Hypography X Prize Entry

[Pyrotex]

From the lack of responses, I'd say this was all pretty daunting. It gets worse.

 

ROCKET SCIENCE LESSON #2

 

You got to do a risk analysis with a "fault tree" on every component of the Lunar Payload, including the Rover. This starts with a diagram of every every "box" or replaceable unit (RU) and how they are connected by data cables, power cables, mechanical links, etc. For each RU, a table is created showing each failure possible and how that failure spreads to other, connected RUs. Consider falling dominos. Consider the poem "for want of a nail, the shoe was lost, for want of a shoe, a horse was lost...".

 

Why, for pity sake?!?! :esmoking: Assume that each RU is 99% reliable, and you have 100 RUs with no redundancy. What is the probability that the collection of RUs will work as planned. Less than 37%. that's 0.99 to the power of 100. About 1 chance in 3. Not good enough.

 

You can address this with redundancy. You can address this by making each component RU MORE reliable. At 99.5% reliability, the same 100 RUs now have a 60% chance of success.

[Jay-qu]

Yes it is daunting, but thats part of it that makes it so exciting! :esmoking:

[CraigD]

From the lack of responses, I'd say this was all pretty daunting.

I, for one, admit to being daunted. A lunar X challenge is much harder to start than, say, a front porch tear-out/design/rebuild, and even this minor project is capable of daunting me! A certain “put up or shut up” factor is involved here, too, I think – it’s easy to propose spaceflight systems when there’s little possibility of actually implementing them in the near future, but to win google’s tens of millions (and science hobbyist near godhood), the team actually has to build this thing, and land it on the moon. I can’t shake the feeling that this would ultimately entail some pretty major commitments – dayjobs quit, personal property liquidated, etc. – taking the participant out of the domain of hobbyist into that of professional space engineer/scientist (best case) or the sad sort of person newpapers and local TV newsrooms run human-interest features on on a slow news day. :friday:

You got to do a risk analysis with a "fault tree" on every component of the Lunar Payload, including the Rover. …

True, but I think we’re still in the idea/brainstorming phase, with at least one major phase – unit/integration testing (in which, if all goes according to (my vaguely envisioned) plan, some lucky person, maybe me, get to play with RC vehicles in a big vacuum chamber) – before we get to risk/failure mode analysis.

 

So here’s some idea/brainstorming:

 

Looking at the project as a whole, I see something like this:

• Launch – Using a commercial system, so a non-issue/someone else’s problem
  
• Propulsion – I’m pretty sure hydrazine thruster(s) of whatever size the design requires can be fabricated, and, due to their simplicity and proven record, are 99.99+ % reliable.
  
• Landing – Been done with much more primitive hardware. 1/6 g in vacuum is a forgiving flight domain. I’m not sweating this.
  
• Rover operation – Fancy RC cars with video cameras. No sweat here, either
  
• Communication – It’s a long way to the moon. This, I’m sweating significantly.
  
• Navigation/guidance – Historically (eg: the 1960s’ Luna program), navigation failure accounts for more failures than anything but launch failures. Determining the position and velocity of unmanned vehicle – essential to getting it to a specific desired position and velocity (ie: stationary on the moon’s surface) – is critical.
  

Lots to talk about. I want to brainstorm about navigation.

 

The traditional navigation system on a moon flyby/orbit/lander determines position by getting optical fixes on points on the earth, sun, stars, and planets. I wonder, could we do better now, using the GPS, or other radio range and direction systems?

 

The GPS is intended to provide precise positions near the Earth’s surface. However, weak radio signals, including the timing information necessary for the system to work, are, I suspect, transmitted into space. Could a sensitive receiver on our spacecraft use these stray signals to get position fixes more accurately than a traditional navigation system? If so, it seems such a system would be simpler, cheaper, and more reliable than the traditional ones.

 

Alternately, could a special ground-based system be used? This would involve having enough ground transmitters to always have a “constellation” of 3 or more widely separated transmitters within effective line of sight of the spacecraft. Vs. existing GPS, it has the disadvantage of having to be built, atmosphere and weather issues, and the advantage of being made as powerful as necessary, reducing the required sensitivity of the spacecraft’s receiver.

 

Alternately, could the spacecraft be the transmitter, and several ground stations the receivers?

 

The key to a radio positioning system like GPS is a precisely timed transmission coupled with a very accurate clock. In commercial near-Earth’s surface, is accomplished with a good crystal clock that sets itself from the satellites’ atomic clocks. A more expensive system could have its own atomic clocks.

