Method of solar occultation

Patent metadata

Field	Value
Publication number	US-9676500-B2
Application number	US-201314386403-A
Country	US
Kind code	B2
Filing date	Feb 25, 2013
Priority date	Mar 20, 2012
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A method of solar occultation, and in particular solar coronagraphy, employing a spacecraft 200 is disclosed. The spacecraft is controlled to achieve a position within a target zone relative to a celestial body, such as the Moon, such that the celestial body occults the Sun, allowing observations of the Sun or the space around the Sun, and in particular the Sun's corona, to be made from the spacecraft. The spacecraft has an orbit 40 around the Earth in a plane S, which like the Moon's orbit 20 in plane M, is inclined relative to the ecliptic plane E. Once inside the target zone, the spacecraft's orbit is controlled such that it remains in the target zone for longer than it would otherwise. This is achieved through the orbit within the target zone being at least partly non-Keplerian, when the orbit is under the influence of spacecraft translational thrust for example. The invention also extends to a method of controlling a spacecraft, to a spacecraft, and to a solar coronagraph comprising a spacecraft and a celestial body.

First claim

The invention claimed is:

1. A method of solar occultation employing a spacecraft, the method comprising:
controlling the spacecraft to achieve a position within a target zone relative to the Moon such that the Moon occults the Sun; and
controlling the spacecraft to observe the Sun or the space around the Sun,
wherein the spacecraft is controlled to have an orbit within the target zone which is at least partly non-Keplerian or approximating non-Keplerian via a discrete set of frequent maneuvers in a perpendicular to the line between the Moon and the Sun and in the plane of the spacecraft orbit, such that the spacecraft is positioned within the target zone for a predetermined time.

2. The method of claim 1 , in which the Sun's corona is observed from the spacecraft.

3. The method of claim 1 , wherein the Sun, as observed from the spacecraft, has a radius Rs and the spacecraft is programmed to be positioned in the target zone, for a predetermined time, which is defined as the zone within which, when observed from the spacecraft, the Moon occults an area within the entire circumference of an occulting disc, representing the outline of the Moon as observed from the spacecraft, in which the area has a radius of at least 1.00 Rs.

4. The method of claim 3 , wherein the target zone is further defined as the zone within which, when observed from the spacecraft, the Moon occults an area of the Sun within the entire circumference of the occulting disc, in which the occulting disc is approximately circular, and the radius of the occulting disc is no greater than 1.05 Rs at at least one point on the circumference of the occulting disc.

5. The method of claim 3 , wherein the target zone is further defined as the zone within which, when observed from the spacecraft, the Moon occults an area of the Sun within the entire circumference of the occulting disc, in which the occulting disc is approximately circular and the radius of the occulting disc is no greater than 1.05 Rs around the entire circumference of the occulting disc.

6. The method of claim 4 , wherein the Moon occults an area of the Sun defined by the circumference of the occulting disc, in which the radius of the occulting disc is no greater than 1.02 Rs.

7. The method of claim 1 , wherein the spacecraft is controlled to orbit the Earth with an elliptical, parabolic or hyperbolic orbit such that, at perigee, the spacecraft is positioned within the target zone.

8. The method of claim 1 , wherein the line between the Moon and the Sun is defined as the x-direction, and the frequent maneuvers are applied in the y-direction, and spacecraft is further controlled to remain within the target zone for a predetermined time by controlling the motion of the spacecraft in a z-direction which is perpendicular to both the x- and y-directions.

9. A spacecraft configured to achieve a position within a target zone relative to the Moon to enable observation from the spacecraft of the Sun or the space around the Sun by occultation of the Sun by the Moon comprising:
a thruster; and
a controller controlling maneuvers of the spacecraft using the thruster,
Wherein the controller is programmed with flight and orbit data so that the spacecraft is controlled to have an orbit within the target zone which is at least partly non-Keplerian or approximating non-Keplerian via a discrete set of frequent maneuvers in a direction perpendicular to a line between the Moon and the Sun and in the plane of the spacecraft orbit, such that the spacecraft is positioned within the target zone for a predetermined time.

Assignees

• Airbus Defence & Space Ltd

Inventors

• Eckersley Steve
• Kemble Stephen

Classifications

• B64G1/1085

  Swarms and constellations · CPC title

• B64G1/242

  Orbits and trajectories · CPC title

• B64G1/105 Primary

  Space science · CPC title

• B64G2001/1064

  Operations & Transport · mapped topic

• B64G1/24 Primary

  Guiding or controlling apparatus, e.g. for attitude control · CPC title