Now that SPIDER has finished its flight, the team will spend the next year or more analyzing the collected data.
We will begin with baby steps, piecing all the raw data into a coherent set of calibrated time-ordered data. These data consist of the data from our millimeter-wavelength cameras, which are essentially ‘snapshots’ taken 120 times a second, together with the data from instrumentation dedicated to our attitude reconstruction. These latter data, which consist primarily of GPS fixes, star cameras and laser ring gyroscopes, must be processed together to determine precisely where our instrument was pointing on the sky at the moment each of the ‘snapshots’ was taken. These are the basic ingredients required to make the sensitive polarized images of the sky.
Once this is complete, another layer of analysis will proceed in which we separate the cosmological signal from galactic radio emission, and attempt to further isolate the fingerprint of primordial gravitational waves in the Cosmic Microwave Background.
Good news! Our team has been able to recover the data collected by SPIDER during her flight over Antarctica. These photos were taken by SPIDER during and just a few hours after launch.
A photo taken during SPIDER’s ascent. Below is the launch vehicle and the crane arm that held SPIDER while the balloon that would carry her was inflated.
A photo taken during SPIDER’s voyage above Antarctica.
After a long period of anxious expectation, the data from SPIDER have been recovered from the landing site, some 2,300 km (1,500 miles) from McMurdo Station. The data, residing on a combination of hard disk and solid state drives, are enroute to Punta Arenas, Chile.
Princeton’s Ed Young, and Don Wiebe of the University of British Columbia are en route to Punta to meet the data, assess the health of the drives, and copy the data. They should be back home by the end of February.
We are incredibly indebted to the British Antarctic Survey for their support in the recovery our data.
This past Wednesday was the first time anybody had been able to reach the location where SPIDER landed almost three weeks ago now.
Because the National Science Foundation has no people or planes out in that part of Antarctica, we partnered with the British Antarctic Survey (BAS) to recover the data from our experiment. As you know, we cannot get any useful amount of data via the available satellite links, so we needed to physically recover the drives.
After quite a heroic effort by the BAS, a guy named Sam Burrell made it out there, recovered the bits of our flight computers that housed the data, and made it back. He is based out of Rothera Station (location noted on the map), which is nearly 1000 miles from the landing site.
Map of SPIDER’s flight. Note the location of the landing site.
The recovery crew had to first get themselves out to a place called Sky Blu, which is about 300 miles away from Spider. After a week of waiting for good weather, they left Sky Blu for the SPIDER landing site on Wednesday. They took a few hours to extract the critical parts that contain, then flew back to Sky Blu. Yesterday, the team flew from Sky Blu to Rothera.
Below is a photo that I received this morning from Sam that shows the pile of equipment they pulled from the wreckage, including the five cylinders and a tidy stack of rectangular computers, which together represent three redundant copies of our data. The photo was taken in the hanger at Rothera.
Equipment recovered from SPIDER.
Don and Ed are enroute to Punta Arenas, Chile, to meet the plane coming up from Rothera on Feb. 10. They will assess the integrity of the hard drives, duplicate the data, and bring it north.
The rest of the instrument, including our science cameras, and most of the electronics, remain on the West Antarctic Plateau, and will remain there over this winter. I’m working on figuring out how to get the rest of it back next year, but for now having the data in hand is all that we could wish for.
At this point, getting data from the site to Rothera, we have dodged a lot of bullets. There are a few left, to be sure, but needless to say this is very good news for us!
SPIDER’s flight path and final resting place. (Image courtesy of John Ruhl.)
Anne Gambrel
SPIDER was released from her balloon at 5:55 am local time today (11:55 EST Saturday, January 17), and parachuted gracefully (we think) to earth. She took a pretty weird tour of the continent. The winds didn’t act exactly as we expected, and we went very slowly along for most of the time. Since our cryogens (the fluids that keep SPIDER cold and operating properly) ran out yesterday afternoon, and the winds would have only pushed us further north, we cut her down. SPIDER’s final landing place appears to be about 70 kilometers from some small bases with landing strips, which might be used for recovery of the data drives and other small parts.
With recovery the last remaining piece of the campaign, much of the crew headed north yesterday. Only six of us remain, and we will all be glad to no longer be on shifts watching for our little data packets. Hopefully we can get a quick recovery done and head north ourselves, but we’re not sure when that will be yet.
SPIDER landed safely on Saturday, January 17, reported William Jones, lead researcher on the project and an assistant professor of physics at Princeton. The crew will now undertake an expedition to recover the data from where SPIDER set down, about 2274 kilometers from McMurdo Station.
From Antarctica:
“By all measures, the data look great. Of course we won’t know until we can look at the full set of data where we stand, but we couldn’t be more pleased at the moment.” -William Jones
SPIDER’s progress on January 14, 2015. The instrument took off from McMurdo Station in the lower left portion of the continent on January 1. SPIDER’s progress can be tracked in real time at http://www.csbf.nasa.gov/map/balloon6/flight660n.htm.
