craft

Oct 17, 2011. Ok – this is a deal – lets assumes – (a) power plant on satellite has 6 surface – each 2 of it can be assumed parallel, looking in opposite direction with solar panel attached, that makes 3 groups by 2, each group orthogonal each other; (b) gyro precession is 1 degree per 4 minutes; (c) magnetometer gives readings (absolute) of a magnetic field with precession 2 degree. First step will be to stabilize satellite (eliminate rotation) to a level 0.5 degree per hour. It can be done by monitoring readings from a solar panels and do correction by rotating stepper motors. Then after 4-5 hours when error is less then 0.5 degree (per hour) magnetometer readings will be prerecorded during two orbits. This gives 2x3x75x75x2 ~ less 100K of data. Data analyzed for min and max of derivative and chunks of data with max and min values can be transferred by backup communication (not require orientation of a craft) to earth control center (~10K of data). On the ground center simulation program of a magnetic field on a low earth orbit will match (by brutal computer run) observed readings with approximated Keplers elements. Basically it will try all possible Keplers elements and find best match for observation reading. When Kepler’s found then for a time equal ½ hour before next communication session can be generated magnetic fields readings which craft has to follow for a proper orientation in a time of beginning of the session. When session will starts, gyro with precession 1 degree per 4 minutes (session time) can orient satellite to perform session. Ground station antenna will use the same logic for orientation with assumption that earth rotates 360 per 24 hours, coordinates and direction to a north magnetic pole can be reliably verified. The picture taken by camera fixed to the craft frame using the same method of orientation (30 minutes of prior picture session) can confirm precision of a method. The same technique will be used to orient craft for a main impulse on a way to the moon, in this case max 160 minutes of predicted magnetic field values needs to be downloaded. More complicated procedure on a way to the moon (travel time 7-9 days) for correction impulses – lets assume the orientation of a magnetic field in each point of trajectory will be stable during at least 1 hour. Direction to the of a moon and earth can be preloaded, then using gyro it is possible to orient craft’s camera (fixed to a frame) to estimated direction to centers of the earth and the moon. Picture can be taken and gyro will return craft back to the orientation before picture session with precision 0.25 degree (basically this mean picture has to be taken in a intervals of 1 minutes). Then magnetometer’s readings can be used to stabilized previous (before session) direction. Solar plant will give another vector for orientation to the sun. Two picture can be processed on board to get direction to the center of the earth and the moon. And calculated earth’s direction can be used for communication session. On correction impulse it has to confirm (by picture) direction to the earth, the moon, the orientation of a magnetic field and using gyro (1 min) before impulse to orient the craft. Brake impulse performed the same way.

This require – gyro/magnetometer needs to be able to collect data during 160 minutes. Collected data must be processed on board to find max and min of a derivative. Stepper motors was to able to perform full rotation of a craft during 1 min. Onboard computer must process images of the earth and the moon to find direction to center of the body. On ground station (tra application, additionally) needs to be able to simulate earth magnetic field on low earth orbit (< 350KM). The same application needs to be able to match trajectory with magnetic field’s readings. On ground test for power plant and orientation system needs to include proper rotation elimination. On ground test for magnetometer needs to include harness with rotation of a magnet in some plane. The readings can be used to debug kepler’s elements matching and debugging orientation system stepper motors commands. Full flight tests can be simulated on a ground. GPS on board system will be used for Kepler’s elements verification. May be trajectory calculation app will work in a distributed mode to speed up process. If in 1-1.5 year frame gyro with precision better then 1 degree per hour can be obtained scenario of a flight can be revised.

Oct 1, 2011 Goals for a test flight are:

(a) confirm backup communication;

(b) confirm power plant working and gyro module working for Keplers elements calculation, data transferred (to earth) using backup communication;

(c) main communication antenna deployment;

(d) main communication session working;

(e) conformation of a GPS readings from Main computer working;

(f) conformation of onboard processing center of earth calculation (from captured image);

(g) conformation of onboard processing center of moon calculation, in a failure of this tests imaginary data and gyro readings has to be transferred back to earth for additional processing;

(h) update of a software on all onboard microprocessors;

(g) simulation of a main engine firing preparation, this includes upload magnetic fields targeting values, gyro position target values, center of earth targeting values.

