What's the hardest part of the Google Lunar X prize?

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E

exoscientist

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What do you consider to be the hardest part of the Google Lunar X Prize Challenge?
The robot requirements are pretty simple. The high data transmission requirements (for high def TV) appear doable by using large, perhaps arrayed, radio telescopes as the receivers on Earth.

For the launch, the obvious thing to do is to purchase space on an existing launch vehicle. According to this page, the delta-v budget to go from LEO to low lunar orbit is about the same as to go from LEO to GEO:

Delta-v budget.
4 Earth-Moon space budget.
http://en.wikipedia.org/wiki/Delta-v_bu ... ace_budget

The delta-v required to go from low lunar orbit to the Moon is also rather low as given on that page as 1.87 km/s.

The cost to GEO is in the range of $25,000/kg so might be in the same cost range to lunar orbit, perhaps 2 to 3 times that to get to LEO.

So you need a lander. What would be the hardest part of getting a soft landing on the Moon? The rocket, navigation, stability, radar ranging to the surface?


Bob Clark
 
M

MeteorWayne

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As currently configured, I'd say the requirement it has to be completed by January 2010 :)
 
W

williammook

Guest
From surface to LEO 9.2 km/sec
From LEO to lunar trajectory is 3.85 km/sec.
From lunar trajectory to lunar touchdown 2.35 km/sec.

A total of 15.40 km/sec

A MEMs based rocket array produces 25,000 kg per sq meter and costs $2,500 per sq m to make out of silicon wafers. MEMS based rockets have a 1,000 to 1 thrust to weight ratio. So a sq meter masses 25 kg per sq m.

http://pdf.aiaa.org/preview/CDReadyMJPC ... 5_3650.pdf

MEMs rocket arrays provide a simple and reliable means to control the attitude of a rocket in flight. They also operate at very high efficiencies. This simplifies many of the systems in rockets. Meanwhile MEMs based gyroscopes and other sensor simplify avionics. Structural mass is therefore reduced to 9% total vehicle weight.

Divide this into four stages each capable of 4 km/sec ideal delta vee using hydrogen/oxygen propellants.
Hydrogen oxygen propellants produce a specific impulse of 450 sec in vacuum and 435 seconds at take off.

Ve = Isp * g0 = 435 *9.802 = 4,263.87 m/sec = 4.26 km/sec
450 *9.802 = 4,410.90 m/sec = 4.41 km/sec

This means the following propellant fractions are needed to attain a Vf = 4.00 km/sec

u = 1 - 1/exp(Vf/Ve) = 1 - 1/exp(4.00/4.26) = 0.608968 = 0.61 = 61%
1 - 1/exp(4.00/4.41) = 0.596278 = 0.60 = 60%

With structure fraction equal to 9% and propellant fraction of 61% leaves payload fraction of 30% for four stages.

Starting with a 100 kg rover as payload - we have

LANDING STAGE
333.3 kg total

233.3 kg propellant
174.3 kg oxygen
29.0 kg hydrogen
100.0 kg payload
30.0 kg structure

100 kgf thrust - 40 sq cm MEMs array

TRANSFER STAGE

777.8 kg total

677.8 kg propellant
581.0 kg oxygen
96.8 kg hydrogen
100.0 kg structure

500 kgf thrust - 200 sq cm MEMs array

UPPER STAGE

2,592.6 kg total

2,259.3 kg propellant
1,936.5 kg oxygen
322.8 kg hydrogen
333.3 kg structure

4,000 kgf thrust - 800 sq cm MEMs array

LAUNCH STAGE

8,642.0 kg total

7,530.9 kg propellant
6,455.0 kg oxygen
1,075.9 kg hydrogen

1,111.1 kg structure

20,000 kgf thrust - 4,000 sq cm MEMs Array

Including payload the empty mass of the vehicle is 1,674.5 kg

http://www.defense-aerospace.com/dae/ar ... July06.pdf

Aircraft Weight (kg) Cost ($ million) Cost per kg ($)
F-15E 20,400 108.2 5,303
caviar 6,000 May 2006
F-18E 13,400 95.3 7,111
JSF 12,000 112.5 9,375
Gripen 5,700 76.07 13,345
Rafale C 9,400 135.8 14,446
Typhoon 9,750 143.8 14,748
gold 18,700 May 2006
F-22 14,400 338.8 23,472

At $5,000 per kg total vehicle cost is - $7.87 million
At $7,500 per kg total vehicle cost is $11.81 million

To build test articles, test flights and the flight itself and other and non-recurring engineering - allow another $8 million.

A total of $20.00 million

Propellant total is 10,671.3 cost averages $3 per kg - so propellant cost per launch is $33,000

Recovering the the equipment is obviously important to keep budgets low.

The booster stage and upper stage have a total delta vee of 8 km/sec - so both are recovered downrange. The third stage accelerates the vehicle to 10 km/sec - GTO velocity. This stage is also recovered after separation - about a day after launch. The fourth stage - stays on the moon - but can be tested by placing it into orbit and then returning it to Earth if desired.

The cos of the materials on the moon then are;

Rover = 100 kg
Stage = 30 kg

Cost $650,000 to $975,000 per flight + $33,000 per launch

Downrange recovery is accomplished by tow planes which retrieve the stages and bring them back to launch center after launch.

