Patent Description:
<CIT>, according to its abstract, states a method and apparatus for autonomous navigation for deep space missions using the sun as the reference body and determining the spacecraft orbit based on observations made on the sun using onboard instruments. Two types of observation data, the direction of the spacecraft relative to the sun as a function of time and the optical Doppler shift due to the motion of the spacecraft relative to the sun, can be used for the spacecraft orbit determination. A dual imaging system which functions as a sun imager taking images of the sun against star backgrounds during the cruise phase and as a regular optical imager taking pictures of the targeting planetary body during the approaching phase is also described.

There is described herein a star tracker comprising an imaging sensor, optionally a visual sensor, configured to receive electromagnetic radiation via a combined viewpath, and a baffle disposed proximate the imaging sensor and comprising a) a star port, configured to receive first electromagnetic radiation associated with a first viewing environment via a first path, b) a sun port disposed at between a <NUM>-<NUM> degree angle to the first path, configured to receive second electromagnetic radiation associated with a second viewing environment via a second path and configured to attenuate a magnitude of the second electromagnetic radiation, and c) a lens disposed within the sun port configured to act as a beam splitter, configured to receive the first electromagnetic radiation of the first path and the second electromagnetic radiation of the second path and configured to combine the first electromagnetic radiation and the second electromagnetic radiation into the combined viewpath.

There is also described herein a spacecraft structure and the star tracker described above, coupled to the spacecraft structure.

There is also described herein a method comprising a) positioning a star tracker such that a second viewing environment containing a sun is within view of a sun port of the star tracker and a first viewing environment different from the second viewing environment is within view of a star port of the star tracker, wherein the sun port is configured to attenuate a magnitude of the view of the second viewing environment, optionally using a filter, and b) imaging the first viewing environment and the second viewing environment with an imaging sensor of the star tracker. The star port is configured to receive first electromagnetic radiation associated with the first viewing environment via a first path. The sun port is disposed at between a <NUM>-<NUM> degree angle to the first path and is configured to receive second electromagnetic radiation associated with the second viewing environment via a second path and is configured to attenuate the magnitude of the view of the second viewing environment by attenuating the magnitude of the second electromagnetic radiation. The sun port and the star port are disposed within a baffle. The baffle further comprises a lens disposed within the sun port configured to act as a beam splitter, configured to receive the first electromagnetic radiation and the second electromagnetic radiation and configured to combine the first electromagnetic radiation and the second electromagnetic radiation into a combined viewpath.

Embodiments thereof are defined by the dependent claims.

Illustrative, non-exclusive examples of features according to present disclosure are described herein. These and other examples are described further below with reference to figures.

The disclosure may best be understood by reference to the following description taken in conjunction with the accompanying drawings, which illustrate various examples.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the presented concepts. The presented concepts may be practiced without some, or all, of these specific details. In other instances, well known process operations have not been described in detail to avoid unnecessarily obscuring the described concepts. While some concepts will be described with the specific examples, it will be understood that these examples are not intended to be limiting.

Described herein is a direct sun imaging star tracker and techniques for operation thereof. In certain examples, a direct sun imaging star tracker is disclosed. The star tracker includes an imaging sensor, configured to receive electromagnetic radiation via a combined viewpath, and a baffle. The baffle is disposed proximate the imaging sensor and includes a star port, a sun port, and a beam splitter. The star port is configured to receive first electromagnetic radiation associated with a first viewing environment via a first path. The sun port is configured to receive second electromagnetic radiation associated with a second viewing environment via a second path and configured to attenuate a magnitude of the second electromagnetic radiation. The beam splitter is configured to receive the first electromagnetic radiation of the first path and the second electromagnetic radiation of the second path and is configured to combine the first electromagnetic radiation and the second electromagnetic radiation into the combined viewpath. The star tracker, in certain examples, is coupled to a spacecraft structure.

In various examples, the systems and techniques described herein allow a star tracker to simultaneously view both the sun and the stars. Such systems and techniques allow for the star tracker to utilize the stars for navigational and other purposes while continuing to observe the sun at the same time. In certain examples, the star tracker is a portion of a spacecraft, but other examples include the star tracker as a portion of other vehicles or structures, such as terrestrial observatories, aircraft, ships, and others.