Sep 1, 2011. Antenna 2.4Ghz – for ground station helical antenna design and manufacturing – it will be better to print such antenna than make it by hands – 3D printing material suitable is Nylon 12. 3D model: (click on picture to see in SolidWorks eDrawings, req automatically installed plugins):

two 3D printing facilities : Ponoko: http://www.ponoko.com/design-your-own/products/2-4ghz-ground-antena-6246 and Shapeways: http://www.shapeways.com/model/322767/2_4ghz_antena.html?gid=sg85851 . After printing all what will be left - to connect flat reflector made from PCB board, and 0.3 dia wire. For mockup of a testing antenna on CubeSat (that one has to be made by hands) 3d model is (click on picture to see in SolidWorks eDrawings):

http://www.shapeways.com/model/322768/small_2_4ghz_antena__for_cubesat_.html?gid=sg85851 or http://www.ponoko.com/design-your-own/products/2-4-ghz-antena-for-cudesat--6245

2.4Ghz band is actually a junk band but according FCC ((http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&tpl=/ecfrbrowse/Title47/47cfr15_main_02.tpl ) and in Canada http://www.ic.gc.ca/eic/site/smt-gst.nsf/vwapj/rss210-issue7.pdf/$FILE/rss210-issue7.pdf it is possible without license to use 4Wt (Canada) and in 1Wt (USA) transmitters (assuming BlueTooth as a core), without limitation on antennas.

For local noise cancellation microchip is: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=QHX220IQT7CT-ND According spec >20dB noise cancellation possible. Manually (which is proved and possible for ground station) can be achieved 50dB noise (junk) suppression.

Also was discussed the same technique for suppress noise on a transmitter – transmitter antenna on satellite oriented to the point on the earth at the same time noise helical antenna looks backward 180 degree. Second (noise) antenna needs to be with receiving pattern covering the same sky area as a ground antenna (this depend on a orbit, otherwise needs mechanical adjustment). Mixing delayed (61.3mm) noise on 2.4Ghz from a particular place on a sky with a transmitting signal, then subtracting same noise on receiver can give ~50+20=70 dB which will be good as it sounds. Complications: it is hard to get precise receiving pattern for noise antennas on transmitter and receiver; such scenario would not work from the Moon.

With active antenna this actually can be done – interesting: does anybody made such experiments?

5 Aug, 2011. Small panic about 526N epoxy – by all parameters it is acceptable (-78C +300C tolerance, flexibility, outgassing, and etc.), but it is not in it http://outgassing.nasa.gov/cgi/sectionb/sectionb_html.sh Material Alphabetical Listing. This (not in list) may be problematic for any composites used in vehicle and craft. Epoxies 517, 556, 568 present in a section B list but it is not suitable.

After contacting manufacturer it was confirmed that 526N actually was tested around 20 years ago for outgassing study and Total Mass Loss at 125C is 0.49 (less then 1%) and Collective Volatile Condensable (at 25C) Materials is (0.00) with curing conditions 2H (93C) and 16H (204C). Epoxy is good, looks like it will be require re run ASTM E-595. Anyway satellite (including vehicle) was to pass vibration tests according launch vehicle profile and thermal-vacuum bakeouts to ensure level of outgassing at minimum vacuum 5x10-4 Torr. Manufacturing of composites was to be documented.

July 21, 2011. Backup communication system – pick power 1W based on

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=583-1143-ND

or http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=583-1142-ND

or http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=3539948&k=dg-m10&stock=1

Last one is preferable – needs one conformation ORBCOMM would it be able to communicate with low earth orbit.

