Integrated antenna system for imaging microsatellites

• US 8,531,524 B2
• Filed: 12/14/2011
• Issued: 09/10/2013
• Est. Priority Date: 12/15/2010
• Status: Active Grant

• Current Assignee: Planet Labs PBC
• Original Assignee: Skybox Imaging, Inc. (Planet Labs PBC)
• Inventors: do Carmo Miranda, Henrique
• Primary Examiner(s): Perungavoor, Sath V
• Assistant Examiner(s): LUO, KATE H
• Application Number:
  US13/326,175
• Publication Number:
  US 20120154585A1
• Time in Patent Office: 636 Days
• Field of Search: None
• US Class Current: 348/144
• CPC Class Codes: B64G 1/1021 Earth observation satellites
• CPC Class Codes: B64G 1/222 for deploying structures between a stowed and deployed state
• CPC Class Codes: B64G 1/66 Arrangements or adaptations of apparatus or instruments, not otherwise provided for
• CPC Class Codes: H01Q 1/08 Means for collapsing antennas or parts thereof collapsible loop antennas H01Q7/02; means for collapsing H-antennas or Yagi antennas H01Q19/04
• CPC Class Codes: H01Q 1/288 Satellite antennas
• CPC Class Codes: H01Q 19/10 using reflecting surfaces
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays
• CPC Class Codes: H04N 7/005 using at least one opto-electrical conversion device
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

Examples of imaging microsatellites are described that have an imaging system and antenna system disposed within the microsatellite body when the microsatellite is in a non-deployed state. The properties of the antenna system can be adjusted such that the antenna system does not impact, contact, or displace the imaging system when the microsatellite is in the non-deployed state. The properties of the antenna system can be adjusted such that the antenna system does not contact or impact the body of the microsatellite or any other structure when the microsatellite transitions to a deployed state. The antenna system can be configured to achieve a desired gain and/or data transmission rate by adjusting properties of the antenna system based on the radiation pattern of an antenna feed and geometric constraints imposed by the imaging system. Examples of methods for designing such imaging microsatellites are provided.

Claims

1. A method of producing a tangible imaging micro satellite, the imaging microsatellite having an interior cavity and an opening, a door configured to cover the opening when the microsatellite is in a non-deployed state and to uncover the opening when the microsatellite is in a deployed state, an antenna system attached to the door, the antenna system comprising a reflector and an antenna feed, an imaging system disposed within the interior cavity and configured to image a field of view through the opening when the microsatellite is in the deployed state, the method comprising:

obtaining configuration parameters for the microsatellite, the microsatellite configuration parameters comprising dimensions of the microsatellite;

obtaining configuration parameters for the imaging system, the imaging system configuration parameters comprising dimensions and layout of the imaging system within the interior cavity of the microsatellite;

determining a layout of the antenna system such that;

(1) the antenna system does not contact or displace portions of the imaging system when the microsatellite is in the non-deployed state; and

(2) the antenna system does not contact portions of the microsatellite when the microsatellite transitions from the non-deployed to the deployed state; and

adjusting properties of the antenna system such that the reflector matches a radiation pattern of the antenna feed and a desired antenna gain or data transmission rate is achieved.

2. The method of claim 1, wherein adjusting the properties of the antenna system comprises adjusting at least one of a diameter, a depth, or a focal length of the reflector.

3. The method of claim 1, wherein the reflector has a focal length and a diameter, and the determining and adjusting are repeated until a ratio of the focal length to the diameter is in a desired range.

4. The method of claim 1, wherein the desired transmission rate is between about 1 Mbit/s and 100 Mbit/s.

5. The method of claim 1, wherein the desired antenna gain is greater than or equal to about 25 dBi.

10. The method of claim 1, wherein the desired antenna gain is greater than or equal to about 10 dBi and less than or equal to about 30 dBi.

6. An imaging microsatellite comprising:

a body having an interior cavity and an opening in the body, the body having a volume envelope less than about 125 cm by 125 cm by 175 cm or a mass envelope less than about 500 kg;

an imaging system disposed within the interior cavity, the imaging system comprising a primary mirror and a secondary mirror;

a door attached to the body, the microsatellite having a non-deployed state in which the opening is covered by the door, and a deployed state in which the opening is unobstructed by the door and the imaging system can image a field of view through the opening; and

an antenna system comprising a reflector and a feed, the antenna system coupled to the door,

wherein when the microsatellite is in the non-deployed state, the feed is disposed between the primary mirror and the secondary mirror, and

wherein while the microsatellite transitions from the non-deployed state to the deployed state, the antenna system moves through the opening without contacting portions of the imaging system or portions of the body of the microsatellite.

