OHB-FACTORS first meeting 2018-08-27

Japan (Y Saito from ISAS, M Hirahara from Nagoya U)
OHB (Fredrik Sjöberg, Gierth Olsson, Peter Rathsman, )
SNSA (Johan Köhler, Ronnie  Lindberg)
KTH (Nickolay Ivchenko)
IRF (Yuri Khotyaintsev from Uppsala, Yamauchi from Kiruna)

9:30-12:00 
(1) OHB presentations for general activity
- Have built up to Max 400 kg
- Have build subsystems for ESA spacecraft
- Provide attitude control(AOCS), propulsion(CP&EP), small satellite technology
- Cleanroom ISO class 8
- In-house control center (for InnoSat etc)
- Experience in Moon mission with electric propulsion (SMART-1 in 2003)
- Experience in formation flight with short distance (PRISMA in 2010)
- Now building series of Innosat, with #1 (Mats) nearly ready

(2) Hirahara/Saito presentation of FACTORS formation flying
- FACTORS (two nearly identical satellites of 160-170 kg wet mass each)
   - Horizontally separated by 1-100 km
   - 2026-2027 Launch, with final proposal to be submitted 2020-2021.
   - perigee 300-400 km x apogee 4000 km
   - Sun-synchronous 104.5° inclination (noon-midnight orbit)
   - eclipse maximum 40-50 min

(3) OHB Presentations of Innosat/Prisma
- Innosat 
   - Innosat-1 (MATS) launch Dec. 2019 (waiting for Piggyback opportunity), 
   - 50 kg without propulsion (20 kg for science payload),
   - 3-axis stabilized with reaction wheels, star tracker, and GPS
   - 0.01 deg. for determined attitude
   - S-band 5 Mbps/ X-band >100Mbps
   - 28 V bus, 5 V for data handling system
   - Safe hold mode by magnetometer for sun-pointing without spin motion
   - Launcher side provides satellite separation device/adapters
   - Seeking low-cost subcomponents every time (inc. Canada, South Africa)
   - All Innosat launched in cold mode
   - Initial critical operation from the OHB building remotely using ESRANGE
- PRISMA 
   - Autonomous formation flying within 1 km distance and autonomous rendezvous
   - Inter-satellite link (but very slow)
   - 3-axis stabilized Two sub-satellites, passive Tango of 40 kg and active Mango of 145 kg including 15 fuel with 3 propulsion system > 200 m/s Delta-V
   - Thrusters of 1 N and (hundred)milli-N micro
   - Separation distance of 2 m and 32 km at min. and max. at 550 km altitude

(4) Discussion on InnoSat-FACTORS formation flight
- Techical summary
   - No special consideration from SNSA side (i.e., InnoSat is normal competition)
   - Innosat-3 A/O is still unclear due to weak SEK (SNSA hopes 2020-2021)
   - InnoSat formation to be horizontally rather than vertically
   - Innosat flies without propulsion and control is done only for FACTORS
   - Nominal time for InnoSat is 1 year
   - Perigee = 400 km for the first year, and FACTORS decreases perigee afterward
   - Allowed mass for InnoSat depends on the capability of new launcher 
   - With extra mass allowance, spot-sheilding solves the radiation problem
- Priority of the feasibility study to fit InnoSat into FACTORS
   1a. Radiation harness for 1 year
   1b. Buttery for eclipse (< 50 min): to survive only spacecraft without observation
   2.  Propulsion
- Logistic summary
   - All improvements are possible depending but they costs extra
   - Actual specification for InnoSat 3 is determined by SNSA, and there is no guarantee that 1a, 1b to be implemented.
   - FACTORS final proposal must not rely on InnoSat 
     (InnoSat adds extra on already good science with only two spacecraft)
   - FACTORS proposal should address three cases regarding Innosat, no Innosat, Innosat without propulsion, Innosat with propulsion.
   - When FACTORS phase starts, OHB personal is ready to attend necessary meeting

(5) Action items
- Viewgraph exchange between FACTORS (Hirahara) and InnoSat/PRISMA (OHB)
- Orbit information of FACTORS to OHB
- Radiation dose estimate of FACTORS to OHB
- Uplink and downlink information of FACTORS to OHB to make common operation
- Mass and size allowance for InnoSat when lifting together with FACTORS to OHB as soon as the new launchers ability is fixed.