Butler Hine, Project Manager, LADEE, Ames Research Center, Moffett Field, CA
- Friday, 01 November 2013
NTB: What has been your day-to-day work with LADEE? And how does that change now?
Hine: Before launch, it was all about the development of the spacecraft, the development of the launch vehicle, the range preparations. We spent all summer out at Wallops doing testing of the spacecraft and integration with the fifth stage and encapsulation into the fairing. We spin balanced it. We checked out its propulsion system.
In the meantime, back at Ames, the mission ops team was doing readiness testing. They were doing rehearsals, they were doing simulations, they were getting ready to operate the spacecraft. And then after launch, all of that changes. You’re no longer in development. You’re actually flying the spacecraft.
Since Friday night, we’ve been very busy doing the initial characterization and tests of all the subsystems on the spacecraft: learning how to fly it, learning all the quirks that you suspect on the ground but never can confirm until you actually get into space. We had our first main engine burn yesterday [Sept. 12] to characterize the main engine and make sure that we could depend on it before we really needed to do the burns for real.
NTB: What were some of the other “quirks” that you noticed?
Hine: Right after we launched, when we first woke up, we noticed the reaction wheels were off. That was because of our fault protection system. It actually did its job. It detected something that it didn’t like and turned off the reaction wheels. Of course, when you’re first waking up after a launch, that gets your attention right away. So that took us about two hours after launch to figure out the proper settings for the fault protection system, and then rest the wheels and turn them on. After that we were operating just fine, but I think it was on Monday, we were in a thermal conditioning mode prior to doing one of our test burns, and in that thermal conditioning mode, we went into safe mode because of the two star-tracker cameras onboard. When the sun was going through the field of view on one of the star trackers, an alignment offset between the two star trackers made the spacecraft think that it had an anomaly. Of course, fault protection is designed to “safe” the spacecraft anytime it sees something that’s unusual. We went into safe mode there, and we discovered what the issue was with the alignment offset, the cameras, and uploaded a new alignment matrix to the spacecraft, which took care of that. Those are the kinds of things that you do when you first wake up and are first characterizing your spacecraft.
NTB: What are your next priorities now that you’ve had a successful launch?
Hine: The next big event is on Friday [September 13]. We’re going to do a perigee maneuver. The way we get to the moon is not a direct trajectory. We go into these elliptic orbits around the earth, and with each orbit, we boost the apogee. By the third orbit, we boosted the apogee far enough where the moon swings by and captures us. We’ve done our first apogee, and now coming up on Friday is our first perigee. At that maneuver, we will do the burn of the main engine and boost our elliptic orbit, but a little higher. So we do three of those before we get to the moon. Right now we’ll do those elliptic orbits for the next couple weeks and then starting Oct. 6, we’ll do our lunar orbit insertion maneuvers.
NTB: Looking back to the summer when you were building this, what would you say were your biggest technical challenges?
Hine: Whenever you have a small spacecraft and a big engine, one of the things you worry about is whether you’re precisely lined up on the center of gravity. So one of the big activities this summer was to spin balance it, and that means you take the spacecraft dry and you put it up on this spin table and you spin it at high speeds. So it’s kind of a nerve-racking moment. You’re taking your “baby” and spinning it very fast. Then we balance it. We do precise balancing of it to get the thruster alignment right over the CG. Then you fill it with fuel, which is also very exciting, because you’re actually putting fuel and oxidizer in the tanks, and then we spin it again because we want to make sure that the thrust alignment is along the center of gravity with a full fuel tank. Those were the most exciting moments this summer were spinning and then fueling the spacecraft.
NTB: How will this work help guide future missions?
Hine: We have a laser communications experiment on board. This is a very promising technology that’s going to be important for NASA in the future. The laser comm onboard the spacecraft will talk to the Earth and transmit data at roughly 622 megabits per second from the moon. That’s kind of the heart of an interplanetary trunk line, where instead of radio communications, we can use optical communications and get a whole lot of bandwidth back. That’s an important technology, and that’ll be used for lots of missions in the future.
As far as the science that we’re getting with our science instruments, any type of basic science to understand the environment of the bodies you visit will help future spacecraft. [LADEE will] characterize the dust environment of the moon, so that when we send other spacecraft to the moon, we’re more aware of any problems or issues and can design around them.
NTB: What is your favorite part of the job, specifically working with LADEE?
Hine: I enjoyed the whole thing. I have a phenomenal team, and working with these people has been a real joy. This is a really hard working group, and I really enjoy every moment working with these folks.
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