M4 (Manfred Memorial Moon Mission)OHB/LuxSpace
The 4M mission is an opportunity mission, in honor of late Professor Manfred Fuchs, founder of the OHB group. The project is conducted by LuxSpace, Grand Duchy of Luxembourg and is a quick, low cost mission aiming at global cooperation whilst presenting challenges opening new ways.
The spacecraft will be part of the last stage of a lunar mission, due to be launched end of october 2014. The trajectory will be a lunar flyby and return to Earth, with 90% chances of re-entry in the atmosphere. The 10% remaining chances lead to a very interesting orbit. The nominal mission duration is 196 hours, 8.17 days. The Lunar flyby will occur 97 hours after injection, 4.04 days. During flyby, the range to EU stations will be 399636km at most and the distance to the Moon will be between 12000 and 24000 km depending on the final injection vector. The spacecraft is located on the Vehicle Equipment Bay of the launcher.
The 4M spacecraft will transmit continuously on 145.980MHz (+/- 2.9kHz) with a 1.5W power input at antenna which is a simple Monopole. This will give S/N comparable to EME signals at Earth’s surface. The transmission is based on a 1 minute sequence and a 5 minutes cycle. The transmission will start 4670s (77.8 minutes) after launch (-0, +600s).
The launch date is 23 October at 1800 UTC.
Mission duration: 5 days minium (enough to go the Moon), possibly 8 days, and a chance to extend afterward.
The following is a tentative set of orbital elements that should remain valid from the launch to at least up to the 27 October when using usual classical and simple tracking softwares that do not integrate Moon.
1 99999U 14298.79728009 .00000066 00000-0 00000-0 0 00006 2 99999 030.6553 295.6956 9746689 147.2577 071.9585 00.10600338000010
The following set is to be used after the flyby from 28 October onwards
1 99999U 14999b 14301.79728009 .00000095 00000-0 21252+9 0 00005 2 99999 054.2430 068.8530 4827223 051.3941 131.1729 00.05703448000012
Orbital Parameter (30 Oct 2014)
Inclination 54.243 RA of A. Node 68.853 Eccentricity 0.4827223 Argument of Perigee 51.394 Revs per day 0.05703448 Period 420h 47m 53s (25247.88 min) Semi-major axis 285 087 km Perigee x Apogee 141 091 x 416 326 km BStar (drag term) 212520000.000000000 1/ER Mean anomaly 131.173
The spacecraft is comprised of the following equipment:
- Primary power source: 28 high energy density, non rechargeable cells, guaranteeing the nominal mission whilst providing 6W to the payloads
- Secondary power source: 2 x 8 Triple layer solar cells and 4 x Li-Ion rechargeable cells.
- An Onboard Computer, FM430 and interface board
- An I/Q modulator
- An RF power amplifier, providing a nominal 1.5W into the antenna
- An L/4 antenna
- RAD experiment fro radiation dose determination on the trajectory
The RAD experiment is a special chip from IC-Malagua (Spain), that is able to accurately measure the Radiation dose rate.
144900 7 -21 4.421 736 4* 73 DE TB2NJL 1 0 0.0 145000 5 -22 4.400 736 2* R47A13-X2X 1 0 0.0 145100 6 -23 4.604 734 4* LPOSTOGLU TR 1 0 0.0 145200 2 -24 4.603 734 3* LX0OHB-4M0234 1 0 0.0 145300 5 -22 4.392 734 3* 145400 11 -18 4.427 734 3* REMEMBER MAN 1 0 0.0 145500 8 -22 4.589 734 3* RABQ044DD3 1 0 0.0 145600 5 -20 4.588 734 3* FRED FUCHS 1 0 0.0 145700 5 -20 4.402 734 3* LX0OHB-4M0235 1 0 0.0 145800 4 -22 4.592 734 3* 144V240A +3C 1 0 0.0 145900 11 -17 4.599 734 1* 73S DE DK6UG 1 0 0.0 150000 0 -27 8.084 273 18 150100 4 -22 4.450 731 3* 73S DE DL6SH 1 0 0.0 150200 9 -18 4.589 731 3* LX0OHB-4M0236 1 0 0.0 150300 4 -23 4.615 731 3* 144V241A +3C 1 0 0.0 150400 7 -22 4.623 731 2* 73 DE CO2JA 1 0 0.0 150500 2 -24 4.614 731 3* 150600 7 -16 4.611 731 3* LOVE + PEACE 1 0 0.0 150700 6 -20 4.607 731 3* LX0OHB-4M0237 1 0 0.0 150800 2 -23 4.626 731 1* 144V241A +3C 1 0 0.0 150900 7 -21 4.597 731 3* 73 DE K1EG 1 0 0.0 151000 2 -24 4.582 731 3* 151100 5 -21 4.611 731 3* 73S DE WB8ELK 1 0 0.0 151200 2 -23 4.587 731 3* LX0OHB-4M0238 1 0 0.0 151300 0 -27 4.648 728 3 151400 9 -21 4.609 728 3* 73 DE WB8ELK 1 0 0.0 151500 6 -21 4.602 728 3* RABR-44DCP 1 0 0.0
Transmit sequence description
To account for the various constraints, mass, size, power, link budget, available average receivng station, an EME mode was selected as the most appropriate way to transmit the data. The transmit cycle is organized in 5 consecutive, one minute sequences starting at 0s of the UTC minute. In addition, to fill in the 1 minute sequence, an additional “analog” sequence is added, that allows the detection of the transmission by longer integration, and provides for the basic data of the S/C. NOTE: the internal real time clock of the OBC may drift by several seconds, even minutes in the course of the mission, due to severe temperature variations. The Transmitter of the payload performs a 1 minute sequence on a 5 minutes cycle starting on UTC hour, based on JT65B mode and ‘human readable’ tone transmissions according to the following sequence:There are 5 successive sequences that are transmitted in a 5 minutes cycle. The content of the analog sequence is the same in all sequences.
