We proposed to carry out Antarctic long-duration balloon flights to extend the JACEE database on primary cosmic ray spectra and composition toward the "knee" at 10**15 eV. Our proposal had originally specified that two flights would be attempted in successive seasons ('93-'94 and '94-'95), followed by a third year of analysis effort. Following approval of funding, we opened subcontracts for our collaborators, J. C. Gregory and Y. Takahashi at the University of Alabama in Huntsville (UAH) and M. Cherry and J. P. Wefel at Louisiana State University (LSU), and began preparations to carry out this program.
In 1993, we took advantage of an opportunity to fly two payloads instead of one. Both were flown from Williams Field during the 1993-94 Antarctic summer season. Each payload consisted of 6 emulsion chamber detector modules, each module with sensitive volume approximately 40x50x18 cm3 and mass approximately 110 kg. The total of 12 chambers represented three times the volume of detector material ever flown before by JACEE in one operation. With the aid of Antarctic Support Associates (ASA) and NSF personnel, all our equipment arrived on the ice on time and in good condition, along with our field team of 4 scientists.
The first flight, JACEE-11, went perfectly until recovery was attempted after one circumnavigation, taking about 210 hrs. The NSBF termination equipment failed, and when the balloon was finally brought down it had drifted out over open water and the payload was lost. The location was recorded for future recovery attempts (see below).
The second flight (JACEE-12) was a complete success, also logging about 210 hrs at float altitudes above 5 mbar. The emulsion chambers were handled with great efficiency by NSF and Navy personnel, and were returned to CONUS promptly and in good condition. Processing of x-ray films and some preliminary mapping of cascades was performed here at the University of Washington. The emulsion plates were processed at NASA/Marshall Space Flight Center by MSFC and University of Alabama personnel. Additional event mapping was also done in Huntsville. Results were excellent, and data acquisition is proceeding well. A list of events identified so far and under analysis is appended. We expect to have preliminary results from this flight available at the time of the International Cosmic Ray Conference this summer (8/95) in Rome.
Following discussions with NSF, ASA and NSBF, it became clear that one of the other groups scheduled for the 1994 season would not be ready in time for integration and deployment. Therefore we made preparations to take advantage of this opportunity to replace the lost payload. We rebuilt a balloon gondola, and prepared a data logger package identical to the lost equipment, and our colleagues in Japan succeeded in funding and preparing the large amount of photographic material required on very short notice. With a June 1 go/no-go decision date, we successfully met an August 3 Mission Readiness Review date. The rebuilt gondola and associated equipment were shipped by sea with the NSBF container in August.
Our emulsion chamber assembly went on schedule despite some last minute concerns about the emulsion plates. The emulsion manufacturer, Fuji Film Corp., also treats acrylic base plates supplied by our group with a proprietary undercoat which allows adhesion of the emulsion layers. This process apparently suffered some quality control problems which we luckily were able to identify via test procedures before committing our emulsion supply. We obtained a useful set of base plates just in time for emulsion chamber preparation. Although the base plates used do not provide perfect adhesion with normal processing, members of our group working with Fuji scientists developed a processing procedure which repairs the problem in test cases.
The completed emulsion chambers were shipped by air via Port Hueneme in mid-November, arriving on the ice in plenty of time for the arrival of our 3-person field team in early December. The field team consisted of J. C. Gregory (UA/Huntsville PI, and team leader), B. Nilsen of LSU, and E. Zager of UW. They were joined later by E. Roberts of MSFC. Dr. Nilsen departed at the end of December, 1994. Dr. Gregory and Mr. Zager remained on site until after recovery, and Ms Roberts took care of preparing the recovered equipment for retro shipment.
