Category Archives: Logistics

Goodbye, Alice

This afternoon I gave my (fairly limited) input to the NASA board investigating our launch mishap.  Fulfilling that last responsibility brings my balloon campaign here in Alice Springs to a close.  Tomorrow I start my long-awaited journey home!

Obviously this was not the outcome I–we–were working so hard towards.  Nevertheless, I believe the NCT team has reason to be very proud of our efforts.  It was a huge challenge to turn around and fly again on a new continent less than a year after our New Mexico campaign.  Ingenuity, perseverance, and effective teamwork were all crucial in overcoming the obstacles we encountered.  On the way, we had help from many people who proved uniformly capable, friendly, and supportive.  The instrument we rolled out to the launch pad two weeks ago was fully prepared to do excellent science.

I am saddened, though, by the reach of the media coverage of our launch failure.  Videos of accidents have a huge visceral impact, so these images will be more viewed and remembered than those from the many successful launches CSBF conducts in the USA, Sweden, Australia, and Antarctica each year.  The impression created–that NASA ballooning is unsafe or wasteful–could not be more false.  For many types of astronomy, stratospheric balloons provide the lowest-cost, most efficient access to space, costing ten or a hundred times less than satellites which can take a decade longer to prepare.  Balloon scientists build affordable telescopes which do cutting-edge science, enriching our understanding of the universe we live in.  The CSBF personnel perform inherently challenging balloon launches with extraordinary capability, exquisite professionalism, and remarkable good humor.

I started this blog two years ago as a way to share what I was learning about stratospheric ballooning with my friends and family.  After the roller coaster of emotions these campaigns have brought, I continue to be convinced of the compelling story presented by this remarkable scientific enterprise.  It has been a privilege to share its drama, excitement, and culture with a broader audience.

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Flight Ready and Waiting

Today we had our formal flight readiness meeting with CSBF–the last stage in the process prior to the flight itself.  The meeting finalizes flight requirements and ensures that everything is “go” for launch.  At this point, we are required to be (and are) prepared to launch whenever the opportunity arises.

That “when” is the major question which will haunt us in the days and weeks ahead.  The launch pad is finally drying out after last week’s rains, and there looks to be a one or maybe two day launch window this weekend for TIGRE.  Obviously, we’re all pulling for good weather for them–they’ve been waiting two weeks already!  There are no guarantees for any of us, though.

For us, sitting second in line, there is now time to catch our breath a bit.  We’re not allowed to make substantive changes to our payload at this point, but we’ll continue keeping a close eye on the health of the system.  Alan and I will continue taking calibration data.  We’ll finally spare some attention for analysis questions and projects that have been sorely neglected in the lengthy rush of packing, shipping, travel, assembly, testing, and qualification.  And heck, maybe we’ll sleep a bit, and read, and sightsee.

Come 3 p.m. each day, though, we’ll be at rapt attention in the CSBF trailer for the weather briefing.

Fit

The last few days have been so momentous that there hasn’t been a spare moment to post about it.  Now that leaves me the challenge of summarizing recent events!

With the total system coming nicely together, we set ourselves a goal of performing a compatibility test with CSBF by the end of the week.  Compatibility is the last major task before declaring flight readiness.  It involves hanging the balloon gondola from the launch vehicle and performing mechanical, electrical, and communications tests to ensure that all interfaces will work correctly on the flight line.  Given the science instrument’s reliance on CSBF equipment for commanding, telemetry, ballast, launch, and cutdown, it is a crucial test for ensuring a successful flight.

With that goal in mind, we set about checking off the final few little items on our checklist.  Wednesday morning we rolled outside early to gather a little bit more data from our aspect systems–our differential GPS, our precision magnetometer, and the magnetometer we use to point the gondola relative to the Earth’s magnetic field.  Unfortunately, just when we got lined up with our north-south reference, the venerable back tire on the gondola cart exploded!

Definitely the last campaign for this tire...

The CSBF mechanical crew volunteered to find a new wheel for us over lunch, but without the ability to maneuver the gondola, we had to postpone the pointing tests.  With that task tabled, we asked the CSBF electronics crew if they could mount the SIP, the electronics package which rides underneath our gondola and handles all of the communications.  Despite the extremely short notice, seemingly the entire CSBF crew appeared instantly at our gondola and set to installing the SIP and its many accessories.  Installing the SIP occupied most of the rest of Wednesday afternoon, but the task went smoothly and we confirmed that all the interfaces worked flawlessly.  One of the advantages of legacy hardware and flight code is that the bugs have been worked out many flights ago!

