Travel Resumes!

Today the NSF announced four days without new COVID cases, so Antarctic travel resumes tomorrow!

The SPIDER and SPT crews here in Christchurch are on the manifest for the first flight. We head to the airport first thing tomorrow, and with luck we’ll be in McMurdo tomorrow night. That said, there’s always the possibility of a flight delay or cancellation, or of a “boomerang” flight that returns to Christchurch due to weather. So we keep our bags packed and our fingers crossed!

Update 19Nov: 48 hour flight delay… sigh…

Update 20Nov: Shuttle pickup at 4:45am tomorrow to make another try for the ice!

Some Highlights Around Christchurch

I write this at the end of Day 12 of our long stay in Christchurch, New Zealand. Almost every day begins with at least a few hours of work from one of the local coffee shops (generally C1 Espresso, which has great coffee / food / WiFi). There is plenty to do, both for projects back home and to help the ice team where we can, though location and time zone make many of these things awkward. Some days that basically fills the day until dinner, but other days we get out and about. There are worse places to be stuck than New Zealand in the spring!

A few highlights below…

Botanic Gardens

Truly gorgeous to stroll around: trees, flowers, greenhouses, an amazing rose garden, and more. We’ve visited this three times so far, seeing different bits each time.

Taylor’s Mistake

We took the bus to the trail head for the Taylor’s Mistake Walk. After a hike through the hills overlooking a beautiful bay and a climb over some mussel-covered rocks, we came out on a lovely black sand beach. We hung out on the beach a while and got our feet wet in the South Pacific before hiking back.

Willowbank Wildlife Reserve

Willowbank Wildlife Reserve is a nice little wildlife refuge / zoo / petting zoo, another short bus ride from downtown. We saw keas (native parrots), kiwis (scuttling around us as we walked through a large darkened enclosure), tuataras (lizard-like reptiles), otters, pigs, capybaras, aggressive families of geese, and more.

Hiking Arthur’s Pass

On Monday Nov. 14th (Sunday in the U.S.) the team rented a car for a day trip to Arthur’s Pass National Park, a couple of hours from Christchurch. Our main hike was Temple Basin, which gains about 1600 feet climbing up into the mountains. The climb was tough on my 42-year-old knees, and the last part had a difficult scrabble with poor footing, but the views from the top were incredible.

We also took a shorter stroll to Bridal Veil falls, which were beautiful


We visited the Canterbury Museum; among other things, this had a remarkable exhibit on Antarctic exploration and history. We also visited the Christchurch Art Gallery, a modern art museum. Both nice, and both free!

Escape Room

The team did a fun escape room themed on an art heist. Came reasonably close to the time record.

Pub Trivia

I have now played Tuesday night trivia at Dux twice, as part of a team with the SPT folks. Both times we came in second (earning us drink vouchers for next time!), and had a blast. A highlight of the second night was the tie breaker question to decide 2nd/3rd: How many times does the word “blood” appear in Shakespeare’s Macbeth? Closest guess wins. It turns out that 42 (the ultimate answer to life, the universe, and everything) was an astonishingly good guess!


We’ve had good meals throughout. As a seafood lover, I want to particularly highlight the humongous oysters we had at a Japanese restaurant, and the green New Zealand mussels Riccardo and I shared before pub trivia – both delicious.

Welcome to the Hotel California Christchurch

I’m writing this from a hotel room in Christchurch, New Zealand, on November 12th – 5 days after my scheduled flight to Antarctica. We’re in a bit of a holding pattern here, as I’ll explain, but I’m hopeful of catching a ride down to join my colleagues in the near future.

The U.S. Antarctic Program

I am traveling under the auspices of the United States Antarctic Program (USAP), managed through the National Science Foundation (NSF). No nation has a sovereign claim on Antarctica. The continent is managed cooperatively by the nations of the world under the Antarctic Treaty, exclusively for peaceful purposes. In many ways, scientific research is the primary activity on Antarctica. In practice, we scientists are only a small fraction of the total population (which can reach 1000 people in McMurdo Station during the summer season). The logistical operations that support human presence in Antarctica are truly massive, and that work is carried out by countless contractors and tradespeople. Nothing we do exists without their hard work.

