can avoid it. :cup:

 

Rumor has it that one of the unsucesfull mars probes failed becouse of the problems with conversions from old english units to metric and vice versa.

 

Anyway, if we design something that will work on earth surface, it will surely work on the moon. Except for the convection driven heat transfer and lubricating. Something we need to test is strenght of any fuel tanks, double pressure instead of vacuum would be better. It could be good info if we would know if aerogels last in vacuum(for insulation). Batteries also have to be sturdy, as well as any camera.

[Kayra]

(Bolding mine)How do you plan to: 1) insert the vehicle into a low orbit? and 2) kill all orbital velocity? without a rocket motor and fuel?

 

Recall we’re dealing with the moon, so neither aerobraking (practically no atmosphere) nor electrodynamic propulsion (practically no magnetic field) are available alternatives, leaving the possibility of some sort of mechanical braking by bouncing/glancing/dragging something across the Moon’s rugged surface at several Km/s. I don’t think there’s any material capable of withstanding that!

 

Ahh, I should explain myself fully when I post (except I am often way too wordy as it is).

I was thinking of using the system Janus described (which I really liked BTW). Drop your orbital speed with a rocket and then discard the rocket, tanks, and structure you do not need.

 

At that point inflate the crash bag on the lower part of the lander (probably a modified cone shape) and extend a telescopic tower 5-15 meter above the lander. This will contain small rockets (pointing down on the cardinal points) to slow decent, and a camera to video the process, and again the physics of this are very simple to model. The position of the rockets would keep the crash pads pointing down, and the lander at a reasonably survivable speed.

 

The crash pad system using a modified honeycomb would require VERY little air to inflate because of the vacuum. Each cell in the crash pad is designed to burst at a specific spot with a hole diameter designed to allow the air out at a specific speed.

 

These systems and the physics involved are used constantly in the motion picture industry and the physics are well understood.

 

Rigging a test for this system should not be that challenging I would think, but not having the practical experience I will leave that to others to determine.

[TheBigDog]

I think I follow you, Kayra. How about if the rockets are only powerful enough to just overcome the gravity of the moon. We monitor the rate of descent. When the rate exceeds x we fire the rockets until the rate of descent falls below y. We then shut off the rocket until the rate of descent exceeds x again. All we are trying to do is stay in a range of speed which the airbag at the bottom of the lander will survive. I also think you are talking about a collapsing airbag, like the ones used for stunt jumps, rather than a bouncing method used for landing on mars. It is just there to absorb most of the energy of impact, but we don't exactly need to touch down gently. We can also film it that way. Very nice thought.

 

Bill

[TheFaithfulStone]

Control will be as follows: we will have a website that is actually hosted by the lander. From there we will be able to look at live camera shots from the rover, and issue commands to the rover. A command can be a series of maneuvers. We might tell it to turn 30 degrees, then move forward for 30 meters. It will begin the maneuver and continue until it is complete, or until it either gets a signal to stop. When it stops we will evaluate the position and send a signal for the next move. The lander will have a wheelbase of about half a meter. It will have a mast that extends up where the antenna for communication with the lander will be located. There will also be a probe used for recharging. I am considering having the lander able to auto guide the rover to the recharger, so once we get it close it can do the final distance with precision.

 

That's some pretty seriously complicated radio engineering.

 

I've built some dangerous remote control robots before, and I can tell you right now that the thing that breaks is the radio controller. Well, it doesn't even break so much as it totally doesn't work the way you expect it to. You'll need some pretty extensive pre-mission testing if you're going to have that much depend on a properly functioning relay station.

 

In a way, you're basically building a cell tower there, since you've got to store the signal and then send it out to a different receiver. (Twice, in fact, since you also get data from the rover over radio.) Also, I think you'll probably have to use two separate protocols for radio comm since you'll have about 2 seconds of lag from Earth to Base, and effectively instant comm between Base and Rover.

 

TFS

[Cold Fusion]

As a physicist I would like to participate. Count me in. Ad Astra

[TheBigDog]

As a physicist I would like to participate. Count me in. Ad Astra

Welcome aboard! Do you have a particular area of interest in the mission?

 

Bill

[Kayra]

Greetings Cold Fusion.

 

I think I follow you, Kayra. How about if the rockets are only powerful enough to just overcome the gravity of the moon. We monitor the rate of descent. When the rate exceeds x we fire the rockets until the rate of descent falls below y. We then shut off the rocket until the rate of descent exceeds x again. All we are trying to do is stay in a range of speed which the airbag at the bottom of the lander will survive. I also think you are talking about a collapsing airbag, like the ones used for stunt jumps, rather than a bouncing method used for landing on mars. It is just there to absorb most of the energy of impact, but we don't exactly need to touch down gently. We can also film it that way. Very nice thought.

 

Bill

 

Simple, robust, and elegant BD. Exactly the control system that we need.

[Jay-qu]

So who has read the rules from post #151? I think its important that anyone participating has an intimate understanding of the rules. The more people that read it the more potential we have to finding shortcuts and the like

 

We dont want to waste time and effort running off on tangents that are either prohibited or useless given the current set of rules.

[freeztar]

So who has read the rules from post #151?

 

I have. I was quite surprised at the requirements (the camera reqs. in particular). We will have to factor these reqs. into our "master plan" as it influences mass, and everything else down the line.

 

I think its important that anyone participating has an intimate understanding of the rules. The more people that read it the more potential we have to finding shortcuts and the like :lightning

 

We dont want to waste time and effort running off on tangents that are either prohibited or useless given the current set of rules.

 

I agree. :naughty:

That is why I proposed a mission outline back in post #50. The outline should include all mission requirements first and foremost.