JACEE-13 was launched on 22 December 1994 and cut down over Victoria Land on 4 January 1995 after 304 hours at float altitude. Local conditions prevented immediate recovery. The ice surface at the landing site prevented the use of fixed-wing aircraft, so Navy helicopter pilots arranged a 2-stage recovery sortie using a fuel cache. Thanks to heroic work in difficult conditions by the pilots and NSBF field team leader Steven Peterzen, all equipment except the gondola frame was recovered in apparent good order. The latter was designed to be expendable in difficult recovery conditions. Attached are plots of the balloon path, pressure altitude, and chamber temperature, recovered from NSBF logs and our own onboard data logger.
At the present time, Prof. Y. Takahashi from UA/Huntsville is on his way to McMurdo to join the R/V Palmer for an expedition to search for and if possible recover the JACEE-11 payload from the bottom of the Ross Sea. The JACEE-13 emulsion chambers are in transit between Pt. Hueneme and Huntsville where they will be disassembled and processed as before. We would like to make special mention of the efficient assistance provided by Mr. Lee DeGalen and his group at Pt. Hueneme, in providing special handling for our time-sensitive emulsion chambers.
Here at UW, we developed an easily-used World Wide Web directory (http://marge.phys.washington.edu/jacee/jacee-13/) which would simplify access to non-numerical as well as numerical data files. This Web directory was successfully used as an open information source during the recent JACEE-13 Antarctic flight campaign. The Web home page directs users to a variety of public information, including a log of email messages describing progress from the JACEE field team in Antarctica, a continuously updated press release describing the project and its status, and a map showing the path of the balloon flight (also updated approximately daily). In addition, the Web page provided access to a set of photographs of the field team and equipment taken on site in Antarctica using an electronic camera, converted to JPEG files and immediately placed on the Web. Our logs show heavy use of this facility, not only by JACEE collaborators checking on progress (including frequent accesses from Japan), but also other members of the scientific community, journalists and agency officials. Following the flight, we were contacted by the editor of an amateur ballooning enthusiasts' magazine, who had prepared an article on the JACEE-13 flight (including photographs) entirely from information downloaded from our Web pages. This demonstrates an extremely valuable route for letting the public know about NSF programs related to their personal interests.
The community relations aspects of the Web pages are useful but less important than their application as tools for simplifying the use of ftp utilities to access our database. Our intention is to establish a secure sub-Web with password access, permitting us to post and exchange preliminary data and draft documents with collaborators, while blocking access by the general Internet public.
Grant funds were used to support a graduate student, Eric Zager, and an undergraduate student helper, Camron Hastings, who assisted with scanning, processing of films, and payload preparation.
We wish to express our gratitude to all NSF, ASA and NSBF personnel who made this project possible.
Although we have thus far prepared three complete payloads, we are in fact only on track according to our original proposal, with one successful flight in 1993-94 and another in '94-'95. The additional time and resources required for preparation of the JACEE-13 payload of course delayed progress on analysis of JACEE- 12 data. We intended to devote the coming year to completing as much analysis of both payloads as possible. However, it appears that once again we may have an opportunity to replace another project in the flight schedule. Since our data are not volatile, and the opportunities for Antarctic LDBF may be limited in the future due to higher demand from other groups as well as possible reductions of funding from NASA, we think it prudent to at least keep this possibility open, and have notified NASA that we are willing to prepare a payload should we receive firm notification of a scheduled flight opening by 1 June 1995. That is the date by which our Japanese collaborators would have to make a non-refundable purchase of photographic materials in order to meet logistics deadlines. This is the same basis on which we proceeded last year. At the present time it is not certain the Japanese groups can secure the necessary funds, but they are pursuing this energetically.
We expect to prepare two papers on our Antarctic LDBF for the upcoming International Cosmic Ray Conference, one describing the payload equipment and techniques used, and the other presenting results from our 1990 test flight, JACEE-10. The overall JACEE database will be updated with all available events and a summary of results from JACEE-1 through JACEE-12 will be presented in a separate paper.
We wish to formally request renewal of our grant at the level planned so that we can continue analysis of JACEE-12 and -13, and possible preparations for our next Antarctic balloon flight.