A total of six vehicles landing at the Apollo landing sites with rovers sporting HDTV - could be placed on the moon for $25 million. Over a three year period - the lifespan expected for these vehicles - a total of 157,788 hours of broadcasts will be made. $158.44 per hour. This includes full duplex two-way control

Assuming 50% sell through of available time, and allowing some profit margin- $300 per hour charge sold in 1/2 hour blocks. Universities and research institutions get a discount, but must buy in larger blocks. Market values would be far higher - especially for revisiting of the Apollo sites.

A company can sign a deal with someone like Virgin to build the six vehicles and land them at the six sites by agreeing to buy all the hours. My company then builds owns and operates the vehicles to deliver 83,333 hours from the moon at $300 per hour. Additional systems can be sold under similar agreements.
 
W

williammook

Guest
Elsewhere I posted a comment that indicated an astronaut in a long duration spacesuit could spend 12 days in space and then re-enter the atmosphere -the suit possessing its own thermal protection. This allows a person to be put on orbit massing only 300 kg. The lunar vehicle described above puts 333 kg into a GTO. It may be possible to use this vehicle, once built, to put individuals into GTO or LFR - Lunar Free Return trajectory. This would be quite a ride! A 33 kg free flying camera system records the journey for posterity, and helps with command and control

Camera
http://www.gadgetizer.com/2005/08/13/na ... ace-balls/

Suit
http://www.astronomy.com/asy/default.aspx?c=a&id=5790
http://mvl.mit.edu/EVA/biosuit/

A lunar free return flight would be sold for $10 million each -

A piloted lunar landing is achieved by creating a larger stage as the first stage booster, and then the booster becomes the upper stage, the upper stage the injection stage, and the injection stage the landing stage. The payload rises from 100 kg on the moon to 333 kg on the moon.

Thrust: 80,000.00 kg - 1.6 sq m.

GLOW: 41,152.26 kg

stage weight: 28,806.58 kg

propellant: 25,102.88 kg
LOX: 21,516.75 kg
LH2: 3,586.13 kg

structure: 3,703.70 kg

For $18.5 million to $27.8 million development cost.

But there's no way to get back!!

Ah, but lookee here;

The landing stage of the smaller stack can be modified to return 320 kg back to Earth by pre-positioning it on the moon before the human got there!! The 333 kg payload will consume 13 kg of consumables by the time they get on board for the return flight!! Also, if we land near a rover, we don't need to bring the camera with us but lose coverage on the return flight.

0.41970 u - propellant fraction
0.50970 u+s - propellant plus structure fraction
0.49030 p - payload fraction

652.67 kg total - at lift off - 250 kgf thrust
273.93 propellant
58.74 structure
332.67 stage total (wo payload)

320.00 payload

2,400 m/sec - Vf
4,411 m/sec - Ve

For $293,700 to $443,600 development cost (assuming completion of the earlier programs)

A flight to LEO can take 3 spacesuited figures to space and back - for a day orbiting the Earth.
$3,500,000 each

A flight to GTO/LFr takes 1 spacesuited figure for 1 to 8 days far from Earth, to vicinity of the moon
$10,000,000 each

A flight to the lunar surface and return to Earth for 1 astronaut - involves 2 launches - one unpiloted
$18,000,000 each

So this is what a modest development program involving lunar landers can do.

With 3 flights per week - at $9 million per flight - that's $1.4 billion per year - starting with unpiloted landers, then piloted earth orbit and lunar orbit - and finally piloted landing on the moon. Total cost less than $60 million - in 3 steps;

STEP 1: Buy 100,000 hours at $300 per hour from six sites for 3 years;

$30 million

STEP 2: Buy 9 flights to LEO for $3.5 million each

$30.5 million

STEP 3: Buy 1 flight to the moon at $18 million

$18.0 million

This builds the smaller launcher with a rover on the moon in step 1. Then, in step 2 build the larger booster and reconfigure the upper stages, and develop the MCP long duration moon suit. In step 3, build the lander and test the suit for lunar conditions.

Additional flights bring about additional boosters to increase the size of the fleet and the flight rate - to achieve our 3 flights per week goal. We offer lunar rovers, lunar orbiters, payloads to Earth orbit, orbital tourism, cislunar tourism, and lunar surface tourism and research. We can also modify the last stage to send payloads to Mars, Venus and Mercury - unpiloted. Also, inflatable structures can be sent ahead, along with supplies, for extended stays on the moon.
 
W

williammook

Guest
NASA's flying eyeball can be adapted for a low cost lunar rover. With MEMs based rocket arrays and actuators, an 18 inch diameter ball filled with propellant with a propulsive skin, would land on the moon and roll around as well as fly around using bursts of rocket power to move. Multiple cameras pointing in all directions with over-lapping fields of view provide a rotating scene that is stitched together into a stationary 360 degree panorama in computer memory using gyro data. In all the vehicle has only one moving part - itself. It is capable of rolling up an incline using rocket power and even hopping over obstacles.

An 18 inch diameter sphere holds 17.98 kg of propellant and masses 1 kg overall without propellant. This gives the sphere 1 hour hover time. It can also land and escape from the moon all by itself. With rolling resistance typical of this type of wheel in the lunar gravity, it provides 1 day to 2 days 'rolling time' depending on the terrain.

http://farm3.static.flickr.com/2218/211 ... 7e57_o.jpg

Power is obtained by taking the hydrogen and oxygen gases boiling off the liquids and using them in MEMs based fuel cells that are 80% efficient. This allows the production up to 40 watts continuously. Boil off alone uses up all the propellant in 90 days. The water is evaporated for heat control. Phased array antennae built into its surface provide a means to receive and send signals in any direction.

