CARA Telecon Minutes Date: July 9, 2001 Time: 1:00 PM Attendance: BU: T. Bania Cornell: CMU: J. Peterson FTS: R. Chamberlin Northwestern: R.I.T: S.A.O: W. Walsh, S. Kim South Pole: C. Martin, C. Kaminski, A. Baker Chicago: J. Carlstrom, A. Harper, N. Odalen, R. Landsberg, J. Bausch UCB: W. Holzapfel UCSB: J. Ruhl Approval of previous minutes: Agenda Items News from the Pole: Weather moderate. Tau 1.2 range with fluctuations of 1.6-1.8. AST/RO observing at 492 GHz as well as 806 and 809 GHz o f the galactic cloud and the Coal Sack. Viper - Problem with chopper secondary. Glue joint broken. Didn't have to take chopper off telescope to fix. M. Newcomb put repair parts on telescope last night. B. Holzapfel reported that he had spoken with M. Newcomb and that the chopper was repaired and starting to take data. -- HOORAY for Matt! Sodar working well. MAPO warm. Partial lunar eclipse. Helium report from A. Barker at Pole - 3900 liters on sight. 3000 liters in 3000 gallon dewar. Bottom 17% not accessible or approx. 1200 liters. Wondering if any way Pole can get to this helium. The bottom is not liquid but should be vapor and there is no way to use. We would need to re-liquefy and Pole does not have a way to handle this process. Question to Pole: What is Pole thinking about emptying out the tank to available storage dewars? Response: Intent of Pole is to empty at end of week when major fill is due. Approximately 1000 liters in other storage dewars. Some smaller storage dewars are not in use and will fill this weekend. Currently in use 1-500 liter, 1-250 liter and 3-100 liter. Should have close to 1500-2000 liters available in the smaller dewars once decanting has taken place: 2-500 liter, 2-250 liter and 3-100 liter. Pole will bring temperatures down with nitrogen and further cool with gas. Question to group: Should we continue to run FTS? Response from R. Chamberlain - all date is good and usable. Decision was to keep FTS running for now but to review after decanting of helium. C. Martin noted that the FTS uses 4 liters every 2 days. Hobart Conference: J. Peterson and T. Bania reported that good information was given on Dome C. There are regular traverses and air support with twin otters. The steel is up for the building that will house 16 individuals. The plan is to winterover in 2003. There are cranes, heavy equipment on sight. Each traverse can carry us to 150 tons. Traverse is less expense than a flight by an LC130. The 2meter IR telescope was not funded by the Australians; their proposal did not even survive the first round of cuts. J. Storey's group was told by the committee that the reason for the rejection is that the IR community in Australia is not that large and there was not enough in kind matching funds. We still need an IR Telescope in the Antarctic. Sight testing is preliminary at this point. Assertions are that Dome C must be better than Pole, but nothing on sight testing like we have a Pole. LC 130 runway is being prepared but US will need to be assured of conditions before US will land. Dome C is 10-15 years behind in ability to support CARA type experiments. J. Storey was happy with number of people representing US. CARA was a resource at the meeting instead of trying to tell them what to do. French, Italian and Australian all said that IR niche for Antarctica is large scale survey work. This is just what AARO is all about. Good thing for D. Peacock to hear at the meeting. There were money people from France, Italy but nothing from the Australians. Politically there is no selection process for science project impact on resources in place at Dome C. For example some CMB projects proposed and on the schedule are not adding to the body of knowledge in that field. Tipper data at Dome C during the summer shows Tau levels lower than Pole during their summer. Wind profiles show wind sheer very low. If we turn this information into "seeing" number then Dome C could be below 2 arc seconds. It would help if the Polar representative from France and Italy send formal request to Carl Erb to have AASTO moved to Dome C. Then action might be taken by US Polar Operations. It is 4 times as far to traverse to Pole then to Dome C. Planning meeting at Raytheon 7/11/01: A. Lane, J. Ruhl, R. Pernic and J. Carlstrom will be attending the meeting. Plans are to discuss the following: AASTO Covered walkway Population Summer Helium - AST/RO would like helium for base opening to run 250. Liters required at least one 250 liter dewar. Snowdrift around AST/RO is becoming problem. AST/RO is beginning to be a basement level instead of 1st floor. Also walkway by Viper is becoming a tunnel. Helium Planning for the future. J. Ruhl was asked by B. Stone to present our thoughts on long term helium needs and how to handle those needs. It was suggested that Raytheon begin procurement of a 4000 gallon dewar. This size dewar would help logistically and might help with the capacity if CARA was using more helium per day, but our needs are really in having a liquid helium supply through the winter and into opening of the station. Memo from A. Frances makes very optimistic assumptions, i.e. boil off is 10 liters per day. We haven't seen that low of a number yet. J. Ruhl believes that the first step in solving the liquid helium problem is to have a liquefier on station. A 4000-gallon dewar is difficult to fabricate within 1.6 years. The liquefier should have a shorter procurement lead-time and we should be able to make the 1.6-year time frame. Cost of liquefier ~$150k, cost of 4000 gallon dewar ~$300k. C. Kaminski reminded us that the cryo barn should be moved to the dark sector. The helium would be easier to move. It was noted that the long term plans for the station doesn't even have a move like this for the cryo barn. The new station plans currently show the cryo facility at the base. If it is decided to purchase a liquefier then a building will need to be constructed to keep the equipment warm. J. Ruhl reminded us that we need everyone to focus on what is required. CARA needs helium for the whole winter season and enough helium to support instruments during the early part of the summer. Concerns were raised on man power to operate the liquefier and power requirements if cryo barn including liquefier were moved to the dark sector. Therefore, J. Ruhl will focus on making the liquefier first priority and than we do not have to rush to secure the 4000 gallon dewar. Raytheon might push for the 4000 gallon dewar as logistically it is easier to take the 4000-gallon to New Zealand. The group concurred that CARA should promote that Raytheon go ahead with procurement of a liquefier, commit to building a facility to house the equipment and then procure the 4000 gallon dewar.