content 22-June-2018 20:54:55

Q&A Cosmic Vision 2015-2025 Briefing

This page provides clarification to the additional questions that have been raised at the Cosmic Vision 2015-2025 debriefing meeting to proposers, which was held at ESTEC on 11 April 2007. Please also refer to the summary page of the briefing meeting - linked from the right hand side - for the questions and answers that were covered already in the meeting presentations.

Q: Is the Cosmic Vision call open to collaborative missions with a cost to ESA under the M class budget?
A: Yes, the call is open to collaborative missions (or contributions to missions led by other space agencies) with a cost to ESA under the M class envelope.
 
Q: How to handle the yearly price escalation, which has to be taken into account for the CV1525 costing?
A: For the cost estimate of the mission proposal the price for economic conditions 2006 (EC2006) should be taken. No escalation (inflation rate) should be applied.
 
Q: Concerning the availability of radio-isotope power generators (RTGs) and implications for a mission to launch late in the 2015-2025 time frame
A:
  • The ESA Science programme has no plans to support a development in Europe as it would exceed the financial capabilities of the programme
  • The current efficiency of RTG's (such as US MMRTG around 2.5 W/kg (End of Life (EOL), Russian RTG technology in the same order) is rather limited
  • A discussion on the impact of replacing solar power with RTG's technology can be found at: JME status report (page 77 to 95) available in the "Jovian Studies Overview" at

    http://sci.esa.int/jump.cfm?oid=40866

 
Q: Launch from Kourou of an ESA mission with NASA contributing RTGs.
A:
  • US-department of Energy (DOE) and ITAR regulations would most likely prohibit such a scenario
  • Use of NASA contributed RTG's would require a launch from US, use of Russian RTG's would require a launch from Russian territory in the framework of international collaborations
 
Q: Question 53.6: Direct-to-Earth communications of a distant mission - combined with Question 10.6: New developments in communication
A: In the short and medium term future deep space communication (link range > 1 AU) will continue to rely on microwave radio systems. Units capable of performing the task exist today. Typical subsystem mass (Ka) is about 20 kg (including ~1.5m diameter antenna), with a power consumption of about 40W. X-band and Ka-band communication systems are conventionally used for deep space communication. A ground station infrastructure (e.g. the ESA 15m and 35m antenna network) exists to support these communication frequencies (see attached table).

Band Wavelength [cm] Frequency [GHz]
X 3.75 - 2.4 8 - 12
Ku 2.5 - 1.6 12 - 19
Ka 1.6 - 0.75 19 - 40

Optical communication has recently been tested successfully in space (e.g. SILEX experiment on Artemis and Spot-4, laser link experiment on SMART-1), but it requires further validation and testing before being base-lined for deep space communications. It should be noted that the potential advantages offered by optical communication in terms of high SNR are to be traded against the need for high pointing accuracy (arcsec level as opposed to degree level), the heavy influence of atmospheric conditions and the limited lifetime of existing laser sources.
In the time frame of the first planning cycle of Cosmic Vision 2015-2025, no major new deep space communication technologies are expected to be implemented. For interplanetary missions, Ka-band is considered the most suitable baseline, while for Earth-orbiting missions (and missions to the Lagrange point) X-band is recommended.
In the longer term future, the developments for RF deep space communications are likely to focus on the Impulse Radio approach: the signal is transmitted as carrier-free, short duration pulses (< μs) that are time-synchronized by an on-board ultra-stable oscillator. The development of a number of components (from power supplies to RF semiconductor components capable of supporting the impulsive regime) is required in order to achieve flight qualification status.
For deep space communication systems at distances below ~20 AU, the reader is also referred to the Jovian Studies overview, available at:

http://sci.esa.int/jump.cfm?oid=40866

For link ranges in excess of ~20 AU, the overview of the Interstellar Heliopause Probe study can be of interest:

http://sci.esa.int/jump.cfm?oid=40927

 
Q: Question 42.2: How to send rapid and instantaneous alerts to Earth (similar to NASA / TDRSS)?
A: The NASA Tracking and Data Relay Satellite System (TDRSS) provides extended view times for LEO satellite communications links, and is capable of transmitting to and receiving data (mainly in S band, with additional capability in Ku band) from any LEO spacecraft over at least 85% of its orbit. The system can also be used to send alert signals thus allowing timely control action, including the reconfiguration of observatories/instruments for simultaneous measurements of given science objects.

ESA does not have such a dedicated system. Nevertheless, given a specific mission scenario (e.g. LEO or HEO mission, orbit inclination, orbit period, etc.) alternative solutions can be investigated to minimise the reaction time of an alert system.

Possible solutions involve the possibility to access a larger number of ground stations, thus increasing the satellite view time for a given orbit. NASA's support, although programmatically more demanding, could in principle be explored. Specific scenarios would certainly be examined by ESA following the selection of the proposal.