<FIG> illustrates a satellite vehicle, in accordance with some examples. <FIG> illustrates spacecraft <NUM> that includes spacecraft structure <NUM>. In various examples, spacecraft structure <NUM> is the main structure of spacecraft <NUM>. Thus, various systems of spacecraft <NUM> is disposed within or otherwise coupled to (e.g., directly or indirectly connected to) spacecraft structure <NUM>. Spacecraft structure <NUM> is constructed from any metallic, composite, or other material appropriate for spacecraft construction. Spacecraft structure <NUM> may include one or more propulsion systems, electrical systems, navigation systems, instruments, power management systems, logic systems, and other such systems.

For example, spacecraft structure <NUM> includes star tracker <NUM>, spacecraft instrument <NUM>, and power system <NUM>. Spacecraft instrument <NUM>, in certain examples, is an instrument for use in operation of spacecraft <NUM>. Thus, for example, spacecraft instrument <NUM> is an observation instrument (e.g., a telescope), a data instrument (e.g., a global positioning system), and/or another such instrument. Power system <NUM>, in certain examples, is a solar panel, batteries, fuel tanks, and/or other such system configured to generate and/or store power for spacecraft <NUM>.

In certain examples, star tracker <NUM> is configured to determine the position of one or more stars relative to spacecraft <NUM>. Star tracker <NUM> allows for the position of the stars relative to spacecraft <NUM> to be determined to, for example, allow for navigation of spacecraft <NUM>. In certain examples described herein, star tracker <NUM> includes a baffle that allows for star tracker <NUM> to simultaneously image the stars as well as the sun.

<FIG> illustrates a block diagram of a satellite vehicle, in accordance with some examples. <FIG> illustrates a block diagram of spacecraft structure <NUM>. Star tracker <NUM> and spacecraft instrument <NUM> are coupled to and/or disposed within spacecraft structure <NUM>. Spacecraft instrument <NUM>, in certain examples, is as described herein and is used to perform operations for spacecraft <NUM>.

Star tracker <NUM> is configured to track stars (e.g., for navigation of spacecraft <NUM>). In certain examples, star tracker <NUM> is configured to also image the sun while imaging the stars. Star tracker <NUM> includes imaging sensor <NUM> and baffle <NUM>. Imaging sensor <NUM> is configured to receive electromagnetic radiation (e.g., electromagnetic radiation within the visual, ultraviolet, infrared, or other wavelengths) and provide an image from the electromagnetic radiation. In various examples, star tracker <NUM> may output imaging data based on the electromagnetic radiation detected by imaging sensor <NUM>.

In certain examples, baffle <NUM> is disposed proximate to imaging sensor <NUM>. Baffle <NUM> is configured to attenuate the electromagnetic radiation received by imaging sensor <NUM> (e.g., decrease the intensity of electromagnetic radiation received by imaging sensor <NUM>). Thus, baffle <NUM> includes one or more filters or other components to attenuate (e.g., decrease the magnitude of) electromagnetic radiation received by imaging sensor <NUM>.

In certain examples, baffle <NUM> includes a plurality of ports. One or more first ports (e.g., sun ports) are configured to receive electromagnetic radiation from the sun and one or more second ports (e.g., star ports) are configured to receive electromagnetic radiation from the stars. The first ports include the one or more filters to attenuate the electromagnetic radiation of the sun. In certain examples, the second ports also include one or more filters, but it is appreciated that the attenuation of the first ports is, in certain examples, greater than the attenuation of the second ports. The first ports and the second ports are configured to image different portions of the sky and, thus, the first ports and the second ports are positioned to be aimed at different portions of the sky. The positioning of the first ports and the second ports allow for stars and the sun to be simultaneously imaged without electromagnetic radiation from the sun affecting (or substantially affecting) the imaging of the stars by the star port.

The baffle <NUM> includes a beam splitter. The beam splitter is configured to receive the electromagnetic radiation from the first ports and the second ports and combine the various electromagnetic radiation into a combined viewpath. Thus, the beam splitter allows for imaging sensor <NUM> to simultaneously image data from the first ports and the second ports and, in certain examples, create a composite image.