With a delta vee capacity of 12 km/sec - this system is quite capable! Far less costly than the larger system described Earlier. In fact a two stage system - with a 180 kg and 60 kg booster stage, to impart 4 km/sec each to the lander/return stage - which operates as a free roving camera.

A total mass of 25 kg and at $10,000 per kg that's $250,000 for the entire vehicle. Its small enough to launch from your ranch!! 250 kgf at lift off! There's another $1,750,000 non-recurring engineering charge. Still, very interesting.

So, the first stage takes you 4 km/sec, then the second stage to 8 km/sec (ideal) but final speed is 6.5 km/sec. Both stages enter downrange and are recovered by an aircraft loitering at the recovery point. The sphere with its own large propellant supply, adds another 4.35 km/sec - burning only a fraction of the onboard propellant. 3 days later is settles to the lunar surface using up another 2.4 km/sec. 6.75 km/sec overall. This leaves 5.25 km/sec left - enough to operate a few hours before departing - or perhaps visiting several apollo sites - flying ballistically to each.

This could be done before the 3 year lunar rover - which is basically the same design, but has solar panels to recharge the self contained hydrogen oxygen system and capturing the water. The more sophisticated system uses MEMs based 'feet' that kick radially outward from the surface to propel the vehicle - without the expenditure of propellant.
 
M

MeteorWayne

Guest
Despite your 3 voluminous posts, I believe mine is the best answer to the question....
 
E

exoscientist

Guest
williammook":2z2dmcy9 said:
From surface to LEO 9.2 km/sec
From LEO to lunar trajectory is 3.85 km/sec.
From lunar trajectory to lunar touchdown 2.35 km/sec.

A total of 15.40 km/sec

A MEMs based rocket array produces 25,000 kg per sq meter and costs $2,500 per sq m to make out of silicon wafers. MEMS based rockets have a 1,000 to 1 thrust to weight ratio. So a sq meter masses 25 kg per sq m.

http://pdf.aiaa.org/preview/CDReadyMJPC ... 5_3650.pdf

MEMs rocket arrays provide a simple and reliable means to control the attitude of a rocket in flight. They also operate at very high efficiencies. This simplifies many of the systems in rockets. Meanwhile MEMs based gyroscopes and other sensor simplify avionics. Structural mass is therefore reduced to 9% total vehicle weight.

...
Thanks for the response. For ease of accomplishing the mission, it might be better to purchase space on an existing launcher to get to lunar orbit.
Could you present your calculations just for a small lunar lander using MEMS propulsion?


Bob Clark
 
E

exoscientist

Guest
MeteorWayne":31e7qxtb said:
As currently configured, I'd say the requirement it has to be completed by January 2010 :)

Actually, it's by 2012 for the $20 million prize, and by 2014 for the $15 million prize.

This team though believes they can do it by 2010:

One Team's Plan to Win the Google Lunar X Prize.
"For the Carnegie Mellon team vying for the Google Lunar X Prize, failure to launch--and land--is not an option."
http://www.spectrum.ieee.org/aerospace/ ... ar-x-prize

Bob Clark
 
W

williammook

Guest
exoscientist":3ixrxrw9 said:
williammook":3ixrxrw9 said:
From surface to LEO 9.2 km/sec
From LEO to lunar trajectory is 3.85 km/sec.
From lunar trajectory to lunar touchdown 2.35 km/sec.

A total of 15.40 km/sec

A MEMs based rocket array produces 25,000 kg per sq meter and costs $2,500 per sq m to make out of silicon wafers. MEMS based rockets have a 1,000 to 1 thrust to weight ratio. So a sq meter masses 25 kg per sq m.

http://pdf.aiaa.org/preview/CDReadyMJPC ... 5_3650.pdf

MEMs rocket arrays provide a simple and reliable means to control the attitude of a rocket in flight. They also operate at very high efficiencies. This simplifies many of the systems in rockets. Meanwhile MEMs based gyroscopes and other sensor simplify avionics. Structural mass is therefore reduced to 9% total vehicle weight.

...
Thanks for the response. For ease of accomplishing the mission, it might be better to purchase space on an existing launcher to get to lunar orbit.
Could you present your calculations just for a small lunar lander using MEMS propulsion?


Bob Clark
Bob, if you had a 20 kg (44 lb) 'eyeball' that I just described, that was 18 inches (457.2 mm) in diameter, you would have something that might be carried along on the next flight to orbit. The big issue is the orbital plane and timing. About 40% of space launches are geosynch orbits - and that means 8 to 10 flights per year. Equatorial orbit is not in the lunar plane. There are vector calculations to do for each launch window. The thing is, is to work with all the folks launching to geosynch and pick the best one to work with, and hitch a ride on there.

