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Minutes of Meeting MEETING meeting date 9-12th March 2009 ref./réf. page/page 1 date de la réunion 18 meeting place ESA-ESTEC, ERASMUS Auditorium chairman Jason P Hatton (ESA HSF-US) lieu de la réunion présidant minute’s date 19th March 2009 participants See Attendee list dates de minute participants subject/objet Minutes of Meeting – Jules Verne copy/copie John Ellwood (ESA D/SRE) Multi-instrument aircraft campaign intermediate science results description/description action/action due date/date limite Monday 9th March 2009 Introduction from John Ellwood (ESA, ATV Project Manager): John Ellwood thanked the science team for their hardwork in performing the campaign. There had been a Long standing interest in doing observations of ATV reentry during ATV development, but initial assessments were not feasible. JV-MAC campaign proposed in late 2007 & succeeded in obtaining detail observations of the reentry Introduction from Tomasso Sgobba (ESA, Chairman of ATV Reentry Safety Panel): Proposed this workshop should be the start of a series of workshops to discuss reentry safety. Future missions may include HTV. Mike Steinkopf (ESA, ATV Mission Director for Reentry Operations). “ATV-CC Mission operations & MAC team interfaces during re-entry observation” See PDF presentation #1 Presented mission operations. Explained modification of post undocking mission to facilitate reentry observations during night which was a requirement of the JV-MAC mission. Also ISS observations (FIALKA) required phasing manoeuvres to put ATV under ISS at time of reentry. The result was a delay of 24 days from undock until reentry. Coordination of JV-MAC reentry observations with ATV-CC, required close cooperation to ensure mission success. This was done through an interface control document, with first trajectory data provide at R-27d, then updates at intervals until R-1day. Also inflight updates of trajectory information were provided by satellite phone to both aircraft. Communications tests identified some off nominal communications issues, but this resolved by retrying & troubleshooting in the case of the Gulfstream V Inmarsat phone. a ESTEC JV-MAC-MoM-9-12Mar2009-v5- Keplerlaan 1 - 2201 AZ Noordwijk - The Netherlands draft Tel. (31) 71 5656565 - Fax (31) 71 5656040 MEETING meeting date ref./réf. page/page 2 date de la réunion 18 Jason Hatton (ESA, JV-MAC coordinator on ESA side) “Jules Verne MAC observation campaign: overview of mission concept, planning & operations” See PDF presentation #2. The general concept of the mission was presented, including instrument package objectives, general organisation & a brief overview of the raw instrument data Q. from audience – how was ATV apparent attitude (eg. elevation / azimuth) data aquired = A. star field + GPS & astrometry of fragments position relative to star field. Jim Albers (SETI Institute, Aircraft flight planning) “ATV Reentry – Aircraft flight planning, execution & lessons learned”. See PDF presentation #3. Flight planning – presented general concept & planning. The aircaft needed to be turned to follow ATV. Effect of wind had to be incorporated into planning, to ensure aircraft pointing in the correct direction. For the Gulfstream V, the most critical parameter was timing of the turn, uncertainties in trajectory were of less concern. Conversely for the DC-8 the trajectory variation (long or short) would require the angle & duration of turn to be varied. Therefore, it was necessary to react in real time to any variations in trajectory. During mission the trajectory of the main fragment was longer than predicted, DC-8 tried to react but increased turn too late to adequately follow main body. Inflight a spreadsheet was used to update the reference points for the aircraft manoeuvres. Three waypoints were provided by satellite telephone which were then input into the spreadsheet. For the GV manoeuvre this was practiced during observation flight approx half hour prior to reentry. Exchange of trajectory data prior to mission practiced & verified. Actual flight paths presented. There was a significant cross wind (100kt) which resulted in some differences in position WRT original plan. This was compensated by flight crew, pointing of aircraft WRT ATV was correct. Actual initial points shifted, but pointing of aircraft was relatively insensitive to absolute position. Also some replanning in Tahiti, GV position moved back to provide better coverage by some instruments (aircraft positioned ~20km further back to permit Clay Center Observatory spectrograph to cover entire trajectory) Lessons learned: Generally went well, but some improvement possible. Good coordination with ATV-CC. First time aircraft turned during observations in a MAC mission, this generally worked well but some constraints particularly for