JT65B data sequence
The data content of the JT65B sequence is described in the following table:
The ‘unique tone 4’ may take 5 different values indicating which JT65B sequence follows:
The analog sequence consist of three times two tones as per the following table:
400Hz: Seq 1 420Hz: Seq 2 440Hz: Seq 3 460Hz: Seq 4 480Hz: Seq 5
Analog sequence demodulation
The analog sequence is modulated in DSB, SC, allowing for stations with non accurate receiver to determine the value of the telemetry by measuring the spacing between the peaks of the FFT. However, even in SSB, recording the signal for several minutes allows a rapid identification of the sequences. This will allow also to identify the Unique Tone 4 that indicates the start of the JT65B sequence. Assuming a sample rate of 11025s/s, the duration of each tone allows a 16k (0.673Hz BW) or 32k FFT (0.336Hz BW) which gives an ‘eye’ decoding increased performance of up to 9dB compared to JT65B. Average should be rather on 3 to 6 dB improvement, mainly depending on the angular speed of the 4M S/C. (Doppler ‘jitter’) and its relative orientation.
What is needed?
- a >12dBic antenna: a 8 elts crossed yagi will do
- less than 1dB cable losses between antenna and LNA
- less than 1dB NF LNA
- a receiver: SSB, 2.4kHz bandwidth, and audio connection to PC
- a PC with sound card
- WSJT software, that can be downloaded from the website of K1JT. WSJT is a software that is widely uszd in EME and its performances are fitting the needs. Actually, there was not much choice. Please note that the UTC synchronisation of the PC is required. Normally it is achieved with an internet connection.
WSTJ10 decoding software (and associated requirements) http://physics.princeton.edu/pulsar/K1JT/index.html.
Use latest release that includes special feature for 4M.
A sample wav file can be downloaded here
The injection will occur over the Pacific Ocean and only Eastern Australia / New Zealand stations will be able to receive the 4M S/C. The 4M is on a “collision” course with the Moon for the FlyBy. The Moon will be at its lowest declination, to optimize the launcher capability. The southern hemisphere stations will be favoured during all the nominal mission. The following view shows the Earth, the Equatorial plane, the Moon and the trajectories (nominal and deviation cases), viewed from -23° latitude (Equatorial plane is ‘above’)
Pointing of the antenna
The problem to solve is that only nominal trajectory is known. The trajectory dispersion is also known. The actual trajectory will be comprised inside the limits.The purpose of this chapter is to examine if it is sufficient to point the antenna on the ‘nominal’ trajectory and verify that the extreme case (+/- 3 Sigma) trajectories yet allow the 4M to be inside the pattern of the antenna. The simulations have been performed with a 25° beamwidth. During the first part of the trajectory up to the Flyby, the nominal and max deviation trajectories are close one to each other, therefore, the nominal trajectory elements may be used. The dedicated website and Facebook pages will be updated as soon as the injection vector is known. For ease of use, tables will be published that will also indicate the Offset pointing in Az and El relatively to the Moon.
the integration of 4M has been completed this night. The S/C is ready for launch. Onboard clock has been adjusted to start JT65B at the UTC minute +/-1 second. It is likely to drift during the mission, and manual offset introduction will be required after a week or so. The launch date is 23 October at 1800 UTC. Beginning of transmission of 4M will start between 1917 UTC and 1927 UTC. Alternatively, use the ‘tracking’ section where you can compute your traking elements by introducing your geographic coordinates. The table can be copied/pasted into a text file. As the apparent movement will be close (and closer) to the one one of the Moon, manual pointing is easy but for the largest arrays. We’ll try to publish equivalent TLE’s to input in usual tracking softwares. The link budget is quite tight, but the first hours should give comfortable signals. QSB is to be expected. As JT65B is used: please remind those not yet too familiar with it that the receiver must not be tuned during the transmission. A dedicated webpage is being written to detail the procedure.
A dedicated java application is also available to automatically transmit the decoded messages to the 4M website and ease the data collection. (Thanks to LSE Space) Alternatively, OM can also transmit the decoded messages by eMail, sending the ALL.txt file.
For those not wishing to use JT65B, please record the signals (11025s/s, 8or 16 bits, mono), taking care not to saturate the recording and NO MP3 please. SpectrumLab is an excellent choice, although some may wish to use simpler recording software.
You can imagine that the team is quite eager to receive the first reports, so , do not hesitate to mail immediately, send decoded messages or even phone or text me at +352 661 678 986. Our friends of IC CMalaga are also quite eager to receive the results of their radiation dosimeter experiment. Basic rules of the contest have been delineated in the blog section. Complete rules will be published soon. Stay tuned on our website or Facebook page. Please disseminate the information and send questions to firstname.lastname@example.org. If possible, help OM’s.
vy 73 and best regards to all.