Best case, your geosynchronous transfer orbit, arcs out from the launch center toward the moon. In this case, you merely have to release after initial boost and apply additional corrective thrust. Best case you add only 0.85 km/sec, (1,900 mph) worst case you add something like 2.00 km/sec (4,472 mph)

This takes you to the vicinity of the moon. When you get close, you go in for a direct landing, and arrive at 2.4 km/sec (5,367 mph) which has to be reduced to 0 km/sec at 0 altitude. Slowing at 1/6th gee (1/3 gee thrust and 1/6 gee gravity) gives you a distance of D = v^2/ (2*a) --- a = 1/6 gee = 9.802/6 = 1.6337 m/s2 applying these figures obtains

D = (2400*2400)/(2*1.6337) = 1,762.91 km

Slowing at 1/3 gee - which requires an acceleration of 1/2 gee on the rocket reduces this to 881.45 km.

These figures are approximate since gravity forces change with distance, and speed changes with distance. A numerical solution, or a closed form solution using the potential equation would change them slightly. These would also be tensor based with a 3d vector field for the application of thrust - pointing in a specific direction in space at a specific point along the approach path. Again, simple application of physics gives you a ROM figure that's pretty close to reality.

Total delta vee of the vehicle after it separates from the rocket carrying it - ranges from 3.25 km/sec (7,267 mph) to 4.40 km/sec (9,839 mph)- depending on the rocket you hitch a ride on where it was launched from, and where the moon was when you separated and where you were and what direction you were going etc., etc., etc..

Since there are candidate rocket launches every other month or so, you have a rich field to choose from. A good PR campaign might hook you up for free!

As mentioned in one of my earlier posts I envision an 18 inch diameter ball - with a number of overlapping HDTV camera sets pointing in all directions at once. The surface of the sphere also has MEMs based phased array antennae that allows the sphere to operate as an 18 inch diameter directional antenna - pointing in any direction. Of course there are MEMs rocket arrays spaced around the sphere as well to provide orientation control as well as acceleration thrust.

Exhaust speed in the vacuum is 4.26 km/sec. Speed requirements for soft touchdown is 3.25 km/sec to 4.40 km/sec. This translates to a propellant fraction of

u = 1 - 1/exp(Vf/Ve) = 1 - 1/exp(3.25/4.26) = 0.5337
= 1 - 1/exp(4.40/4.26) = 0.6440

For a 20 kg (44 lb) device this is 10.674 kg of propellant (23.4828 lbs) at the lower speed. 12.880 kg (28.3360 lbs) to carry out this mission with MEMs rockets.

So the mass budget for the device is;

20 kg total mass
12.9 kg propellant mass
7.1 kg remainder

Now I mentioned earlier structural mass of 9% should be doable in this type of device. That's 1.8 kg - and includes all the camera chipsets and so forth - they're all MEMS! - carefully crafted and assembled. That leaves the balance 5.3 kg ADDITIONAL PROPELLANT!

Some of this will evaporate (and power the MEMs based fuel cells)

The rest will be used to move the little ball around the surface of the moon. This includes awesome camera shots - aerial flight as well as rolling along the surface. Resting the device lasts up to 20 days on what's left. Rolling on the surface it can move 6 hours or so - at hundreds of miles an hour. At slower speeds it will last longer. It can hover for 20 minutes.

So shots can be taken high, low and so forth.

I envision that the device will come in for a touch down at one of the 6 Apollo landing sites, do a quick circle taking only a few seconds around the entire site - this will allow the cameras to get enough data for a 3D data set if done right. Then coming to rest - perhaps atop the LM landing stage. Once the 3D model is built, a tour is planned, and the ball quickly zips through it.

The ball may have enough oomph to visit a second site. Let's find out

Here's the data on the 6 landing sites;

Mission... Site Location......... Latitude.... Longitude.... Date of Landing
11....... Mare Tranquillitatis.. 0°41'15" N 23°26' E..... July 20, 1969
12....... Oceanus Procellarum 3°11'51" S 23°23'8" W.. Nov. 19, 1969
14....... Fra Mauro............... 3°40'24" S 17°27'55" W Feb. 5, 1971
15....... Hadley-Apennines.... 26°06'03" N 03°39'10" E July 30, 1971
16....... Descartes................ 8°59'29" S 15°30'52" E April 21, 1972
17....... Taurus-Littrow.......... 20°9'55" N 30°45'57" E Dec. 11, 1972

We can use the dot product to figure out the distance and bearing between all of these points - there's quite a number of them. We take them two at a time p=a1,b1 where a and b is longitude and latitude. q=a2,b2

Any vector that points to a point on the surface of the moon will have length r=1,737.1 km. So the right side we have r^2 * Cos[angle between p & q] for the dot product. On the left side, we can pull the r's out of the dot product, and cancel them with the r's on the right side. Let t represent the angle between p and q. Then if the latitude and longitude of our two cities, p and q, are (a1,b1) and (a2,b2), we have

11 to 12 = 1,422.5 km initial bearing 264°58′43″
12 to 14 = 179.6 km initial bearing 094°46′37″
14 to 15 = 1,094.0 km initial bearing 033°17′29″

and so on...

Now, from this data, and knowledge of lunar gravity, we can calculate the speed needed to carry out a ballistic transport between these sites - and from that calculate how much propellant we need to burn.