 

I suspect that at least one of these options is a significant improvement on a more traditional guidance system. In essence, they take advantage of our current technological ability to make such precise timings that we can determine transmitter-to-receiver distance down with great precision by measuring the travel time of the signal.

 

Of these options, the first, using the existing GPS satellites, is most attractive to me, because it could be very inexpensive.

[Mercedes Benzene]

I'm getting excited now.

 

 

I'd like to focus primarily on propulsion if that's okay...

Doing some research, it seems that most of the work can be done for us with preconstructed systems. Here's one website that I found interesting:

 

Monopropellant Hydrazine Thrusters

 

It seems lots of companies have systems that can be made to order, and will then be ready to assemble.

[silverslith]

A big limitation is obviosly the need for hardened electronics. This could be avoided if a sensible earth-moon vehicle is used. putting the goods inside a snowball of frozen fuel is the answer for getting any microelectronics through the rad belts. over 50 tons of shielding is needed otherwise. If you use your fuel as the shielding then no probs. Daytime moon is still a bit messy tho.:naughty:

[Pyrotex]

And so, we come to (you knew this was coming)...

 

ROCKET SCIENCE LESSON #3

 

Once you have the outline of your WBS (it needn't be complete), then you must start your design with the most important things: REQUIREMENTS.

 

Generically, a requirement (or "reqt") is just a statement of something your design must provide, accomplish, or withstand. There are three levels of requirements:

 

1. Mission Reqts. What must the overall mission provide, accomplish, fulfill, etc.

For example:

1.a. The mission shall place a remotely controlled rover on the surface of the Moon.

1.b The mission shall be accomplished by November 15, 2012.

1.c The mission shall cost no more than US$ 95,000,000.

 

2. System Reqts What each major system must provide, accomplish, fulfill, withstand, etc.

For example:

2.a The lunar rover system shall weigh no more than 5.7 kg.

2.b. The lunar rover shall function for at least 12 days.

2.c. The lunar rover shall travel at least one kilometer in its lifespan.

2.d. The lunar rover shall return full visible spectrum digital photographs of 3 megapixels each; at a maximum rate of 10 photographs per second.

 

3. Component Reqts. What each component must provide, accomplish, fulfill, etc.

For example:

3.a. The rover motor assemblies (including electronics) shall operate within the temperature range of -10C to 100C for a minimum of 90 days.

3.b The motor assemblies shall operate in a Lunar radiation environment for a minimum of 90 days.

3.c The motor assemblies shall operate in vaccuum for a minimum of 90 days.

 

If we were to be as exhaustive as NASA is, our payload section, with landing system and rover, would require about 6 shelf feet of reqts documentation. :naughty: We can probably get by with a dozen 1-inch 3-ring binders.

 

Why reqts? Because they drive design. Somebody designs a wonderful motor assembly capable of driving the rover at 10 mph. But wait, the system reqts only demand 1.5 mph. That motor is over designed, and probably weighs too much and certainly takes too much electrical current. It's out of spec. But isn't 10 mph better than 1.5 mph? Not necessarily. What if the wheel and axle design can't support 10 mph? What if the batteries aren't big enough to go that fast. And besides--everybody agreed to 1.5 mph! Your fancy shmancy motors have bollixed up everybody else's design and threatens to sabotage the project. Sorry, but it's true. ;)

 

Agreeing on reqts keeps everybody designing toward the same consistent vision. It keeps weight down, minimizes resource demands, avoids technological risk, promotes success.

 

Of course, the down side is, that means you'll find "the perfect" RC buggie that will carry a big camera with zoom, and it puts the whole payload way over the agreed upon mass limit for the rocket. Damn. Reqts keep enthusiatic, but narrowly focused engineers from forcing everybody else to redesign THEIR systems.

[Pyrotex]

I, for one, admit to being daunted. ...Of these options, the first, using the existing GPS satellites, is most attractive to me, because it could be very inexpensive.

I have talked to a couple of **real** rocket scientists and they are very doubtful that GPS could be used at the Moon. GPS use reflector antennas to put 95%+ of their transmission on the surface of the Earth. From an altitude of about 500 miles. (more or less) At 125,000 miles, the surface of the Moon is 250 times further away. So any GPS radio power that "leaked" in the Moon's direction would be diminished by another factor of 62,500! :eek:

 

Sorry, but that idea, though brilliantly creative, prolly won't work. :(

[Pyrotex]

ROCKET SCIENCE LESSON #4

 

"Where to Start"

 

Brainstorm the overall concept of the project until you can write down the basic mission requirements. Probably 1 or 2 pages.

