Nebula
Newsletter of the Leeds Astronomical Society
October 2016
Volume 44 Number 2
INTERSTELLAR TRAVEL WITHIN OUR LIFETIMES? – MAYBE!
by Chris West
It sounds absolutely incredible, I
didn’t quite believe it myself at the
time of reading about it on the
BBC Science and Nature website,
but, it’s true! There are plans to
send a multitude of ‘nano probes’
fitted with scientific data recording
and observational equipment to
Proxima Centauri at a velocity of
around 20% of the speed of light
sometime in the 2030s. After a 20
year journey, the probes would
reach the Proxima system and start
collecting spectrographic and bio-
chemical data of Proxima and any
planetary bodies in orbit around
the star.
But, first, a bit of background in-
formation on humanity’s dreams to
reach other star systems from our
own Solar System. A few philos-
ophers and intellectuals since the
Middle Ages have speculated that
there was an infinitude of stars like
our Sun out there in deep space,
such as Nicholas of Cusa, who
lived in the 15 th Century. In time,
the distances of some of the stars
began to be worked out more pre-
cisely than in earlier times. By the
19 th Century, the first stellar paral-
laxes were accurately worked out.
With the coming of the 20 th Centu-
ry, rocket engineers and propulsion
experts began to take very serious-
ly the possibility of humans
launching starships, within a cou-
Inside …
Artist’s impression of nearest exoplanet, Proxima Ce ntauri b (ESO)
ple of centuries, to the nearest
stars to our Solar System. E.E.Doc
Smith popularised the idea of the
interstellar drive, which could uti-
lise a fictional device named hy-
perspace, allowing starships to
jump from one star system to an-
other within seconds and circum-
venting the limitations imposed by
the speed of light limit within
normal space. By the 1940s and
50s, later, younger science fiction
writers such as Isaac Asimov, Ar-
thur C. Clarke and Brian Aldiss
carried forward and developed the
idea of whole galactic societies,
made possible by starships star-
hopping through this weird hyper-
space.
In the 1960s, propulsion experts
like Dr Robert Bussard in the U.S.
proposed what was named the
Bussard Ramjet, a fusion rocket in
which a huge scoop would collect
the diffuse hydrogen in interstellar
space, ‘burn it on the fly’ using a
proton-proton chain reaction, and
expel it out of the back. This craft
could, theoretically, accelerate to
near the speed of light, thus mak-
ing use of time dilation effects in
order to shorten the duration of
journeys to other stars for any fu-
ture, intrepid, interstellar explor-
ers.
Alpha Centauri lies at a distance
of 4.37 light years. It consists of
three stars; the pair Alpha Centauri
A and Alpha Centauri B, and a
small, faint, red dwarf, Proxima
Centauri, that may be gravitation-
ally bound to the other two stars.
Alpha Centauri A has 110% of the
mass and 151.9% of the luminosity
of the Sun, and Alpha Centauri B
is smaller and cooler at 90.7% of
President’s piece page 3 Blast from the Past page 7 The Sun
Galactic Mergers page 4 Passage of Ti me page 8 Solar System Cycling page 11
Pluto’s Name page 6 ‘Big History’ page 9 Observi ng Reports
page 10
page 13