From Champaign to New Zealand

Travel to Antartica is a lengthy process. First we travel by commercial carrier to our gateway city: Christchurch, on the south island of New Zealand. In my case this took about 29 hours, and looked like:

  • Bus from Champaign to Chicago O’Hare airport
  • Fly O’Hare to Houston
  • Fly Houston to Auckland (15 hours in a middle seat, but at least it was a bulkhead…)
  • Fly Auckland to Christchurch

Once in New Zealand, we all get assigned hotels to stay in. Mine was not walkable to the town center, but it was straightforward to Uber back and forth each day to be able to walk around and see people.

Clothing Issue

The next day we head to the Antarctic departure terminal for clothing distribution, where we attend safety briefings and get issued our Extreme Cold Weather (ECW) gear. We are given a hefty bag full of gear that will keep us warm in even the most extreme environments. In fact, some of it is too warm for our practical needs in McMurdo in the summer: the famous Big Red parka is fantastic for cold days, for example, but most days I expect to wear Little Red (an insulated windbreaker) and sweaters.

Photo from ECW issue: Big Red parka, hat, neck gaiter, insulated gloves, wind pants, white bunny boots (cut off in photo, but similar pair visible in background). (Photo by Riccardo Gualtieri)

Change of Plans: The Pause

I was manifested for the next C-17 flight to McMurdo the following morning. During clothing issue, however, we started getting news from up north that something was going on with travel. The NSF soon announced a pause in all travel to the continent for two weeks, to address a substantial outbreak of COVID-19 among the station population. By later that afternoon we scientists knew that we wouldn’t be going down anytime soon – only a handful of medical personnel. I was hand-carrying some assorted bits for SPIDER, and fortunately I was able to hand them off to one of the station doctors who I met on the commercial flights south.

And so now we wait. The NSF is working through a difficult situation, working to balance critical operations, scientific research, and the health and safety of station personnel. Everyone is working hard to keep things going. In fact, I’m very happy to report that the SPIDER team on the ice is currently ahead of my straw-person schedule for the season! Those of us off-continent are keeping in close communication with the ice team to help where we can. As PI I’m the point-of-contact for our team’s logistics, and I’m happy to keep work like that off the ice team’s plate.

Christchurch is a nice town, and it’s a beautiful spring. I’m spending my days mostly with a number of colleagues from the South Pole Telescope (SPT), working in coffee shops and sharing meals and outings. I’m trying to help the ice team and keep on work back home as best I can, given the time zone difference. But it’s also a frustrating limbo, feeling like I’m on some kind of vacation when I have responsibilities at home and in Antarctica.

The Avon River meandering through downtown Christchurch
My office for the foreseeable future – C1 Coffee, Christchurch.

Southbound Again

It’s time for another trip to Antarctica, so it’s time to resume these posts (a little belatedly, since I’m already on my way). I expect they’ll be a little less detailed and frequent this time around (check out the prior posts for more detail!), but I still want to give a flavor of what we’re up to for family and friends. For more details and photos, you should take a look at postings by Elle Shaw, a Ph.D. student in my research group at Illinois; Dr. Steve Benton, a research scholar at Princeton; and on our team Twitter account.

Explaining the mission

SPIDER is a powerful instrument to observe the cosmic microwave background (CMB) – the afterglow of the hot early universe. Since light takes time to travel across the universe, when astronomers (and the rest of us!) look out into space we look back into time. We see our friends across the room as they were a few billionths of a second ago; the Sun as it was 8 minutes ago; night-sky stars as they were years or centuries ago; and galaxies as they were millions or billions of years ago. The CMB is the oldest light we can observe: the glow emitted back when the entire universe was an opaque, hot plasma – sort of like the surface of the Sun, but everywhere. The universe’s expansion has stretched the wavelength of this light from the visible and infrared down into the microwave regime, leaving a radio-wave (actually millimeter-wave) glow across the entire sky.

