Today the Gilroy Lab team awoke at 4am to get to the Space Station Processing Facility (SSPF) building at Kennedy Space Center (KSC). We had a 6 am Pre-Task Flight Integration meeting with the NASA team who places our experiment into the space hardware. However, we had spent all yesterday setting up our samples and had to arrive at the SSPF today a bit earlier to apply the finishing touches. Yesterday we made 40 Petri plates each freshly planted with 64 Arabidopsis seeds. Twenty plates will go into the BRIC hardware to be launched into space but we always make a duplicate set, just in case something goes wrong and we have to set the whole thing up again. Space flight means you plan for just about everything to go wrong, just to ensure it won’t.
The Petri dishes had been sitting under lights overnight, a treatment we use to synchronize seed germination once they are on board the International Space Station (ISS). However, it is necessary to cool them down in the fridge before they go into the BRIC spaceflight hardware. The cold prevents the plants from growing for the 4 days it takes to get to the ISS (two days till launch, and then two days in transit to the ISS). The astronauts will unload them from the Dragon capsule and allow them to warm up to room temperature and then they will germinate. In our case the room temperature just happens to be in a room orbiting about 250 miles above our heads!
The timing of integration is key because we do not want to plant too far in advance of launch or the seeds will germinate even in the cold and then our experiment will be ruined. Our BRIC-19 experiment is “late stowage” which means it will be packed into a cold bag and placed into SpaceX’s Dragon capsule as late as possible prior to launch (about a day before). That might sound simple but it’s actually a huge challenge for the NASA team to decide when to conduct integration, because more than one delay or “scrub” of the launch means that our experiment may sit around too long to guarantee no germination till it is on the ISS. With more than 2 days of delays, an entire sample set will have to be tossed and replaced with a new one that we need to have already prepared.
Here’s the tricky part: NASA has only so much spare hardware for our experiments and in our case it is the number of extra PDFU (Petri Dish Fixation Units), the casettes that each of our samples sits inside of, which is critical. Not only do we need enough (20) for the samples going into space but additionally, every experiment needs a control. In our case, our control will be a mirrored set of PDFUs containing plants that we will grow on Earth at 1x gravity. We will put these inside Kennedy Space Center’s ISS Environmental Simulator (ISSES), a growth chamber that controls its temperature to be identical to that of the ISS. So now we need a total 40 PDFUs (ground control and flight). That’s a lot of PDFUs.
We play some tricks to extend our PDFU stocks. Our samples are good for 2 consecutive days of launch attempts, that is, if the launch is cancelled on day 1 our sample is still good for the next day’s launch attempt. After 2 days we have to replace everything. So the game we play is to integrate our control samples 2 days after our flight samples. If the flight is delayed 2 days, our controls are swapped for our old flight samples and we make new controls. Therefore with a rolling window of launch attempts we will always have a new set of samples that can be turned over every 2 days for flight. That’s even more PDFUs! We have enough PDFUs for up to 3 scrubs; after that we have to get “creative” and recycle the old PDFUs.
So, a rocket launch really is rocket science and as we all know rocket science is hard. Getting everything perfect in the rocket and having acceptable weather for a launch is a huge challenge and it is amazing how regularly rockets actually go up. For CRS-4, the launch schedule has been very fluid as everyone tries to hit the magic combination of hardware readiness, weather and usable launch window. We’re currently on for 2:16 am EST on September 20th with a backup at 1:53am the following morning. So we’re all peering at the weather, and planning how to deal with every contingency. Fortunately, we know that the teams at SpaceX and at NASA are amazing and so the only reason to lose any sleep over the whole thing is the need to get up at 2:00 am on Saturday to watch the launch. But for the sake of our sanity, how about everyone reading this blog please “cross your fingers” that SpaceX’s CRS-4 WILL launch on Saturday morning!