on April 22, 2012
If you are a Star Trek fan, you know that Mr. Scott is the Starship Enterprise's Chief Engineering Officer; Captain Kirk couldn't do without him. Mr. Scott's passion is starships and their engines. When possible, he'd skip shore leave on some idyllic planet so he could study his starship drive tech manuals. He would have liked Long's book . . . .
Parts of the book are highly technical. How technical? There are 53 pages featuring one or more formulas to calculate exhaust velocities, specific impulses and etc. There are 40 tables of mission types, profiles and etc. There are 53 line drawings and pencil sketches of concept spacecraft, starships, propulsion schemes and etc.
For Mr. Scott, this book would be a look-back at the struggles of early 21st century engineers and scientist in conceiving of a means to traverse the immense distance to the stars. Their current spacecraft could only achieve a tiny fraction of the speed of light; flight times to the stars would be thousands of years. They were faced with a grand challenge . . . .
Walk before running: Sending humans to a nearby star would require huge massive ships; difficult to accelerate, with flight times longer than a lifespan and uncertainty of habitability of any planets at flights end. Human voyages should be preceded with probes; they are smaller, easier to accelerate, but will their instruments survive the long flight?
Crawl before walking: In Long's roadmap (Table 17.1), the way to proceed is with precursor missions to distances much closer to home. Each iteration would be further out, faster, and of longer duration. These missions - in Astronomical Units ( Earth's distance from the Sun) - would be out to 200 AU, and then 1,000 AU, and then 10,000 AU before trying for Alpha Centauri ( 278,261 AU ( 4.4 LY)).
The price tag for a probe to Alpha Centauri would be astronomical. As much as astronomers would be thrilled to get close-ups of this star system, it will be a hard sell to tax payers. The real driver of these future developments would be the discovery of an Earth-like planet: in size, temperature, atmosphere, and stable orbit around a nearby star, and then the clamoring to go will begin . . . .
Overall: This is a good compilation of ideas, many of which you may have seen before, if you follow this subject. The book is like a text book; it has exercises at the end of each chapter. It is not without errors, but then, what book is?
on March 13, 2015
Deep Space Propulsion is the title of the book, yet surprisingly little of it actually adresses this topic. The book contains a broad set of essay-like chapters about many topics, including spaceflight history, extrasolar planets and various means of propulsion for solar system travel. It also shows many concepts for spacecraft of various levels of sophisitication and quality.
However the style of the book is very non-scientific and inaccurate. The author creates many claims and makes "obvious" assumptions, which are by far not obvious. He e.g. states that it would be nonsense to assume that we would take 300 years of technological advance to reach Jupiter (with human crews), yet does not explain why he is of that opinion. Given the fact that we have not set foot on another celestial body for 45 years, this is not an obvious claim. And this is only one exampled, where the authors enthusiasm clouds his judgement and argumentation. most of the argumentation is made up of such biased assumptions and claims - the fact that one of the presented spacecraft concepts is basically the starship enterprise (include saucer section and warp drive) adds not to his credibility.
There are few formulas used and sometimes they are used profoundly wrong. For instance the author claims that from the equation for relativistic momentum it can be seen that this momentum becomes zero for v = c. But this is wrong and had he analysed this equation, which is even in his book, he would have realized that. It reaches infinity, the direct opposite (en.wikipedia.org/wiki/Tests_of_relativistic_energy_and_momentum). And therefore the whole argumentation of the author about this subject is invalid. This only adds to the impression of a very shallow level of sophistication and not to the credibility of the British Interplanetary Society. I recommend avoiding this book, which had a promising topic, but turned out to be lame.