[Turtle]

So who has read the rules from post #151? I think its important that anyone participating has an intimate understanding of the rules. The more people that read it the more potential we have to finding shortcuts and the like :(

 

We dont want to waste time and effort running off on tangents that are either prohibited or useless given the current set of rules.

 

I read them through & through today. Quite the remarkable amount of ruleage on the advertising, marketing, & legal-sign-away-your-rights-to-a-lot of-specific-stuff kind. :hihi: :doh: No really. You have to include the X-prize peoples logo on the CRAFT in such a way so that it is included in the self portraits. Just one example.

 

On the cool side, if we produce a prototype early on that does it all on Earth, we can qualify for 'special' help. We can (well, have to) take it on tour for educational and promotional events. Right up BigDog's proposed alley! :naughty: Also in that alley, the requirement that we encrypt our signal and give them the key of course.

 

Sorry for running on...what was the question? :) Oh yeah...yes I have read the rules. :lightning

[Pyrotex]

I think I follow you, Kayra. How about if the rockets are only powerful enough to just overcome the gravity of the moon. We monitor the rate of descent. When the rate exceeds x we fire the rockets until the rate of descent falls below y. We then shut off the rocket until the rate of descent exceeds x again. All we are trying to do is stay in a range of speed which the airbag at the bottom of the lander will survive. ...

It is an exceedingly clever idea, Big Dog, so clever in fact, that it pains me to criticize it at all.

 

But... (1) A restartable rocket engine is complex as hell. Trust me on this one. Getting a system reliability of 90% or more will be a real pain. A "light once and it burns until it's gone" rocket can be 99.99% reliable without too much cost.

But... (2) The rocket you describe would require a much larger mass of fuel to do the same job as a burn-once rocket with high decelleration. Think of it this way: consider a rocket in a gravitational field, any strength, call it 1 "jee". If I fire the rocket against the grav field, then 1 jee of my acceleration is "wasted". 10 jees of "felt" accelleration actually gives me only 9 jees of "motion" accelleration; 3 jees of "felt" acc gives me 2 jees of "motion" acc; 1 jee of "felt" acc gives me 0 jees of "motion" acc -- as you would expect because now I am merely HOVERING. I am wastefully burning all my fuel just to fight gravity and not increasing my speed at all.

 

Your "gradual firing just to keep the speed slow" rocket would be fuel inefficient for same or similar reasoning. :cheer: I am so sorry.

[Kayra]

Pyrotex: Hmm, that makes perfect sense, and is something I had not considered.

 

So freefall to a calculated point and firing a one time rocket (or rockets?)would be the way to go for highest efficiency?

 

It would still seem the calculations on when to fire the rockets should be fairly easy (for a rocket scientist :cheer: ) to calculate, or am I wrong?

[Buffy]

A little warning before y'all go off the deep-end depending on us programmers to "automate everything":

The South African National Defence Force "is probing whether a software glitch led to an antiaircraft cannon malfunction that killed nine soldiers and seriously injured 14 others during a shooting exercise on Friday."

 

B and Chac might have some other interesting tid-bits....

 

There is always one more bug, :cheer:

Buffy

[TheBigDog]

It is an exceedingly clever idea, Big Dog, so clever in fact, that it pains me to criticize it at all.

Lucky for me a little pain never stopped you. I was thinking about this after I posted it. Continually overcoming a force will take far more fuel than doing it just once, and is far more complicated. Still, at some point you need to control your rate of descent, otherwise the target velocity and point in space is a really narrow window to hit from 400,000 km.

 

Imagine we use the idea from Janus for a highly elliptical LEO, but it is so elliptical that we let the ship get caught by the gravity of the moon. Then as we fall to the moon all we need to do is hit as gently as possible. No orbiting the moon, just letting ourselves be drawn to the surface by gravity. We have an engine who's sole purpose is to remove all of our speed so end up "stopped" a fixed distance above the surface. At the moment that we are stopped we disconnect from that rocket and let it fly off into space consuming the rest of its fuel. At that point we use descent rockets to bring us to a landing. The trick is to get as close to the surface as possible with the slow down to minimize the fuel and hardware needed for the final descent and landing.

 

The physics for this should be pretty straight forward. Is there a simulator we can play with, or can someone make a simulator for the launch to landing portion of the mission?

 

Bill

[freeztar]

That sounds better TBD.

 

While were on the subject of landing, I think it would be beneficial for everyone to take a look at this link. It is the 2006 Lunar Lander Challenge. The 2007 Challenge is coming up at the end of October.

X PRIZE Foundation: Northrop Grumman Lunar Lander Challenge 2007

[TheBigDog]

Great link, freezy! It got me thinking about our own practical testing. I think that attaching a large helium balloon to simulate the lower gravity would be key. Controlling the flight that way under 1G instead of .17G is over-stressing the engineering really required for lunar performance.

 

I am sticking with the Rover. I want desperately to play with large RC cars get to where I am controlling them via a web connection. Who knows, when I get it working I can rig it up so people can log in and control the test rover right here at Hypo.

 

Bill

[Turtle]

...

I am sticking with the Rover. I want desperately to play with large RC cars get to where I am controlling them via a web connection. Who knows, when I get it working I can rig it up so people can log in and control the test rover right here at Hypo.

 

Bill

 

I keep thinking of the Earth-bound applications too BD. A rover could rove deserts or forests or other wilds areas. And while I'm screwin' the Moon, I think I'll take a joust to screw the X-prize people too. :) Seems to me they are letting teams do all the work while they sit back & rake in the cash from the marketing. The $30 million prize is spit in a very large bucket. So screw them, and we instead build and finance the rover and launch as we planned, and do the raking in ourselves! :cheer: