Once SPIDER was over the horizon, the ice team divided their time between two major efforts: flight monitoring (day and night shifts) and packing. The accelerated schedule imposed on us this year required the entire SPIDER and CSBF teams to leave the ice on December 27th and 30th, with the exception of two personnel to assist with recovery and shipping logistics. This meant an intense push by the packing team to get our entire lab inventoried and into sea containers for the voyage home. The packing team did an amazing job, though as one of the first people returning north I didn’t see the conclusion.
The Voyage Home
On Monday the 26th I visited LDB one last time. I sorted and packed a few items to return to Illinois, had a good post-campaign discussion with the CSBF team, and enjoyed one last LDB lunch. Then back to McMurdo to return borrowed skis, visit with the monitoring team, and pack my bags. That evening those of us departing on Tuesday had “bag drag”: we brought all of our stuff up to Building 140 to be weighed, and left our checked bags to be palletized for the flight.
The next morning after breakfast we headed out to the airfield on Ivan (the Terra Bus) for our flight north. On our way in we were happy to see the South Pole flight carrying Sasha and Riccardo take off, at long last! After a little time in the Willy Field galley, we boarded our LC-130 for the 7-hour flight to Christchurch. The moment we disembarked in Christchurch, everyone remarked on how different the air tasted: humidity! life!
We all stayed overnight in Christchurch. The two students I traveled with (Simon and Vy) prepared to set up our new SPIDER ground monitoring station at the airport the next day, so they could take full control while the rest of the team traveled on Thursday. I caught a 6am flight to Sydney, followed by flights to Los Angeles (14 hours!!), Chicago, and finally Champaign. Between flights and layovers, I landed at Champaign more than 33 hours after takeoff from Christchurch (though on the same calendar day, thanks to crossing the International Date Line!), and about 55 hours after rolling out of McMurdo aboard Ivan. It was a long and uncomfortable journey, and neither of my checked bags made it with me (both were delivered the following day). But it was a real joy to make it home and see my family again.
I write this at home on December 30th (31st in McMurdo / Christchurch). The last of our science team has made it to Christchurch, where data monitoring will continue until flight termination. SPIDER swung within 600km of Pole before spending the past few days dithering around the opposite side of the continent, near the edge of the Filchner Ice Shelf. Wind speed are low, and the future path is uncertain: will SPIDER swing around back toward McMurdo, return to Pole, or head somewhere else? In the meantime we’re getting good observation time at a favorable latitude.
I expect I’ll post again when SPIDER terminates, and as recovery plans develop. And then the real fun begins – analyzing the trove of new data SPIDER has provided. But for now we watch SPIDER’s progress, and look forward to the new year.
Christmas this year was a welcome relief after the stress of launch prep and LOS, and a chance to celebrate with the team one last time before we begin leaving the continent. The official banquet was on Christmas Eve (Saturday), with a low-key Sunday brunch on Christmas itself.
Flight Monitoring Takes No Holiday!
SPIDER is still in the air, and we need to keep monitoring it. Once LOS ended we set up a monitoring center back in McMurdo, in Crary Lab. Team members rotate in and out day and night, checking on SPIDER’s health and pondering / fixing anything strange in the data.
As a personal aside: king crab has been more or less my favorite food since I was a kid. Once a year each August my family would go out to dinner at a local steakhouse, as a combined celebration of birthdays / anniversary / etc. We’d all order the king crab, and I have best associations with that meal. I have not had king crab in years, however, since the fishery has more or less collapsed. This menu was thus a real personal treat after an intense few weeks… I had seconds of everything.
After dinner most of the team took a stroll out to Hut Point, on the rumor of penguins in the area. No such luck, but it was still a nice stroll.
A White Christmas
I guess Christmas in Antarctica is always white, but it was nice to see a dusting of snow Christmas morning.
Ready to Head Home
Antarctica has been nice, and I’m proud of our successful campaign. But I miss my family and home, as was brought home very hard by a call to them on (their) Christmas Eve. Very much looking forward to departing for Illinois this week.
Now with the benefit of two more days and one decent night’s sleep, I can add a few more notes about SPIDER’s launch.
What Does it Take to Launch?