Star tracker <NUM> and spacecraft instrument <NUM> are communicatively coupled to controller <NUM> via communications network <NUM>. In certain examples, communication network <NUM> is any type of wired and/or wireless network that communicates data and/or power to and from controller <NUM>. Controller <NUM> includes, in various examples, a memory, a processor, and other logic device components. Controller <NUM> is configured to receive data, performs calculations, and provides outputs (e.g., control instructions) to various other systems of spacecraft <NUM>. Thus, for example, controller <NUM> is configured to receive data from imaging sensor <NUM> and create an image from the data.

<FIG> illustrates a side representation of a direct sun imaging star tracker, in accordance with some examples. <FIG> illustrates portions of star tracker <NUM>. Star tracker <NUM> includes imaging sensor <NUM> and baffle <NUM> disposed proximate to imaging sensor <NUM>. Imaging sensor <NUM> includes one or more sensors configured to sense electromagnetic radiation through one or more bandwidths (e.g., infrared, visual, ultraviolet, and/or other bandwidths). In certain examples, imaging sensor <NUM> is one sensor, while other examples include a plurality of sensors, such as an array of sensors, for imaging sensor <NUM>.

In various examples, some or all of the electromagnetic radiation that reaches imaging sensor <NUM> will first pass through baffle <NUM>. Baffle <NUM> is positioned proximate to imaging sensor <NUM> (e.g., in front of imaging sensor <NUM>). In various examples, baffle <NUM> includes beam splitter <NUM>, sun port <NUM>, star port <NUM>, and filter <NUM>. One or more light paths are further included within baffle <NUM>, including first path <NUM>, second path <NUM>, and combined viewpath <NUM>.

In certain examples, star port <NUM> is configured to view first viewing environment <NUM> through first view perspective <NUM>. Star port <NUM> is thus configured to view objects within first view perspective <NUM>. First view perspective <NUM>, in the example of <FIG>, allows for star port <NUM> to view first viewing environment <NUM>. In certain examples, first viewing environment <NUM> includes stars <NUM>. Electromagnetic radiation generated by stars <NUM> are a part of first viewing environment <NUM>. In certain examples, the electromagnetic radiation generated by stars <NUM> enters through star port <NUM> and reaches beam splitter <NUM> via first path <NUM>. First path <NUM> is a pathway within baffle <NUM>.

Sun port <NUM> is configured to view second viewing environment <NUM> through second view perspective <NUM>. In certain examples, second viewing environment <NUM> includes sun <NUM>. Electromagnetic radiation generated by sun <NUM> is a part of second viewing environment <NUM> and is imaged through sun port <NUM>. In certain examples, stars are also a part of second viewing environment <NUM>. However, because the intensity of sun <NUM> is much greater than the intensity of the stars, electromagnetic radiation from sun <NUM> will wash out the view of the stars within images of second viewing environment <NUM>. As such, in certain examples, when imaging sun <NUM> within second viewing environment <NUM>, the stars within second viewing environment <NUM> are unable to be imaged.

Filter <NUM> attenuates the intensity of electromagnetic radiation from second viewing environment <NUM> that passes through sun port <NUM>. In certain examples, filter <NUM> attenuates up to <NUM>%, up to <NUM>%, up to <NUM>%, or more than <NUM>% of the electromagnetic radiation from second viewing environment <NUM>. Filter <NUM> is, thus, configured to attenuate electromagnetic radiation from second viewing environment <NUM> to a magnitude that allows for simultaneous imaging of first viewing environment <NUM> by star port <NUM> and second viewing environment <NUM> by sun port <NUM> without washing out either view. In various examples, filter <NUM> is any type of filter that will attenuate electromagnetic radiation in any bandwidth. Though <FIG> illustrates filter <NUM> disposed in front of sun port <NUM>, it is appreciated that filter <NUM>, in other examples, is disposed along any portion of second path <NUM>.

Electromagnetic radiation from second viewing environment <NUM> enters through sun port <NUM> into baffle <NUM> and reaches beam splitter <NUM> via second path <NUM>. As described herein, the electromagnetic radiation passes through filter <NUM>. Filter <NUM> attenuates a portion of the electromagnetic radiation of second path <NUM>, as described herein. Variously, first path <NUM> and/or second path <NUM> include one or a plurality of stages that includes various filters, reflectors, and/or other equipment for attenuating or enhancing the electromagnetic radiation.