Our goal is to look at the faint polarization pattern of that glow, mapped across the sky. If we saw a particular sort of pattern in that polarization, called a “B-mode” (basically a curled, pinwheel pattern in how polarization changes across the sky), it would be a sign of the presence primordial gravitational waves: faint ripples in spacetime produced during the period of inflation that begins our cosmic narrative. Detecting such gravitational wave “noise” would give profound insight into the physics in operation at our universe’s very beginning.

This measurement is very difficult for two major reasons. The first is that the B-mode pattern (if present) is exceptionally faint, requiring enormously sensitive instruments. SPIDER and similar instruments use sensitive detectors called bolometers, cryogenically cooled to a fraction of a degree above absolute zero (the lowest possible temperature, at which all molecular motion would stop). These detectors are housed in cryogenically-cooled receivers, designed both to limit the thermal glow of the instrument themselves, and to avoid systematic effects that could confuse our measurements of the sky. The second is that we must look at the CMB through the glow of our own Galaxy. Emission from Galactic dust and synchrotron processes can mimic our signal, and must be somehow separated from our maps of the sky

This is where SPIDER-2, our current mission, comes in. SPIDER’s first flight in 2015 mapped the sky at two frequencies (“colors”): 95 GHz and 150 GHz. SPIDER’s second flight will add three new receivers to observe at 280 GHz. At this frequency Galactic dust glows much more brightly than it does at 95 or 150 GHz, and so by combining information from the three maps we can distinguish dust more effectively from primordial light. Unfortunately the Earth’s atmosphere is relatively opaque at this frequency, making such observations difficult from the ground. From a stratospheric balloon we can get a nearly-space-like pristine view of the cosmos, producing measurements that will have lasting value both to SPIDER and to the rest of the community (through informing Galactic dust models).

SPIDER’s three new 280 GHz receivers were built here at Illinois, by graduate and undergraduate members of my research group over the years. The basic telescope architecture is very similar to that we developed for the first flight, but with a variety of modifications to accommodate new 280 GHz detector arrays designed and built at NIST in Colorado. Receiver development and characterization has been a major task of my group over the past few years. We’re very proud of the results, and looking forward to getting them on the sky!

Ph.D. student Elle Shaw (left) and undergraduate Kaliroe Pappas (right) assembling a SPIDER-2 receiver in our lab.

An Unexpected Party

This trip has been long-awaited, and the lead up filled with twists and turns. SPIDER has been nominally ready for its second science flight since before the pandemic. Our 2019-20 deployment was postponed by a lack of space on the ice (due to payloads delayed from the prior season), while the 2020-21 and 2021-22 Antarctic ballooning seasons were canceled entirely by the COVID-19 pandemic. This delay has been very disappointing and difficult for the whole team. We had applied for renewed funding for 2021-24 (this time with me as nominal Principal Investigator) in hopes of one last chance, and we felt those hopes slipping away.

We began 2022 with a great deal of uncertainty that we would get to deploy this time either, due to the urgent deployment of a different mission of unusually high priority. When this mission waived off this spring, we were suddenly offered full funding and the chance to fly this season! This was an incredibly challenging prospect: SPIDER’s main cryostat had been effectively in mothballs for two years, and we needed to assemble a team and pack/ship many tons of cargo to Palestine, Texas in May for pre-flight deployment. This was frankly an incredibly stressful time for everyone, not least me – as new PI, I was dropped into a lot of high-stakes planning very fast! NASA was extremely supportive, our team came together, and we signed the papers and got everything where it need to be.

Our team had a successful campaign this summer at Columbia Scientific Balloon Facility (CSBF) in Palestine, Texas. This is a dry run for Antarctica: the whole payload comes out of shipping containers, we assemble and cool it down, certify it for flight operation, and pack it back up for shipment to the ice. All of this happened at breakneck pace due to the exceptionally early shipping deadlines imposed by pandemic-era shipping delays. Between unexpected child care issues and a bout of COVID, I joined for less of the campaign than I’d hoped. But the team performed exceptionally, the payload worked well, and everything headed to the ice on time. You can read more about it on Elle’s blog.

A view of the SPIDER payload in the high bay at CSBF in Texas.

