Deployable booms
An articulated boom comprises a support arm with a plurality of hingedly-connected joints. The arm is adapted and arranged to carry an antenna reflector so that in use, the reflector can move between a first stowed position in which the reflector is in folded condition and a second deployed position in which the reflector is in deployed condition. A spacecraft incorporates into one or more of its sides a plurality of such articulated booms. The support arms of the booms can be advantageously positioned at the circumference of the associated reflectors when in a stowed position, so as to allow the reflectors to be neatly stacked together within a space defined by the launch vehicle fairing.
1. An articulated boom for a space based antenna reflector system having an antenna reflector supported on said boom; wherein:
said boom comprises a support arm having at least three hinged joints;
said support arm is adapted and arranged to carry the antenna reflector so that in use, the antenna reflector can move between a first, stowed, position in which the reflector is nested within a predetermined volume of a spacecraft; and a second, deployed, position in which the reflector is deployed in space outside said predetermined volume;
said support arm includes a dog-leg portion located between two of said hinged joints, that permits stowage of said antenna reflector in said stowed position; and
said dog-leg portion is configured and positioned such that said dog-leg portion extends at least partially along a circumference of the antenna reflector when said antenna reflector is in said stowed position.
2. The articulated boom as claimed in claim 1 , wherein at least one of said hinged joints comprises an articulated stepper motor harmonic drive unit.
3. The articulated boom as claimed in claim 1 , wherein at least one of said hinged joints comprises a spring-operated mechanical hinge.
4. The articulated boom as claimed in claim 1 , wherein:
the antenna reflector has a diameter of approximately 3.5 meters with an associated focal length of approximately 7 meters; and
the support arm is configured to be sufficiently long to carry the 3.5 meter antenna reflector.
5. The articulated boom as claimed in claim 1 , wherein the hinged joints are bolted using flexible metal brackets, which brackets are sufficiently flexible to accommodate changes in material properties of the boom in response to temperature variations between +140° C. and −180° C.
6. The articulated boom as claimed in claim 1 , wherein:
one end of the support arm is mounted to an associated feed structure of the spacecraft, via one of said hinged joints; and
the opposing end of the support arm is mounted to the antenna reflector, via another of said hinged joints.
7. The articulated boom as claimed in claim 6 , wherein:
in the stowed position, the antenna reflector is foldably mounted to a sidewall of the spacecraft on a plurality of hold-down points; and
said hold-down points are operably released prior to deployment of the reflector.
8. The articulated boom as claimed in claim 7 , wherein said hold-down points are formed such as to provide a degree of compliance, such that the boom and the spacecraft do not impart unwanted thermal expansion loads on each other.
9. A spacecraft comprising:
at least two booms of the type claimed in claim 1 ; and
at least two antenna reflectors that are deployable on said booms from at least one side of the spacecraft.
10. The spacecraft as claimed in claim 9 , wherein support arms of the at least two booms are positioned at a circumference of associated reflectors when in the stowed position, so as to allow the reflectors to be stacked together within a space defined by an associated launch vehicle fairing.
11. A spacecraft incorporating into at least one side thereof
(a) a first hinge-mounted support structure including an antenna reflector with a boom as defined in claim 1 ; and
(b) a second different hinge-mounted support structure for carrying a plurality of antenna reflectors.
12. A reflector system for space-based applications incorporating an antenna reflector with supporting boom as defined in claim 1 .
13. An antenna structure incorporating a reflector system as defined in claim 12 .
14. The articulated boom as claimed in claim 1 , wherein, in said stowed position, said dog-leg portion lies within a first plane that is substantially parallel to a second plane defined by said antenna reflector.
15. The articulated boom as claimed in claim 14 , wherein:
the dog-leg portion is coupled to the spacecraft by a hinged joint that provides for pivotal rotation of said dog-leg portion about a pivot axis; and
said pivotal axis is substantially parallel to said first plane.
16. A spacecraft having an antenna reflector supported on a boom; wherein;
said boom comprises a support arm having at least three hinged joints;
said support arm is adapted and arranged to carry the antenna reflector so that in use, the antenna reflector can move between a first, stowed, position in which the reflector is nested within a predetermined volume of the spacecraft; and a second, deployed, position in which the reflector is deployed in space outside said predetermined volume;
said support arm includes a dog-leg portion located between two of said hinged joints, that permits stowage of said antenna reflector in said stowed position; and
said dog-leg portion is configured and positioned such that said dog-leg portion extends at least partially along a circumference of the antenna reflector when said antenna reflector is in said stowed position.
17. The spacecraft as claimed in claim 16 , wherein an associated feed structure is mounted to a separately-formed floor of the spacecraft.
18. An articulated boom for a space based antenna reflector system having an antenna reflector supported on said boom, said boom comprising:
a first hinged joint for connecting a first end of said boom to a wall of a spacecraft;
a second hinged joint for connecting a second end of said boom to said antenna reflector; and
a third hinged joint which connects a first portion of said boom to a second portion of said boom at a point intermediate said first and second ends of said boom; wherein
said boom is adapted and arranged to carry the antenna reflector so that in use, the antenna reflector can move between a first, stowed, position in which the reflector is nested within a predetermined volume of said spacecraft; and a second, deployed, position in which the reflector is deployed in space outside said predetermined volume;
one of said first and second portions of said boom includes a dog-leg portion that permits stowage of said antenna reflector in said stowed position; and
said dog-leg portion is configured and positioned such that, when said reflector is in said stowed position, said dog-leg portion is disposed in a plane adjacent one side of said antenna reflector, and extends in said plane at least partially along a circumference of the antenna reflector.