A couple of shots in the cosmic shooting gallery

Quite likely, most people in the US and around the world could care less about today’s fly-by of asteroid 2012 DA14. Today’s meteor burst over Russia is another story.  It is important to state that these two events are completely unrelated.  Purely coincidental that they should happen on the same day.  One of them, we knew about in advance, and there is TV coverage to go with it.  The other one completely took us by surprise.

If 2012 DA14 has any chance of hitting at all, the earliest opportunity will be in 2080. And the chances are 1 in 4,762,000.  (Orbital and impact info)  Today, around 11:25am PST (2:25pm EST / 19:25 UTC), it is making a close approach at 17,500 miles (27,600 km) above the Earth’s surface. Fortunately, it is well clear of the orbit of geosynchronous communication satellites. JPL has announced that NASA Television will cover the event.  (Live coverage at: NASA TV and JPL Ustream)

A few hours before its arrival, a meteor hit the atmosphere of the Earth over Russia’s Urals region.  A few hundred people were injured and there was some broken glass.  The Earth’s atmosphere was thick enough to cause the meteor to burst before it could hit the ground.  The resulting shock wave caused the injuries and property damaged that followed.  (CNN story)  Various sources report the original size of the rock to be about 10 tons.

Below is amateur video caught of the meteor entering the Earth’s atmosphere.

In fact, the Earth is swimming in a cosmic shooting gallery.  How many bullets or pellets are swimming around with our planet’s name on them?  Our catalog of asteroids has dramatically increased in recent years.  Scott Manley, a hybrid of astronomer and game nut, has put the discoveries to music.  Note the red dots are the ones that are potentially hazardous to Earth.  The dots are very small.  You may not be able to distinguish them on a small screen.  You will notice a vast difference when you play the video on a screen with HD resolution.

Marcia Smith, a respected analyst who writes SpacePolicyOnline.com has posted her own commentary regarding the two events.  She also provides a pointer to Phil Platt, of “Bad Astronomy” fame, who is collecting photos as fast as he can.

I’m continuing to collect notes about near Earth objects, particularly asteroids, and what we might do about it (as one of my spare time activities).

A month of drafting (and why would I do this?)

Here’s a piece of artwork that is probably familiar to many who are learning to do drafting and design by computer.

CDI60-Proj1-CustomerAssembly

There is nothing special about it, except that I drew this one, following the instructions in the workbook as precisely as possible.1 Actually, I drew half of it. The thin vertical plate, with two bolts, the rod it attaches to, and the guide assembly in the foreground were drawn by me. The vertical block in the back and the darker plate that it connects to were provided as part of the homework exercise.

This drawing is the result of about four weeks of CAD practice using SolidWorks. Half of this was done in the CAD lab at De Anza College, in Cupertino, California.2 The other half was done on my home machine, which I hastily modified to run Windows 7. To my surprise, I was told that SolidWorks requires Excel to manage its bill of materials. The user interface on SolidWorks, and many other CAD programs, is very rich.  By comparison, simple spreadsheet functions (not full Excel) are fairly trivial.

For those of you who think that I am primarily a computer scientist who is picking up engineering, that is perhaps partly true. On the other hand, my diversion into computer science started from engineering.  Decades ago, I grew up using mechanical drawing pencils, T-square, right triangles, a variety of scales, compass, and French curves. (The latter refers to a piece of plastic, not a people or person.)

All this was well before the invention of the personal computer. The programming I did professionally started on IBM System/370 and Amdahl 470  computers, although I had learned on IBM 360.  There was no AutoCAD, no Adobe Photoshop or Illustrator.  These tools came much later with the invention of the raster graphics workstation.  (By contrast, there were tools like CADAM, but I’m told they required mainframe computers.)  So in doing nearly four decades of computing, I managed to miss the computer-aided drafting and design revolution. A better way to say it is, I knew about the revolution, but I had no access.3

Why SolidWorks?  Why not Creo or AutoCAD?  The simple answer is that most of the aerospace groups that I’ve personally dealt with in the last three years were doing mechanical design using SolidWorks. Both SolidWorks and Creo (formerly Pro/Engineer) are parametric modeling tools.  So is AutoDesk Inventor.  AutoCAD is not.

After a career of computing, with an excursion into VLSI design, why do this now?  There are several reasons for this.

  1. Back in high school, you could divide up prospective engineering students taking shop courses into two major camps: those with electrical circuit skills and those with mechanical design skills.  I was in the latter camp.  I would much rather deal with Newton’s Laws than Kirchhoff’s Laws.  (A couple of decades later, I decided that a serious engineer should be grounded in both. However, I should caution that I know very few engineers who actually deal in both.)
  2. In recent years, I’ve gotten into discussions with aerospace people about various aspects of vehicle design. This includes small launch vehicles, and small satellites and making them survive re-entry.  We’ve even talked about exploration of planetary bodies and their moons with dense atmospheres.  One of these projects is progressing beyond the design concept phase.  I’ve discovered that in doing a vehicle design, I am very hampered by not having a drafting table or CAD software.  Furthermore, analysis of some of these designs will require computerized finite element methods.
  3. The technology of 3D printing (also known as additive manufacturing) is emerging beyond rapid prototyping.  Industrial use of 3D printing is taking off, and consumer 3D printers are beginning to emerge.  For space exploration, it is even more important.  It provides an alternative to continually bring up finished products from Earth to orbit, and then launching them onto interplanetary trajectories.  It makes more sense to process raw material in very little gravity and energy, and utilize the resulting feedstock in 3D printers to create space structures.

For the immediate future, my goal is to work on small vehicle designs and hopefully explore 3D printing.  And perhaps design my own furniture.

Footnotes:

1. The design exercise for the drawing is from Engineering Desgn with SolidWorks 2012 by David C. Planchard & Marie P. Planchard.

2. Yes, I now have a real student ID card and student parking permit.  And I am feeling the pain of homework deadlines.

3. Strangely, in the late 1980s, I ended up working with senior designers on full-custom design of VLSI circuits. For a while, I had pretty good access to VLSI CAD, although I didn’t have any prior training in the field.  A little over a decade later, I supplemented that with courses in VLSI and ASIC design.