 

Make a list of the top 10 "tasks" the mission must accomplish. Like: get to the Moon; slow down; navigate to right place; land; activate rover; etc. Come to an agreement in principle as to how each of these "tasks" shall be done. For example, "navigate" could be done either from the ground or autonomously with a star-tracker.

 

Complete the top level of the Work Breakdown Structure (WBS) to at least the system level, and to sub-system level if it's easy. Probably 1 or 2 pages.

 

Take first crack at defining the reqts for the systems in the WBS. Probably 1 or 2 pages per system.

 

Break each system down into sub-systems as necessary; and sub-systems down into components as necessary.

 

Make pretty drawings of each system. Demonstrate with the drawings how each system is going to fullfil its share of the mission reqts; and its system reqts.

 

Complete the system reqts. Draft the sub-system reqts. About 1 page per sub-system.

 

For each system and its sub-systems, start a list of all the potential failures. For example: motor switch fails OFF; battery overheats; rover falls over; etc. Discuss possible failures, their likliehood, and what can be done to avoid or overcome them. For example: supply redundant motor switches; provide passive cooling to battery with radiators; supply motor override shutoff via a tilt-meter. About 2 or 3 pages per sub-system.

 

Design each system with as much detail as you can. Estimate mass and volume. Add up all masses and volumes to verify you still meet mission reqts.

 

Etc. Etc. Etc.

[Turtle]

I have talked to a couple of **real** rocket scientists and they are very doubtful that GPS could be used at the Moon. GPS use reflector antennas to put 95%+ of their transmission on the surface of the Earth. From an altitude of about 500 miles. (more or less) At 125,000 miles, the surface of the Moon is 250 times further away. So any GPS radio power that "leaked" in the Moon's direction would be diminished by another factor of 62,500! :eek:

 

Sorry, but that idea, though brilliantly creative, prolly won't work. :(

 

I agree the GPS is doubtful for Moon use. A couple corrections: the Moon is 250,000 miles away and the GPS satellites orbit at ~12,600 miles above Earth. This source says they use only a 27 watt transmitter...High Sensitivity GPS - Wikipedia, the free encyclopedia

 

In order to receive our signal, do we have to contract with existing radio receivers? :eek:

 

That is all. :(

[Pyrotex]

I agree the GPS is doubtful for Moon use. A couple corrections: the Moon is 250,000 miles away and the...GPS satellites orbit at ~12,600 miles above Earth. This source says they use only a 27 watt transmitter

...In order to receive our signal, do we have to contract with existing radio receivers? ...

Thank you for correcting my numbers. See what happens when you are too lazy to do research and trust to memory instead??? :eek::eek::(:(:doh:

 

Yes, we would need to contract with NASA, Australia or the Netherlands to use one (or more) of their deep space receivers to get back our pictures and to send our remote control commands.

[Kayra]

Navigation:

Are laser range finders capable of working accurately over these distances? If so perhaps the following might be enough for navigation purposes.

 

Point a laser range finder at the center of the earth and record the distance.

Pulse a radio beam towards the earth at a known frequency, and embed the results of the laser range finder in the pulse.

 

On earth, you would track the source (accurately enough?) of the radio. This would give you Range, Location (in all 3 dimensions), speed the object is moving away from you (through Doppler Effect on the radio signal), and lateral speed my tracking each pulse over time.

 

Could a system navigate accurately enough for our purposes with this given set of information?

[Jay-qu]

Navigation:

Are laser range finders capable of working accurately over these distances? If so perhaps the following might be enough for navigation purposes.

 

Point a laser range finder at the center of the earth and record the distance.

Pulse a radio beam towards the earth at a known frequency, and embed the results of the laser range finder in the pulse.

 

On earth, you would track the source (accurately enough?) of the radio. This would give you Range, Location (in all 3 dimensions), speed the object is moving away from you (through Doppler Effect on the radio signal), and lateral speed my tracking each pulse over time.

 

Could a system navigate accurately enough for our purposes with this given set of information?

I doubt it, because the ranging accuracy would be limited by the topology of the surface of the Earth - which if its ground and not ocean, would not be very good. But it could be used for a rough estimate as the craft travel to the moon perhaps?

[CraigD]

Are laser range finders capable of working accurately over these distances? If so perhaps the following might be enough for navigation purposes.

 

Point a laser range finder at the center of the earth and record the distance…

I think you’d have insurmountable problems with a LIDAR on the spacecraft due to the earth’s atmosphere. Getting a detectable laser return from the Apollo LLRE corner reflectors on the moon’s surface from the Earth’s surface takes a powerful laser, a fairly large telescope, and a very sensitive light detector, a trio like that found at the McDonald Laser Ranging Station.