July 20, 2011. Main onboard computer and power station. Computer Rabbit with industrial temperature requirements. 3 Microcontrollers to control orientation’s stepper motors, flash memory, 5 high-capacitance capacitors, 3 type of a solar panels with separated method of deployment (flexible one will be extended using springs). All power capability – 1W.

July 19, 2011. Astro- navigation system needs pin hole camera (20 g) and software processing captured image in main onboard computer. Format of a captured image JPEG. Source code for a extracting image available…. In ground tests can be included processing image from available space videos converted to exact format from a camera. Also for matching starts and the Moon it is possible to do series test on a ground and Photoshop mock-up images of a Moon. Full system must be tested on orbit before attempt to fly to the Moon.

July 18, 2011. Communication system 2.4GHz. For a small cube-type satellite it will be impossible to test full helical antenna (562mm) , as a result all test has to be done on shorter one (100mm), this will reduced gain from 17dB to 9dB and increase half power bandwidth from 25 to 60. Analog part of a communication system was not designed yet. Communication protocol is all software related topic, nothing complicated. For communication system needs to build 2 portable ground stations. Station needs orientation platform (using for a amateurs telescopes) for following satellite on a sky. Each station needs to be equipped with 4 helical antenna. Stations will be used later for communication with a probe on path to the moon.

July 17, 2011. Orientation system will include 3 stepper motors. For a test on 1kg total mass it will be require motors with bearing. Suitable weight for each 30 g. And lubrication can be changed to molybdenum. Gyro sensor readings should be compared with targeting XYZ values. Onboard main computer has to be adaptable to different type of motors, (a) different inertia momentum, (b) delays of control to avoid oscillation. Dynamic parameters of a system has to be calculated (not predetermined) using same gyro-sensor. Placement of 3 stepper motors may be not in a center of mass – as a result to support orientation along any of 3 axes, system should calculate parameters by itself. On ground tests for a system can be done only for one axe, and in plane intersect center of mass. In worth case scenario it will require to download new binary for orientation system (effectively for a main onboard computer).

July 16, 2011. GPS any way needs to be developed for correct main impulses direction. Electronics can be done in 2 weeks, and software will be major development. First it will transfer ID29,30 satellites reading using backup communication. Then by formula on a ground calculates Keplers elements and transfer orbit params back using backup system. Weight for a sensor 25 g. For ground tests can be used the same TRA app with 5 GPS satellites Keplers element and simulation of a ID 29,30 data. When formulas finalized and errors estimated the same source code can be inserted into a flight main computer. No backup calculations of Keplers elements in microcontrollers.

July 15, 2011. Check - which systems from a craft can not be tested on a ground but in orbital flight. The critical one

(a) GPS data collection from raw data ID 29,30;

(b) orientation system (on a ground it can be only a simulation),

(c) communication system with 2.4 GHz,

(d) orientation system with 3 axes

(e) astro-navigation system (calculation direction to the center of Earth, and star matching system).

(f) backup communication.

July 13, 2011. NASA workshop. Talk about active experiments on Apollo sites, no power require for measure distance using laser from the Earth observatory and reflector on a Moon. Seismometers data will be really interesting by science community. Why not to combine all together – small sensor with nanowatt power requirements, radioactive heater of a couple milligrams to heat electronics at lunar night, modulation system on reflector, light weight solar panel (even if after couple years it will might be enough), place everything under surface/dust for thermal protection (or use power harwested from ceramic elements). Same modulation system on reflector can be used for transferring any data from a Moon without big power plant.

July 12, 2011. Fiasco on Team Plan B speech – engineers do not like to talk about “political agenda”, even on a first day of a summit was a lot of talks about how to attract investments, and protection of intellectual property. Common outcome of a first day was – more likely investment to teams will come in a form of “angel’s investments”. Anyway one check box in requirements by Boris Chertok done – Patent System on Software is in a mess, and has to be changed, and this is aside from our project. Never say – “I made the mistake”, but every time explain – “What a interesting problem I faced last week!”