While the example of <FIG> illustrates baffle <NUM> with a star port portion that is longer than a sun port portion, other examples include sun port portions that are just as long or longer than the star port portions. In certain examples, the field of views of sun port <NUM> and star port <NUM> are different. That is, for example, as sun port <NUM> is configured to be concentrated on sun <NUM> while star port <NUM> is configured to image stars <NUM>, sun port <NUM> has a field of view that is smaller than the field of view of star port <NUM>. For example, in certain such configurations, the field of view of star port <NUM> is twice as large, three times as large, or multiple times that of sun port <NUM>.

The electromagnetic radiation of first path <NUM> and second path <NUM> are combined by beam splitter <NUM> into combined viewpath <NUM>. The combined electromagnetic radiation then reaches imaging sensor <NUM> along combined viewpath <NUM>. Thus, combined viewpath <NUM> includes electromagnetic radiation that is a combination of the electromagnetic radiation of first path <NUM> and second path <NUM>. As imaging sensor <NUM> receives the combined electromagnetic radiation of combined viewpath <NUM>, the image output by imaging sensor <NUM> includes both sun <NUM> and stars <NUM> within one view. In various examples, proper attenuation of the electromagnetic radiation of sun <NUM> prevents wash out of stars <NUM> from the image. As such, the resulting image is useful for navigation through using stars <NUM> and for viewing of sun <NUM> as well as any objects in front of sun <NUM>.

In various examples, beam splitter <NUM> is a flat piece of glass. The glass is, in certain examples, aluminized with a thickness that optimizes the amount of reflectivity or transmission between first path <NUM> and second path <NUM>. Beam splitter <NUM> includes, in certain examples, a spectral dichroic filter for filtering light from one or more directions (e.g., beam splitter <NUM> includes the spectral dichroic filter on the portion where solar light passes through), such that the maximum amount of stellar light is passed through star port <NUM>, while low sensitivity regions of imaging sensor <NUM> is used for sun port <NUM>. For example, a dichroic beam splitter is configured to pass only a very narrow band of blue light. In such a configuration, the solar image would be able to have higher spatial resolution while imaging sun <NUM>, with no loss of signal for the stellar image. Such a configuration allows for superior imaging and prevents burn out of portions of imaging sensor <NUM>.

As shown, star port <NUM> and sun port <NUM> are configured to image different portions of the environment. Thus, first viewing environment <NUM> and second viewing environment <NUM> are different portions of the sky. In certain examples, first path <NUM> and second path <NUM> are non-parallel to each other and, thus, star port <NUM> and sun port <NUM> are disposed at angles to each other.

As such, star tracker <NUM> as described herein allows for imaging of both sun <NUM> and stars <NUM> with one star tracker and without a filter wheel or other mechanism. Such a configuration allows for a star tracker to image the sun with less parts, less weights, and improved reliability.

<FIG> illustrates a side representation of a further example of the direct sun imaging star tracker of <FIG>, in accordance with some examples. <FIG> illustrates star tracker <NUM>. In <FIG>, star tracker <NUM> includes lens <NUM> disposed over filter <NUM> of sun port <NUM>. In certain examples, lens <NUM> is an additional lens disposed over filter <NUM>. Though the example shown in <FIG> couples lens <NUM> to filter <NUM>, other examples includes lens <NUM> disposed a relative distance away from filter <NUM>.

Lens <NUM>, in certain examples, is added to sun port <NUM> to shorten and/or lengthen the effective focal length of sun port <NUM>. Shortening the effective focal length allows for sun <NUM> to be detected over a wider field of view (e.g., sun <NUM> appears smaller on imaging sensor <NUM> and, thus, in the image, visible over a wider field of view). Lengthening the effective focal length allows for sun <NUM> to appear larger on imaging sensor <NUM> (e.g., for better imaging of targets in silhouette against sun <NUM>).

