Post by Jochem HuhmannPost by Pat FlanneryBut the first practical test of an ion engine was only a two years ago
after decades of easy, safe ground based lab research.
No, there was Deep Space 1, and decades before that SERT II (although
the NASA PAO seems to have oddly forgotten that mission when it was
http://www.grc.nasa.gov/WWW/ion/past/70s/sert2.htm
And I even dimly remember some russian, err, soviet mission with an
(experimental?) ion engine much earlier... can't find it right now. It
was some interplanetary probe, I think.
Jochem
--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take away."
- Antoine de Saint-Exupery
Soviet Mars Propulsion - Nuclear Electric topic index
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Nucear electric ship
Credit - © Mark Wade
The serious development of nuclear electric propulsion began after
issuance of the decree of 23 June 1960, as a result of which ten design
bureaux and other organisations tackled technical questions related to
its development. OKB-1 specialised in theoretical studies, experimental
tests, materials technology, and equipment trials (including reactors).
Korolev decided to collaborate with TsNII-58 (Chief Designer V G
Grabin) for the reactor. This design bureau had designed the water
moderated reactors which were already providing power in Tashkent,
Riga, Kiev, Alma-Ata, Hungary, Rumania, DDR, Czechoslovakia, and Egypt.
Grabin was at that time developing the first experimental fast neutron
reactors using liquid metal cooling (SR-1 and SR-3) which were in
operation in Obninsk at the Physics-Energy Institute (FEI).
In the beginning, development and test work was oriented towards
providing power for an electric engine for manned interplanetary
flight. The nuclear electric engines for the initial TMK-E Mars
spacecraft design of 1960 used 7 MW of nuclear power. Later reactor
research was expanded to cover application of nuclear power for
scientific, economic, and military objectives in space.
OKB-1 and FEI studied various methods for transforming the reactor's
thermal energy to electrical energy to power the engine (steam
turbines, gas turbines, MHD, and direct thermo-electric conversion).
This analysis indicated that direct thermo-electric conversion was
clearly the best approach.
First stage testing of nuclear electric propulsion began in 1962 and
the original draft project N1 of that year foresaw the use of this form
of propulsion in multi-module orbital base stations and interplanetary
spacecraft. In 1965 Section 12 (Manager I I Raikov) of OKB-1 completed
work with FEI on a draft project for a nuclear electric propulsion
engine YaERD-2200 for interplanetary crewed spacecraft. The YaERD-2200
consisted of two independent stages. Each had a nuclear reactor and an
electric engine, with electrical output of each being 2,200 kW and
total thrust 8.3 kgf.
The engine featured direct thermo-electric conversion using a fast
neutron reactor; a coolant system using low activity isotope Lithium-7
in a single loop shared by both the reactor and engine; and an electro
plasma engine with an efficiency of 55% and a specific impulse of 5500
sec
The reactor / engine design was upgraded to 5,000 kW total power in
1966-1970. The revised design could be used in single block (YaE-1 and
YaE-1M) and multiple block (YaE-2 and YaE-3) applications. A single
Block YaE-1 would have an electrical output of 2,500-3,200 kW with fuel
for 4,000 to 8,000 hours of operation. Block YaE-1M would have an
output of 5000 kW. Total thrust of the engine would be from 6.2 to 9.5
kgf with a specific impulse of from 5,000 to 8,000 sec. In three block
applications, electric capacity would be 3 x 3,200 kW and 3 x 5,000 kW.
The Aelita MEK design of 1969 used a total of 15,000 kW.
Development of nuclear electric propulsion continued throughout the
1970's. In accordance with the decrees of 8 June 1971 and 15 June
1976 this was now concentrated on development of the more modest
nuclear electric rocket stage 11B97. This stage would have an electric
capacity of 500-600 kW and would use specialised plasma-ion electric
engines using standing plasma waves and anodes. In 1975 nuclear
electric propulsion work was reorganised within NPO Energia into a
special complex 7 (Manager M V Melnikov). In 1984 it was renamed
section 7 (Manager P I Bistrov, and from 1993 Y A Bakanov). Through all
these reorganisations functional test of the reactor and engine
components continued. Concepts for the direct thermoelectric
transformation of energy could not be realised without a new class of
refractory and high temperature materials, new heat pipe concepts, and
other new technology. To develop these technologies it was necessary to
build new materials test facilities, high temperature tests stands, new
experimental shops to develop methods to handle and work new refractory
alloys (niobium, molybdenum, wolfram, vanadium) and insulative and
magnetic materials.
