NASA Technical Reports Server (NTRS) 20110016547: The StarLight Space Interferometer

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by  NASA Technical Reports Server (NTRS)

The StarLight Space Interferometer
NASA’s Jet Propulsion Laboratory, Pasadena, California
Two papers describe the StarLight craft, and the main innovation embod- of the papers presents a detailed de-
space interferometer — a Michelson in- ied is a modification that makes it possi- scription of the optical layout and dis-
terferometer that would be imple- ble to reduce complexity by eliminating cusses computational modeling of the
mented by two spacecraft flying in for- the third spacecraft. The main features performance; the other paper presents
mation. The StarLight formation flying of the modification are (1) introduction an overview of the requirements for op-
interferometer project has been testing of an optical delay line on one space- eration and design, the overall architec-
and demonstrating engineering con- craft and (2) controlling the flying for- ture, and subsystems.
cepts for a new generation of space in- mation such that the two spacecraft are This work was done by William Folkner,
terferometers that would be employed located at two points along a specified Michael Shao, and Peter Gorham of Cal-
in a search for extrasolar planets and in parabola so as to define the required tech for NASA’s Jet Propulsion Labora-
astrophysical investigations. As de- baseline of specified length (which tory. Further information is contained in
scribed in the papers, the original could be varied up to 125 m) perpen- a TSP (see page 1)
StarLight concept called for three space- dicular to the axis of the parabola. One NPO-30726
Champagne Heat Pump
Relatively safe and environmentally benign working fluids can be used.
NASA’s Jet Propulsion Laboratory, Pasadena, California
The term “champagne heat pump” The concept of heat pumps based on The organic-liquid/carbon dioxide ab-
denotes a developmental heat pump other absorption cycles energized by heat sorption/desorption cycle of the cham-
that exploits a cycle of absorption and has been understood for years, but some pagne heat pump is similar to the
desorption of carbon dioxide in an alco- of these heat pumps are outlawed in many water/ammonia cycle, but carbon dioxide
hol or other organic liquid. Whereas areas because of the potential hazards is nontoxic and environmentally benign,
most heat pumps in common use in the posed by leakage of working fluids. For and one can choose an alcohol or other
United States are energized by mechani- example, in the case of the water/ammo- organic liquid that is also relatively non-
cal compression, the champagne heat nia cycle, there are potential hazards of toxic and environmentally benign. Two
pump is energized by heating. toxicity and flammability. candidate nonalcohol organic liquids are
isobutyl acetate and amyl acetate. Al-
though alcohols and many other organic
Generator CO2 @ 250 °F liquids are flammable, they present little
(250 °F, 1,400 psi) 1,400 psi
or no flammability hazard in the cham-
Alcohol/CO pagne heat pump because only the non-
250 °F 2 flammable carbon dioxide component of
Heat
the refrigerant mixture is circulated to the
evaporator and condenser heat exchang-
ers, which are the only components of the
heat pump in direct contact with air in
Heat Exchanger 1 habitable spaces.
Supercritical
Precooler (100 °F) The champagne heat pump (see fig-
ure) includes a generator — essentially a
Weak heated pressure vessel — wherein a solu-
Solution CO @ 560 psi tion of carbon dioxide in the absorbent
2
Absorber Strong Heat liquid is heated to generate pressurized
(100 °F, 560 psi) Solution Exchanger 2 carbon dioxide. In a typical application,
CO
2 the solution is heated to a temperature of
Alcohol/CO
100 °F 2 250 °F (121 °C), causing the carbon diox-
ide to be desorbed at a pressure of about
Heat
1.4 kpsi (9.7 MPa). The carbon dioxide is
1,400 psi precooled, typically to about 100 °F (38
°C) while at this high pressure, then ex-
Evaporator
(40 °F, 560 psi) panded to a pressure of about 560 psi (3.9
Heat MPa); this expansion provides cooling to
about 40 °F (4 °C). The carbon dioxide
then passes back through a heat ex-
Carbon Dioxide Is Absorbed and Desorbedin a thermodynamic cycle similar to that of a water/am-
monia heat pump. The champagne heat pump is so named because the desorption part of its operat- changer to an absorber, which is another
ing cycle is reminiscent of carbon dioxide effervescing out of alcohol-containing champagne. pressure vessel wherein the carbon diox-
26 NASA Tech Briefs, January 2004