A simplified estimate can be calculated using the formula for parabolic trajectory;

range = V^2 / g

assuming a 45 degree launch angle. Actual numbers will be slightly different but these will be close.

where V is the velocity we require, g is the moon's gravity 1.6337 m/s2 - we have the ranges calculated above, so we re-arrange the equation and solve for v

SQRT(range*g) = V

Transit.... Kilometers... Ballistic Velocity
11 to 12 1,422.50 km 1,524.45 m/sec
12 to 14 179.57 km 541.64 m/sec
14 to 15 1,093.96 km 1,336.86 m/sec

So taking the trajectory from Apollo 12 in Oceanus Procellarum to Apollo 14 in Fra Mauro takes 0.55 km/sec - and we calculate the propellant fraction needed to do that and we get;

u = 1-1/exp(0.55/4.26) = 0.12112

We calculated at landing that we had 5.3 kg of propellant aboard a 1.8 kg craft - for a total of 7.1 kg -to toss this total mass the distance needed requires that 12% of it be ejected by the rockets;

0.12112 * 7.1 kg = 0.8599587 kg ~ 860 grams ~ 0.9 kg (budget)

this we can easily do since we had 5.3 kg of propellant left when we arrived at the first landing site.

12 to 14 - 0.9 kg
14 to 15 - 1.7 kg
15 to 11 ... 962.2 km range initial bearing 139°59′36″
1,253.77 m/sec propellant fraction 0.254757885
4.5 kg propellant remaining - total mass at start 6.3 kg
1.6049728077 kg ~ 1.7 kg

2.8 kg of propellant is left over - divided among the four sites that 0.7 kg of propellant - that's enough to fly around the site a little ways, roll around the site a lot, and sit at the site for quite a while.

So, you can see after the vehicle lands at one site, it can fly to the others ballistically in a few minutes time - in less than a day the device can get high resolution 3D data sets of the sites, high resolution maps from above, and explore close up artifacts left behind and take some cool picture of the territory between the sites.

The vehicle masses 1.8 kg - and at $5,000 per kg - that's $9,000 to build one - once you do the engineering work needed to design it. That's about $6 million. I could get it done in 18 months - I'd like to build own and operate it. There's also the ground station which is another $4.5 million or so - this of course includes design of entire systems. The prize goes to the investors, I build own and operate the equipment and own the images produced.
 
W

williammook

Guest
This is NTSC - not HDTV - but a number of them located over the surface of an 18 inch ball would prove interesting
http://www.hy-line.de/fileadmin/hy-line ... _brief.pdf

HDTV may be available for this if we look for it...

MEMS Gyroscope
http://www.st.com/stonline/stappl/cms/p ... /p2318.htm

MEMS Accelerometer
http://www.st.com/stonline/products/fam ... meters.htm

MEMS Integrated Phased Array Antennae
http://www.ist-world.org/ProjectDetails ... ea62a4e290

MEMS fuel cell
http://www.engr.uconn.edu/~jmfent/CMU402.pdf

all representative...

These are mounted on the outside of a pair of nested spherical propellant tanks

Two spheres.
18.2 kg of liquid hydrogen and liquid oxygen. 15.6 kg of liquid oxygen. 2.6 kg of liquid hydrogen.
LH2 is 0.07 kg/liter. LO is 1.14 kg/liter. So, you need

15.6 / 1.14 = 13.6842 liters of LOX
2.6 / 0.07 = 37.1429 liters of LH2
50.8271 liters total

A ball with 50.8271 liters of volume has a diameter of 45.96 cm (18.1 inch)

V = (4/3)*pi* radius^3

so

radius = (V * (3/4)/pi)^(1/3)
diam = 2 * radius
= 459.585 mm

Placing a sphere of Oxygen at the center of this large sphere, subtracts out the oxygen volume, and provides a compact spherically symmetrical system.

A ball with 13.6842 liters of volume has a diameter of 29.68 cm (11.7 inch)

contains the oxygen.

The mems devices are placed on the outside of the outer shell.

Aerogel insulation provides both structure and thermal barriers with very little weight.

http://www.sciencedirect.com/science?_o ... e4ab8075b9

A set of nested tubes supports the smaller sphere inside the larger sphere. The inner tube conducts liquid oxygen from the very center of the system. The outer tube conducts liquid hydrogen from the interface between the larger sphere and the smaller sphere. Flexible diaphragms expand from the outside of each sphere pressing propellant toward the center - gas separation swirl valves (centripetal force) separate out the boil off from the liquid. The boil off pressurizes the diaphragms - hydrogen to hydrogen, oxygen to oxygen. A gaseous bleed system feeds the fuel cells which power the device. Liquid water formed from this process is evaporated to provide heat management. The cryogenic liquid system feeds the MEMS based rocket arrays

http://www.me.berkeley.edu/mrcl/rockets.html

http://sci.tech-archive.net/Archive/sci ... 00120.html

A dozen cameras - spaced around the sphere, a dozen rocket arrays - ditto - a dozen pentagonal MIPA - all encasing aerogel tanks.

Finally encased in a sponge rubber jacket enclosed by a PET film 200 microns thick - through which the cameras peer - with cutouts for the rocket arrays - the PET has vapor deposited on the back side aluminum - making the ball highly reflective to sunlight. The system is very tough, doesn't change its CG as it depletes its fuel.

Total system weight 1.8 kg (3.96 lbs)

2,765.6 cm2 1800 grams --> 650 milligrams per square cm.

200 micron PET 0.24 mg per square cm - resistant layer
8 micron Al 0.02 mg per square cm - reflective layer
10,000 micron foam 14.00 mg per sq cm - spring layer
500 micron MIPA 125.00 mg per square cm - antennae/computing layer
etc., etc.,

This of course is all preliminary, but you get the idea of how we can do this sort of thing...