William C. Jones, Assistant Professor of Physics
We are still collecting data with our instruments, and plan to continue for another few days. At that point we expect to arrive at a location that would be favorable for recovery. By then we will have collected enough data so that our primary concern becomes a good recovery.
The process of recovery depends greatly on where (and how) SPIDER lands. In all likelihood, someone from our team will be flying out to the payload with two or three personnel from the Columbia Scientific Ballooning Facility (CSBF). The priority will be the recovery of the science data and the CSBF flight systems.
SPIDER has now been at float for a little over a week. The payload has been very slowly wandering south, a different trajectory than you’d usually expect for a Long Duration Balloon (LDB). Normally they make circular trips around the continent, but SPIDER is doing her own thing, wandering in an approximately straight line.
While SPIDER was in our line of sight, we could communicate with the payload with high bandwidth — it was almost no different than commanding and data streaming on the ground. For those first couple of days, we got to make tweaks and get fast feedback and got all the systems in nominal working configuration.
SPIDER’s progress on Jan. 8, 2015. SPIDER launched from near McMurdo Station at the lower left of the continent.
The change to over the horizon telemetry was stark. Now, our standard operating mode is through an Iridium (satellite) link. This link provides us with a data packet approximately the size of a text message every 15 minutes, providing us with a few snippets of temperature data, pointing information, and system states that inform us only about gross health of the system. We can also give commands through this link, although commands can take up to a minute or two to get to SPIDER, and then you have to wait up to 15 minutes to get a new packet to confirm that your command went through.
I was very nervous before flight about this limited information, but it has in fact been quite sufficient. SPIDER is boring. It is just working. It’s a great position to be in, especially since there are remarkably few knobs you can tweak to fix anything now that it’s up there!
Inside the control room.
Once a day, we get to turn on our high bandwidth antenna and get data streams and fast commanding. We can get about 20 minutes of compressed data for about 80 detectors (out of SPIDER’s 2000 detectors) during this high bandwidth period, which means that we get to spend the whole next day obsessing over this tiny data set and seeing what we can learn from it.
And let me tell you, analyzing real CMB data is awesome. We have a running joke in SPIDER about what qualifies as “science”. We’ve done a lot of experimental physics that very much does not feel like science, but a lot more like grunt work or art and crafts. Without a doubt, we are now definitely doing science, and it is the coolest thing I’ve ever done. I can’t wait to have all that data at my finger tips once we get our hard drives back!
The past 48 hours has been a whirlwind, crash-course in the thrilling ride that is scientific ballooning. As I write this, SPIDER has been officially declared ‘at float’ at an altitude of 36 kilometers, our cryogenic system is functioning beautifully, our attitude control and pointing reconstruction systems are being brought online and tuned up, and we’re about to start working with the detectors in the low-loading environment they were designed for. If you had told me we would currently be at this point yesterday morning, there’s a good chance I would have laughed in your face and said something snarky given the experience of other payloads we’ve witnessed this season.
Hang Test
New year’s eve started out with an opportunity for our hang test. As has become abundantly clear in witnessing the many scrubbed launches of other payloads this season, weather is the master of our fates here at the Long Duration Balloon facility (LDB). The weather man from the Columbia Scientific Balloon Facility (CSBF) does his best to understand the weather systems here so that we don’t end up stuck in a snow storm while we’re testing systems on our highbay porch, or having our payload whipped around by the winds while hanging from the Boss (the vehicle that conveys the instruments to the launch site). Needless to say, his job is a bit stressful. When the forecast the day before New Year’s Eve changed from “pretty bad out there” to “low winds, maybe just some fog that’ll burn off in the morning,” we jumped at the opportunity to roll SPIDER out onto the deck, hook up to the Boss and carry out our compatibility hang test.
As mentioned in an earlier post, compatibility is when we hook up to the launch vehicle and drive a bit away from the high bay building so NASA’s CSBF folks can hook up all their systems and test radio communication links while our team goes through a practice launch on our end. The riggers also work out the mechanical details of attaching to our payload and weigh us in to determine the appropriate amount of ballast to fly with. It ends up being a long day, since there are many systems to check, many procedures to carefully go through, and usually, many hiccups that need to be worked through to ensure a smooth launch day. If all goes well, the payload gets deemed ‘launch ready’ and the science team goes back to taking care of whatever last minute changes need to happen and waiting for a launch opportunity. SPIDER’s hang test day was remarkably straightforward. We worked hard in the days before the test to prepare everything and make sure our procedures were outlined in detail, so aside from a vacuum pump starting to freak out in the cold Antarctic weather, everything went as planned and we were launch-ready at the end of the day.
Getting picked up on the highbay porch by the Boss for our hang test.
SPIDER hanging from the Boss, with Mt. Erebus in the background.