Balloons like ours only launch on perfect days. The balloon has a total volume of 34 million cubic feet; only a fraction is filled with helium on the ground, but the helium expands to fill the volume at the lower pressures of float altitude. The balloon is massive and pushed around by the slightest wind, so the launch crew needs near-zero surface winds in order to handle it safely. This needs to last for a few hours, enough time to lay out and inflate. This is doubly true for SPIDER, which bucks in even a light breeze due to the massive sail formed by its sun shield. When the balloon is released it swings up above the payload, temporarily extending about 900 feet above the ground before final release. This means we also need vanishingly-small low-level winds at these altitudes so that the balloon does not pull away before the payload is released from the launch vehicle, which would endanger the launch crew (and the payload). Antarctic weather is fickle, and we really need special weather conditions to launch.
Furthermore, even if you can launch the balloon, you don’t really want to until the stratospheric winds are in the right configuration. This is a big part of what makes Antarctic ballooning special: circa December a polar vortex sets up that will take balloons on a circular path around the Pole, staying over solid ground (land or ice) for weeks on end. Launch too early or too late in the season and you won’t have this wind pattern, and can drift out to sea.
Worse yet, showing up for a launch attempt is an exhausting and time-consuming operation occupying more than three dozen people. For a launch at 0900, the launch crew might show up at LDB circa midnight, and the science team must show up even earlier to prepare. The payload must go through many steps:
system checkout and head out to the deck
attach NASA flight electronics
transferred from our crane hook to that of the launch vehicle
move away from the building for further checks
move out to the pad if winds are holding
lay out and attach flight train and parachute
Attach balloon and start inflation (only if we’re definitely going, because the balloon can’t be folded back up without damage)
Even an aborted launch attempt involves many hours of work outside in the cold, and is tough on the sleep schedule. Special personnel density restrictions this season (imposed on station in November) mean that the launch crew down here is stretched especially thin, even after 2 of the 3 science payloads were canceled and their teams kept home.
Worst of all, we found out in mid-December that these personnel restrictions would force our entire LDB team to leave continent by the end of the year, weeks earlier than planned. That would force us to give up and start packing well before Christmas, ending the season almost before it began. We were on the clock, and at the mercy of the weather.
Groundhog Day: Launch Attempts
Our early weather briefs indicated two possible days (Saturday 17Dec and Wednesday 21Dec), but with a great deal of uncertainty due to a chaotic weather pattern around McMurdo.
Saturday 17Dec: We showed for a first nominal launch attempt even before we were quite ready, because this was forecast as a great launch day and time was short. We had the long-shot goal of breezing through compatibility testing and heading to the pad if conditions allowed. In practice the winds never died down enough to even go outside for compatibility testing, so this was a bust. Furthermore, the stratospheric winds were setting up slower than expected
Monday 19Dec: Compatibility testing, which ended up being a very long day. But conditions looked good for Tuesday, so we took a nap after work and headed back that night.
Tuesday 20Dec: First “real” launch attempt. Got pulled back from the deck but the winds never died down enough to head to the pad.
Wednesday 21Dec: Second launch attempt, but the weather was even worse: cloudy and breeze, with no expectations of improvement.
Thursday looked poor but Friday good, and the launch crew was required to take a rest day soon. So we planned to take a day off from launch attempts and do a liquid helium refill and some electronics work. But we can’t afford to miss a launch day, so we on the science team requested a weather evaluation Wednesday evening to see if we should show Thursday. We found improving but still risky conditions, but we had almost no days left on the calendar to try. So at about 1900 we decided to go again, even on very short sleep. And I’m very glad we did.
Launch Day – Thursday 22Dec
Launch day went quickly and smoothly, as such things go. Scientist teams headed in at 2200 and midnight, with a couple of sleepers hitching a ride at 0330 with the galley crew. Roughly speaking: payload pickup at 0200, road closed at 0500, headed to the pad at 0600, inflation began at 0800, launch at 10:28 (just minutes shy of the solstice). This was thanks to an unbroken string of great piball readings of the wind profile (most released by our camp manager, Rose McAdoo, but a few by students Elle and Jared!). It was a beautiful sunny day, and a pleasure to be outside. And I even managed to squeeze in a long-postponed call during inflation to talk about Antarctica with my daughter’s 5th grade class (yay, South Side Elementary!).
After launch there is a period of celebration, and then work to do. The team checks pointing control and performance during ascent. In the upper atmosphere the wind dies down, and we get enough control of the payload to point it (notably away from the Sun!). Then tuning of the attitude control system, detector checkouts, and commencement of science scans.