July 11, 2011. NASA, big wind tunnel, metal and composites really nice. It is interesting how was organized tools storage. SOFIA infrared observatory – impressive (Why I am not a scientist?!). Really impressive Team from Barcelona.

July 10, 2011. San Francisco is colder then Vancouver

July 9, 2011. TSSOP cases not only be light weight (twice as SOIC) but size of PCB needs to be smaller – all electronics will be inserted inside frame (tube) – routes has to avoid side edges, on perimeter of a board has to be placed crush-protecting holes, two rows on each side at least.

July 8, 2011. Soldering passed perfectly. New soldering station works fine (never before use hot air) SOIC cases is ok. TSSOP was actually better then SOIC. For next round (after analog part finished) needs to retrace PCB for TSSOP because of different pins assignment.

July 7, 2011 – PCB arrived – funny conversation with custom – what is it for? What a company doing with it? How and where it can be used? (On a Moon?!). No need to pay duties and taxes on PCB! Actually this can be a major problem for a project – today it is possible to order all rover’s parts from metal shop over internet, each part will cost around 200USD/CDN (total 35 parts * 200 = 7000CDN), if to order 25 rovers it will be just twice expensive. Development process each time needs to make one change, or another and order another modified part. What about delivery?! Delivery costs is not in same proportion as a manufacturing – delivery for some unknown reason is only available from big parcel service company. All other companies do not what to listen to a question – Can you send my carbon fiber supplies by post office or by different delivery company? Results - with a price of a PCB $51 – delivery costs $40. For $150 solar panels – delivery, duties, taxes, multiplication calculations was total $100. And this not all – money not only a problem - time is lost – delivery time of 3 days can be stretched to 2 weeks. Last month parts costs $1200 and delivery was $357 – more then 25%.

July 1, 2011 - Source code for debugging (MSVC 2011): dac_adc.cpp, dac_adc.h, dac_adc.rc, dac_adc.sln, dac_adc.vcxproj, Rsource.h, stdax.cpp, stdafx.h, targetver.h. It supports all comands implemented inside 16LF88 (see STM_LTRX.c) result of DAC stores in file DatOut.txt

June 31, 2011 – PCB was ordered - will be ready after holidays in US and Canada, Parts ordered (it takes a time to check sizes and temperature tolerances for each chip). SOIC case:

U1 - 74AC161 counter 4 bit (just in case – can be 4040) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-25962-1-ND

U2 - 74HC4040 – counter 12 bit http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-7375-1-ND

U3 - 74AC00 - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC74AC00DGOS-ND

U4 - 74AC04 - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-25960-5-ND

U5 - CY7C199CN (memory) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=428-1954-5-ND

U6 - HI 3338 (DAC) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=HI3338KIBZ-ND

U7 - PIC16LF88 (backup microcontroller) http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en010243

U8 - 74AC174 (bad choice – just was at nearest shop) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=568-2628-5-ND

U9 - (switch/jumpers for setting delay)

U10 - 74AC161 (again was available - can be 4040) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-25962-1-ND

U11 - 74HC4040 counter 12 bit for receiver http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-7375-1-ND

U12 - 74AC04 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-25960-5-ND

U14 - 74AC00

U15 - CY7C199CN (memory for receiver) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=428-1954-5-ND

U16 - ADS930 (ACD 8 bit 30MHz) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=ADS930E-ND

U17 - PIC16F88 http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en010243 Memory and 16LF88 is from -40 + 85C, all another is -55+125

TSSOP case:

7400 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-4288-1-ND

7404 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-1054-1-ND

74HC4040 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-7376-1-ND

74HC161 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-6433-1-ND

32K http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CY7C199NL-15ZXC-ND

pic16lf88 (not for now): http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PIC16LF88-I/SS-ND

75AC74 (-45+85) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-1064-1-ND or

74HC174 (in a case of one trigger only needed) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-4274-1-ND

will be ready again after 1-4 July.