DC-8. Better coordination needed between observers & flight planning early in process. Some aircraft pointing errors. Internal comms in GV good in cockpit, but difficult to get feedback from observers & GV cockpit. In DC-8 inputs from observers to crew through headset, but 1-2 people between observers & pilots which delays transfer of information. Peter Jenniskens (SETI Institute: JV-MAC Principle Investigator). “Overview of status of analysis & key results to date – ATV-1 Jules Verne MAC” See PDF presentation #4 Overview of status of analysis & key events. The overall timeline was presented which shows the key events. The main explosion resulted in a glowing cloud. The ATV intensity did not increase according to the theoretical light curve. No clear indication of tumbling in photometric data. A number of flares were observed prior to explosion. Brightening faster than predicted may be result of ablation processes. Slitless was spectroscopy used extensively, permitting direct imaging plus spectra. Visual example is DSLR slitless spectroscopy, the AlO & Sodium spectra are quite apparent on the image. A Series of flares & flashes seen preceeding the main explosion, the earliest flares had a very strong emission of magnesium. Later flares prior to main explosion released a lot of AlO. Main explosion at 13:36:19UT 29Sep2009. The Main explosion overexposed most instruments, but in INT instrument MEETING meeting date ref./réf. page/page 3 date de la réunion 18 recorded an unsaturateds reflection in window. After explosion a very strong signal was detected, which turns out to be Lithium this is part of one of the three main objects. Lead object visible after last main fragment break up has a strong line emission. Explosion cloud has a defined brightness Review of HDTV video’s by Peter Jenniskens & Jason Hatton The video’s from the Gulfstream V and DC-8 were show. The general features & events were explained & how data can be exploited. Antoine Bavandi (ESA, TEC; HDTV camera operator on DC-8) “Number of fragments for E-HDTV recording”. See PDF presentation #5 Fragments were counted from the Utah State HDTV recording. This was compared to the HDTV from NASA-Ames, Antoine’s / Mike Taylor’s camera & low light / intensitifed cameras. When Compared to low light camera images, this does not show significantly more bright fragments. Therefore, the HDTV record can be used for fragment counting, this is important for comparison to models. Estimate 400-500 fragments detected. Q. What is the minimum size of fragments that can be detected. This needs to be calculated based on size & surface area. Perhaps spectroscopy can be used to identify specific fragments (eg. batteries) as a reference to cross calibrate size. Fragment sizes were counted by hand. Hans Stenbaek-Nielsen (Univ. Alaska Fairbanks; HFRS instrument PI): “ATV Re-entry path by triangulation”. See PDF presentation #6 Triangulation of trajectory from tracking camera’s. Used data from the WATEC camera’s. GPS recordings provide position and time to within a few tens of meters. Look angles determined from background stars. Used software developed by Hans Nielsen, originally developed for chemical cloud tracking (Aurora / upper atmosphere research). Star fitting, reference to SAO catalogue includes spectra characteristics. Calibration for brightness. Images are relatively flat, except at edge of field of view. Distortion of field is not a significant problem for this analysis since field of view is quite small. Data available from both camera’s for a part of trajectory. Initial calculations done for each 10s on main fragment. Each image set presented & calculate triangulated trajectory. One challenge for two point observations is that the same fragment may look different (eg. different brightness) from the two different view points. This can make identification of individual fragments difficult. Text file of look angles available. Accuracy calculations: Pixel resolution gives 100-600m resolution at distance of ATV. GPS accuracy approx 100m. This also defines how many individual fragments can be seen in tracking camera’s. Star field astrometry is a few pixels (eg. limited by refraction effects). The ATV is moving at ~8km/s. Therefore each frame = 250m along track uncertainty (however comparison with high frame rate imagers would allow more accurate along track determination). Refraction is important for negative elevation angles, where stars are not readily visible. Calculated this effect & effect is to shift altitude by ~1km. For brightness estimates most data is saturated. However, this is not a significant problem, since the brightness of the object is expected to follow a Gausian profile, so it may be possible to use this on the ATV data. Software used for this analysis can in principle
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