This initial tuning is enabled by our Line-of-Sight (LOS) link: a relatively high bandwidth radio connection available for the first day or so, as long as the payload is visible above the horizon. After LOS dies out SPIDER goes into over-the-horizon (OTH) mode, with much lower data rates. We still have some decent satellite transmitters on board (Iridium Pilot, TDRSS, etc.), but these cause radio interference in our detectors, so we turn them off as much as possible. For most of the flight, SPIDER essentially communicates via text messages full of highly-compressed status bits.
LOS is a busy time. Everyone sleeps in staggered schedules, which is hard after so many days of launch attempts. I don’t think I slept longer than a 1-3 hour nap for several days. But we’re excited for SPIDER-2 to do its work!
SPIDER-2 is aloft! Our payload launched yesterday, December 22, 2022, at 10:28 local time (UTC: 09:28 on 21 Dec). This was coincidentally less than 20 minutes before the solstice. The whole team is thrilled, and eagerly hunting through the first telemetry data. Then it will be time for some science!
A few photographs are below. More another day when I’ve had a bit more sleep…
My collaborators and I are here in Antarctica for one reason: to fly a balloon-borne telescope called SPIDER. SPIDER is designed to observe the cosmic microwave background – the literal glow of the early universe. It is an exceptionally complicated instrument: six telescopes full of microwave optics and superconducting electronics; a massive (1300L) tank of liquid helium to keep it all cold; a motor system to turn and point it during flight; and electronics and sensor systems to monitor and control the whole shebang. It has taken our team seven weeks to prepare it for flight. Below are a few photos and notes from along the way.
Arrival and Unpacking
Even weighing in at 3 tons, SPIDER is incredibly lightweight for what it is and does. It needs to be strong in just the right ways, with lightweight materials (aluminum, carbon fiber, some titanium) and careful engineering design. It is also very large. It thus cannot be shipped to the continent as a unit, but must be largely assembled on-site. This has occupied much of our time since arrival.
LDB camp opened on October 29th (a day early!), with major cargo arriving that day and the next. SPIDER arrived in three sea containers (two 10-foot, one 20-foot) and one large crate for the cryostat itself. The sea containers arrived in Christchurch via ocean-going container ships from Port Hueneme, while the cryostat arrived on a C-17 SAAM flight from McChord Air Force Base. All containers were then carried to Antarctica in October aboard C-17s.
These containers aren’t just SPIDER’s flight hardware and spare parts: we begin the season with an empty high bay, and there are no hardware stores in Antarctica. We thus also need to bring a fully-outfitted lab, with all the tool chests, supplies, electronics, tape, and fasteners we might ever need. This year that even included a small milling machine, 3D printer, belt sander, and much more.
SPIDER’s six microwave receivers (telescopes) are the eyes through which it views the early universe. Each needs to be unpacked and carefully prepped for installation into the cryostat. The system takes so long to cool that we have only one chance – get everything right the first time!
Prepping the Cryostat
Cooling the Cryostat
SPIDER’s cryostat is a fancy thermos bottle, designed to maintain a cold interior in warmer surroundings. On November 9th the SPIDER cryostat was complete, and we began to pump it down to vacuum (slowly and carefully, because of delicate membrane filters inside). After a week of this the team filled it with liquid nitrogen, which slowly dragged its interior down to a chilly 77 degrees Kelvin (-321 degrees Fahrenheit) over the next several days. And there we waited for the final fill, with liquid helium, to reach a mere 4 Kelvin (-452 degrees Fahrenheit).
And there we waited for about 12 days – a few days longer than planned – because our liquid helium had not arrived. To support the SPIDER campaign, NASA arranged to ship 9000 liters of liquid helium to Antarctica – a massive (and expensive!) logistical endeavor. Some logistical problems led the first batch to be delayed. After heroic work by LDB staff and NSF leadership, the dewars started rolling in a few days before Thanksgiving, and we were able to continue cooling. Detector reached operating temperature (0.3 Kelvin) by the end of November.
SPIDER is supported on a lightweight (but very strong!) carbon fiber frame, with a reaction wheel to turn it in azimuth and two elevation drive pistons to change its elevation. The cryostat was placed on the frame just before the liquid helium cooldown began.
On December 5th we took it for a brief trip outside to point the detectors at the sky. Beautiful day, and a great occasion for pictures with the team!