The Campaign Begins

The fall has been spent on preparations for the ice: getting the team members physically-qualified (PQ – medical exams), final making sure that all of our cargo arrives on time, making arrangements for teaching coverage and family, and even buying long underwear and socks. Our first team arrived on the ice October 26th, including Elle. Another student of mine, Sho Gibbs, joined a couple of days later. Work in the Long Duration Balloon (LDB) high bay began ahead of schedule on October 29th, and all is well underway.

First arrivals on the ice! From left: Jared, Johanna, Simon, Suren, Joseph, Susan, and Elle.

My ice flight was eventually set for November 7th. The first team members arrived on the ice November 25thI shared Halloween with my kids, said goodbye to everyone, and headed to the airport on November 3rd. Southward!

Halloween 2022: Henry (age 7, chameleon) and Alyssa (age 10, ninja). I’ll miss you!


Today was the day we’ve been building up to for so many years: launch!   Today the telescope that so many of us have put so much time into was tied to a giant helium balloon and thrust into the stratosphere.  It was a day of incredibly high highs and low lows, and in a real sense the day is not over yet.  Before I take a nap, here is a bit about what it was like.

SPIDER had its pickup rehearsal on Tuesday and its hang test on Wednesday.  These were intensive events, both for our team and for the riggers and CSBF engineers who support Antarctic ballooning.  Late Wednesday we suddenly found ourselves in a spell of clear weather expected to last through most of Thursday, with a tired team and a less-than-full liquid helium tank.  After the hang test we hurried SPIDER back into the high bay and spent the afternoon and evening filling it to the brim with liquid helium and finishing last-minute taping jobs.  The riggers, engineers, and most of our team went back to get some shuteye before our first launch attempt, scheduled for 10 a.m. Thursday morning – New Year’s Day.

A launch attempt is an elaborate process that begins long before the target launch time.  Members of our team arrived early to prepare, some staying overnight, some taking shuttles to LDB at 1:30 and 3:00 a.m.  The riggers and CSBF team arrived in time to attach SPIDER to the Boss at 4:00 a.m.

I was part of the “late” shift – I slept fitfully, arrived at 7:30 a.m., and hoped to be fresh for launch and line-of-sight.  By the time I arrived, SPIDER was loaded on the Boss and pulled back from the deck.  Circa 8 a.m. SPIDER proceeded to the launch pad, followed by support vehicles carrying the flight train and helium gas.  The balloon did not go out at this stage: it can’t easily be put back into its box, so it’s only unfurled when it’s go time.

The Boss taking SPIDER out to the pad, with Mt. Erebus in the background.

The Boss taking SPIDER out to the pad, with Mt. Erebus in the background.

The spool, on its way to the pad.

The spool, on its way to the pad.

Two trucks filled with helium gas, heading to the pad.

Two trucks filled with helium gas, heading to the pad.

At least two scientists stayed on the Boss at all times pre-flight to check on the pump maintaining the vacuum on the superfluid tank.  Around 9 a.m. we were given a window for photos, so a bunch of us trooped out to the launch pad in hard hats to take a few last pictures of (and with) SPIDER.  Everything was happening quickly and according to plan, and we all dared to believe it would all come off easily on the first try…

Selfie with SPIDER, launch-ready on the pad.

Selfie with SPIDER, launch-ready on the pad.

Lorenzo and I, representing the Caltech detector team on the ice.

Lorenzo and I, representing the Caltech detector team on the ice. (photo by Steve Benton)

Hero shot with SPIDER

Hero shot with SPIDER (photo by Steve Benton)

The flight train (parachute and hang lines) laid out from the payload.  The balloon will attach to this end.

The flight train (parachute and hang lines) laid out from the payload. The balloon will attach to this end.

By late morning the winds had turned, and the launch conditions had become marginal at best.  So we waited. The weather didn’t look good for the coming couple of days, so we all hoped to be able to get off the ground.  Many times we were certain we were going to pack up and go home, until the wind gave us a glimmer of hope. It was agonizing.  So late in the season, with bad weather on the way, it wasn’t clear when (or if) there would be another good launch day.  Even if there was, every day of delay is very costly in additional liquid helium.  On a more personal note, I have a wife and daughter at home and will be moving to a new city soon after I return; every day of delay is hard on my family.  I spent much of the day pacing, inside and outside, as did many of my colleagues.

