Astronautical Engineering



Table of Contents

1. Personal Context

I grew up in the space race era but had no specific interests in it. My dad was a systems engineer on classified space programs, so I was aware but we didn't discuss.

Then I recently heard of a "rocket scientist" who thought other fields of intellectual pursuit were trivial compared to rocketry -- that they could be learned in 3 weeks. As a challenge I decided to study rocket science for 3 weeks. Thus this page.

2. Overview

Sometimes known as "rocket science". Covers getting into space, performing tasks there, and (usually) coming back to Earth. Since transport is done with non-air-breathing rockets, the field covers rockets used in atmosphere too (hobby, cruise missiles, etc.)

After early hobbyist efforts, and Germany flying bombs, the field was driven in the Cold War first by ICBMs and then by man-to-the-moon. The field struggled with complex technical problems, and solved them with enormously expensive designs. By the late 1990's however, rocketry had become an understood technology. The references below are essentially summations of lessons learned, at the tail end of the excitement.

We are now in an era in which rockets get to orbit routinely, and satellites can be designed and built by amateurs. Really complex missions (e.g., spy satellites with high resolution imaging and ability to thwart attacks) still require detailed work, but even that is supported by texts and design software.

The big picture design tasks:

  • Define the mission, and thus the rqmts.

  • Determine the "payload" -- the actual useful part of the mission. Cameras, radio beacons, anti-satellite laser cannons, etc.

  • Determine the location and orientation. E.g., spy satellite might fly really low and be able to retarget to get good images, while a broadcast communications satellite might be geostationary and just keep more or less in position.

  • From this determine the secondary propulsion systems. Typically, you get into LEO (low earth orbit) by some means and then use liquid fuels to get to the right orbit (e.g., GEO -- geosynchronous earth orbit) via firing a control rocket at the orbit's perigee. Then use compressed gas or ion jet or some other low-force mechanism to keep the payload oriented.

    You need enough fuel to maintain control for life of mission. Maybe even enough to decelerate the satellite enough to reenter the atmosphere, to burn out or recover by parachute.

  • Next, work out the (electrical) power rqmts and design. Might use a battery, or solar cells, or a fuel cell, or a thermionic generator. May need battery for when you are in earth's eclipse (night).

  • We now have the payload mass (dry mass plus propellants and electrical fuels). This must be pushed into LEO. That lets us pick the launch vehicle (there are quite a few, with different payload capacities). Each has its own diameter and fairing, so the satellite will have to fit inside that -- e.g., solar panels may have to be folded and then deployed when in orbit.

    Interestingly, the launch vehicles have specific required payload mass -- if your satellite is too light, they have to add ballast. This creates an opportunity for "nanosatellites" -- small payloads piggybacking on the main mission. "CubeSat" is a world of 10cm x 10cm x 10cm satellites launched in LEO via something like a spring-loaded Pez dispenser.

  • Generally you have to talk to the satellite to monitor its position, fuel reserves, mission status, and to give new instructions. This is done with telemetry, and normally performed by ground stations.

  • It takes quite a bit of radio sophistication to talk directly from Earth to a satellite (and puts a power load on the satellite), so sometimes a satellite relays to another satellite which (with more powerful radios and bigger antennas) talks to Earth. This also helps if your satellite is "over the horizon" from your ground stations.

    This relay can be done with a pre-designed "constellation" of satellites, or with a "cluster" of a lot of satellites each capable to talking to peers.

  • The cluster idea is also useful in combating system failures. Launch enough low-cost satellites so the system still works if a few are lost on launch and others are lost due to subsystem failures.

    If your mission can use this approach (e.g., the payload is cheap compared to the launch), then you can shift from hyper-expensive space-certified components to commercial components with a bit of sheilding. Mission costs drop, and so does the time from notion to launch.

  • After the mission you can just leave your system up there, but you might ram into it on your next mission. Such space junk or debris may be traveling (relative to you) about 10km/sec in LEO, or 0.5 km/sec in GEO. There is now general agreement to provide enough fuel to get satellites back to re-entry after mission life.

3. Technical Background

You need adequate math to handle systems of differential equations, spherical and elliptical coordinates, and the underlying math for mechanical engineering, electrical engineering, and chemistry. But you don't have to be an expert in each of these fields. Given the math, the texts below give adequate subject-specific material.

My impression of the rough equiv of typical degree programs is:

  • Orbital mechanics: BS engr or physics
  • Space environment (radiation, atomic oxygen, magnetics): BS engr or physcs
  • Rocket propellant chemistry: MS chem. It helps if you are also familiar with the chemistry of "double base" smokeless gunpowders.
  • Rocket design: MS mech engr, with experience in aeronautics for the nozzle design and in-atmosphere phase of launch.
  • Communications paths: MS elec engr, specifically radio systems, antennas, and error budgets.
  • Payload design (e.g., optics): BS engr, with specialized training as needed (e.g., optics). This may be extended with PhD level materials research -- e.g., getting an optically smooth surface while suffering launch stresses and atomic oxygen.
  • Computing (both design tools and mission software): BS CompSci. Much of the skill historically was doing a lot with very simple computers. ArduSat takes care of that.
  • Mission design: Experience as a systems engineer or systems architect, familiar with alternatives analyses.

