Questions from the European colleagues & Answers (only) from the Chinese engineers present for Y.-W. Zhang and S.-G. Yuan Chinese Academy of Space Technology

Q1: Is a 3-axis stabilized Sun-Pointing Spacecraft, like STEREO and SOHO feasible? A: It could be feasible, but depends on the scientific requirements Confirmed later: Near earth orbit Promised precision: degree/s In reality 1arcsec/s (no experience for L1)

Q2: What would be the orbit? A: Lissajous or Halo, also depends on the mission requirements

Q3: What is the available electrical power? A: The conceptual answer would be around 60~70W at least for all payloads.  confirmed later: W

Q4: What is the maximum payload mass? A: The conceptual answer would be around 100kg at least for all payloads.

Q5: Fuel is needed for station keeping. For how long time can the mission be maintained? We dream of a time of about 6 years minimum, beginning near solar activity maximum though the next minimum! A: If it is necessary and we have enough money we could do that. confirmed later: Life time, limit 3 years for design (?)

Q6: Some pointing stability is needed, in particular for the optical instruments. We have to find a compromise such that the cost for spacecraft pointing remain within limits and that the effort for internal pointing provisions inside the instruments also remain within limits. A: Thank you for your very kind consideration.

Q7: Are there already plans for a project structure: program/project manager - Project scientist - Science Working Team – PIs- etc? A: We have not any formal organization of the project by now. Not only for scientists group but engineers group.

Q8: What will be the telemetry rate? Will it be continuous (optimum), or buffered on board? For which time periods (that probably depends on the number of available ground stations)? At which rates? A: Sorry, no idea at moment. But the continuous downlink could be impossible because we need real time support from the deep space network if that. confirmed later: data rate could be a few Mbps in near earth orbit satellites. No experience for L1 satellite yet.

Q9: A minimum uninterrupted telemetry rate is highly desired for transmitting most essential data in near real-time, for on-line space weather monitoring. Is that possible? A: As above, if we need the support from Deep Space Network, we need the involvement of the government.

Q10: Telescopes need some space, in particular: length, say 1.5 m maximum. Possible? A: Conceptually no problem

Q11: For the radio antennae one should also look for the STEREO example. A: Conceptually yes

Q12: The magnetometer should be located on a little boom, probably extendable, probably in the permanent spacecraft shadow. See STEREO. A: OK, we will have the shadowed side of the 3-axis stabilized spacecraft.

Q13: The normal procedure for a project like this one would be: Call for ides (done)- Call for mission proposals (assessment study by interested scientists with modest engineering advice, (at present) Selection by agency for Phase A study Public AO (Announcement of Opportunity) Instrument proposals submitted and selected Final approval by agencies to begin Phase B (hardware) Etc. In this context: Is an AO (i.e., contest!) foreseen? If yes: who writes it and who selects? A: Who will write the AO I think it is not very urgent at the moment. If it is very clear and ready, Chinese colleagues could do that. But may we need a template of that because we have no experience on that.

Q14: What are the main project mile stones: Prepropsal submission, Approval for Phase B and Issue of AO, Final Mission approval, Malor reviews, Instrument delivery, Launch A: At the moment I can not answer your question. But generally we need following high level reviews for spacecraft:  Phase 0 review  Phase A review  Phase B review  Delivery review  Preshipment review  Launch ready readiness review  Commissioning and go-ahead review

Q15: Where is mission control and which are its duties? A: If the mission control center is in China, there should be two centers: For spacecraft operation, they should do: Routine tracking; Spacecraft status monitoring; Spacecraft control; Contact with the payload center. For payload operation, they should do: Payload operation and control; Payload status monitoring; Cooperation with the spacecraft operation center; Communication with the different ground station and issue the tracking planning.

Q16: What do we do with the data on ground? What will be the role and the responsibility of the Europeans after launch? Is there a dedicated space weather warning center foreseen?  May we need some data centers to distribute the scientific data. At least one center in China, at least one center in Europe.  The role and the responsibility (only payloads) could be:  The routine support of the payload operation;  Joint scientific team activities;  Mutual support between the spacecraft and payloads.  There is not a dedicated space weather center in China formally at this moment. But several institutions are trying.