Defining the Preferred case Action 7 CLOSED_SWT35: SWT to define decision process to define HAC or LAC based approach. Deadline next SWT.

Defining the Preferred case Summary of discussion As discussed at the last SWT. We decide which trajectory to follow for the rest of mission – Either a scaled HAC or a scaled LAC Scaled HAC LTP1 LTP2 LTP3 Decide based on activity measurements Scaled LAC LTP1 LTP2 LTP3

Defining the Preferred case Summary of discussion As discussed at the last SWT. We decide which trajectory to follow for the rest of mission – Either a scaled HAC or a scaled LAC Scaled HAC Decide based on activity measurements HAC Scaled LAC Outgassing LAC 1 1.5 2 2.5 3 3.5 4 Heliocentric dist. (AU)

Defining the Preferred case From this, a list of items that were iterated via email in February within the SWT (two similar lists).

Preferred case 1) We have to get the actual activity value 1) The SWT propose which pre-landing measurements will be used to define cometary activity 2) Consider criteria for defining the preferred case (make feedback into 1)  3) The SWT agree criteria for either a scaled HAC or scaled LAC (and hence retain the agreed segmentation). Last November we discussed % of HAC or reference to the Snodgrass predictions): close to Snodgrass - go for scaled LAC, close to 40% LAC - go for scaled HAC. 4) The SWT define how to monitor evolution of activity and hence the way the scaling works (to avoid being forced to jump to the HAC unnecessarily). 5) Define a schedule for trajectory group interactions. 1) We have to get the actual activity value  2) We have to decide what we do with this value (projection into future): go for modified LAC, modified HAC  3) We have to monitor the actual value and compare it to the projected one. 4) In case of deviations we have to decide what to do.

Preferred case 1) We have to get the actual activity value 2) We have to decide what we do with this value (projection into future): go for modified LAC, modified HAC  3) We have to monitor the actual value and compare it to the projected one. 4) In case of deviations we have to decide what to do.

Preferred case 1) We have to get the actual activity value 2) We have to decide what we do with this value (projection into future): go for modified LAC, modified HAC  3) We have to monitor the actual value and compare it to the projected one. 4) In case of deviations we have to decide what to do. Summer 2014 would provide measurements of: The nucleus mass and density. The gas production rates. Anything else? Based on 1, we must determine which projection into the future to utilize and how to implement the projection (i.e. how to scale one of either the HAC or the LAC). There is no scope for defining a third option.

1) We have to get the actual activity value  2) We have to decide what we do with this value (projection into future): go for modified LAC, modified HAC  Activity = 110 % LAC Go for Scaled LAC, where scaling is 120% LAC. Preferred case HAC Preferred case= 120% LAC Outgassing / elephants per furlong LAC August 2014 1 1.5 2 2.5 3 3.5 4 Heliocentric dist. (AU)

Preferred case 1) We have to get the actual activity value 2) We have to decide what we do with this value (projection into future): go for modified LAC, modified HAC  3) We have to monitor the actual value and compare it to the projected one. 4) In case of deviations we have to decide what to do. On LTP timescales Carry out monitoring of activity versus projected activity. For LTP004, this will provide expected uncertainty of outgassing. However, if the projected value is wrong, is there anything that can be done? Is this simply a transition to the HAC if we got it wrong? We have to make a very good choice at 2.

For LTP4, TRAL delivery by late September 3) We have to monitor the actual value and compare it to the projected one. 4) In case of deviations we have to decide what to do. On LTP timescales For LTP4, TRAL delivery by late September LAC HAC LTP7 ? Preferred case= 120% LAC Outgassing / elephants per furlong LTP6 LTP5 LTP4 August 2014 LTP7 TRAL LTP6 TRAL LTP5 TRAL LTP4 TRAL 1 1.5 2 2.5 3 3.5 4 Heliocentric dist. (AU)

For LTP5, TRAL delivery mid November 3) We have to monitor the actual value and compare it to the projected one. 4) In case of deviations we have to decide what to do. On LTP timescales For LTP5, TRAL delivery mid November LAC ? HAC LTP7 Outgassing / elephants per furlong LTP6 LTP5 LTP4 August 2014 LTP7 TRAL LTP6 TRAL LTP5 TRAL LTP4 TRAL 1 1.5 2 2.5 3 3.5 4 Heliocentric dist. (AU)

For LTP5, TRAL delivery mid November 3) We have to monitor the actual value and compare it to the projected one. 4) In case of deviations we have to decide what to do. On LTP timescales For LTP5, TRAL delivery mid November LAC HAC LTP4 Preferred case= 120% LAC Measured activity lower LTP5 Preferred case = 110% LAC? LTP7 Outgassing / elephants per furlong LTP6 LTP5 LTP4 August 2014 LTP7 TRAL LTP6 TRAL LTP5 TRAL LTP4 TRAL 1 1.5 2 2.5 3 3.5 4 Heliocentric dist. (AU)

Defining the Preferred case Skeleton planning for LTP – In March we will require approval of HAC trajectory by trajectory group. Propose this is done via simply email. Impact of updated comet information on HAC should be minimal. For LAC we should also consider approval of LAC trajectory in May timeframe. Once comet is better constrained in August, update of trajectory where appropriate is carried out, TRAL update and iteration with skeleton group to check consistency. Beginning of September, Trajectory group approve trajectory and final TRAL created.

Defining the preferred case Key point is what can be refined in TRAL given the small timescale? Decisions are required in a 6 week window for LTP4. We need to define the mechanism and decision making process at this meeting or within 1-2 weeks after. I think realistically these tweaks are covered by the following: orbit altitude, flyby altitude and length of time we believe bound orbits are possible. DISCUSS…

CONCLUSION Preferred case: An outgassing value to be used to scale the LAC must be determined by August 2015. Suggestion that small team of Instrument representative + IDSs gather prior to that date to provide this value. This then scales the LAC. This value is derived each week to examine evilution of activity to feed into next LTP.

Had two options – use scaled LAC OR scaled HAC. Baseline scaled LAC. If activity in summer is 150% LAC – Scaled HAC is used. Question is # bound orbits – can a RSGS provide quick analysis of scaling versus bound orbit number. An outgassing value or activity level to be used to scale the LAC must be determined by August 2014. Group made up of ROSINA, Virtis, MIRO and ALICE with support of the IDSs report to PS and provide an activity level, APREF1. APREF1 used to scale the LAC for LTP004. This will provide us with a certain number of bound orbits. In September and October, group made up of ROSINA, Virtis, MIRO and ALICE with support of the IDSs report to PS and look at evolution of A biweekly, in November provide value APREF2 September SWT meeting provides an opportunity to examine evolution from APREF1 as a broader group. APREF2 used to scale the LAC for LTP005.

Extra slides

ALAC is activity level of LAC in August 2014 APREF1 is activity level determined in August 2014 APREF1used to scale the LAC for LTP004. Outgassing APREF1 ALAC LAC August 2014 1 1.5 2 2.5 3 3.5 4 Heliocentric dist. (AU)

Outgassing / elephants per furlong HAC APREF2 A6 A5 Outgassing / elephants per furlong A4 A3 A2 A1 APREF1 LTP5 LTP4 August 2014 LTP7 TRAL LTP6 TRAL LTP5 TRAL LTP4 TRAL 1 1.5 2 2.5 3 3.5 4 Heliocentric dist. (AU)

HAC Snodgrass Outgassing / elephants per furlong LAC August 2015 1 1.5 2 2.5 3 3.5 4 Heliocentric dist. (AU)