The electronics crew starts the SIP.

Wednesday afternoon and Thursday morning we spent on some thankless, tedious, but crucial jobs:  tightening all the jack screws on all of the cables not yet firmly connected.  While we are testing the system, we leave the cables plugged in through friction alone.  Sometimes this causes a cable to work lose and give buggy readings, but it’s far easier to determine that and plug it in again than it is to screw things in and out every time we need to make a small change.  Still, it leads to a Augean task at the end.  Many of the screws–particularly on the flight computer–are very difficult to access.  Others are bent, twisted, or nearly stripped.  We got everything fastened eventually, though, so the cables should remain secure for flight.

Two other small tasks proved time consuming.  We distributed small temperature sensors throughout the gondola, taking care to place them as on the previous flight.  We also installed the mylar solar shields which surround the instrument cradle and deflect the extremely bright visible sunlight at float.

With the SIP in place, yesterday afternoon we were ready to check the final balance of the gondola.  One more piece remained to be integrated, though:  the SIP cage.  This metal frame mounts under the gondola and helps protect the SIP from damage on landing.  On our last flight, though, we landed directly upright, and both the SIP cage and the SIP were crushed.  When our machinist at SSL rebuilt the SIP cage for this flight, he changed the mounting of the cage as well.  Before, it hung on brackets from the bars at the base of the gondola.  In an effort to strengthen the gondola and improve the cage’s strength on impact, the new version slides over pegs that stick out the bottom of the gondola frame.

I’ve been worrying about those pegs since I first laid eyes on them.  I knew if they bent, we wouldn’t be able to get the SIP cage on, and we’d have precious little chance of repairing the pegs.  We’ve taken great care to keep the pegs off the ground and out of trouble, and we’ve been successful.  The SIP cage itself has mostly been in storage, out of the way.

Yesterday, though, when we went to slide on the SIP cage, it didn’t fit.  The front two tubes were more than an inch out of alignment!  Whether due to the heat in the container or pressure in transit, at some point the cage had warped.  In an instant, we went from planning for compatibility the next day to being unsure if we’d need to rebuild the cage.  Despondent, we went home to sleep on our options.

This morning, we had some lengthy discussions with the CSBF mechanical crew.  The approach we converged on was to jack the cage arms outwards with a 4×4 and a hydraulic jack.  The original hope was to push the arms beyond our desired length and create a permanent bend, but we quickly found that the cage just sprung back to its original dimensions.  Instead, then, the CSBF crew cut a 2×4 to length and wedged it into the arms.

Setting up the jack.

Streeeetch...

After finishing some tests of the instrument electronics, after lunch we took a deep breath and tried to fit the SIP cage again.  We installed tapered tips on the pegs to help guide them in, applied plenty of grease, and then used the gondola weight to lower the gondola onto the cage.  Everything came together so smoothly it was hard to remember that there’d been any problems!  Elated, we finalized the placement of the ballast hoppers before taking the cage off.

It fits!

With the problem of the SIP cage solved, we’re now ready for compatibility.  Unfortunately, another problem looms: the weather.  There have been frequent thundershowers the last few days, and the ground outside the hangar is too wet to drive the crane.  Also, since there are more showers in the vicinity we’d run the risk of getting caught out in the rain.  So, we’ll hold off on compatibility until probably Monday.  It’s no great loss, as the airport is too wet for TIGRE to launch, either!  We’re all in a holding pattern, then.  We’ll use the time to catch our breath, perform calibrations with our recently-arrived sources, and finalize our observation planning.

Cranes live in lakes, right?

On interesting side effect of all this rain: we’re seeing the Todd River in flood a second time!

The Todd flooding through the Gap.

Several roads crossing the Todd were closed.

Dependencies

With our large project and small team, at any given time each of us has a to-do list longer than we can read in one sitting.  For the most part, we each choose tasks to work on based on mood or momentum.  In the last few days, though, I’ve been trying to determine which of our myriad of checkboxes is limiting our progress towards the distant but looming goal of flight readiness.

The two most immediate items on that prioritized path are finalizing the detector connections and installing the shields.  Our heavy bismuth germinate (BGO) shields surround the NCT detectors on the bottom and the sides, reducing background from the atmosphere.  Installing them is a risky and dicey procedure, though, so we want to make sure our detectors are behaving as they should and the connections are all good before we wall them off.  All this takes time, consultation, and reference to archival data.  We’re making progress, but it’s not as clear cut as determining that things turn on.