June 29, 2011 - PCB layout done: adcdac_1.pcb It takes 3 days. Possible to reduce time to 1, needs to accommodate to a tool before using it.

June 26, 2011 – Now attempt to use quartz crystals with 30MHz frequency – Crystal give ether 3 or 6 MHz instead of 30.

June 23, 2011 – Time was spend on investigation – which software to use for creation PCB and schematics. Tried Multisim – schematic was created fast, library not full but similar cases can be used, good but expensive. It gives quick routing, only one problem - it better be used when needs to make a PCB board with all component soldered, different PCB manufactures does not accept Multisim format. PCAD was tried long time ago and it is not preferred schematic tool (may be because I am not an electronic engineer and do not understand benefits of PCAD). Tried another two applications, including free software in Windows and Linux. Best choice is Express PCB. Schematic available: adcdac.sch

Routing will be next.

June 22, 2011 – No ideas how to solve problem – suddenly after connecting LED to random legs on random chips (for visualizing) receiver became a good boy! Removing one LED creates a noise, inserting to another place removes noise. Place of insertion does not matter. Turned out – power supply instead of regulated 5V gives 5.5 – insertion of a LED suck more current and reduce power to 5V. Ok – forget about 5V – and switch to 3V (which is kind of 3V 3.1, 3.2 - depend of LED, amount of chips, and etc.) everything become perfect – messages flying, units responding, etc.

June 21, 2011 – Porcupine was extended to receiver. Nothing works even previously working transmitter. CY7C199CN require bypass capacitors. Yes - needs to RFM. Each memory chip gives a noise, 0.1mF helped, but communication with microprocessor receiver units (terminal app over serial port used) does not work. Applying bypass capacitors to all chips did not helped. Switching units (the same software in each did not helped) – transmitter working and receiver persistently on strike. Was enabled Master Reset in 16LF88 – reset on Transmitter works, reset on Receiver noisy – garbage on output port without any pattern.

June 19, 2011 – Unfortunately Alex’s skills in digital design is really rudimentary. A lot of time was spend on prototyping. Especially in debugging logic NAND and NOT gates. Good simulation of a digital logic will be beneficiary, but any way - transmitter is ready in a form of a porcupine’s bread board and works.

June 17, 2011 – IUP (Inter Unit Protocol) was re-designed from old code – now each unit has serial output connected to nearest unit’s serial input. I.e. main computer serial output connect to Transmitter’s serial input, then Transmitter’s serial output connected to Receiver’s serial input, and Receiver output connected back to main computer serial input. In passive state bytes from any units travels (looping) over entire net. Integrity of all network can be verified by any units individually. NAND gates can be used to bypass un-functional unit. RST in high state will enable transmit data btw nearest units, and pull-down resistor can be used to skip broken. Both microcontrollers (16LF88) for LDF (Laser Distance Finder) transmitter and receiver designed to be exactly the same (difference in command “wW” and “wV’ – W set W/R high, and V set ports bus into input mode). Source code: STM_LTRX.c, and for and project: STM_LTRX.mcp, STM_LTRX.mcw

June 10, 2011. Digital part:

U1 - 74AC161 counter 4 bit (just in case – can be 4040) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-25962-1-ND

U2 - 74HC4040 – counter 12 bit http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-4214-5-ND

U3 - 74AC00 - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC74AC00DGOS-ND

U4 - 74AC04 - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC74AC04NGOS-ND

U5 - CY7C199CN (memory) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=428-1954-5-ND

U6 - HI 3338 (DAC) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=HI3338KIBZ-ND

U7 - PIC16LF88 (backup microcontroller) http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en010243

U8 - 74AC174 (bad choice – just was at nearest shop) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=568-2628-5-ND

U9 - (switch/jumpers for setting delay)

U10 - 74AC161 (again was available - can be 4040) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-25962-1-ND

U11 - 74HC4040 counter 12 bit for receiver http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-7375-1-ND