Since the device is capable of very high delta vees - it should be possible to fly it on high suborbital flghts to test its capabilities. It may even be possible as I mentioned above, to dispense with the launcher - and build a subscale launcher.

A direct launch to the moon with two or three stages, without going into orbit around the Earth, would allow recovery of the booster stages without long downrange recovery. Also, the entire system is visible to the receiver array during boost phase if this is done.

3 2 1 stages
20--> 60-->180 total weights

20 40 120 unit weights

An 18 inch sphere sits atop a 23 inch sphere and that sits atop 33 inch sphere. Each with their own MEMS rockets, own cameras own communications setup. A sabot like EPS foam cone with ablative PET skin each with spherical cutouts holds each sphere in place and provides a protective aeroshell during ascent. This is the only mechanical connection between the spheres.

A 74 inch stack of cones - a cone with a 14 degree opening angle between the smaller and middle sphere. A cone with a 21 degree opening angle between the middle sphere and the larger sphere. 270 kgf at lift off.

A 6ft 2in Christmas tree with rounded top and bottom.

A direct ascent to lunar trajectory - without going into orbit - made at moonrise - allows direct tracking of all components for 12 hours until moonset - which means that the payload would be over 30,000 miles on its way before it set in the sky - and would be 50,000 miles up when it rose again.
 
W

williammook

Guest
Some folks asked me about the diapragm holding the propellant to the intake manifold. Its a folding geodesic structure similar to this origami geodesic sphere made of paper here - except materials are more appropriate for a cryogenic environment

http://www.flickr.com/photos/pascalin/341291424/

There is bleed of gas through the interfaces between the radial struts and feed lines penetrating the diaphragm - but since teh gas behind the diaphragm is the same as the liquid in front - that's not much of an issue. There is a MEMs based cryogenic unit built into the wall of the oxygen tank. There are actually MEMs heaters on the interior wall of the oxygen tank to maintain pressure of the oxygen diaphragm.

http://sbir.nasa.gov/SBIR/abstracts/02/ ... -9079.html
http://www.iop.org/EJ/article/1742-6596 ... 34_106.pdf

A shallow cylinder cut into two pieces with the cut plane at a slight angle mounts the 14 degree cone to the 22 degree cone at the equator of the middle stage. This cylinder is equipped with a piezo motor that changes the angle of the upper stage relative to the lower stage during ascent through the atmosphere. This more than wings helps guide the vehicle during its aerodynamic phase. The booster sphere has its surface covered with MEMs rockets described earlier. By painting a thrust vector across the bottom of that sphere, thrust vector may be gimbaled at will, along with the pressure vector during ascent - providing complete control of the vehicle during this phase. The ring separates when the middle stage ignites after MECO.

http://www.flexmotor.com/page2.htm
http://www.zyvex.com/Products/UMWS_001a.htm

A flexible spherical form inflates after stage separation and the 22 degree cone pitches over and flies heavy side down back to Earth - where the boost sphere rotates 180 degrees presenting a TPS surface. After slowing to subsonic speeds the sphere rotates back to launch position and executes a touchdown with remaining propellant. This is less massive than wings wheels or parachutes.

Sound speed in air is 331.5 m/sec Exhaust speed is 4,260 m/sec Structural mass is 9% stage weight. Propellant is 61% total weght with an extrate 0.7% of that total left behind after flight as high pressure gas. Venting this gas through the MEMS rocket array provides additional propellant flow.

1 - 1/exp(0.33/4.26) = 0.074 ~ 7.4% preopellant mass

but this is of the reduced mass - which is 0.097 of original lift off mass for the stage. This means total popellant needed is 0.7% !!

This is calculated from sound speed - actual terminal velocity of a light weight large volume shell is considerably less than sound speed - so there is plenty of propellant on board to land the spacecraft downrange just using ullage on board. Reducing the oxygen by 0.7% and increasing the hydrogen by 4.2% - leaves the total mass unchanged - but with MEMs based jets - and using atmospheric oxygen, the vehicle is capable of flying a significant distance.

http://en.wikipedia.org/wiki/Terminal_velocity
http://www.memsuniverse.com/?p=1266

While Apollo rightly used very conservative techniques to get men to the moon, unpiloted systems can be less conservative. Consider a line drawn between the centers of the Earth and Moon.

Its easy to see that a trajectory can be drawn from any point on the surface of the Earth to any point on the surface of the moon - passing through this line where the gravity of Earth and Moon are equal. The angle at which that trajectory passes through the line varies with position on the spheres as does the speed. The launch angle and speed and landing angle and speed vary with relative positions too.

This is the direct ascent trajectory to the moon (and back)

http://en.wikipedia.org/wiki/Direct_ascent

On a rotating Earth, if you launch near moon-rise toward the moon, you will be able to track the ascending vehicle for up to 12 hours before the moon sets again. The burn-out angle here is 90 degrees - and if you fire at moonrise, you get a boost from the Earth's rotation in proportion to the cosine of the latitutde of your site. So, a lunar operator need not have an extensive communications array.- all major boost operations will have taken place by the time the launch center sets.

Having one other radio reciever at the antipodes will give nearly continuous coverage. For a launch center in White Sands NM, the antipods is in the South Central Indian Ocean between Africa and Australia.

http://www.umsl.edu/~fraundorfp/nanowrl ... globe.html

While a cargo ship can be gotten quite cheaply these days, and outfitted with an antenna array and sent to the Indian Ocean, and communicate back to White Sands via satellite data link - A tetrahedron of points, with one of them at White Sands achieves total coverage, and keeps all the points on Land (China, Australia, Europe and South America.) And gives the opportunity to bring in foreign partners.
 
