The DR (Design Review) meeting for FOXSI happened today at the Wallops Flight Facility. Everything went smoothly though a few action items were noted. Some bullet points from my notes follow (revised 10/19/2009 to include suggestions by L. Glesener):
- During the launch (i.e. with the motors firing), we can expect short (millisecond) drop-outs in power. We should consider (and test) how these power drop-outs will affect us.
- It was noted that a previous experiment had a problem with saturation which paralyzed their experiment. We should add such a test to our procedures.
- The exact location of the cooling system which will hang on the rail, preferably as close to the payload as possible, has not yet been resolved. Ted Nelson(?) may be able to help out with this problem or someone could travel to White Sands prior to launch to figure this out on site
- For range safety, a complete procedure needs to be written up about the FOXSI alignment process (using the x-ray tube) and sent to Wallops. All lasers (even those whose power output is less than 5 milliwatts) need to be declared through some forms provided by Wallops. Also, all radioactive sources need also be declared. Forms can be gotten from T. Gass.
- A stand (which can be leveled) to hold the the FOXSI payload can be provided by Wallops. It would be useful to get some photos of it.
- Connectors and cabling for the shutter door and SPARCS will be delivered to SSL for harnessing.
- The shutter door may also be delivered to SSL.
- The SPARCS system has never been pre-programmed for multiple targets in the past. Command uplink is the usual method which means that we will always have a choice to go to the next target or not. The exact sequence need to be discussed in light of the minimum mission success criteria.
- A accelerometer will be provided by Wallops during the vib test and can be placed anywhere. Paul suggested it be placed on the free end of the metering tube.
- It was noted that the range requires clearance to allow the rocket to transmit. Since clearance is not always possible, a direct wired connection to the formatter output would be useful.
- SPARCS takes about 4 seconds to move from one target to another. Also, SPARCS need to be within 20 arcminutes (1200 arcseconds) of Sun center to be able to do its job. The pointing alignment is most sensitive to the LISS alignment to instrument.
- There are currently 8 other experiment flights ahead of FOXSI.
- As of today a rocket has been committed for the FOXSI flight but manufacturing is behind therefore there is no actual rocket available.
- There is some contention at Wallops about not having solar missions meet first at Wallops to ensure that the mission is ready before sending everyone to White Sands. Until further notice, the plan is still to go straight to White Sands for mission readiness review.
- Need a new uplink command to enable the shutters (one time event).
- White Sands will not schedule the launch date until I&T is finished. If I&T occurs/completes on schedule, then we can expect the launch plan to be within a week or two of the currently estimated date.
Some more notes (added 10/19/2009)
Steven Christe [1], S. Krucker [1], L. Glesener [1], B. Ramsey [2], T. Takahashi [3]
1 Space Sciences Lab, U.C. Berkeley
2 NASA/M.S.F.C., Huntsville
3 Astro-H team, Japan
Presented at SPIE 2009 (link)
Abstract
The Focusing Optics X-ray Solar Imager (FOXSI) is a NASA sounding rocket payload scheduled to fly in late 2010 to observe hard X-ray emission (HXR) from the quiet Sun. To date, the most sensitive HXR images are made using a rotating modulating collimator aboard the Reuven Ramaty High Energy Spectroscopic Imager satellite (RHESSI). However, the rotating modulation technique is intrinsically limited in sensitivity and dynamic range. FOXSI uses nested-shell, grazing-angle optics and silicon strip detectors to achieve an angular resolution of 12 arcsecs (FWHM) and ~1 keV energy resolution. FOXSI will be a pathfinder for future solar HXR observatories.
The FOXSI SPIE proceedings manuscript has just been submitted! Now FOXSI is finally part of the official record and not just a proposal!
We are finally back from the Stray light facility at the MSFC after completely some tests though not the ones we were expecting. After testing the single-shelled FOXSI module, it was clear that something was wrong. The laser alignment seemed to suggest that something was off with the shell. We were unable to get the laser down to a nice clean spot. The subsequent x-ray tests confirmed this. The focus was not a spot but always a ring. We tried to focus by searching in the z direction but hit up against the end of the z stage. The z stage was centered when we closed the bell jar so alignment was probably not the problem. Also, the image was not a perfect ring but had a large asymmetry which was suggested to be caused by a problem with one of the spider grooves. Since the spider had not been cleaned, it is possible that a small piece of metal was stuck in the grove with the shell pushing it out of true. This theory does not explain why we were not able to focus down to a point.