U12 - 74AC04 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-25960-5-ND

U14 - 74AC00 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-4214-5-ND

U15 - CY7C199CN (memory for receiver) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=428-1954-5-ND

U16 - ADS930 (ACD 8 bit 30MHz) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=ADS930E-ND

U17 - PIC16F88 http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en010243

memory 128kx8 32-SOIC http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=428-1967-ND

memory 2Mx8 52-TSOP http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=428-1986-ND

memory 1Mx8 44-TSOP http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=706-1056-ND

Connector to main computer will be on same bus as 16LF88

16LF88 pin assignments:

RA0,1,2,3,4,7 will be DATA0,1,2,3,4,5

RB0,1 will be DATA6,7

RB2 - serial input RB4 == W/R (out)

RB5 - serial out RB6 == RST (out)

RB7 == CLCR (out) Operations:

1. Transmitter starts with resets W/R = 0, CLCR =0, RST = 0, then set RST=1 sequence “2wcrR2” where

“2” unit == “transmitter” communication tag

“w” set W/R low

“c” set CLCR low

“r” set RST low

“R” set RST high

“2” end communication with transmitter unit (closing tag)

This will reset counter and transmitter ready to accept data into a memory.

2. Microcontroller (or main computer) will store in transmitter memory wave (data or for laser byte 0xFF coded “on” or 0x00 coded “off” state) to be transmitted CLCR = 1, W/R = 1 then needs to set on bus 8bit data to store in memory and set CLCR will clock-in byte into CY7C199CN

Sequence : “2CW88888888wCc2” where

“2” unit tag (transmitter)

“C” CLCR set high

“W” W/R set high

“8” is just a helper command it will store sinus wave in 4096 bytes for debugging Each byte value will stored on a raising CLCR (first byte is not important) At the end of 32K bytes needs to set W/R = 0 CLCR = 1 and back CLCR =0

“wCc” Closing tag for unit is == “2”

3. Now transmitter memory ready – oscillator signal with 30MHz will clock-out data from memory to DAC (U6 - HI 3338). For debug it can be 2Mhz from 16LF88 on a pin 12 (RA6) by setting configuration bits, or by disabling clock on RA6 it can be manually set pin 12 on/off. Sequence is (for oscillator, and 2MHz debugging ): “2wcrRVC2”:

“2” –transmitter unit

“w” – W/R low

“c” – CLCR low

“r” – RST low – this will reset counter

“R” – RST high

“V” – W/R will be in low and data bus on 16LF88 will be set in input mode on RA and RB

“C” – CLCR high and oscillator drives counters. On each rising edge data will be send to DAC and on each failing edge of oscillation DAC fill latched previous byte.

4. Transmitter and receiver uses same oscillator. It is possible to set delay for receiver to start to store DAC data into receiver memory by switch/jumpers U9. Delay can be useful because on long distances 25 km == laser beam travels 50km time delay == 1.(6) E-4 sec, this for a frequency 30MHz require to store digitized samples in 5000 bytes (for laser beam travels from a craft and bounced back from a Moon surface). Error in calculation will be 10-20m. Less data to be processed (by microcontroller) faster (less delay) to measure distance. Ideally instead of jumpers possible to set comparator this will trigger receiver to run by some delay. Roughly 16LF88 running on 8MHz (2Mil or /sec) can process one measure per sec. This give (at speed 2800m/s) 1 ms accuracy of 0.01 to start break engine. At the same time main computer will be able to process 50 measurements per sec. To confirm calculation looks like needs to start measure 8-9 sec before impact by main computer – when first measure will be obtained, needs to switch for a backup microprocessor and compare calculated time. Speed of a craft does bring error in time travel 1.(6)E-4 of a laser beam around 1 m. Speed of a craft can be calculated by two different measurements by calculation difference distances and knowing time btw measurements.