If you have read my web pages (and their references) on math, physics, chemistry, and engineering, then astronautics will be do-able. Yes, "it is rocket science", but then again rocket science isn't quantum field theory.

4. Hobby Rockets

People have been shooting off rockets since long before Goddard, and there are still amateur rockets. They go up, they may take a few readings or pictures, and they come down. Weather balloons go higher.

Here are some representative sites:

5. Hobby Satellites

Amateur Radio folk put the first "hobby" satellites in orbit. CubeSat and ArduSat carry on from there. Representative sites:

6. Real missions

NASA and other national and commercial launch vendors have shifted from running big space programs to helping others do missions. This has a fuzzy boundary with hobby satellites. You get OSS software and NASA-provided mission analysis. Representative sites:


In military tactics, you want "high ground", to make gravity your accomplice rather than adversary. The ultimate high-ground is space-based weapons. ICBMs mark the apex of that path.

Once we humans realized ICBMs carry A-bombs and H-bombs, and that the only mutually assured destruction (MAD) can prevent their use, we shifted the target to man-to-the-moon, space telescopes, entertainment broadcasts, and of course spy satellites, as ways to use the technology. (Dreamers talked about colonizing the moon and mars, but no one with a pocket calculator takes that seriously.)

However... Drones (UAVs) are a cheaper way to get very high resolution visual, audio, and radio imagery. Drones are also better at unmanned long-range killing. Fiberoptics are better at high-speed communications. Cell towers are better at wireless.

The space business isn't going away. Satellites are good for spying on foreign nations and for the non-military spinoffs (e.g., earth sensing, weather, forest fires). The gluttonous military-industrial-congressional complex will tout those for every billion they can squeeze out of the citizenry.

Still, the single most important lesson from the whole space program was the sight of "Earthrise" over the lunar horizon. We have just one habitable planet, and we humans are making a real mess of it. Let's re-direct the space-race funding and enthusiasm to accomplishing sustainable living here on Earth.

8. References


CD Brown. "Elements of Spacecraft Design". American Institute of Aeronautics and Astronautics, 2002. ISBN 1-56347-524-3. 610 pp.

Like many of the others, this covers the whole mission design effort. However, it is notably good on orbital mechanics (including interplanetary trajectories), attitude control (keeping the vehicle oriented), and power system.


T. Furniss. "A History of Space Exploration". Lyons Press, 2003. ISBN 1-58574-650-9. 192 pp.

This appears to be a coffee-table picture book -- lots of pictures and not much text. But as you read, you discover the author actually knows the subject, and has strong opinions on what worked and didn't work. Worth reading for political/technical context.


V. Hardesty, G. Eisman. "Epic Rivalry: The inside story of the Soviet and American Space Race". National Geographic, 2007. ISBN 978-1-4262-0119-6. 273 pp.

This is insightful and hardcore history, covering both Soviet and American sides of the effort. I scanned it briefly. Important for historical context, but not for the technology of rocket science.



B. Elbert. "Introduction to Satellite Communication", 3rd ed. ARTECH House, 2008. ISBN 978-1-59693-210-4. 447 pp.

Covers a lot of material, but not thoroughly. From context, I get the impression that this is the book for non-tech managers to read so they have a clue what their tech people are talking about. Of course the book itself claims much more than that, but it doesn't stack up to the other texts.


G. Maral, M. Bousquet. "Satellite Communications Systems", 5th ed. J Wiley, 2009. ISBN 978-0-470-71458-4. 713 pp.

Theory and design practices for space communications. Includes telemetry for the satellite itself, ground stations, linkages among clusters and constellations for satellites, orbits, data protocols, et al.


GP Sutton, O Biblarz. "Rocket Propulsion Elements", 7th ed. John Wiley, 2001. ISBN 0-471-32642-9. 751 pp.

Details of rocket design, including mission rqmts (e.g., launch to earth orbit, change orbit, maintain orientation), physics and chemistry of propellants, design of nozzles, supporting issues (pumps, controls, testbeds, etc.).

This is the story on rockets per se.


JR Wertz, WJ Larson, eds. "Space Mission Analysis and Design", 3rd ed. Kluwer Academic Publishers, 1999. ISBN 0-7923-5901-1. 969 pp.

This is part of the "Space Technology Library". It is the single most useful book I found for both project management and technical. Other books specialize on one aspect or another, but this one is a thorough reference review.

If you can only read one text, this is it. If you can only read one chapter in this text, read ch 10 ("Spacecraft design and sizing"), which starts with mission rqmts and derives spacecraft and launch vehicle design.

Creator: Harry George
Updated/Created: 2013-12-02