W

williammook

Guest
A soda can is a good representative example of the underlying structure of the tanks tubes and struts. Soda can aluminum that is 0.005 in (1/8 mm 125 microns) thick. This is 33.8 mg per sq cm - 20% of our 650 mg per cm2 budget.

Soda can aluminum is easily stamped at these dimensions, and can be electrochemically machined to very high tolerances for mounting all manner of MEMs devices as well as aerogels and other components. Also the material is easily and precisely welded with electron or laser beam at these thicknesses and all in all very precisely done at very low cost. A dozen pentagons are pressed into appropriate shape forming 1/12tth of the total sphere, further machined and MEMs devices mounted.and teh pieces then welded together.

http://technologyinterface.nmsu.edu/Spr ... /index.pdf

Another method of assembly - one adapted to a more or less continuous production - is to take a strip of aluminum and cut it with a laser to a precise width, and roll it through a roller that has continuously varying roller diameter - trim cut to precise dimension after rolling - then wrap into a spherical form - with one continuous weld seam. The strip which only tapers at the beginning and end of the welds - the poles - is micro machined and parts added assembly line fashion before the final weld.

This is the reverse of an old tyme apple peeler. Here we take the aluminum skin and form itinto a precise sphere

http://zedomax.com/blog/wp-content/uplo ... eler-2.jpg

The wrapping process is controlled dimensionally from the outside, built around the propellant feed lines described earlier. A modified numerically controlled lathe would allow the production of thin shell parts of very precise dimension - and any cylindrically symmetrical form - cylinders, cones, ogive sections, rocket nozzles, you name it.
 
E

exoscientist

Guest
In regards to the stability during the descent, I remember seeing this video:

Video of Multiple Kill Vehicle Test Scares Me Silly.
By Jesus Diaz, 9:00 PM on Mon Dec 8 2008, 172,592 views

http://gizmodo.com/5104917/

This operates on thruster pulses for directional control. It looks also like the main thrust engine is also pulsed.
This type of system would have the advantage of allowing the lander to move to more than one location after landing.
This reminded me that the Mars Polar Lander and Mars Phoenix Lander engines were also pulsed:

Martian cliffhanger resolved at last.
Phoenix lander’s propulsion system works, nine years after setback.
By James Oberg
NBC News space analyst
Special to MSNBC
updated 9:10 p.m. ET, Sun., May 25, 2008
"Did NASA cut corners on engine testing?
"Back in the 1990s, as a cost-cutting measure, Polar Lander's engines were never actually tested. Instead, they were certified purely on the basis of previous flight experience. In the “circle-the-wagons” embarrassment that followed Polar Lander's loss, NASA officials admitted the error but refused to reveal which space vehicle had carried such thrusters in the past.
"At the time, there were rumors that the engine was used for a military multiple-warhead carrier mounted on an intercontinental ballistic missile. As such, the engine would be qualified to start up in a warm underground silo, for a mission of no more than 30 minutes ending in nuclear annihilation. The idea that this would be "close enough" for use on a chilly 10-month flight to Mars seemed preposterous — but no one would confirm the rumors.
That was then, and this is now: Lewicki said he had no problem discussing Polar Lander's engine.
“It’s a standard Aerojet engine, model MR-107-N,” he happily told me when asked. “Before it flew on MPL, it had flown on intercontinental ballistic missiles.” Its predecessor, the MR-107, had also flown in an upper stage for the small Athena satellite launcher in the 1990s, the Encyclopedia Astronautica Web site notes.""
http://www.msnbc.msn.com/id/24780686/wid/7279844//

This MR-107 engine is now used on civilian craft including those two Martian landers:

MR-107.
http://www.astronautix.com/engines/mr107.htm


Since we know it was able to operate successfully in the cold of the Martian arctic and the quite thin atmosphere on Mars, it would be a good choice to use on the Moon.
They have also been used for thousands of times so they are well tested. They also use a monopropellant so they have a simplicity of operation.
Depending on how "open source" the design of Phoenix was, it might be a good model to use for a lunar lander. After the failure of Mars Polar Lander there were several public critical reviews of that program, leading to the successful fixes applied to Phoenix, so the public information revealed during these reviews might allow a lunar analogue lander to be constructed.



Bob Clark
 
K

kert

Guest
The hardest part ?
- Red tape
closely followed by
- securing a launch which doesnt blow up ( See Planetary Society solar sail saga )
 
W

williammook

Guest
http://scitation.aip.org/getabs/servlet ... s&gifs=yes

X-ray welding is interesting. An x-ray hologram - a pair of x-ray diffraction grattings that rotate independently of one another - are used to focus an x-ray beam to higher intensities through the volume of a material. This allows heating in the depth as well as the surface of a solid. This makes for a tougher more durable weld. It also allows creamic/metal composites.

While titanium is nearly twice the density of aluminum, it is nearly 4x as strong as Aluminum. So, a titanium shell 25 microns thick (0.001 in) is nearly as strong as an aluminum shell 125 microns thick, but weighs only half as much!