A bit after 3 p.m. our fortunes turned, and the NASA team decided that conditions were good.  There was jubilation in our high bay, and throughout LDB.  The balloon was laid out and attached to SPIDER.  Inflation began near 4 p.m.  We all gathered at the edge of the launch pad to watch, scarcely believing that we would be dangling years of work from the rapidly-growing gas bag upwind of the Boss.  In the final moments our project leader, Bill Jones, stood on a lift to remove the final piece of pump plumbing and close up the corresponding door in the sun shield.

SPIDER and its balloon, ready to launch!

SPIDER and its balloon, ready to launch!

The balloon, with cloud-capped Erebus.

The balloon, with cloud-capped Erebus.

Launch came at 4:59:38 p.m. McMurdo time (NZDT).  The balloon was released and swung up over the gondola.  The Boss danced back and forth a bit to align SPIDER under the balloon, then released it to fly free.  The release made a loud sound which struck fear into the hearts of those who built the gondola, but SPIDER was no worse for wear.  We all jumped for joy and hugged one another.

I took a brief video of the launch with my iPhone, focusing on the balloon:  Jon Gudmundsson took a higher quality video focusing on the payload itself:



After a few moments of celebration, it was back to work.  The team needed to check the functionality of all of SPIDER’s systems, tune up its gondola and pointing systems, and start understanding the data it was producing.  As of this writing, all of the major systems are working spectacularly.  The balloon is currently floating 120,000 feet above us, still clearly visible in the sky as it drifts lazily toward the horizon.

Working on SPIDER here in Antarctica has been an incredible experience.  It has taken me to one of the most amazing locations on earth to do something totally crazy, all in service of understanding the workings of the universe.  I couldn’t ask for a better team of people to work with, both down here and back at home.  Now it’s time to do some Science.

Farewell, SPIDER.  Enjoy space...

Farewell, SPIDER. Enjoy space…

Ready to Fly!

Today SPIDER completed its final pre-launch milestone: compatibility, commonly called the “hang test”.  This means that we are flight-ready for the next available launch date, which could be as soon as tomorrow (New Year’s Day 2015, our time).  Fingers crossed…

The hang test is both a rehearsal of launch operations and a test of all in-flight communications and control systems.  The completed payload was hung from the Boss (our launch vehicle, a highly-customized crane) and lifted off of our deck.  We had a pre-rehearsal test of that process yesterday, during which we ironed out a few procedure kinks (i.e. how to reach the top of the gondola to install the Boss hook!).  The CSBF team then installed a handful of launch parts on the undercarriage, notably the solar panels that power the NASA electronics package and the ballast hopper.  SPIDER uses a pump to maintain its superfluid helium tank on the ground (at float it is just open to space), so that pump needs to be carefully transferred to the deck of the Boss.  The Boss then carried SPIDER back from the deck as if to take it to the launch pad, held it there for a couple of hours while we checked telemetry, and then returned it to the deck.

Now it’s time to get this in the air and do some science…

Fully operational battle station

Fully operational battle station!

SPIDER hanging from the Boss, as it will during launch operations.

SPIDER hanging from the Boss, as it will during launch operations, with Mt. Erebus in the background.

SPIDER with the happy parents: Bill and Barth, PIs of our project!

The proud parents: Bill and Barth, PIs of our project.


This morning saw the second LDB launch of the season!  The payload, COSI, is a gamma ray telescope built by Steve Boggs’s team at Berkeley and collaborators.  COSI uses an array of cooled germanium detectors to measure the energy and direction of incoming gamma rays from space, based upon the way they Compton scatter among the detectors.

