 Subunit 3.4, Phase B. The final phase in the formulation period, Phase B, focuses on developing detailed requirements from the high-lover requirements defined at the system requirements review and establishing a baseline system design that's consistent with all of these requirements. Phase B is also a time to complete any technology work required to ensure that all technologies are ready for implementation as you move forward in the life cycle. Phase B activities include generating detailed requirements that are consistent with the high-level requirements that were defined earlier in Phase A and approved at the system requirements review, completing plans for the verification and validation of the system, establishing a preliminary design that's consistent with the defined requirements, completing technology maturation activities to ensure that all technologies are ready to go for implementation, and developing a detailed plan for implementation that includes updated cost and schedule estimates. Again, at the end of Phase B, really what you're trying to do is make sure that you've laid out a really good plan to go into phases C and D into the implementation period, and that's what's going to be reviewed as you're kind of closing out Phase B. Are you ready to really proceed into implementation? I'm currently the project manager for the Transiting Exoplanet Survey Satellite Test. We were just awarded, we just started Phase B, and our mission is going to go in Earth orbit in 2017, and our goal is going to be to look for exoplanets around other stars, follow on more or less to what Kepler has been doing recently. So this mission is going to be fairly small. It's a NASA parlance, it's a middle-sized explorer mission, and maybe smaller than an SUV, but the goal here is to get this thing built and developed and flown within about a four-year time frame. So when you look at that life cycle, and you think about maybe for a human spaceflight vehicle, the life cycle might take 15 or 20 years, 10, 15, 20 years. For a mission like my mission, we might go through the whole life cycle in about four or five years, and so start to finish. And so we are very worried in Phase B about a couple things. One is technology maturation. So before we get into the part where we're going to build the spacecraft, we have to make sure all the technologies are mature and ready to go. On our mission, we have a couple of technologies. Specifically, if you see these four cameras on the front of the spacecraft, there are some technology challenges with optics and CCDs that have to be mature before we'll be ready to build this. And so during Phase B, before you get to the actual building of the spacecraft, we'll spend money to mature those technologies, maybe do some testing of them to make sure that, or under the vibration of launch, they won't fail or the heat of space and the cold of space, they won't fail. We'll do that testing now so that we'll have less risk once we hit the part of the program where we're going into implementation. So Phase B is key for technology maturation. When you get through Phase B, you want to know that all your technologies are ready to go. If you ever look at the technology readiness scale that's used by NASA, you'll see that TRL-6 is a technology readiness level where we have to have technologies proven that they can survive the environment that they will be used in. We could do that during ground testing, or you could do that by using heritage hardware that's already flown. But either way, you have to prove that all your systems are capable of surviving both the launch environment and the on-orbit environment. So we're working on that right now. And you're also working on deciding what you're going to probably make and what you're probably going to buy. Some components we're going to build in-house, some components we're going to go out to different manufacturers, vendors out in and just buy certain parts of the spacecraft. We're deciding right now is, again, we have this one concept. What are the things we're going to make? What are the things we're going to buy? We're also doing some trades. So there are trade studies involved in Phase B. We're looking at things like, you see this big sunshade. There's a reflective gold sunshade up on top of the cameras to keep the light and heat of the sun out. We're looking at whether we should make that a little bit taller and whether we should redesign it to a different shape. We're looking at the advantages and disadvantages. The key to what Phase B is all about is, are there some tweaks you want to make to this design to optimize it? So Phase B is a big time for trade studies, technology maturation, and making sure that you're ready to go into the implementation part. The primary technical review during Phase B is a preliminary design review. Now, at this point, the system is getting more and more detailed and you're breaking the system down into smaller and smaller pieces to be able to work them. So at this point, what preliminary design review is going to, as it states, is going to be a review of your preliminary design, preliminary design of the entire system. Now, before you hold a preliminary design review, you may actually hold a series of either subsystem preliminary design reviews or sometimes at NASA we call these smaller increments peer reviews where you'll actually maybe have a small review of one part of the system and make sure the requirements and the design have matured in that area. And then after you've held that series of smaller reviews, then you'll hold a full system preliminary design review. So preliminary design review, we're going to use it as a single review that happens at the system level and that's where we're going to talk about it. But you've got to remember that prior to this, because you've now broken the system down into so many small pieces to be able to be worked at the detailed level, that there may be a whole series of technical peer reviews going on to ensure the system is mature enough at the small levels before you actually try to hold this big system level review. But let's talk about what's in the system level review. So you are going to go through and look at your detailed requirements that you've been developing in phase B. So there's requirements, some constraints, and there's performance measures or values that you've put on how much thrust do I need to be able to get out of the thrusters? How much power do I need to be able to get out of the battery? These are performance measures, things you've defined that says, you know, whatever components I end up using have to be able to perform at a certain level to be consistent with how the system needs to work overall. So all of that will be reviewed at your preliminary design review. Remember at the system requirements review, you define high level requirements, maybe call them level one, two, and three. They're very high level set that come down from the system objectives. Here you're going down to much more detailed requirements like all the way down to, for each component of the spacecraft, whether it be a battery, whether it be a thruster, what are the specific requirements for every piece of the system. So when we say detailed system requirements, that's now the level you're down to, is that at preliminary design review, you've defined all the requirements that are going to be required to make or buy every component of the spacecraft, and that's the level of detail we're talking. The flow down of requirements from those high level requirements has to now be completed all the way down to these low level requirements, and there needs to be some traceability back up to the system objectives. So if I say I need a thruster that performs with a certain performance level, I should be able to tell you that in the end, I can trace a path all the way back from that detailed requirement for the thruster all the way back up into the system objectives that says, yes, this is the right thruster requirement to be able to meet those high level objectives. So if you understand, at the end there's going to be many, many, many requirements at the detailed level, but all of them should be traceable back up into how they help you meet that overall set of system objectives that the stakeholders define way back in pre-phase A. You're also going to review your high level internal and external system interfaces, make sure that they've all been clearly defined, and now these interfaces will go to very detailed levels between components of the system. You also, in this review, show that your preliminary design is expected to meet all these requirements that you've defined at an acceptable level of risk, that there's nothing that you're going to have to do. Maybe this review team is going to be looking for areas where maybe you've defined a requirement that's going to be very, very difficult to meet with the technologies that are available in the marketplace. And so if there are those kinds of areas, maybe you have to do some assessment of if that technology can't work and it doesn't end up working out. Maybe I have a fallback that can't quite meet the requirements, but it can almost meet the requirements and I've identified what impact that would have in my overall system performance and my ability to meet objectives. And so the review team is going to be looking to see that you've got this design that they think could really be matured through implementation at an acceptable level of risk. And risk here could be defined as, you know, within the amount of money and schedule and again, being able to meet technical performance. That's what they're going to be looking for. They're also going to be looking to see that all your required technology maturation activities have been completely done and that all of your testing of technologies has been completed and that you're ready to go into implementation. They're also going to be looking to see that the results of any actions that they gave you back in your mission design review, again back in phase A, have been completed so that you're ready to go and you have no further things to close out as far as actions from the previous review. There are no additional resources for this subunit. Feel free to skip ahead to the next video.