While the examples in <FIG> and <FIG> illustrate examples wherein the portion of baffle <NUM> that includes first path <NUM> and star port <NUM> is disposed at a <NUM> degree angle relative to the portion of baffle <NUM> that includes second path <NUM> and sun port <NUM>, other examples, such as the example in <FIG>, disposes the various paths and ports in different configurations and/or at different angles. <FIG> illustrates a side representation of another direct sun imaging star tracker, in accordance with some examples.

In <FIG>, the portion of baffle <NUM> that includes star port <NUM> and first path <NUM> is disposed at a non-right angle to the portion of baffle <NUM> that includes sun port <NUM> and second path <NUM>. Beam splitter <NUM> is accordingly rearranged so that the electromagnetic radiation of first path <NUM> and second path <NUM> is combined into an appropriate combined viewpath <NUM> for imaging sensor <NUM>.

<FIG> illustrates a side representation of a further direct sun imaging star tracker, in accordance with some examples. <FIG> illustrates star tracker <NUM> that includes baffle <NUM> disposed over imaging sensor <NUM>. Baffle <NUM> includes lens <NUM> disposed within second path <NUM> and lenses <NUM> and <NUM> disposed within different portions of first path <NUM>. Thus, separate lenses are used for the different focal paths of first path <NUM> and second path <NUM>. Lenses <NUM> and <NUM> are disposed within baffle <NUM> (e.g., behind sun port <NUM> and star port <NUM>, respectively) while lens <NUM> is disposed at star port <NUM>, similar to lens <NUM> of <FIG>.

Lenses <NUM> and <NUM> and <NUM> allow for the focal length of the respective second path <NUM> and the first path <NUM> to be shortened or lengthened. As described herein, a shorter focal length for sun <NUM> would enable a wider field of view around the sun (e.g., allow for the sun to be observed over a larger field of view) while a longer focal length for sun <NUM> would allow for greater detail of the view of sun <NUM> and any objects in silhouette against sun <NUM>. Additionally, a shorter focal length for first path <NUM> would allow for stars <NUM> to be positioned accordingly within the view (e.g., in combination with positioning of beam splitter <NUM>). A shorter focal length for first path <NUM> allows for stars <NUM> to be seen over a wider field of view.

<FIG> illustrates a flow chart of example direct sun imaging star tracker operation, in accordance with some examples. <FIG> illustrates a technique <NUM> of operating the star tracker described herein.

In <NUM>, the star tracker is initialized. As such, the star tracker becomes operational and is configured to image various portions of the environment proximate to the star tracker (e.g., the sky around the star tracker). In <NUM>, the star tracker is positioned. Positioning of the star tracker includes, in certain examples, positioning the sun port so that the sun is visible within the image received through the sun port. The star port is accordingly positioned so that the sun is not visible within the image received through the star port. In certain examples, as part of positioning the star tracker, the solar panels (e.g., power systems <NUM>) of the spacecraft are oriented in the same direction as that of the sun port. As the sun port is configured to view the sun and the solar panels are most efficient when oriented towards the sun, orienting both in such a manner allows for efficient operation of the spacecraft. Thus, the plane of the solar panels is positioned to be normal to the rays of the sun in such a configuration.

<NUM> includes techniques for imaging the sun and stars around the environment of the star tracker. Thus, the first viewing environment is imaged in <NUM> and the second viewing environment is imaged in <NUM>. Imaging of the first viewing environment and the second viewing environment is, in certain examples, performed around the same time or during overlapping time periods. The first viewing environment, in certain examples, includes a sun. Thus, a baffle of the star tracker appropriately attenuates the electromagnetic radiation of the sun of the first viewing environment so that, in the combined image generated from imaging the first viewing environment and the second viewing environment, both the sun and the stars are visible.

Based on the imaging in <NUM>, a combined image is generated in <NUM> (e.g., from the electromagnetic radiation of the combined viewpath). The image is a representation of both the first viewing environment and the second viewing environment and, thus, includes both the sun as well as any stars within the first viewing environment. In certain examples, washout from the intensity of the electromagnetic radiation generated by the sun within the second viewing environment results in the image not including any stars that are present within the second viewing environment.