For the benefit of the proposal preparation, the author/s shall indicate the needs and the importance of such an alert system with respect to the science objectives. The impact of different reaction delays should also be discussed, with specific reference to the baseline mission orbit (or eventually with reference to the possible orbit options).

As an example, assuming a Low Earth Orbit scenario, with a satellite altitude of 1000 km, the orbit period (Tp) would correspond to 105 min, while typical view times (Tv) for a single ground station pass would be about 10 min. In this case (i.e. in absence of any specific view time augmentation solution) the maximum (worst case) reaction time would be Tp – Tv ~ 95 min. The addition of a second ground station (at an optimised location) would allow decreasing the maximum reaction time to about 40 min.

 
Q: How the two AO, Cosmic Vision and Exploration Programme AO will interact, knowing that the two schedules seem not to be coherent?
A: The CV AO and the Exploration AO are independent from each other. This has been described in the Cosmic Vision Call. Hence, the schedules are different.
 
Q: What will be the goals of the payload AO of the Cosmic Vision programme during the definition and implementation phase?
A: The payload AO in the CV plan will be released at the very beginning of the Definition Phase at the latest. The aim is to pre-select payload complements which will be studied during the Definition. At the end of the parallel competitive Definition Phase, there will be a down-selection from 2 to a single mission. The payload of the selected mission will have to be confirmed via the approval of a Multilateral Agreement (MLA) negotiated between ESA and the instrument funding Agencies before the mission enters implementation. This is described in the Call. At the level of mission proposal preparation, it should be emphasised that the issue of payload AO is premature as only a model payload will have to be considered.
 
Q: Can members of the ESA science directorate participate to proposals and their name/s appear on the proposals?
A: With the exception of Research fellows, no staff members of the Science Directorate are allowed to participate in the proposals.
 
Q: Could you provide the contact information for the Letter of Support expected from the Chinese Space Agency?
A: Proponents intending to involve Chinese groups in their proposals should contact the following address:
    Professor JI WU, Director Executive
    Center for Space Science and Applied Research
    CHINESE ACADEMY OF SCIENCES
    P.O. Box: 8701, Beijing
    China
    Zip Code: 100080
    Email: wujicenter.cssar.ac.cn
 
Q: Japanese colleagues say that NAOJ is a national agency, which is involved in both ground- and space-astronomy. Is it considered as a partner by ESA?
A: The only Japanese counterpart of the ESA Science Directorate is ISAS/JAXA.
 
Q: What is considered by ESA as partner in Australia? Is the Australian Space Council a partner?
A: The ESA partner organisation in Australia is the Commonwealth Scientific and Industrial Research Organisation (CSIRO).
 
Q: We are planning on submitting an M-Class proposal primarily calling for ESA to procure a major piece of spacecraft hardware for a JAXA mission. One of the instruments on the mission is being jointly provided by institutes in Japan and South Korea. Do we need to seek a letter of commitment from Korea (KASI) as well as Japan?
A: Given that the mission is led by JAXA, their endorsement is sufficient.
 
Q: For several missions (including SPICA) with Japanese contribution, letters of commitment have been arranged to be signed by the executive director of ISAS. Is this adequate, or do the letters have to be signed by JAXA's director as well?
A: A letter signed by the director of ISAS is sufficient for the proposal.
 
Q: We are planning on sending copies of the proposal only to European funding agencies from ESA member states that are currently envisaged as financially contributing to the mission if it is successful in the first selection phase. Do we need to send copies to any other bodies?
A: No.
 
Q: Are the Letters of Commitment to be attached to the proposal required only from international partners or also from the space agencies of the ESA member states participating in the proposal?
A: The need for a letter of commitment from an ESA member state agency depends on the nature of the foreseen involvement.
  1. If the national involvement is restricted to payload elements (i.e. an instrument or part of it), there is no need for a letter of commitment.
  2. If the proposed national involvement is for elements of the mission which are the usual responsibility of ESA (for example, a telescope, a system or subsystem of the platform, etc...), then a letter of commitment is needed in support of the proposal.
 
Q: The estimates of the CaC for non-ESA states is in local currency with a conversion to Euro based on June 2007 exchange rates. Is this OK?
A: Yes. For the cost estimate of the mission proposal, the price for economic conditions 2006 (EC2006) should be taken. No escalation (inflation rate) should be applied.
 