Post by Jochem HuhmannFrom 1966 to 1982 many test stands were built to develop these
materials and test components of the systems. The final result was the
11B97 engine, powered from a reactor with a 200 litre core containing
30 kg of uranium fuel. In 1978 this engine was studied for use as a
reusable interorbital space tug for launch by Energia-Buran. In 1982,
according to the decree of 5 February 1981, NPO Energia developed for
the Ministry of Defence the interorbital tug Gerkules with 550 kW
maximum output and continuous operation in the 50-150 kW range for 3 to
5 years. In 1986 an interorbital tug was studied to solve the specific
application of transporting heavy satellites of 100 tonnes to
geostationary orbit, launched by Energia.
In 1986 RKK Energia updated the 1969 MEK design for launch by the new
Energia launch vehicle. The propulsion section was essentially the same
except that for safety reasons two completely independent redundant
reactor / engine assemblies were used in the place of the single unit
of the MEK design.
Energia retained the electric engines of the 1969 MEK design but
dropped the nuclear ractor for its 1989 Mars expedition design. This
spacecraft used the same thruster arrays requiring the same power
output (15 MW) as the 1986 nuclear design. But in this case two
enormous panels, each 200 m x 200 m would generate a total of 15 MW of
power at earth. The use of ultra-thin (less than 50 micrometer) / low
mass (0.2 kg per square meter) photovoltaic cells with a high specific
power value (up to 200 W per square meter) minimised the weight of
these vast arrays. The total mass of the electric engines, structure,
and solar panels was 40 tonnes. The power generated would be used
primarily by two ion engine clusters mounted perpendicular to the
living block. In high-power mode these would have a specific impulse of
3500 seconds. They would consume 165 tonnes of xenon propellant during
the voyage (of 355 tonnes total spacecraft mass).
In the 1990's Energia studied use of nuclear electric propulsion for
the scientific development project 'Mars - Nuclear electric propulsion
Stage' under contract to the Russian Space Agency and the project 'Star
- Soarer' under contract to the Ministry of Atomic Industry. These
studies looked at designs for the 2005 period. At the beginning of the
1990's a new type of nuclear generator was studied, that would have a
capacity of 150 kW in the transport role and provide 10-40 kW to power
spacecraft systems while coasting. This was designated ERTA
(Elecktro-Raketniy Transportniy Apparat). Technologies and concepts for
this engine were studied by FEI and other organisations. A modular
concept was adopted. In 1994 ERTA was studied for launch by Titan,
Ariane 5, or Energia-M launch vehicles. The reactor weight was 7,500 kg
and it could provide up to 10 years of electrical power traded off
against 1.5 years of powered flight.
Aside from this work on the 150 kW design, there was also an
examination at the same time of the use of nuclear electric propulsion
for Mars expeditions. Single and multiple launch approaches were
considered. For a single-launch complex of 150 tonnes a nuclear
electric propulsion unit of 5 to 10 MW with enough fuel for 1.5 years
would be required. For the multiple launch design, a power of 1 to 1.5
MW and fuel for three years would be required.
In 1994-95, RKK Energia, and NASA's Jet Propulsion Laboratory analysed
the project 'Mars Together'. This studied the use of spacecraft using
solar arrays or nuclear reactors of up to 30 to 40 kW for insertion
into Martian orbit and operation of a side-looking radar to digitally
map the surface. As a preliminary step a demonstration launch was
proposed of a spacecraft with a mass of 120 to 150 kg, a solar panel
area of 30 square meters and engines with a thrust of 3 kW. Objectives
of the experiment would be understanding of the changing of the orbital
altitude with continuous work of the ion engine for several hundred
hours. http://www.astronautix.com/articles/sovctric.htm