The balloon also generated a large amount of interest, since COSI is the first science payload for NASA’s new super-pressure balloon (SPB).  SPBs, also known as Ultra-Long Duration Balloons (ULBDs) are designed to stay aloft for hundreds of days, rather than the dozens achieved with current heavy-lift balloons.  Unlike most payloads, which spiral around the Pole and land in Antarctica, COSI/SPB hopes to leave the continent entirely and fly for months across the ocean.  COSI hopes to be recovered in Chile or Africa, but should get plenty of useful data back over telemetry even if it is lost in the ocean.  ULDB flights are hugely anticipated in the astronomical community, because they will enable extremely long mid-latitude flights – a real competitor to a satellite for certain applications (and much, much cheaper!).

I was lucky enough to be on-station to witness this one in person (which involved coming in on a 3:30 a.m. shuttle before they closed the road…).  During launch prep a thick fog rolled in, such that we couldn’t even see the Boss from the edge of the pad.  We missed the initial inflation entirely, including the unique “tow balloon” that lifts up the top portion of the SPB during the initial stages of inflation.  Fortunately the fog rolled back during inflation, allowing us to see the action.

COSI preparing to launch.  The balloon is on the left, the launch vehicle holding COSI on the right, the flight train in between.

COSI preparing to launch. The balloon is on the left, the launch vehicle holding COSI on the right, the flight train in between.

Launch was made particularly spectacular by the haze left by the dense fog bank.  From our vantage point the balloon eclipsed the sun, which was incredible to watch.  My colleague Jon Gudmundsson has posted a great video of the launch, up through the eclipse.

COSI/SPB released into the foggy sky!

COSI/SPB released into the foggy sky!

During COSI’s initial ascent, ice crystals formed a remarkable halo around the sun.  This formed a hazy, sparkling rainbow (actually multiple “icebows”) that the payload drifted by, as well as a dramatic spotlight effect beneath the sun.

COSI aloft, passing by an icebow (rainbow caused by ice crystals)

COSI aloft, passing by an icebow (rainbow caused by ice crystals)

A bizarre spotlight effect beneath the sun, just after launch.  The Boss is visible just to the right of the spotlight.

A bizarre spotlight effect beneath the sun, just after launch. The Boss is visible just to the right of the spotlight.

Congratulations to the COSI team!  Our turn comes next…

Adelie Penguin!

Today at LDB we were graced with another distinguished visitor – an Adelie penguin!  These are substantially smaller than the Emperor that visited two weeks ago, but all the cuter for it.  The penguin hung out at LDB for much of the day (in fact, he’s still outside our high bay as I write this).

After an active spell before I arrived, he spent a good bit of the late morning chilling out on his belly.

Today's distinguished visitor: an Adelie penguin!

Today’s distinguished visitor: an Adelie penguin!

His activity increased a bit after lunch, particularly when a helicopter flew fairly low over LDB on the way to Willy Field (itself an unusual event).  The thumping noise reverberated off the shipping containers and got the penguin a little excited, so that it scampered around in front of me frantically (which was fantastic – I need to post an animated GIF of that) and got a little closer to me than I would naturally have gone.  It calmed down fairly quickly once the helicopter passed.

"SPIDER is over there!"

“SPIDER is over there!”

Ready for a close-up

Ready for a close-up

Later in the afternoon it was nap time for the penguin, where he remains currently.



Finally, a couple of photos by others:

Obligatory buddy shot; the penguin scooted a little closer to me than I intended! (photo by Sasha Rahlin)

Obligatory buddy shot in front of LDB (photo by Sasha Rahlin)

Penguin scooting majestically before SPIDER (photo by Cynthia Chiang)

Penguin scooting majestically before SPIDER (photo by Cynthia Chiang)

White Christmas

Christmas day out at LDB was a beautiful one.  It started snowing on Christmas Eve and throughout much of Christmas, leaving the ground soft and the air filled with big, fluffy snowflakes.  Our night shift took advantage of some time alone with the cryostat to decorate the payload for the holiday season, a nice surprise when the rest of us arrived in the morning:

SPIDER's Christmas decorations, courtesy of night shift.

SPIDER’s Christmas decorations, courtesy of night shift.

