Saturday, August 15, 2015

Mars is just a little bit closer now...

What follows is a tale told by an idiot, full of sound and fury, signifying...well...quite a lot, actually.

On a hot August day in coastal Mississippi, NASA and Aerojet Rocketdyne tested an engine which will help power America's next great rocket - the Space Launch System (SLS) - to destinations beyond low Earth orbit...something that no crewed vehicle has accomplished in more than 40 years. But first, a bit of exposition is in-order.

After the retirement of the Space Shuttle in 2011, and the cancellation of the nascent Constellation program shortly after that, many considered NASA to be 'dead'. In fact, I've spoken with several people who ardently believe that NASA was shut-down after the Shuttle program ended. Nothing could be further from the truth.

While it is true that no crewed launches have occurred from US soil since the Shuttle was 'put to pasture' (which is a shame...and perhaps a topic for a later blog entry), lack of manned flights does not equate to NASA being a moribund agency. The dynamics of spaceflight have changed in a relatively short time. No longer are rockets the domain of deep-pocketed governments - private companies are now competing to take cargo and crew to low Earth orbit and the Internal Space Station (ISS) is now host to many non-governmental experiments.

Where does that leave NASA if not to launch astronauts to the ISS? Exploration, that's where...and that's the purpose of SLS - to be an exploration-class vehicle to take humans back to deep space, and to destinations which were the domain of fanciful dreams just a few generations ago. In order to do that, hardware must be tested...and re-tested...and tested again. That testing and validation were the driving forces behind Thursday's test.

Complete RS-25 assembly.
Photo courtesy Aerojet Rocketdyne.
Not your grandfather's rocket engine
Though the RS-25 engine is essentially the same as the Space Shuttle Main Engine (SSME), there are some significant differences, key of which is the engine's "brain" - the controller. Many years have passed since the initial design of the SSME...and while it may have received an occasional update over the life the Shuttle, SLS required something a bit...'smarter'.

Aerojet Rocketdyne had been testing a modernized variant of the Saturn-era J-2 engine (the J-2X), which was to be used in the now-canceled Constellation program...and was in contention to be used as the upper-stage engine for SLS. Though down-selected in favor of the RL10, the modern controller from the J-2X could be modified to work on the RS-25.

Beyond testing the new controller, the engine will also be running at higher thrust levels than it did during the Shuttle's tenure...and the cryogenic propellants will reach the engine at a colder temperature and higher pressure. Though fully capable of pushing more power than it did on a Shuttle flight, engineers desired to not do so as the engine would be subject to greater 'wear and tear'...and since it was meant to be a reusable engine, that additional stress would result in higher costs.

However, since SLS isn't going to be reusable (other than, perhaps, the Orion crew capsule), engineers are comfortable pushing the engine harder, with each of the four engines producing approximately 550,000 pounds of thrust.

RS-25 in testing conditions on the stand.
Photo courtesy Aerojet Rocketdyne.
These go all the way to '111'
With the engines now projected to deliver 111% of the original design's thrust, a mighty roar was sure to be heard across the bayou of southern Mississippi. To quote a good friend: "Any day that NASA gives you ear plugs is pretty much guaranteed to be a good day."

This was to be my second static engine test, the first of which was for the upgraded Solid Rocket Booster (SRB) in Utah earlier this year. At that event, we were warned to not look directly at the exhaust plume. Thinking that the 2.5 kilometers between us and the booster should be sufficient to attenuate the blinding brightness, I chose to look at the exhaust. Ouch - the light...IT BURNS! I think I had spots on my vision for the next hour or so.

So, since NASA had seen fit to provide us with earplugs, I was not going to question the need for hearing protection - the plugs were inserted as soon as ignition time neared. Though I heard no countdown, certain visual clues indicated the time was near...well, that and the clock inched towards 4:00 PM, which was when the test was supposed to occur.

I guess you just had to be there
Through the cushioned protection of the earplugs, the engine roared to life with a mighty 'WHOOSH!' followed by a loud, sustained crackle and roar and cloud of steam. Nothing I've ever done in life could've prepared me for the visceral experience this engine test would be. Even the SRB test in Utah paled in comparison to the symphony of sight, sound, and feeling from the RS-25. While the SRB was a distant 2.5 kilometers away (about 8,200 feet), the RS-25 would be a scant 1,200 feet away.

