FACTORS meeting at KTH and OHB-Sweden 2019-09-04

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Minutes, 2nd FACTORS Meeting at KTH
2019-09-04 09:30-12:00 

Kazuo Tanimoto (Meisei Electric Lab, Executive Officer) PM, Syst, engineer
Tomoya Fukami (Meisei Electric Lab, Aerospace and Defense System Division) syst. engineer (2nd at Meisei)
Masafumi Hirahara (Nagoya U)
Hirotsugu Kojima (Kyoto U)
M. Yamauchi (IRF Kiruna)
Manabu Shimoyama (IRF Kiruna)
Stephan Buchert (IRF Uppsala), supplement to Yuri Khotyaintsev 
Nickolay Ivchenko (KTH)
Andris Vaivads (KTH)
Per-Arne Lindqvist (KTH)
Göran Markund (KTH)
(remote attendance: Meisei Electric)

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Minutes, FACTORS Meeting at OHB Sweden
2019-09-04 13:30-16:00 

Ronnie Lindberg (SNSA), national satellite program
Peter Ratsman, (OHB Sweden, CTO, supervise R&D activities, head of Technical Department)
Nils Pokrupa, (OHB Sweden, head of spacecraft department)
Masahisa Hirahara (Nagoya U)
Hirotsugu Kojima (Kyoto U)
Kazuo Tanimoto (Meisei Electric Lab, Executive Officer) PM, Syst, engineer
Tomoya Fukami (Meisei Electric Lab, Aerospace and Defense System Division) syst. engineer (2nd at Meisei)
Masatoshi Yamauchi (IRF Kiruna)
Manabu Shimoyama (IRF Kiruna)
Stephan Buchert (IRF Uppsala) 
Andris Vaivads (KTH)
(remote attendance: Yoshifumi Saito)

<This is second meeting, first meeting one year ago>


========= technical part (at OHB and KTH) ===========
* Present status of FACTORS (Hirahara, at both KTH and OHB)
- STP community mission, and first formation flying mission in JAXA, targeting "S-class mission" that is expected to launch every 1-2 years using epsilon rocket (ERG was one of them).
- Working Group (pre-phaseA1) was approved last year, and started April 2019.
   (1) For two main spacecraft of 150-200 kg / 70x70x90cm (20kg propellant, 4x1N thrusters, 76kg payload) each.
   (2) Assuming 60-70 kg third spacecraft that is externally provided.
- Review of the Working Group proposal pointed out that
   (1) Need international collaboration in instrumentation (from cost problem)
   => Swedish contribution to the instruments in the main spacecraft is a baseline
   (2) From science, third spacecraft is extremely important but the S-class budget can provide only two.
   => Swedish contribution of the third spacecraft by Innosat is extremely important
- Due to longer "mission definition phase" that ISAS recently implemented, expected launch was delayed to 2029-2031 instead of 2026-2028.
- For the S-class, two missions are already approved (incl. SLIM), and 2-3 missions are "almost approved". 
- Like the present selection, the next AO (2021 or 2022) will probably select 2-3 missions.

* Present status of the launch vehicle (Hirahara, at OHB)
- Synergy Epsilon rocket will replace the present Epsilon rocket after 2022, but its ability is not clear
- Might have to compromise the apogee (between 3500 - 4000 km) and inclination (75-85°) with perigee starting at 400 km and finally 300 km after 1 year.
- The post boost (fourth) stage will insert all spacecraft to the target orbit without spin including Innosat.  - No propulsion is required to Innosat for orbit insertion.
- Two options of launch configuration (all in the same plane or 2+1 stacking configuration)
   => Innosat stacking on top of FACTORS can complicate interfaces (Nils)

* Short presentation of the Innosat program (Ronnie, at OHB)
- Call every 3 years (depending on SEK-EUR rate) and proposal to implementation about 4 years 
- Science review selects up to 3 candidate for phase A/B1 study, and selection of one after considering technological/programatic constraint
- It is ok to resubmit proposals.
- Having international collaboration (formation flight) in proposal does not give bonus in the evaluation
   => The "expected launch date" must be within several years, and "launch in 10 year future" should not be proposed

* Innosat update (Ronnie and Nils, both at OHB)
- Innosat-3 call will be issued as soon as Innosat-2 project starts (may be end of 2021?)
   => We should aim Innosat-4 (call after 2024-2025) if FACTORS launch is around 2029-2031.
- OHB considers "enhancement" of Innosat from future needs and commercial value (Nils).
   e.g., Innosat-2 will have small propulsion for attitude control (dVs 100-200m/s if monoprop, 200-400m/s if electric propulsion).
- radiation environment (Nils)
   In some cases, Innosat uses <15krad component, and no counter-radiation is so far implemented
   