The image is analyzed in <NUM>. In certain examples, analysis of the image is performed by one or more controllers as described herein. Analysis of the image includes one or more of, for example, analyzing the image of the sun (e.g., to confirm that the sun is depicted within the image via confirmation of its angular diameter and/or to determine sun spots or any other features of the sun), analyzing the image of the sun to determine the presence of objects in front of the sun, analyzing the stars within the image for navigational purposes (e.g., to determine the actual position of the spacecraft by determining the position of the stars), and/or other such analysis.

In certain examples, though the image is generated from the electromagnetic radiation of both the first viewing environment and the second viewing environment, the image is a single image that combines (e.g., overlays) the first viewing environment and the second viewing environment. Thus, though the first viewing environment and the second viewing environment are different portions of the environment, the image combines both into a single environment. As such, the stars in the image are shown to be proximate to the sun even though they are actually in two different positions. Thus, in various examples, a controller analyzing the image determines that, due to washout from the intensity of the electromagnetic radiation generated by the sun within the second viewing environment, any stars within the image are located within the first viewing environment. The controller is then able to navigate using the stars while observing the sun, all from the same image.

Examples of such images are described herein. <FIG> illustrate example images obtained by a direct sun imaging star tracker, in accordance with some examples. <FIG> illustrates an example of image <NUM> created from electromagnetic radiation through a sun port of the baffle described herein. Image <NUM> represents the image created from the electromagnetic radiation of a second path as described herein. Image <NUM> includes sun <NUM> and satellite <NUM> disposed in front of sun <NUM>. Image <NUM> has been sufficiently attenuated so that satellite <NUM> is viewable in front of sun <NUM>. In certain examples, satellite <NUM> is, alternatively or additionally, space debris, or another object of interest.

<FIG> illustrates an example of image <NUM> created from electromagnetic radiation through a star part of the baffle described herein. Image <NUM> represents the image created from the electromagnetic radiation of a first path as described herein. Image <NUM> includes stars <NUM> within the viewing environment of the star port.

<FIG> illustrates an example of image <NUM> that combines the electromagnetic radiation received through the sun port and the star port of the baffle described herein. Thus, image <NUM> represents the image created from the electromagnetic radiation of a combined viewpath after a beam splitter. As such, image <NUM> includes both sun <NUM>, satellite <NUM> in front of sun <NUM>, and stars <NUM>.

As shown in image <NUM>, stars <NUM> look to be within the same viewing environment as sun <NUM> and satellite <NUM> and sun <NUM> overlaps with some stars <NUM>. However, in certain examples, as the sun port and star port image different portions of the environment, the position of stars <NUM> in actuality do not overlap with the position of sun <NUM>. The overlapping is due to the beam splitter combining the electromagnetic radiation of the different portions that are imaged by the sun port and the star port. In certain examples, analysis of image <NUM> is performed by identifying all stars <NUM> contained within image <NUM> as being imaged from the viewing environment of the star port.

<FIG> illustrates image <NUM> that includes a neutral density image of sun <NUM>. Image <NUM> illustrates an alternative image of sun <NUM>. Such an alternative image is used in certain examples in the imaging of portions of the viewing environment.

While the systems, apparatus, and methods disclosed above have been described with reference to spacecraft and the aerospace industry, it will be appreciated that the examples disclosed herein is applicable to other contexts as well, such as observatory, automotive, ship, aircraft, and other mechanical and vehicular contexts. For example, the systems and apparatus described herein is, in certain other examples, mounted on a gimbal of an aircraft. Accordingly, examples of the disclosure is described in the context of a spacecraft manufacturing and service method <NUM> as shown in <FIG> and vehicle <NUM> as shown in <FIG> as applicable to such other contexts.

<FIG> illustrates a flow chart of an example of a vehicle production and service methodology, in accordance with some examples. In some examples, during pre-production, method <NUM> includes the specification and design <NUM> of vehicle <NUM> (e.g., a spacecraft as shown in <FIG>) and material procurement <NUM>. During production, component and subassembly manufacturing <NUM> and system integration <NUM> of vehicle <NUM> takes place. Thereafter, vehicle <NUM> goes through certification and delivery <NUM> in order to be placed in service <NUM>. While in service, in certain examples, vehicle <NUM> is scheduled for maintenance and service <NUM> (e.g., modification, reconfiguration, refurbishment, and so on).

