Acronyms, notations and symbols

Space Nuclear Systems: Introduction

Figure 1 - Solar irradiance (W/m2) in
the solar system, as a function of distance from the Sun

Figure 2 - Need for large solar panels to collect
solar energy for missions to explore outer planets (assumption of
30% conversion efficiency).

Figure 3 - 238Pu decay reaction (left)
and 238PuO2 pellet glowing under its own decay
heat (right)

Figure 4 - Radioisotope heater delivering 1 Wth,
weighing 40 g, overall dimensions Ø 2.6 x H 3.2 cm

Figure 6 - Illustrations of some of the iconic space
exploration missions that were only made possible by the use of thermoelectric
radioisotope generators (equipment circled in white).

Figure 7 - Principle of the neutron-induced nuclear
fission reaction

Figure 8 - Illustration of the sub-systems that
make up a space fission nuclear generator to power a spacecraft.

Figure 9 - Illustration of Kilopower: a space fission
nuclear power generator from 1 to 10 kWe (from [10]).

Figure 10 - Soviet BUK/BES-5 3 kWe nuclear generator

Figure 11 - Illustration of the SP-100 100 kWe nuclear
power generator

Figure 12 - Power range of the three types of terrestrial
power reactors and, by comparison, that of space power reactors

Figure 13 - Illustrations of the Westinghouse eVinci™
terrestrial microreactor (~ 5 MWe) and its 40 kWe &#34;derivative&#34; version
for lunar application.

Figure 14 - Minimum isothermal surface area required,
as a function of temperature, to radiate 1 MWth into space (assuming
an emissivity coefficient of 1).

Figure 16 - Illustration of a nuclear thermal propulsion
vehicle for transporting astronauts from Earth orbit to Martian orbit
(after [17]).

Figure 17 - Artist&#039;s view of the JIMO (Jupiter Icy
Moons Orbiter) nuclear-electric propulsion spacecraft project, identifying
its main components (from [22]).

Figure 18 - Diagram of a transport vehicle for a
manned mission to Mars, combining nuclear-electric and cryogenic chemical
propulsion.

Figure 19 - Comparison of the operation and performance
of two space thermal propulsion technologies

Figure 20 - Photos of ground tests of the NERVA
XE&#039;, a prototype nuclear thermal engine as close as possible to a
flight engine (taken from [25]).

Figure 21 - Illustration of the general design of
a nuclear thermal propulsion engine based on NERVA technology: the
SNRE (Small Nuclear Rocket Engine).

Figure 22 - Architecture of a nuclear electric propulsion
system equipped with a fission electronuclear generator, showing the
main sub-systems.

Figure 23 - Illustration of the NUKLEON, a.k.a.
Zeus, a 1 MWe nuclear-electric space transportation vehicle.