Chandra X-ray Observatory Report Mar 09, 2012 ---------------------------------------------- During the last week the observing schedule was interrupted by a high-radiation event that activated the science instrument safing sequence (SCS 107) and stopped observing at 00:29am EST on Mar 7. All spacecraft actions were nominal. Real-time procedures were executed on Mar 7 to disable SCS-29, which was enabled during the safing sequence, and to update the observation identifier number, to aid CXCDS processing of the interrupted observation. Observations that were impacted will be rescheduled. Mar 07, 2012 Telecom Summary ---------------------------- SCS-107 executed nominally due high HRC antico shield rates at 067:05:29:47z. The radiation environment is still showing increasing rates. The CME related to the day 067 X5 flare is not expected to arrive until about the time we would nominally begin observing on the next orbit. An optimistic science resumption plan will begin using the 068:1835-1935z pass as an uplink opportunity, with a check of HRC rates and Go/No-Go call. Load products will be developed for this during the day with a review expected later today. A CAP will be run to change the ObsID later today to aid CXCDS processing. Mar 08, 2012 Telecom Summary ---------------------------- The particle flux levels remain high and are predicted to remain elevated for ~10 more hours. As a result plan "A" for science resumption (the MAR0812 products) is a No-Go Plan B for resumption is to target a uplink for the 070:0000-0100z comm pass (7pm EST Fri). The schedule will require re-arrangement in order to include the M31 observation (ObsID 13280). Mar 09, 2012 Telecom Summary ----------------------------- The hard proton environment is still elevated. There was an M6 X-ray flare at 03:00z and an associated full-halo CME. It is uncertain whether the MAR1012 science resumption will be able to proceed. Review of the MAR1012 products will go forward so that we can use them if conditions permit. A Go/No-Go telecon will be held at 7pm EST on 111159# to decide on using MAR1012. A version of CAP 1189 will be used to check the HRC antico shield rates if the environment seems settled enough to proceed with MAR1012. If the radiation environment hasn't settled enough to proceed with the MAR1012 products, the remaining vehicle segment of the MAR0512 schedule will be activated and a plan C developed that will target a science-mission resumption with the ascending CTI at rad-zone exit on day 071. Mar 09, 2012 afternoon Telecom Summary -------------------------------------- The radiation environment is too elevated to resume the observing schedule at the current pass. The GOES proxy for the HRC antico shield rate and the E1300 rate are ~5x and ~3.5x their safing thresholds respectively. The MAR1012A products have been approved for Vehicle-load only use and the first segment will be uplinked as a "maneuver-only" load. The MAR1012 is preferred over continuing with MAR0512 for the thermal profile. A "plan-C" set of products, MAR1112 will be released this evening with a targeted review time of 12:00 or 13:00 EST tomorrow. These would be uplinked at the 071:0345-0445z pass tomorrow pending the outcome of the Go/No-Go telecon. Chandra is in the rad-zone during this comm so proxies will be used to judge the radiation environment. Mar 10, 2012 Telecom Summary ----------------------------- Assessment of the radiation environment: given the GOES HRC antico shield proxy rate at ~1.5x threshold at the time of the telecon and its slow rate of decline it was deemed likely that SCS-107 would be triggered shortly after RadMon enable at rad-zone exit. It was decided not to proceed with the MAR1112A replan products. Effects from a CME associated with the M6 flare of Mar 9 are still anticipated. We will stand down on working replans until an assessment of the radiation environment at the 9am Tag-up on Monday. The hope is that we will be able to uplink a resumption plan Monday evening/night. The second vehicle segment of the MAR1012A products will be used as maneuver-only loads. Mar 12, 2012 Telecom Summary ---------------------------- The high-energy particle fluxes (as measured by GOES) and EPHIN E1300 rate are low enough to restart observing but the low-energy proton flux (as measured by ACE) is too high due to s shock that is just passing. With the CME passing the ACE rate is expected to drop. We will target a restart for the 073:0355-0455z pass. This will have a few hours for observing before rad-zone entry (RadMon disable ~072:12:42z). The will be a Go/No-Go telecon at 11:30pm EDT on 111159# for the observing resumption. ACIS plans to execute a CAP for a long CTI measurement at the 072:2020-2120z pass. This would be preceded by a CAP to check the HRC antico shield rates.