SPIDER returning to the porch, being disconnected from the Boss and reattached to our high bay overhead hoist. You can see one of the riggers up top in a cherry-picker disconnecting our pivot from the hook, while Professor William Jones looks up from below.
Launch
Being declared launch ready on New Year’s Eve didn’t necessarily surprise me. It’s been a long campaign, and the team has been working really hard to get to this point. What surprised me is how quickly the forecast for “horrible weather” on New Year’s day turned into “a really good launch opportunity” while we were carrying out our hang test. And what shocked me was that launch opportunity turning into our actual launch and not one of many scrubbed attempts, which we had come to expect after the other two payloads this season had several scrubs each.
Launch day started out with a 3 a.m. shuttle to LDB the morning after our hang test and a marathon evening of liquid helium transfers to fill our cryostat to the brim. I was part of the early morning team to get us out on the high bay porch quickly so CSBF could take over as soon as they arrived. Our well-rehearsed roll out went flawlessly and the Boss was soon chilling on the launch pad with SPIDER ready to go. After finalizing a systems check, out team took some time to relax, enjoy the sunshine and snap some photos of our payload with Erebus in the background while we assumed launch operations would commence shortly. And then…the winds shifted and it started looking like a scrub day. The forecast for the rest of the week wasn’t promising either, so we waited on the pad while CSBF discussed with our team how damaging waiting for a later launch would be to our science, how rough of a launch we thought our payload could safely deal with, and how long our cryogenic system could safely stay out there. The mood in our makeshift control room went from celebratory to anxious, depressed, even manic as we waited for hours.
Getting some quiet time on the Boss with SPIDER, a few hours before launch. It was surreal being the only person on the launch pad for a bit while some of our team and all of the CSBF folks grabbed lunch.
Some of the ballooning vets remained even-keeled as the day evolved, but most of our team is new to this. It was difficult to change one’s mindset from the initial excitement and disbelief over unreasonably beautiful weather that couldn’t possibly result in a scrub to the realization that the weather near the surface was completely disconnected from the higher altitude winds blowing 10 knots in the wrong direction that could lead to disaster. That realization was made especially difficult for those of us who had started thinking about being able to head home to families, including children, spouses, and pregnant wives, within a few days.
By the time we had all come to terms with what we thought was the inevitable scrub day and slowly started preparing the highbay for the payload to return…the winds shifted again, and all of a sudden the balloon was taken out of its box and we were go for launch! Once the CSBF team started inflating the balloon, the overwhelming wave of relief, excitement, and pure adrenalin rushed over the entire team. While they can still scrub a launch at that point, once the balloon is out and inflated, there’s a lot more resistance to turn back. At that point, I pulled up a folding chair from the neighboring COSI highbay and sat down with one of their team for a good view of the launch. The science team’s job was done for now, and there was nothing to do but sit back, enjoy the sun and the view, and jump up and down with the unique combination of excitement about the remarkable instrument we were about to launch into the stratosphere and fear it might get destroyed at the instant of launch.
Seconds after launch.
Here’s a video of the launch taken by former Princeton graduate student (now Princeton postdoc) Jon Gudmundsson, who had a unique vantage point since he was part of the small team on the Boss disconnecting some vacuum hardware on our cryostat minutes before launch.
One of the Princeton graduate students, Sasha Rahlin, couldn’t contain her excitement and ran around hugging everyone outside observing the launch.
The launch seemed a bit rougher than what would be ideal, but there wasn’t any visible damage to the payload as it took flight. We all ran back into the highbay to verify all systems were still functioning and that the rough launch hadn’t compromised anything. One by one, subsystems were turned on, tests were performed, and applause broke out when success was declared. At times, it seemed too good to be true; none of us expected the initial systems check to be so successful and work nearly ‘out of the box.’
Our command center back inside the highbay with everyone anxiously monitoring the various subsystems (and trying with difficulty to post status updates to Facebook if their subsystem checked out or couldn’t yet be tested!)
Jamil Shariff, one of the University of Toronto graduate students, pointing out our first move in elevation after launch. This was one of the first of many moments that received a roaring round of applause from all of us in the highbay as each subsystem came online and seemed to be functioning perfectly.
Of course, there is still a lot of work over the next few days for the SPIDER team to ensure a successful flight, and even more work over the next year to understand the remarkable data we hope to collect, but I have faith this team can do it. I’m incredibly proud of everything we’ve accomplished together, and honored to be a part the team. Right now, we’re all an interesting amalgam of exhausted, thrilled, and wired by caffeine, as we watch the balloon disappear from view. I can’t think of a better way to ring in the New Year. Happy New Year!
The balloon carrying SPIDER, now a barely visible white teardrop right-of-center in this photo, high above the clouds at 36 km altitude.
Follow our blog as the crew assembles the SPIDER experiment and prepares for launch.
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Jet Propulsion Laboratory
Cardiff University
National Institute of Standards and Technology
Canadian Institute for Theoretical Astrophysics
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University of Cambridge