For their part, the shields turned on fine, but we found higher background rates than we expected.  With ground backgrounds poorly characterized and influenced by everything from the presence of smoke detectors to the composition of the hangar cement, sorting this issue out has been a headache.  So far, though, careful tests by Jane and Zach suggest the shields are working as they should.

Steve has been busy building an electronic isolator to report the cryostat temperature.  Alfred and Ming-Zhe are working on the test solar panels.  I’ve made a few minor changes to the flight software, and Alan continues to improve our ground support software.  Alan and I are also discussing our calibration plans–if and when the sources we need arrive!

Keeping it all straight is a task in itself, but we’re helped by great support from team members still at home.

Targets

This morning’s flight requirements meeting with CSBF was smooth.  Alice Springs looks like a great place to fly from–the size and emptiness of the continent allow for long flights before cities or the coast force a cutdown.  Unfortunately, we’re unlikely to be able to take full advantage of the space due to the timing of the campaign.  Our primary targets are up at night, when the balloon cools and drops lower in the atmosphere, making it harder to see.  After a couple of nights, we’ll exhaust our ballast and may not be high enough to continue productively.  We would (and hopefully someday will) get more data from a fall campaign.

This is probably a good point to revisit some projections I made after the last flight for the shape of this campaign.  We had planned for a long-duration, around the world flight departing from Alice Springs, but safety clearances restricted us to a conventional turnaround flight of 1-4 days.  As discussed above, the spring campaign makes a longer flight irrelevant anyway.

One simplification of the shorter flight is that we can power ourselves on batteries alone.  Since our solar panels were a source of major problems in the last flight, we feel a lot more comfortable.  We’ll fly a couple of small test panels to prepare for future flights, though; Alfred arrived today to start work on those.

Our New Mexico flight also featured pointing problems due to our rotor; after the flight, we tracked the problem down to a bubble under one of the strain gauges that measures the torque on the rotor.  Its irregular output kept the pointing feedback loop from working.  With a new gauge glued in, the rotor has been rock solid.

For me at least, the flight requirements meeting also was a reminder that our target readiness date–cued to the winds–is fast approaching.  We’ve got a lot of systems to check out and check off!  For the next few days our focus is on making sure the detectors are performing correctly; as more systems are added, making modifications becomes increasingly difficult.  We also started checking the large BGO shield pieces that help reduce background from outside the field of view.  Determining the dependencies for the tasks to be completed is challenging–maybe it’s time for a Gantt chart!

We Could Hardly Contain Ourselves

Today was by all accounts a red-letter day.  Most crucially, the container was delivered this morning!  We unfortunately missed seeing the side-loading trailer drop it off, but we were nonetheless very excited to see it sitting comfortably outside the hangar after its long journey.

You've come a long way, baby.

Even better, when we opened it up, our equipment looked no worse for the wear on initial inspection.  Many of the cable ties we’d used to secure some of the gondola parts had stretched or broken, but everything looked fine.  The CSBF crew did a masterfully smooth job forking our crates into the hangar, and suddenly we had lots of unpacking to do!

Unloading the gondola pallet.

Even the cradle crate came out smoothly.

Beginning to unpack.

About that time, I got a call from Steve and Jane, our engineers, who’d successfully made a 1.5 hour connection in Sydney and arrived in Alice Springs.  We got them checked in to our hotel and took them to lunch.  Then Alan picked up his rental car–greatly increasing our transportation flexibility!–and we all headed back to the hangar.

Australian phone numbers have confused all of us!

After the fourteen hour flight to Sydney, the tight connection, and the four hour flight to Alice Springs, I expected Steve and Jane to be tired, but they set to unpacking our crates with energy I had trouble matching!  By the end of the day, the form of our workspace was already taking shape.  Impressive work for one day!

Settling in.

Holding Pattern

Not much news or progress today.  Our 40′ container is in Alice Springs, but the side-lifting trailer needed to deliver it was out of town.  Hopefully tomorrow we’ll get it; then we’ll be able to begin work in earnest.  It was a beautiful, cool day today, though–our first without rain–and most of us managed to squeeze in a walk or a run.

Tonight we went to the grocery store to stock our kitchen for the weeks ahead.  That proved a bit of an adventure, with fruit prices per kilogram, sliced lunchmeat costing AU $60/kg (US $24/lb), and scarcely any familiar brands or products in sight.  (Even those which we recognized had renamed their products:  viz., Kellogg’s Frosties, Rice Bubbles, and Sultana Bran.)  Still, it was a pleasure to come home and realize we could grab a quick snack or an easy meal when we wanted.