Pab Pa

This then gives an estimated probability of P(A B) 3.08 x 10 4 for any G-class star containing a bio-active planet. This number is likely to represent an approximate upper bound on the probability for the occurrence of Earth-like planets within extrasolar systems based on current data. The perturbing effects due to the higher eccentricities found in extrasolar gas giants has not been included in this analysis. This further indicates nothing about how solar systems are...

L M v

Where e is the eccentricity of the orbit and J is the angular momentum of the orbit. This may be further written as e GM 2a where a yf e2 1) is the semi-major axis. This is an important result in classical mechanics The energy of an elliptical orbit depends upon the semi-major axis. Hence for a planet its energy mass is e -v2 r GM r and the same energy per mass obtains for a spacecraft in this kissing orbit at its semi-major exist e GM 2a2. It it then apparent that the delta-vee required for...

Electromagnetically Accelerated Nanobots

A hot topic in advanced technology in these early days of the 21st century is nanotechnology. While the future trajectory of this technology is very uncertain, it is worth writing a short chapter on the prospect for the use of these as interstellar probes. Nanotechnology is the engineering of systems on the molecular or near molecular scale. These systems are computers with an instruction set encoded on molecules, in a way similar to what nature provides with DNA. These instructions are then...

Special Relativity

In spite of the success of Newton's three laws of motion for two centuries some problems began to arise. These problems were the absence of an aether electromagnetic waves were though to travel on, a precession in the orbit of Mercury not accounted by perturbations from the other planets, and the inability of classical physics to account for the distribution of light frequencies by a non-reflecting hot body, called a black body. The last of these loose threads in the physical world view was...

Eph rmc J l

Below is a table that compares gammas with the fraction Eph mc Equations 8.5 and 8.6 indicate the need to reflect a lot of photons Assume that this sail craft is powered by some solar collector near Earth. If the collector is near Earth there are about 1500 watts m2 of power of solar radiation. For a year as 3 x 107 sec a meter would collect 4.5 x 1010 J. So the mc2 equivalent is about 5 x 10 7 kg. So collecting area is important. To reach a y 2 in one year requires an area of around 1.7 x 106...

R n F

The angle of the radial vector along the lens would be 0 2 r R. which for n 1.5 it is easily found this lens will have a thickness of 60 m. Obviously this is not practical due to the huge mass of such a lens. However, a Fresnel lens will work. The material set into concentric Fresnel zones which act as a slice of the lens at some radius. The sum of these over all concentric zones will concentrate light in the same fashion that a single lens does 8.2 . This technique is used...

The Interstellar Neighborhood

This chapter discusses possible destinations for low gamma spacecraft. There are a number of G-class stars accessible to low gamma spacecraft. These might have terrestrial planets worth exploration. Most of the nearby stars are M-class red dwarf stars. It is unlikely that biologically active planets exist around these stars. However, since they make up the largest number of stars in the galaxy they are still systems worth a close examination, possibly by a starcraft. The stars within 10 light...