 

A couple of alternatives might work:

• LIDAR on the spacecraft aimed at the Apollo LLREs. There are 3 of them (and a couple of Soviet Luna equivalents), so a simple triangulated fix is possible (though I’m not sure if Earth-based observations have located the LLREs with precision sufficient to realize LIDARs roughly 0.1 m precision), and there’s no lunar atmosphere to attenuate the laser beam.
  
• Place a corner reflector on the spacecraft, and range it from several of the ground observatories used to range the moon using the Apollo LLREs. Getting enough of these observatories to participate, synchronizing them sufficiently, and monopolizing their time enough for near-realtime guidance, might be a difficult feat of procurement.
  

[Turtle]

Thank you for correcting my numbers. See what happens when you are too lazy to do research and trust to memory instead??? :doh::lol::doh::lol::doh:

 

No worries; I'm a licensed technical editor and as such required by law to make corrections where I see heirs even if they are from someones mammary problems. :lol: :D

 

Yes, we would need to contract with NASA, Australia or the Netherlands to use one (or more) of their deep space receivers to get back our pictures and to send our remote control commands.

 

This put me to thinking of scheduling. How much lead time is required to buy time on these receivers? Then there is the launch rocket...what's the lead on that? How big a deposit?

 

That's all I got. ;)

[GAHD]

Yes, we would need to contract with NASA, Australia or the Netherlands to use one (or more) of their deep space receivers to get back our pictures and to send our remote control commands.

 

• Space Exploration Technologies (SpaceX), run by entrepreneur and X PRIZE Foundation Trustee Elon Musk, which is offering competing teams an in-kind contribution, lowering the cost of its Falcon Launch Vehicle. SpaceX is the first preferred launch provider for this competition;

• The Allen Telescope Array (ATA), operated by the SETI Institute, will serve as a preferred downlink provider for communications from the Moon to the Earth; operated by SETI, which will provide downlink services at no cost to competing teams;

The UPLINK portion still seems fuzzy, but the launch and downlink portions are well in hand thanks to the "Strategic Alliances" x-prise has so conveniently made.

[Theory5]

Hey guys.

as I said I'm going to be an infrequent member of this but a 'rover base" that recharges them? no. they should be self sufficient at the very least. i know about cost and all that but If, say there is a communication malfunction or somthing, say a bug in the hardware or just bad driving the rover could go into a crater and get stuck, or run out of power, or be flipped over. Then where would we be? Now, what is the gravity on the moon? 1/4 earths? I don't remember. but how about low gravity planes (or closer to VTOL craft or heli's). Like remote control little flyers? Cheap cost, you don't even need wings! Now fuel costs a lot right? so how about somthing else? not solar sails (to slow) but how about..... no wait Im going about this all wrong. Bouncing things. Giant wire frame balls. Like a hamster ball. a bit bigger than that. if it bounces or rolls over? no biggy.

just keeps going.

Now I know that is a big abstract from your way of thinking, but why limit yourselfs to small remote control car like vehicles?

 

just a suggestion.

so about this landing vehicle, you guys want use that airbag like thing? or what?

[TheBigDog]

I like the ideas Theory5, but there is some method to my madness in wanting to recharge the rovers at the base. In a word, moondust.

 

The moon is covered with very fine, dust that gets into and onto everything. If you have solar panels on the rover it needs to protect them from this dusty menace. On mars the wind can be used to blow off the dust, but there is no wind on the moon. There is also the hazards associated with rolling over the rover. I like the idea of a rover that cannot be stopped. Over sized wheels so that even if it flips or flops it can still be driven. All of the electronics would be sealed inside to protect from the dust. Even recharging would be done by proximity, like a SoniCare toothbrush rather than with contacts. The lander would have the solar panels fixed up high, above any dust that would be kicked up by the slow rolling rovers. If done properly this could give you a reliable unit on the moon that might last for years. Multiple rovers give you more chance of success, and keeping them dirt simple and cheap is a big key. Hell, if the rovers eventually die off more could be sent to the proximity of the lander. You could even space out landers like gas stations, allowing rovers to move over great distances, as long as they can make it to the next lander for a recharge.

 

No matter what configuration you run you have the risk of communication failures. You want to avoid single points of failure that will kill the whole mission, but by the nature of things they cannot be completely eliminated (at least not as I have seen yet). Over design, proven technology and some designed redundancy will be the keys to success in budget.

 

I had thought about the hamster ball too. It is appealing, but dust is the problem with that one too. The outside would become coated in dust blocking any hope for getting electricity from light. But you still might be able to get electricity from heat! Hmmm...

 

Bill