While my expectations for sight and sound from the event were easily surpassed, I was wholly unprepared for the FEELING of the engine. Every crackle and thump from the engine was accompanied by a tangible pressure wave. I could feel it in my chest...I actually *saw* shirts flutter in concert to the waves...and this was only one engine! Imagine the cacophony which will accompany the four engines from core stage's full-burn test in two year's time.

I don't know if you watched the event live, or if you have since seen replays like the one below, but there is nothing - NOTHING - that can compare to the experience of being there. I am truly sorry that I lack the skill to convey the wash of emotions and feelings that I felt with this test. Yes, it was that impressive.

What's next?
NASA and Aerojet Rocketdyne will analyze the data from the test, and perform a few more tests and should wrap-up design validation before the end of this year. After that, the next big event will be the core stage 'green fire, which will be all four flight engines firing at once - something that hasn't happened at Stennis Space Center since the days of Apollo.

SLS is a big deal. It's big for's big for America...and, yes, it's big for humanity. The successful test brings us one step closer to the moon, to Mars, and beyond. I don't know about you, but I'm excited. The rumors of NASA's death have been greatly exaggerated. Not only that, but I think the agency's most incredible accomplishments may still be ahead of us. 

Monday, August 3, 2015

Nest Thermostat - a 1.5 year review...

Ah, the Nest I love it so. However, is it a love borne of a supportive, and useful, piece of technology...or that of the desires of a gadget fiend to sate the hunger of acquiring more in his 'tech arsenal'? Well, after having lived with it for nearly 18 months, I'm ready to give my verdict...but first, a little backstory.

The thermostat that I had been using was a simple, 'dumb' digital thermostat which was included with the new HVAC system I had installed in 2007. Why 'dumb'? Because all it could do was display the temperature and operate in the mode the user selected - heat, cool, fan auto/on, auxiliary heat. That's it. It wasn't even programmable. And, if I'm being honest, I don't think it ever really worked that well. But hey - it was 'free'...well, it was included in the $7,000.00 HVAC installation, so perhaps 'free' isn't the correct word.

Anyway, it had done its job...plugging away...helping to keep us cool in the summer and warm in the winter. Year after year, season after season, it sat there - stupidly - sending a signal to the HVAC unit to heat or cool as the condition warranted and then sending another signal to turn off when the temperature had been reached. Until one day it didn't.

One weekend morning in March 2014, I began to emerge from my slumber and heard the HVAC system running. It had been a cool night, so the fact that the heat was running wasn't unusual. After a few minutes, while still lying in the bed, I heard the system turn off. As I lay there, pondering whether or not to get up, I heard the faint sound of the heat re-engaging. Knowing that wasn't right, I immediately sprang up to check the thermostat - maybe one of the kids had messed with it...I hoped. such luck. The thermostat indicated that the system wasn't running, and that the inside temperature was several degrees higher than the set temperature...yet the system was obviously still cranking out heat. After several minutes of troubleshooting, it was apparent that the thermostat was to blame. I knew that installing a thermostat to pre-existing wiring was a pretty simple task, so I headed off to a home improvement store to get a replacement.

But what kind of replacement? Another 'dumb' unit? How about something a tad smarter - something that could be programmed? Or...maybe...that awesome piece of HVAC hardware for which I'd been lusting for a while: the Nest Learning Thermostat. But was it worth it? At $250, it is significantly more expensive than other, less "intelligent" thermostats...but it has a svelte appearance, and the gadget fiend in me *really* wanted it. After a few minutes of internal debate, I opted for the Nest and headed home, ready for a quick installation.

Prior to even needing a new thermostat, I'd watched several videos about it...and almost all of them made it a point to say how easy the Nest is to install. Having seen many people, of vastly different skill sets, install it, I had little trepidation about the task ahead. After removing the faceplate from the old thermostat, I proceeded labeling the different wires as to their function (labels are included in the kit). Labeling complete, I unfastened the wires and removed the old thermostat from the wall...exposing a large, ugly hole in the drywall, from which the bundle of wires emerged.