In certain examples, each of the processes of method <NUM> is performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator includes any number of aerospace manufacturers and major-system subcontractors; a third party includes any number of venders, subcontractors, and suppliers; and an operator includes, in certain examples, an airline, leasing company, military entity, service organization, and so on.

<FIG> illustrates a block diagram of an example of a vehicle, in accordance with some examples. As shown in <FIG>, the vehicle <NUM> (e.g., a spacecraft) produced by method <NUM> includes frame <NUM> with plurality of systems <NUM>, and interior <NUM>. Examples of systems <NUM> include one or more of propulsion system <NUM>, electrical system <NUM>, navigation system <NUM>, and environmental system <NUM>. In various examples, other systems are also included within vehicle <NUM>. Although an aerospace example is shown, the described principles are applicable to other industries, such as the automotive industry.

<FIG> and <FIG> are representations of a baffle of a direct sun imaging star tracker, in accordance with some examples. <FIG> illustrates baffle <NUM> that includes star port <NUM> and imaging sensor receiver <NUM>. Imaging sensor receiver <NUM> is configured to receive imaging sensor <NUM>. <FIG> illustrates a side representation of baffle <NUM>. As shown in <FIG>, baffle <NUM> includes star port <NUM> and imaging sensor receiver <NUM>. Sensor port <NUM> is disposed on an end of imaging sensor receiver <NUM>.

Furthermore, baffle <NUM> includes one or more internal baffles <NUM> disposed within its view paths. In various examples, internal baffles are included within first path <NUM>, second path <NUM>, and/or combined viewpath <NUM> to, for example, accommodate requirements on solar, lunar, and/or Earth pointing exclusion zones. As such, internal baffles <NUM> allow for limiting of the viewpoint of its associated port.

Baffle <NUM> further includes sun port <NUM>. Sun port <NUM> includes one or more lenses and, in certain examples, one or more filters to attenuate the magnitude of sunlight. The sun port <NUM> is disposed at an angle to first path <NUM>. The sun port <NUM> is disposed at between a <NUM>-<NUM> degree angle, such as a <NUM> degree angle as shown in <FIG>, to first path <NUM>. In certain such configurations, sun port <NUM> attenuates the magnitude of sunlight through one or more filters, acts as a beam splitter due to its orientation, and, in certain examples, changes the focal length of sun port <NUM>. A lens disposed within sun port <NUM> acts as the beam splitter. Sun port <NUM> thus combines first path <NUM> and a view of the sun into combined viewpath <NUM>. In additional examples, sensor port <NUM> and/or sun port <NUM> includes a star reflective mirror or another such lens. Thus, for example, sensor port <NUM> in certain examples includes a lens. The lens, in certain examples, aids in focusing of images for imaging sensor <NUM>.

<FIG> and <FIG> are representations of a direct sun imaging star tracker, in accordance with some examples. As shown in <FIG> and <FIG>, star tracker <NUM> includes baffle <NUM> and imaging sensor <NUM> disposed within imaging sensor receiver <NUM>. Baffle <NUM> includes star port <NUM> and sun port <NUM>. As shown in <FIG>, combined viewpath <NUM> is directed into one or more sensors of imaging sensor <NUM>.

Claim 1:
A star tracker (<NUM>), comprising:
an imaging sensor (<NUM>), optionally a visual sensor, configured to receive electromagnetic radiation via a combined viewpath (<NUM>); and
a baffle (<NUM>), disposed proximate the imaging sensor (<NUM>) and comprising:
a star port (<NUM>), configured to receive first electromagnetic radiation associated with a first viewing environment (<NUM>) via a first path (<NUM>);
a sun port (<NUM>) disposed at between a <NUM>-<NUM> degree angle to the first path (<NUM>), configured to receive second electromagnetic radiation associated with a second viewing environment (<NUM>) via a second path (<NUM>) and configured to attenuate a magnitude of the second electromagnetic radiation; and
a lens disposed within the sun port (<NUM>) configured to act as a beam splitter (<NUM>), configured to receive the first electromagnetic radiation of the first path (<NUM>) and the second electromagnetic radiation of the second path (<NUM>) and configured to combine the first electromagnetic radiation and the second electromagnetic radiation into the combined viewpath (<NUM>).