5. Sequence for measure distance is: “1wcrRVC2wcrRC” where

“1” receiver’s unit tag

“w” W/R set low for receiver

“c” CLCR set low for receiver

“r” RSR set low for receiver

“R” RST high (receiver reset done)

“V” W/R set low and data bus on 16LF88 receiver will be set in input mode on RA and RB

“C” CLCR high on receiver and receiver ready to digitize data

“2” unit transmitter tag

“w” W/R low for transmitter

“c” CLCR low for transmitter

“r” RST low for transmitter

“R” RST high for transmitter (transmitter ready t send data to DAC)

“C” oscillator connected to counters on transmitter data clocked out with 30MHz – delay passed and receiver memory already with measure data

6. Sequence to read receiver memory is “w2whhhhhhhh1” Where :

“w” – W/R low on transmitter

“2” closing tag for communication with transmitter

“w” – W/R low on receiver (prev tag was opened communication with receiver)

“h” – read measurements in chunks of 4096 bytes

“1” – closing tag for communication with receiver

7. Bus data and control signals RST, CLCR, W/R will be sheared with individual microprocessors (backup) and main computer – this require commands for microprocessor “L” – listen – in this case both units will put all ports RA,RB into “input” mode.

June 5, 2011. LDF will consists from:

Oscillator 30MHz 3-5v

ADC 30Mhz 8 bit

Memory for storing digitized data from ADC 32-64Kbytes.

Counters Microcontroller for ADC

Interface for a main onboard computer

Sensor for a red laser

Amplifier with variable gain

Optical system

DAC 30Mhz 8 bit

Memory for storing transmitted data to DAC 4Kbytes

Counters

Microcontroller for DAC

Interface for main computer

Laser 0.5W (red)

Key transistor for controlling and modulation laser’s impulses.

Optical system for a LDF

June 3, 2011. During descent, to ignite brake engine at 2800 m/s requires real time distance measurement to Moons’ surface. We think radar or laser can be used. Weight for radar is heavier of the two concepts, around 2-3 kg, which is too large for our small landing vehicle design. Alternative approach is a Laser Distance Finder (LDF). In this case weight will include only two optical lenses, electronic equipment and mounting, significant saving in total mass of a probe. Off-shelf laser range finders can work on maximum distance for a couple kilometres.

Requirements – measure distances from 30 km to 5km, reflection from a lunar dust, 0.5W laser.

Additionally (a) if it possible the same system can be used to transfer data by laser beam and (b) be used to measure distance to reflectors on a moon on early approach stage.

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The Craft will be a polygonal aluminum frame mounted on the top of the vehicle frame. Fixing both frames together will be done via pins removable by inflating air-bags system. On the craft’s frame will be mounted 4 fixed impulses engines and a low trust engine. 4 engines will be mounted orthogonal to each other with center axes project via centre of mass of a probe. Firing sequence – fist orbit correction, second orbit correction, main impulse, brake impulse will be each time projected via the centre of mass of the probe.

Hermetically sealed parts of a frame will at the same time tanks for a liquid (ethanol/alcohol) propellant body for a low trust engine. Pumps will be require to precisely adjust probe’s centre mass position.

While in a flight, the probe's orientation will be performed via inertia momentum created by the rotation of three masses. Those masses will be mounted to stepper motors located close for central mass point inside two fixed engines frame. Third stepper motor will be mounted directly to a craft’s frame.

Engines will be carbon fibre cylindrical boxes. Small compartments will be in two of engines to accommodate stepper motors with rotating masses. Graphite nozzle will be mounted inside rear part of each engine.

Same rotation momentum will be used to control thrust vector direction at engines firing.

Location of a low-thrust engine not determine et, but it must be orthogonal to plane of 4 fixed impulse engines.

Requirements for a vehicle’s mass 6 kg on a Moon surface brings requirements for a total mass on a low earth orbit to100kg. That weight puts a craft onto a category of amateur satellites. Amateur satellites usually launched as a second payload for a regular launch. It will be desirable to stay in limits of 100kg, otherwise price for a launch can be high. Here is a reference for a OSCAR type:

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

and CubeSat type:

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