Month: August 2012

I was watching the Mars Science Laboratory Lander (@MarsCuriosity) land and I thought about some of the discussions that had occurred during the NASA Social meeting to celebrate the 50th Anniversary of Cape Canaveral. We had people from the launch teams join us for some discussions. One of the comments that @NASA_Caley made resonated with me, “There are 7 minutes of terror for landing. For launch, we had 44 minutes of terror.” She then went on to explain all the things that were thought of in the process of planning the route for Curiosity.

I am sure that my post will gloss over some things, but I am still reeling at how many things had to be accounted for.

Let’s say you want to send a projectile (Curiosity) from a source object (Earth) to a destination object (Mars), what do you need to consider. Well first you need to think about the location of the objects relative to each other so that you can point the projectile in the proper direction. But what is the right direction?

If the two objects are stationary it is pretty easy, just aim from one toward the other. If the objects are rotating at different speeds, it gets more challenging. The Earth revolves around the Sun in basically 365.25 days, Mars since it is farther away makes the same revolution in approximately 688 days. As a result the relative position of the two objects changes constantly. The knee-jerk reaction is to say to send the projectile when the two objects are closest to each other. So let’s declare two basic variables, location of source, location of destination.

Oh wait, that is really a more complex variable than those simple statements of source location and destination location would indicate. These objects are not just spinning around the star at the center of our solar system, they are also spinning around their own axis. Their axis and orbital paths are also not perpendicular or parallel to each other. So these locations are not in one plane with just X & Y coordinates but actually in three axises.

Seems to make sense, the locations relative to each other will be the shortest distance and the shortest travel time. Yes, travel time, a new variable. The travel time has to be accounted for as the objects will move relative to each other as the projectile travels from the source to the destination. The easiest way to think about it, is leading a target, many of us do it while playing video games, or shooting rubber bands at people. So you have to account for the amount of time to get from Point A to Point B while both points are moving. You definitely need to know the speed of the projectile to know the travel time.

The speed of the projectile is not a simple value, it is also another variable of the equation that needs to be considered. The obvious answer is to make things travel as fast as possible. However there is always a trade off. To make things move quickly requires lots of thrust. So you need to have more fuel to allow for more thrust. Fuel has mass which means that you need more fuel to get that mass in motion. The designers need to determine the proper balance between speed, launch weight, and time to travel to destination. Don’t forget to include the mass of the projectile in there. Hopefully the mass has been determined but it might still be in flux. Is that one variable or four variables? I would say it is three interrelated variables, as the designers will work within a mass budget. What about the time it takes to get up to speed? I guess we can just use average speed… that 44 minutes of launch is not that significant compared to the approximately 253 days and 14 hours of cruise. It is just 0.012002182215% of the total time. That is tongue in check.

While leaving Earth there are some other things to consider. Such as not hitting the International Space Station or other satellites. Plus one also has to consider the biggest satellite out there along the way, the Moon. We have to steer clear of that, and its gradational pull. Wait we can use its gravitational pull to speed us up some more or to adjust the course.

So as you can see just a little math.

This math was done and allowed for landing within 1.5 miles of the desired landing site after a journey of approximately 350,000,000 miles. Yes, they can do some adjustments in flight, but those have to be calculated as well. To put this in perspective  to get the same resolution you would need to land on a single human hair (0.04mm) from 14km (8.7 miles) and not hit anything, seen or unseen, during the flight.

Did you remember to compensate for the satellites going around Mars?

Pretty impressive. It isn’t rocket science, it is math and physics.

Faithful followers may have noticed that recently there has been a large amount of NASA and space related content from me. Some people think that this is new, in reality it has been an interest of mine for most of my life. One of the earliest experiences I can recall is watching the launch of the American half of Apollo-Soyuz in July of 1975. It is so clear to me, I even remember the room I was in at home down to the orange carpet.

My grandfather worked as a civilian  at Fort Monmouth as part of the U.S. Army Electronics Command (CECOM), my understanding was in the Electronics Technology Laboratory. I remember us building models of TIROS satellites and talking about how relay communication worked when I was younger. He would share all sorts of stories and technology with me. I even had a jumpsuit like an astronaut that either my mother of grandmother made me. I even remember taking my first plane trip when I was six years old to visit my aunt, uncle, and cousin in the Washington DC area to go to the Smithsonian Air and Space Museum. From that same summer I remember the MacNeil/Lehrer Report about the Viking landings in 1976. One of the few toys/game I miss from my youth was a puzzle I got at the Smithsonian Air and Space that showed all sorts of facts about flight and space. I used to put that puzzle together all the time. It was not just to put the puzzle together and see the pictures, it had text on it so I could read about the X-15, the Wright brothers, and things in between.

In the early 1980’s I was fanatically following the Space Shuttle Project. I clipped articles and read magazines and covered my walls in articles and pictures. One of the cool things was I once again went and visited my family in the Washington DC area. My aunt worked in the Department of Education and luckily for me happened to be in a shared building with NASA. So that day not only did I get to go to the Smithsonian Air & Space Museum again, I also literally got to walk the halls of NASA. How cool was that. I remember looking at the pictures on the wall and being awe struck. The coolest thing was that my aunt found some posters for me of the Space Shuttle. I mean original when the external tank was white. I also did all the typical space fan things such as building model rockets purchasing telescopes and sky gazing. My grandfather coached me through some math puzzlement so I could learn more.

Then came high school, I can remember sitting in biology class when the Challenger explosion occurred. Literally down to which seat. It was a sad day.

Once NASA got flying again, college and girls started to fill my attention. I was still interested in technology I just did not have as much time. Unfortunately at that point space flight got to be “common place” and I was not following it as much day to day or project to project. Through my job as an audio integrator I got to work on projects at the KSC Visitor’s Center, including the Saturn V Experience. Since I was living in Florida I went to a few launches.

I still watched and read quite a bit about space and space flight, but more of history than current. I read and watched The Right Stuff, From the Earth to the Moon, Lost Moon … etc. So I never lost the interest, I just was not as actively studying it and following. Then a friend of mine got selected to take part in a NASA Tweetup Event for a launch. I started following space more and more. I subscribed to the NASA twitter streams. I started getting the daily news letter. I would stream NASA TV when hockey wasn’t on. It started creeping back in. Heck the last three books I have read are about space.

I kept entering for chances to take part in NASA Socials (the new name for tweetups as it is not just twitter). I kept on not getting selected, however I kept entering as hope spring eternal. Then came the one that I finally got picked for,”Celebrate Kennedy Space Center’s 50 Years of Human Spaceflight“. I would get to see the cool stuff you don’t get to see during the normal tours. I would get to go to the place where the program got off the ground. There was not a moment of hesitation I would be going, the hesitation was how would I pull it off.

The Lovely and Talented Wife (a.k.a. @GentlyMad) said she would help with the driving. Flying was cost prohibitive and driving approximately 20 hours each way on my own did not seem like a good idea.  But it was on, I told the boss I was taking three days off and off we went.

Now comes the back half, digging out from the 1,000+ pictures I took and trying to capture as much of the experience as I can in words. So in the new few days and weeks expect to see heavy amount of space content coming. I expect the trend to continue for a while. Actually to quote the L&T Wife, “I hope the space bug continues”. So if you will excuse me, I have to go pack for another business trip, upload some photos, review some photos, and watch Mars Curiosity landing coverage.

Originally posted: August 5, 2012