Q: What is the cost of the GAIA platform?
A: The procurement cost of an already developed platform depends considerably on the actual degree of re-use (as opposed to the level of any required changes and the related engineering effort) and on the procurement schedule (with the lowest cost corresponding to the shortest delay with respect to the last procured platform).
It is important to note that the GAIA platform presently under development includes several design features strictly related to the observation scenario of this mission (e.g. deployable sun-shield hosting part of the solar arrays, high-precision pointing with star tracker-payload hybridisation, micro-propulsion thrusters for spin/precession motion, X-band phased array antenna), features that impact on total cost and may not be necessarily required in the case of a more conventional 3-axis stabilised astrophysics mission.
Under the assumption of limited design changes and of a procurement schedule no more than 3 to 4 years after GAIA, the recurring platform cost would be in the range of 45 to 50 Meuro (Economic Conditions 2006).
 
Q: What is the cost of the Herschel platform?
A: The procurement cost of an already developed platform depends considerably on the actual degree of re-use (as opposed to the level of any required changes and the related engineering effort) and on the procurement schedule (with the lowest cost corresponding to the shortest delay with respect to the last procured platform).
Unfortunately the procurement schedule for the first M and L missions does not allow anymore the possibility to contemplate procurement of a recurrent Herschel-Planck Service Module (SVM). One should therefore assume that the development-procurement of this kind of platform will be in the range 70 to 80 Meuro (Economic Conditions 2006).
 
Q: What are the "ESA internal costs" and what is their relevance (table 5 of Annex 4)?
A: As any other organisation/company, ESA has internal costs to sustain in order to continue to operate. In the case of the Science Directorate projects, the internal costs amount to about 11% of the total ESA Cost at Completion (CaC).
Such internal costs include different items, such as organizational overheads, the project team labour and any technical assistance provided by other ESA directorates. Thanks to a lean internal organisation, the Directorate has managed to limit the internal costs to a very low fraction of the total project cost.
The "ESA internal costs" percentage indicated in table 5 is provided to the external community with the goal of explaining the typical cost allocations of a science project, thus allowing a preliminary estimate of what level of resource remains available to other key cost items, such as the industrial procurement, the launcher procurement and operations.
Following the selection of the proposals, and the results of the planned assessment activities, the preliminary cost estimates will be progressively refined, thus increasing their accuracy.
 
Q: What are the design maturity and system level margins applied to ESA studies?
A: Design maturity and system level margins are applied to the main resource budgets (mass, power, propellant) of any space project. Such margins are indispensable in order to account for design and manufacturing changes that are bound to take place when moving from an early concept phase to detailed implementation (e.g. requirements evolution, unexpected difficulties during the qualification programme, etc.). For the purposes of the proposal preparation, the following basic rules are to be applied in the preparation of preliminary resource budgets. Concerning mass and power budgets:
  1. Indicate clearly the nominal mass (and power) associated to key equipments. The nominal mass (and power) are best engineering estimate values and do not include any margins.
  2. Apply the following design maturity mass (and power) margins to the nominal values indicated in 1. above:
  3. 5% for "Off-The-Shelf" items
  4. 10% for "Off-The-Shelf" items requiring minor modifications
  5. 20% for new designed/developed items, or items requiring major modifications
  6. Calculate the total nominal dry mass at launch (and nominal power) by including the design maturity margins applied at equipment level as from 2. above.
  7. Calculate total dry mass at launch (and total power) of the spacecraft by adding a further system level margin of 20% of the nominal dry mass at launch (and of the nominal power).
Detailed mission analysis and corresponding Delta-V budgets are not strictly required in the proposal, as they will be subject of dedicated analysis in case of proposal selection. Should preliminary information exist, the following basic rules are recommended:
  1. Indicate clearly the nominal Delta-V associated to key mission manoeuvres.
  2. Apply the following Delta-V margins to the nominal values indicated in 5. above:
  3. 5% for accurately calculated manoeuvres (trajectory manoeuvres as well as detailed orbit maintenance manoeuvres)
  4. 100% for general orbit maintenance manoeuvres, over the specified lifetime (maintenance manoeuvres calculated in detail shall be handled according)
  5. 100% for attitude control and angular momentum management manoeuvres
  6. Gravity losses (for instance: impulsive manoeuvres performed by chemical propulsion engines) shall be quantified and added to the Delta-V budget.
  7. In case of Gravity Assist Manoeuvres (GAM), an allocation of either 15 ms-1 (planetary GAMs) or 10 ms-1 (GAMs of planetary moons) shall be added for chemical propulsion to the Delta-V budget for each GAM, to account for preparation and correction of these manoeuvres. In case of electrical propulsion, 35 ms-1 shall be applied for each GAM.
  8. In case of electric propulsion, a 5% Delta-V margin shall be foreseen for navigation during the cruise phase, to compensate for trajectory inaccuracies.
Obviously the sum of the total spacecraft dry mass, launcher adaptor and propellant shall be compatible with (lower than) the launcher vehicle performance for the specific mission launch scenario.


Last Update: 31 October 2007

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