* Discussion on requirement to Innosat (all)
- 1 year nominal mission, and low perigee means the mission is cannot be extended to long. 
- Orbit maintenance for 1-year, starting from 400 km x 4000 km, with > 300 km x 4000 km after 1 year.
   The newly implemented propulsion for Innosat-2 is only for attitude control and can hardly be used for perigee-maintenance
   Keeping orbit requirement might be possible without propulsion because apogee is high and drag coefficient can be smaller for Innosat than FACTORS 
   => We need orbit calculation of Innosat (50 cm square) targeting perigee of 300 km after 1 year operation.
- Expected 1-year dose is 100 krad after 2 mm aluminium.  
   => OHB will consider the best solution for the counter-radiation.
- Mission requires survival of Innosat during eclipse, although the instruments are switched off.  Due to 75-80° inclination, orbit precession in both longitudinal and latitudinal direction, and hence we can determine the launch window such that equatorial apogee when the orbit is placed in the noon-midnight meridian for 1 year.  
   => Duration of the eclipse is TBD, and wait the result of orbit calculation 
- Spinning capability 
   OHB does not see high demand of spinning platform  
   Good for science but KTH/IRF does not have wire-boom deploying technology (for Freja, it was a part of SC structure by OHB) and developing wire booms deployable from Innosat should be again discussed in the Swedish community.
   => In the proposal, nominal attitude control should be 3-axis stabilized, and the spinning platform shoud be mentioned as "desirable" option to be studied during phase-A.
- Inter-spacecraft communication
   Not necessary because GPS method of distance control is accurate enough even 1 km separation.
   However it would be nice to have if we implement an autonomy system to protect payload radiation using  time radiation monitor by the energetic particle instruments on the FACTORS side.
   => developing automatic payload-control system using radiation monitor should be discussed in the future 

* Other list of questions on Innosat from Japanese side
   => OHB will answer the questions on page 14 of Hirahara's document on 2019-09-06

========= science part (at KTH) ===========
* Confirmation of Swedish contribution to main spacecraft for two options, with and without Innosat 
- LP on FACTORSx2 (still optional depending on mass budget) and Innosal
- Subsystems for the electric field measurements on FACTORSx2 as we have agreed in the spring (same as 2019N proposa)
- Neutral-ion mass-separating velocity distribution analyser on FACTORSx2 and most likely innosat
   => With longer develop time, this is well feasible.
  
* Discussion on apogee (how much can we decrease apogee without loosing much science)
- Freja (apogee 1700 km) almost never saw the acceleration region. 
- Cusp acceleration region may require 4000 km.  
  => compensation to 3500 km and compensating instruments (mass) must be further discussed

* On design of EPWI: electric field/plasma wave investigation (Kojima)
- Does not include BBELF-plasma mode 
- Current design of antenna is 10 m tip to tip with 6 monopole antennas in each dpacecraft
- Phase velocity of the electrostatic waves is comparable to velocity of spacecraft, and the wavelength are around 10 m range. 
   Longer antennas may be disadvantageous for detecting these waves. 
   Short antennas have disadvantage for electromagnetic waves, and it is difficult to get the DC field.
- possibility of interferometry (Andris)

* Confirmation of science payload for Innosat (1=mandatory, 2 is either choice, 3 is optional)
- We expect at most 12 kg total payload with 18 W power (this can be reduced to 7 kg + 12 W if needed)
  (1a) Magnetometer + boom (1 m) 1 kg + 2 W including boom
  (1b) LP + boom (1 m x 1‐4) 2 kg + 2 W (+ 1 W margin)
  (1c) electron spectrometer (ISAS?) 0.01‐10 keV 2 kg + 3 W
  (1d) DPU just for data buffer (TBD but system side can decide)
  (2a) ion spectrometer (IRF?) 0.01‐10 keV 2kg+4W or
  (2b) neutral (IRF) 1‐100 eV or < 1000 km/s 5 kg + 7 W
  (3) STEIN (USB/SSL) 2‐100 keV ion‐neural‐electron 0.5 kg + 1 W

* Related mission proposal
- Daedalus mission (targeting 100-200 km altitude with similar science as Innosat) could be a good candidate for collaboration, although this mission is just one of three "Earth observation" finalist (two others are Radar satellites).

========= others ===========
* Short presentations of teams (Andris, at KTH; Tanimoto, at OHB)
- presentation of KTH (Andris)
- presentation of Meisei Electric (Tanimoto)
    Established 1938, since 2012 member of IHI group with space-related staff ~100
    (IHI group is the subcontractor for epsilon rocket). 
    Many of ISAS's instruments (e.g., for JUICE, MMS, MMO/MPO)
    Environment test facilities: shock, vibrations, termvac, EMC, clean room (class 7), clean bench (class 5)