Ti 4.54 g/cc 434 MPa
Al 2.70 g/cc 115 MPa

A strip of Titanium foil 3 mm wide and 219 m long would make a 45.72 cm (18 inch) diameter sphere that weighs only 75.8 grams!!

The manufacturing system I envision modifies a numerically controlled lathe with an automated x-ray welding head. The entire lathe moves, to keep the heat affected zone in the beam - which is formed by a compact synchotron source.

Multiple layers of titanium can be weleded atop one another to increase thickness, with the x-ray beam penetrating through the surface heating the interface.

Chemical milling of titanium (or aluminum) foil before its welded in place, is possible

http://www.techmetinc.com/chemical_milling.html

Placing MEMS devices on the surface - again using X-ray welding techniques to create a robust titanium/ceramic bond - as well as placing structs and fasteners for mounting the foam and PET cladding and shells - as well as reduced carbon carbon composite for advanced thermal protection.
 
E

exoscientist

Guest
On Bautforum.com was mentioned a partnership between the Odyssey Moon GLXP team and NASA Ames to use the lunar lander Ames is developing:

Engineering TV.
MoonOne Robotic Lunar Lander.
"Odyssey Moon's partnership with NASA will allow them to develop the "MoonOne" (M-1) lunar lander based on the Common Spacecraft Bus (CSB) developed at the NASA Ames Research Center."
http://engineeringtv.com/blogs/etv/arch ... ander.aspx

Exclusive Video: Meet the Spacecraft That Could Save NASA a Fortune.
* By Aaron Rowe
* May 7, 2008
http://www.wired.com/wiredscience/2008/ ... -meet-the/

There has been some grumbles on this forum that this partnership with NASA Ames gives Odyssey Moon an unfair advantage in the $30 million prize competition:

Odyssey Moon WINS the "Odyssey Moon Lunar X Prize".
http://spacefellowship.com/Forum/viewtopic.php?t=7639

This hovering vehicle developed by NASA Ames also seems to operate by pulsed thrusters. It may very well be that it was developed as derived from the MPL/Phoenix lander designs.


Bob Clark
 
A

andrew_t1000

Guest
I would have thought the hardest part is getting out of Earth's atmosphere, after that it should be easy!

I am trying to get a team together for the N prize, I'm thinking LTA, then a rocket.
Anyone interested or who has ANY ideas give me a yell!

andrew_t1000@live.com.au
 
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scottb50

Guest
andrew_t1000":3vs3jn4t said:
I would have thought the hardest part is getting out of Earth's atmosphere, after that it should be easy!

I am trying to get a team together for the N prize, I'm thinking LTA, then a rocket.
Anyone interested or who has ANY ideas give me a yell!

andrew_t1000@live.com.au
I would say the hardest part is getting to LEO.
 
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scottb50

Guest
access":1uu8uon3 said:
andrew_t1000":1uu8uon3 said:
I am trying to get a team together for the N prize, I'm thinking LTA, then a rocket.
Anyone interested or who has ANY ideas give me a yell!

andrew_t1000@live.com.au
see my post here http://www.space.com/common/forums/viewtopic.php?f=15&t=19632
LTA might save 1-2% of the cost of getting to the moon, you still have to get to enough velocity to get from LEO to the moon. It would still need a pretty big rocket even for a small lunar payload. In other words the balloon would add to the cost more then it would save.

The optimum mission would be a shared ride to LEO with a commercial or test launch of a newer vehicle, say a free ride on the upgraded Falcon 1 or an early Falcon 9. The easiest way from LEO would be a highly elliptical orbit with ejection of the lander as the orbit goes around the moon. Using an inflatable airbag should work for landing and something similar to available remote controlled toy cars, modified for lunar use; fitted with solar panels, large wheels, a communication antenna and, obviously a camera.

If you figure the surface vehicle weighing about 20 pounds and solid motors for transit and descent the launch weight could be under 1,000 pounds.
 
A

access

Guest
What could go wrong landing at several thousand mile per hour onto the moon and using airbags to land!!!!!!! it's so ingenius the lack of substantial gravity won't cause any problems.


Despite that the rest of your post isn't bad. Although I believe a balloon launched rocket would put a substantial dent in the cost of launch (By the way that is for the N-prize, launching 9 grams into orbit not the lunar x-prize)
 
S

scottb50

Guest
access said:
What could go wrong landing at several thousand mile per hour onto the moon and using airbags to land!!!!!!! it's so ingenius the lack of substantial gravity won't cause any problems.

I thought it was understood the landing would be at a much lower speed. Say your lunar flyby is at 500 miles the lander could initially enter an orbit with a single burn that would put it in a very low, just above the highest terrain, a final burn would set up a rather sedate fall to the surface. The biggest problem would be sizing the engines to compensate for problems with the preceding burn. The final motor might better be liquid powered, though this would add weight.

Well protected by the airbag the surface vehicle could stand up to quite a few bounces before rolling to a stop.
 
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access

Guest
For a airbag landing to work on the moon the vehicle would have to be quite slow so you would be better of sizing up your rocket slightly and landing with hydraulics taking the extra force.
 
S

scottb50

Guest
access":2rti4zst said:
For a airbag landing to work on the moon the vehicle would have to be quite slow so you would be better of sizing up your rocket slightly and landing with hydraulics taking the extra force.
I was trying to keep it as simple as possible. Descend as far as possible, based on local elevations, slow enough to drop to the surface and bounce to a stop.
 
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