7. The imaging microsatellite of claim 6, wherein the imaging system further comprises:

a primary baffle associated with the primary mirror; and

a secondary baffle associated with the secondary mirror,

wherein the feed is disposed between the primary baffle and the secondary baffle when the microsatellite is in the non-deployed state.

8. The imaging microsatellite of claim 6, wherein the primary mirror and the secondary mirror are spaced apart by two or more support struts, the feed is disposed near a focus of the reflector by a feed support, and the feed support extends between two adjacent struts when the microsatellite is in the non-deployed state.

9. The imaging microsatellite of claim 6, wherein the reflector has a diameter d and focal length f and a ratio f/d matches a radiation pattern of the feed.

11. A method of manufacturing an imaging microsatellite having an integrated antenna reflector, the method comprising:

attaching a door to a microsatellite body, the door being configured to transition from a closed position to an open position, wherein in the closed position the door covers an opening in the microsatellite body and in the open position the door uncovers the opening;

securing an imaging system within an interior cavity of the microsatellite body, the imaging system being positioned to image a field of view through the opening when the door is in the open position;

coupling an antenna reflector to the door such that the antenna reflector is within the interior cavity when the door is in the closed position; and

positioning an antenna feed such that the antenna feed is in a fixed position relative to the antenna reflector when the door is in the open position and such that the antenna feed does not contact or displace any portion of the imaging system when the door is in the closed position,

wherein the antenna reflector and the antenna feed move through the opening of the microsatellite body in an unobstructed manner when the door transitions from the closed position to the open position.

12. The method of claim 11, wherein attaching the door to the microsatellite body comprises attaching an opening mechanism to the satellite body and to the door, wherein the opening mechanism is configured to provide an axis of rotation for the door and an opening torque on the door to transition the door from the closed position to the open position.

13. The method of claim 12, further comprising attaching a release mechanism to the microsatellite body, the release mechanism configured to secure the door in the closed position, the release mechanism actuatable to release the door and allow the opening mechanism to transition the door from the closed position to the open position.

14. The method of claim 11, wherein the imaging system comprises a telescope comprising:

a primary mirror;

a secondary mirror; and

a secondary support configured to secure the secondary mirror in a fixed position relative to the primary mirror.

15. The method of claim 14, wherein securing the imaging system within the interior cavity of the microsatellite body comprises securing the primary mirror, the secondary mirror, and the secondary support within the interior cavity such that the antenna feed is disposed between the primary mirror and the secondary mirror when the door is in the closed position.

16. The method of claim 11, wherein a ratio of a diameter of the antenna reflector to a width of the door is greater than about 50%.

17. The method of claim 11, wherein positioning the antenna feed comprises securing the antenna feed to an antenna feed support and attaching the antenna feed support to the antenna reflector or the door.

18. The method of claim 11, wherein the fixed position of the antenna feed relative to the antenna reflector is approximately a focal point of the antenna reflector.

19. The method of claim 11, wherein the microsatellite has a volume envelope less than or equal to about 125 cm by 125 cm by 175 cm or a mass less than or equal to about 500 kg.

20. The method of claim 11, wherein the antenna reflector and the antenna feed are configured to provide a gain greater than or equal to about 10 dBi and less than or equal to about 30 dBi.

21. An imaging satellite comprising:

a body comprising an interior cavity and an opening in the body;

a door attached to the body, the door configured to;

cover the opening in the body when in a closed position, and

uncover the opening in the body when in an open position;

an antenna system comprising;

an antenna reflector attached to the door, the antenna reflector having a focal point and a diameter configured to allow the antenna reflector to pass through the opening in the body, and

an antenna feed secured approximately at the focal point of the antenna reflector when the door is in the open position; and

an imaging system disposed within the interior cavity and configured to receive radiation entering the interior cavity through the opening in the body when the door is in the open position;

wherein the antenna system is configured to fit within the interior cavity without contacting or displacing any portion of the imaging system when the door is in the closed position.

22. The imaging satellite of claim 21, wherein the body has a volume envelope less than or equal to about 125 cm by 125 cm by 175 cm.

23. The imaging satellite of claim 21, wherein the body has a mass less than or equal to about 500 kg.

24. The imaging satellite of claim 21, wherein the imaging satellite is configured to launch as a secondary payload on a launch vehicle configured to launch a primary payload.