As I examined the set-up, it was obvious that I would not be able to mount the thermostat directly to the wall. Though unfortunate, as it would diminish from the aesthetics a bit, Nest had included a mounting plate for just such a situation. However, using this plate meant that the length of the wires was just a tad too short. So I had to get the wire strippers out to cut the cable sheath so the individual wires would be the correct length. It took a bit of finagling (that's a proper engineering term - trust me), but I eventually had the wiring complete and the Nest mounted. After a quick boot-up process, it was now time to configure it. Was installation as easy as I was expecting? No...but it wasn't that difficult, either.

Configuring the Nest was pretty simple. One connects it to their wireless network (you do have a wireless network, right?), answers a few simple questions, and then selects which mode to enable (heat, cool, heat/cool). One can get configure many, MANY more options via the web interface and/or the smartphone app.

Usability and Worth
OK, here is the information about which one is likely the most curious: How easy is it to use, and is it worth $250? To answer the first part, very. The settings, both on the thermostat itself and on the web/smartphone interfaces, are easy to understand and implement. Some settings - such as 'auto away' and 'time to temperature' - are only available once the Nest has had time to 'learn' the individual characteristics of one's home and HVAC system.

As for the latter part of the question, maybe. Yes, that's right - it might be worth $250...or it might not. It all depends on what one expects to get out of it. I hoped to see a noticeable decrease in my energy bill, but I didn't. Apparently, since I had set the Nest to the same temperatures that I had used on my 'dumb' thermostat, I was already in an energy-efficient 'zone'. Additionally, it is rare that my home is wholly devoid of people, so the Nest's 'auto away' feature was almost never utilized. Therefore, I was disappointed that I was unable to have the Nest 'pay' for itself in any real capacity.

However, I do enjoy being able to check, and change, the temperature from the comfort of my bed...or couch...or chair...or from halfway across the country. Not only can I check the temperature, but I can get a humidity reading, too...which was quite helpful this past Spring. Though the inside temperatures weren't bad, the humidity had risen to the point of concern for mold growth. Yes, I could "feel" that the humidity was high, but having definitive proof was definitely helpful.

Of course, all of this information at one's fingertips might also have a downside: I tended to micro-manage the HVAC settings. In a clever ploy to entice energy conservation, Nest gives a 'green leaf' indication on the thermostat if the settings are deemed to be 'energy efficient'. Much as an economy meter in a car may encourage one to drive with a lighter gas pedal, the green leaf may prompt one to turn the temperature up/down a few degrees to earn that coveted green leaf. I know I did that. In fact, I had the settings configured so that I earned a leaf EVERY DAY. I was in the top 5% of users in my area. Good, right?

Well, not so much. With all the 'good feelings' from the leaf awards, I could buy a coffee at long as I also had $5.00. In the meantime, the people in the house were miserable because the humidity was unbearable. I live in Georgia...and if you've ever been here, you know that we're not known for our dry summertime air. With the AC running less, there was little opportunity for the HVAC system to pull the moisture out of the inside air. Dropping the temperature by 1 degree Fahrenheit (from 78F to 77F) made all the difference in the world. Humidity dropped nearly 20 percentage points and the house was comfortable...but I lost my leaf. Though I still occasionally feel that competitive tug, I've since given up on earning any awards for energy conservation. I don't know if Nest *really* differentiates geographic areas in their definition efficiency...but if they don't, I think it's important they do so since 90F in Atlanta is far more uncomfortable than 90F in Albuquerque. 

I also feel that Nest is missing out on a key supplemental product line: remote sensors. Though our house has two levels, we only have one HVAC system. If Nest were to produce a remote sensor I could place in the basement area, the main thermostat may conclude that simply turning on the fan for 15 minutes to 'stir' the air might reduce temperatures enough to preclude running the compressor for a while. Seems like a simple enough addition to the line.

Would I buy the Nest Thermostat again, given the opportunity? Possibly...but I would also take a closer look at some of the other systems out there. Seeing as how I gained no savings by integrating a smart thermostat, the key selling point (beyond price) is going to be the device's feature set and extensibility. There are more competitors in the market today, and though Nest is still the frontrunner, they're no longer the only player in the game.