870 Encyclopedia of the Solar System
2. Program Evolution
2.1 Launch Services
Sputnik, orbited on 4 October 1957, galvanized a huge re-
sponse from the United States. Less than 12 years later,
two astronauts walked on the Moon. However, in both the
USSR and the USA, it was an existing legacy that enabled
launch of the first satellites in 1957 and 1958. Strategic
weapons programs had had high priority in both nations
for many years.Sputniks,Explorers, andDiscovererswere
launched on early versions of intermediate-range and in-
tercontinental ballistic missile boosters. With modifications
and increasingly powerful upper stages added, these boost-
ers have continued to serve in both programs, up to the
present day, for sending spacecraft out into the solar sys-
tem.
Today, while the RussianSoyuzand AmericanAtlasand
Titancarry on as direct descendants of the early ICBMs,
they are accompanied byDelta(an IRBM derivative but
later vehicles with the same name are wholly new) the air-
launchedPegasus, and a whole suite of ex-Soviet vehicles
able to launch both smaller and larger robotic spacecraft
beyond LEO. The space shuttle was also briefly used as
a planetary mission launch vehicle for a period in the late
1980s and early 1990s.
In time, space mission developers in other nations,
driven primarily by a desire to have assured, indepen-
dent access to space but also by a desire for their own
organic technology advancement, began to provide their
own launch services, at first for low Earth orbit (LEO)
missions and later for missions beyond LEO, including
geosynchronous (GEO), lunar, interplanetary, and plane-
tary ventures.
In Europe, after some false starts with missile-derived
vehicles, the unique Ariane series of rockets, designed ex-
clusively for space, began and has now led to the creation
of the powerfulAriane V, capable of sending multiton pay-
loads into geosynchronous orbit and beyond.
In Japan, two separate lines of vehicles were developed,
one by the Institute of Space and Astronautical Science
(ISAS, primarily for science) and one by the National Space
Development Agency (NASDA, primarily for applications
and technology). ISAS and NASDA are now parts of the
Japan Aerospace Exploration Agency (JAXA).
In China, theLong Marchvehicle series began with
Soviet-derived technology but soon diverged into a more
indigenous form. In India, launch vehicles were developed
for both LEO and GEO applications missions.
The first LEO missions with human crews were launched
by Soviet and American ICBM-derived rockets. But when it
came time to send humans beyond LEO, far larger vehicles
were needed. The Moon Race of the 1960s saw the creation
of the giantSaturn VandN-1 (Fig. 1). Both of them have
now passed into history.
Following the end ofApolloand its Soviet lunar com-
petitor (which never flew successfully), both nations fell
back to LEO for human missions and both developed
partly reusable launch systems intended to service space
stations—the American space shuttle and the Soviet/
RussianBuran. The shuttle has carried many American hu-
man missions into LEO, butBuranflew only once, without
crew, and was then mothballed. The ancient and reliable, ex-
pendableSoyuzbooster continues to deliver crews, equip-
ment, and supplies to the International Space Station (ISS),
a successor to the American Skylab and the Soviet and
Russian Salyut and MIR stations.
The search for lower cost launch services, regarded as
a key to future space development, has led over decades
to the spending of resources equaling billions of dollars in
studies and aborted vehicle developments, with as yet no
promising result. However, work continues on a variety of
approaches including air launch, hybrid air-breathing and
rocket propulsion, and alternatively just extreme simplifi-
cation in booster design.
Even without a radical launch cost reduction, a human
breakout into the solar system is conceivable through the
use of extraterrestrial resources. With energy and especially
materials collected off Earth, in a manner that has come to
be called in-situ resource utilization (ISRU), great savings
are possible in the mass that must be lifted from Earth.
However, this technique has yet to be demonstrated at a
large enough scale for its true potential and its real compar-
ative costs to be known.2.2 Tracking and Data Acquisition
Without some way of delivering robotic mission results to
Earth, it does not matter what else works or does not work.
In the time before the invention of radio, space science fic-
tion authors assumed that signaling with light beams would
be used. In a way they were right: Optical communications
using lasers may yet become the method of choice in certain
applications. Meanwhile, however, telemetry, tracking and
orbit determination, command, and science in deep space
are entirely dependent on radio technique.
For the first satellites, tracking stations were improvised
based on previous military communications systems. For
missions to the Moon and beyond, however, it was necessary
to adapt methods used by strategic defense radar develop-
ers and radio astronomers. Huge antennas, supersensitive
receivers, transmitters with enormous power output, and
advanced data recording and processing all were needed.
From the outset, a difference in philosophy guided So-
viet and American deep space engineers. In the then se-
cretive USSR, the initial plan was to have spacecraft turn
on their transmitters only when over Soviet territory, thus
requiring ground stations in only the eastern hemisphere.
(In response to that, an American deep space signals inter-
cept site was built in Eritrea.) In the US, on the other hand,