After this poor showing by the FOXSI module, we put in a single FOXSI shell. This shell was mounted at the center in a a plate with a circular cutout. The shell was dropped into the hole and four spots of epoxy hold it in place (the usual method is to have the shell float in the circular opening and apply epoxy all around the opening). This shell gave much better results. Analyzed images coming soon…
After some delays, we finally have a single-shelled foxsi module and are setting up for some testing at the Stray Light Facility at the Marshall Space Flight Facility. Unfortunately the scheduled vibration test has been canceled for this week.
The foxsi module in the bell housing waiting for an optical laser alignment.
The resolution (keV) of the FOXSI DSSD as a function of temperature
Here is a summary of our last telecon as well as an update about the optics from Brian Ramsey.
-] Ishikawa-san will be visiting SSL/Berkeley next week starting on Monday for the week. An ASIC and interface board will be delivered to SSL and design and testing will begin.
-] A meeting between the Berkeley FOXSI team and Takahashi-san and Tajima-san is organized for the afternoon of Sept 15th at Stanford in order to further discuss detector work.
-] A summary of the FOXSI MIC meeting at Wallops was presented. We’ve found that the FOXSI payload is a fairly simple payload compared to most and there should be little to no problems accommodating our needs. A pdf of the FOXSI MIC presentation is online.
Some concern about the optics versus launch vibrations was expressed by the Wallops team. Testing of the optics is therefore advisable. Vibration loads specifications will be sent to us by the Wallops team. It was also found out that the weight of the optics may not be an issue due to the dynamics of the rocket. It may be best to maintain their current weight though reducing the weight is certainly necessary for a future space-based mission so this problem should not be forgotten.
The Wallops rocket team will now work with us to prepare a rocket plan which will be presented through telecon in about 45 days (around Sept. 29th).
-] We’ve created a google calendar to keep track of the FOXSI schedule. Here is an html link to access it in a browser. To import it into your favorite calendar program use the following links, ICAL or OTHER.
The next FOXSI telecon will take place in about a month. We will send out an email to schedule it.
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An update on the optics from Brian Ramsey:
We are waiting for completion of the mandrel blanks. They are coming back here from a local machine shop for a special stress-relieving heat treatment then go back for a final cut. After that we send them out to another shop in central Alabama for an electroless nickel coating, then back here for diamond turning. All the fixturing for the diamond turning machine is being made at the same time. We had a design review on this fixturing a week ago and the models show us that we shouldn’t have a sag problem which could lead to vibrations in the turned part. We’ve also done some more tests on the machine to check that the head and tail stock are perfectly aligned (we don’t normally turn long, thin parts —- the HERO ones were all ground as they only had straight cone figures — so we had to configure a tail stock specifically for the FOXSI parts). So,this all looks good. Our prescription modeling is nearly finished. Ron has been constructing a global optimization for all 7 shells. He said he will have the data for us next week.
The meeting went well! Our powerpoint presentation can be found here. I’ve also put some pictures online.
Here is a summary of our last telecon.
-] The SSL FOXSI team and the Nihon FOXSI team will meet at SLAC the week of the Sept. 15th. Old ASIC boards (as well as detectors?) will be delivered for testing with SSLs prototype FPGA. Interface will remain the same between old and new ASIC.
-] Drawings for optics mandrels have been completed. Modeling of polynomial prescription for optics is ongoing. Results should be sent out soon. Final mandrel prescription must be decided on end of August.
-] Test of new optics alignment system will take place in early september.
-] The next telecon will take place on 18th of August (19th Japan time).
Here is a summary of items which were discussed in this meeting.
1] Terada-san (Yukikatsu) was designated as the main FOXSI-Japan contact (terada at phy.saitama-u.ac.jp).
2] Tajima-san, Hiro (htajima at slac.stanford.edu) & Watanabe-san, Shin (watanabe at astro.isas.jaxa.jp) were designated as the main DSSD ASIC contacts.
3] The project schedule needs to be updated to include a more detailed description of the detector development including but not limited to trips to Berkeley (July or August?) and Japan (???), and final ASIC delivery (Jan 2008?).
4] Descriptions of all available detectors (Si & CdTl) including but not limited to pitch sizes, thickness, energy resolution, number of pixels, power requirements, and test results were requested by the Berkeley team.
5] Preliminary ASIC output specifications were also requested by the Berkeley team so that initial FPGA programming can begin as soon as possible.
6] A Mission Initiation Conference (MIC) has been organized with the NASA Sounding Rocket Team in Wallops, Virginia, on August 15th. The Berkeley team and MSFC team will be attending.
7] FOXSI conference calls will occur approximately once a month (more if needed). Details for the next conference call will be sent out soon.
