Kwatsi
Outstanding RNDZ and docking, very few issues
Right on schedule the crew has ingresed and are preparing to handoff the OBSS
Started with powering up systems
Slight problem with a GPC, transient problem that took it down for RNDZ, was a loss of redundancy
When we power them up for RNDZ and docking we fly with 3 redundant computers
All comps talk on same data busses and ideally they see and say the same things
They talk to each other and compare notes
If 1 outputs something different to the others they vote it into failed state
When we power them up we flip a switch and it activates them
The switches have detents that can be temperamental if you don’t carefully move them you can get a rebounding effect
This happened to comp number 3
The other 2 computers saw this and thought it had a problem so voted it out
Don’t think there’s anything wrong with the comp, loading a new software image to it tomorrow morning
Flew RNDZ and docking with 2 comps its within experience and rules
This happened before on STS 122
Don’t think it’s a real hardware problem, expect to get it back to full functionality in a day or so
Spectacular site when Atlantis arrived and performed the RPM
Fortunate that ISS had KU coverage and we could see it in real time
After RPM we manoeuvred flawlessly to V Bar and we had a flawless and smooth docking
Docking mechanism drove the hooks and ring in for a hard mate
So far everything is going very well and theres no significant problems
Questions
Q: What do you need to do for the rest of the mission for the GPC, do you carry spares?
A: Do not carry spare GPC’s, decided some years ago that we didn’t need to carry spares. We have 5 on board. When the other computers in the common set vote a computer out we have to reload the computer from the onboard hard drives so it has a fresh software image and all the flags are reset. IPL (initial program load) takes 25 – 30 mins. Will let it run for several hours after the IPL.
Q: Do you still need this docking port in the future? Thoughts on the final docking?
A: This docking adapter is designed for ADPS won’t really use it for a VV in the foreseeable future. Might be used as a closet. RNDZ is trained more than other things; we had rehearsed it a lot so it represented a big game day for the team. On the one hand we were excited but at the same time it started to weigh on the team that it was the last one.
Q: Cryo margins? (Philip !)
A: Have thoroughly assessed cryo margins. 1 day 3 hours above nominal 12+0+2 mission. If this margin remains stable we’ll ask the MMT on FD5 to formally extend the mission. Waiting as theres a variety of things that influence how much cryogenics we see in the tank. Dynamic motion can cause some of the gas to go between gas and liquid so sometimes you see a decrease in the pressure. These transients stabilise over time and so we can ensure we have enough.
Q: Does this include MPLM buy back? (Philip!)
A: Yes
Q: Speak about significance of 6 person ISS crew for the last time ?
A: This mission is important for the future of the ISS. Agency is in the mist of a significant shift in policy. Moving into season where were leveraging commercial providers, who haven’t flown people in space. In space flight the job is always harder than it appears at first glance. The supplies the crew are bringing are really insurance. Until we get some regular delivery system online were limited in how much we can resupply the ISS. The significance of the visit of the crew is felt by the astronauts on board you can sense an increase in emotion from all the crew members.
Q: What emotions washed over you when you saw Atlantis approach the station ?
A: I was having a number of flashbacks. My first experience with Atlantis was as a trainee. The first time I saw Atlantis from MCC was my first year with NASA in 1995 was doing training with life support systems. The first docking of a shuttle with MIR. I was thinking about the defining moments of my career. I won’t say I got close to welling up but it was a powerful moment that I tried to keep discrete to not distract the team.
Q: How will things change now 10 people are on the ISS?
A: The ISS is huge and there will be plenty of room to operate. The crew will be very efficient. Doing cargo transfer for the next few days, will be like an army of ants. (But the crew are bigger than ants) Theres a break in transfers for the spacewalk on FD5. Will end up having fewer crew on both spacecraft in the future and will get some more efficiency by them not tripping over each other but loose something due to less man power.
Q: How many GPC’s do you need for the shuttle to operate ?
A: During ascent and entry we have all 5 computers up and in a redundant set. Looking at the same busses and talking to each other making sure all there calculations agree. We could sustain a failure of 2 and still have enough to vote. 5 computers are massively redundant and we need this for ascent and entry. 1 computer runs completely different software this is a backup flight system to guard against a endemic software issue. For RNDZ and docking due to the critical nature of the burns we like to fly with 3 computers in a redundant set so we can take 1 - 2 failures. In todays instance it simply took away some redundancy. During docked phases we only use 1 GNC computer and another that does system functions management, Right now theres no impact to orbiter functionally. If GPC 3 doesn’t come back it represents a loss of redundancy for entry. But we can still do re entry. Will examine it if it happens.
Q: What if another GPC is lost ?
A: Loosing 2 prior to entry is a loss of redundancy but from a data processing perspective the shuttle can re enter but we will need to understand the nature of the failure. Loosing 2 is highly unlikely. Need to understand if there’s some systemic software issue.
Q: Could the shuttle re enter safely with 1 GPC ?
A: If we loose more than 2 we consider it a significant loss of redundancy that has safety implications and we would look at coming home at the earliest opportunity. Theoretically we could land with 1 GPC but it’s a situation we don’t want to be in.
Q: Have you lost more than 1 GPC in the past?
A: Not since I’ve been flight director. In the last several years the computers have been reliable. Any faults have been like the one we saw today we call it a “switch tease”
People were going a bit overboard about the GPC failure werent they ?