Dressed Up and Ready to Go
In flight SPIDER is protected from the intense sunlight at altitude by a large sun shield. This is built of a carbon fiber frame, filled out with foam panels and wrapped in aluminized mylar. The sun shield also supports the various satellite antennas with which we will communicate with SPIDER in flight. SPIDER also has cone baffles atop its six receivers, and aluminized mylar absolutely everywhere for sun protection. Plus a giant solar panel wing, to provide the 2 kW of power SPIDER needs to function.
One of the nice parts about life in McMurdo (unlike Pole) is the outdoors. The weather is much more benign than at Pole, and there are stunning views and good hiking terrain right around the station. A few destinations from the early weeks…
An easy stroll from our dorms takes us to Hut Point Peninsula, location of a hut built by Robert Falcon Scott’s Discovery Expedition in 1912. It was beautiful out the evening I arrived, so I met up with a few SPIDER folks for a stroll out to the peninsula (see a prior posting).
The hut itself is a historical site, and off-limits to hikers. Last time I was here it was cordoned off for restoration and I never got inside. But this season there was an open house a week or so after I arrived. We waited in the cold, and were allowed to walk through a few at a time.
On another walk out in mid-December the sea ice had started to break up and form melt pools, some with seals frolicking inside.
A rocky hill overlooking the station, with fantastic views down to McMurdo and out on to the sea ice. Steve, Riccardo, and I took a hike up there on a clear day. We encountered some visitors from Scott Base on the same hike, as well as a plaque commemorating the nuclear reactor that operated there in the 1960s.
Hut Point Ridge Loop
A walk over the windy ridge from Hut Point around to the back of town. A nice walk with Elle, Susan, Steve, and Simon.
The Pressure Ridges
Our LDB Camp Manager, Rose McAdoo, took us on a tour of the pressure ridges near Scott Base. These are ridges of blue ice, forced up by collision between the sea ice and the permanent ice shelf. They’re huge, and incredibly striking.
The pressure ridges are also full of Weddell seals. These mostly just lounge around like giant slugs, but we saw a few snuggling with pups. One actually prevented us from starting the tour! A seal was lounging across a choke point at the very beginning of the trail, at the one point we cannot go around. The Antarctic treaty forbids us from interacting with the animals… so we were stuck! In the end we took the tour loop in reverse, and thankfully the seal was gone by the time we got to the end so we didn’t have to go back the long way.
Thanksgiving is an important holiday in the U.S. Antarctic Program. It’s traditionally observed on Saturday rather than Thursday (effectively only one day after U.S. Thanksgiving, thanks to the International Date Line), to allow most station personnel to take a two-day weekend to celebrate and unwind. A two-day weekend may sound normal, but it’s a big deal down here: we all officially work six days a week, and this is the first full weekend many of the early-arrival staff have gotten since August.
The SPIDER science team has a tight schedule to integrate the payload, so we generally keep the lab open 7 days a week. We also run early and late shifts, with overlap from lunch through the afternoon. Each team member is expected to take a staggered day off every week or so, mostly at their discretion (or when someone reminds them to). Even with the days off it’s a grueling pace and a stressful time, and we are all far from family and friends. This makes holidays all the more important, and the McMurdo community does their best to make them special.
Turkey Trot 2022
Thanksgiving in McMurdo begins with the Turkey trot: a 5K-ish loop around town, starting and ending at the chapel. This is mostly a fun run: some competitive runners, but plenty of people in costume and cheering squads on the sidelines. But it also has some substantial hills up and down the transition, and the special challenges of the Antarctic climate. Today’s conditions: overcast, 18F, wind chill of 3F.
I am not a runner, and I’ve never run any kind of a race in my life. But there’s a first time for everything! I cobbled together an attempt at running clothes, registered for a placard, and joined the chilly crowd for the 10am start. I didn’t think through the course, didn’t push hard, and just followed along in the cheerful pack. It ended up not being a full 5K (the lead runner got ahead of the team sent to mark the turnaround!), so the course was a little short. But it was fun! I had a middle-of-the-field finish. Should do this again some time…
The McMurdo galley pulls out all the stops for holiday dinners, and most of us bring (or scavenge…) one decent shirt to wear to them. We made a reservation for the whole SPIDER team to eat together Saturday evening, along with most of the LDB team. We also invited John Kovac of the BICEP/Keck team, who had an unexpectedly long stay in McMurdo on his way to Pole. It was a good meal with good people, and a good reset for the work ahead.