Steve put up pictures (and a poem!) on his blog – see there for more and better photos!  I’ve attached my favorite of his: SPIDER, fully decorated, seen through the open high bay doors in the snow:

SPIDER seen through the open high bay doors in the snow.  Photo by Steve Benton.

SPIDER seen through the open high bay doors in the snow. Photo by Steve Benton.

The LDB galley had served us a fine holiday lunch on the 24th.  Since most of the CSBF ballooning folks are from Texas, the galley decorations included a little Texas charm:

Tiny Christmas tree in the LDB galley

Tiny Christmas tree in the LDB galley

The 25th and 26th were days off for almost everyone in McMurdo, but not for us.  Our payload is almost flight-ready, but we still had a lot of work to do.  We returned to time in town for dinner, however, which was again an absolute joy.  The main course was among my favorite foods: delicious beef, king crab legs, and assorted other seafood.  It was a good evening, and a good break.

Christmas dinner at McMurdo: beef, king crab legs, and much more

Christmas dinner at McMurdo: beef, king crab legs, and much more

Since we’re across the international date line from the U.S., I called my family in the morning from LDB.  I’m enjoying Antarctica, but still looking forward to getting SPIDER in the air and returning home.

Hanging Out on the Porch

SPIDER is fast approaching flight-readiness, which is very exciting for all of us here.  Last week saw the installation of its last major components: the sun shield, the wing, and the solar panels.

The sun shield is an enormous shell built from carbon fiber struts and gift-wrapped with aluminized Mylar.  It surrounds the back of the instrument like a turtle shell, protecting it from the glare of the sun and supporting our communication antennas.  At balloon altitudes the air is so thin that parts couple to their surroundings mostly through radiation.  A part facing the sun will quickly heat and even melt, while one in the shade will lose its heat to the blackness of space and fall to very low temperatures.  The Toronto team has put enormous effort in to planning out SPIDER’s thermal architecture: which parts should be mirrored or painted white, which need radiator fins, and how heat should be exchanged between hot and cold parts.  SPIDER will fly with its back to the sun, with the sun shields protecting the delicate instrumentation as it scans black sky.

The wing is an asymmetric extension to one side of the sun shield.  It gives SPIDER’s telescopes a little extra sun protection on that side, so that it can scan a little closer to the sun and cover a bit more sky.

The solar panels are SPIDER’s power plant, providing the electricity needed to operate the entire payload.  SPIDER’s solar cells live on a single massive panel on the wing side of the payload, giving the whole instrument an asymmetric appearance.  They face backward toward the sun in flight, charging a set of car batteries through a charge controller.

With SPIDER nearly complete, we took it on its first trip outside the high bay.  We opened the bay doors and slid it out onto our porch, hanging from the rail crane just as it will hang from the balloon.  We spent some time scanning the instrument, checking the solar panels under sunlight,  and calibrating the pinhole sun sensors – simple light sensors behind pinholes which record our orientation with respect to the sun.  We came back inside when we encountered a few issues with an external pump (later fixed).

This week we’ll be carrying out more extensive testing outside of the high bay, including flight systems and communications.  Launch is fast approaching…

SPIDER sliding out onto the high bay porch, hanging from the central crane rail.  The central white cylinder is the cryostat, with its six telescope apertures.  The sun shield surrounds the back, with the wing extension on the right.  The solar panels peek out from behind the wing.  Liquid helium and liquid nitrogen dewars are arrayed on the porch edge in front of SPIDER.

SPIDER sliding out onto the high bay porch, hanging from the central crane rail. The central white cylinder is the cryostat, with its six telescope apertures. The sun shield (not quite complete) surrounds the back, with the wing extension on the right. The solar panels peek out from behind the wing.  The cardboard lens caps of the three star cameras are visible below and to the upper-right of the cryostat.  Liquid helium and liquid nitrogen dewars are arrayed on the porch edge in front of SPIDER.

SPIDER on the porch, as seen from within the high bay.  The solar panels and reflective sun shields are clearly visible, as are several cold scientists.

SPIDER on the porch, as seen from within the high bay. The solar panels and reflective sun shields are clearly visible, as are several cold scientists.  Communication antennas project from the top of the sun shield.