SYSTEMS AND METHODS FOR ESTIMATING PARAMETERS OF A SPACECRAFT BASED ON EMISSION FROM AN ATOMIC OR MOLECULAR PRODUCT OF A PLUME FROM THE SPACECRAFT

• US 20160347482A1
• Filed: 05/27/2015
• Published: 12/01/2016
• Est. Priority Date: 05/27/2015
• Status: Active Grant

• Current Assignee: Aerospace Corporation
• Original Assignee: Aerospace Corporation
• Inventors: DIMPFL, William L.
• Granted Patent: US 9,963,251 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B64G 1/14 Space shuttles reusable launch rockets B64G1/006
• CPC Class Codes: B64G 1/66 Arrangements or adaptations of apparatus or instruments, not otherwise provided for
• CPC Class Codes: B64G 3/00 Observing or tracking cosmonautic vehicles

Abstract

A parameter of an actual spacecraft can be estimated based on a spectroscopic image of an emission from an atomic or molecular product of an interaction between an atmospheric gas and an atomic or molecular species in a plume from the actual spacecraft. The actual spacecraft can be characterized by a set of values of at least N parameters. An N-dimensional lookup table can store information about a plurality of simulated emissions, each being from the atomic or molecular product of a simulated interaction between the atmospheric gas and the atomic or molecular species in a plume from a simulated spacecraft characterized by a corresponding set of values of the N parameters. A simulated emission can be selected based on comparisons between the information about the simulated emissions and the spectroscopic image. A value of at least one of the N parameters of the actual spacecraft can be estimated based on the selected simulated emission.

Claims

1. A computer-implemented method for estimating a parameter of an actual spacecraft based on a spectroscopic image of an emission from an atomic or molecular product of an interaction between an atmospheric gas and an atomic or molecular species in a plume from the actual spacecraft, the actual spacecraft being characterized by a set of values of at least N parameters, the method including:

obtaining an N-dimensional lookup table stored in a non-transitory computer-readable medium, the lookup table storing information about a plurality of different simulated emissions, each simulated emission being from the atomic or molecular product of a simulated interaction between the atmospheric gas and the atomic or molecular species in a plume from a simulated spacecraft characterized by a corresponding set of values of the N parameters;

selecting a simulated emission based on comparisons between the information about the simulated emissions and the spectroscopic image; and

estimating a value of at least one of the N parameters of the actual spacecraft based on the selected simulated emission.

2. The method of claim 1, wherein the N parameters are selected from the group consisting of:

view angle, range, spacecraft mass, engine thrust, engine lip angle, remaining propellant, angle of attack, atmospheric relative speed, plume velocity, atmospheric composition adjacent to the spacecraft, atmospheric density adjacent to the spacecraft, ambient temperature, and amount of the atomic or molecular species in the plume.

3. The method of claim 1, wherein the estimating includes interpolating the value of at least one of the N parameters of the actual spacecraft based on the information about the simulated emission and the spectroscopic image.

4. The method of claim 1, wherein the information about the plurality of simulated emissions includes a simulated image of each of the simulated emissions.

5. The method of claim 4, wherein the spectroscopic image and the simulated image each are two-dimensional, the method including selecting the simulated emission having a simulated image that most closely matches the spectroscopic image.

6. The method of claim 4, wherein the simulated image includes a simulated three-dimensional radiant field.

7. The method of claim 6, wherein the spectroscopic image includes a spectroscopic three-dimensional radiant field, the method further including constructing the spectroscopic three-dimensional radiant field based on a pair of stereo spectroscopic images of the emission, and selecting the simulated emission having a simulated three-dimensional radiant field that most closely matches the spectroscopic three-dimensional radiant field.

8. The method of claim 6, wherein the spectroscopic image is two-dimensional, the method including generating a plurality of two-dimensional simulated images at different view angles, and selecting the simulated emission having a two-dimensional simulated image that most closely matches the spectroscopic image.

9. The method of claim 1, further including selecting the simulated emission based on an a priori known value of at least one of the N parameters of the actual spacecraft.

10. The method of claim 1, wherein the emission includes a wavelength of approximately 336 nm.

11. The method of claim 10, wherein the atomic or molecular product is nitrogen monohydride.

12. The method of claim 1, wherein the emission is selected from the group consisting of:

OH(A→

X) electronic emission resulting from interaction between atmospheric gas and an atomic or molecular species in the plume, plume CO vibrational infrared emission excited by collisions with atmospheric atomic oxygen, CO(a→

X) Cameron band ultraviolet emission resulting from a two-step interaction of plume methane with atmospheric atomic oxygen, plume H₂O vibrational bend mode infrared emission excited by collisions with the atmospheric gas, and plume H₂O asymmetric stretch mode infrared emission excited by collisions with the atmospheric gas.

13. A system for estimating a parameter of an actual spacecraft based on a spectroscopic image of an emission from an atomic or molecular product of an interaction between an atmospheric gas and an atomic or molecular species in a plume from the actual spacecraft, the actual spacecraft being characterized by a set of values of at least N parameters, the system including:

a non-transitory computer-readable memory storing an N-dimensional lookup table storing information about a plurality of different simulated emissions, each simulated emission being from the atomic or molecular product of the interaction between the atmospheric gas and the atomic or molecular species in a plume from a simulated spacecraft characterized by a corresponding set of values of the N parameters; and

a processor coupled to the non-transitory computer-readable memory and configured to select a simulated emission based on comparisons between the information about the simulated emissions and the spectroscopic image, and to estimate a value of at least one of the N parameters of the actual spacecraft based on the selected simulated emission.

14. The system of claim 13, wherein the N parameters are selected from the group consisting of:

view angle, range, spacecraft mass, engine thrust, engine lip angle, remaining propellant, angle of attack, atmospheric relative speed, plume velocity, atmospheric composition adjacent to the spacecraft, atmospheric density adjacent to the spacecraft, ambient temperature, and amount of the atomic or molecular species in the plume.

15. The system of claim 13, wherein the processor is configured to estimate the value based on interpolating the value of at least one of the N parameters of the actual spacecraft based on the information about the simulated emission and the spectroscopic image.

16. The system of claim 13, wherein the information about the plurality of simulated emissions includes a simulated image of each of the simulated emissions.

17. The system of claim 16, wherein the spectroscopic image and the simulated image each are two-dimensional, the processor being configured to select the simulated emission having a simulated image that most closely matches the spectroscopic image.

18. The system of claim 16, wherein the simulated image includes a simulated three-dimensional radiant field.

19. The system of claim 18, wherein the spectroscopic image includes a spectroscopic three-dimensional radiant field, the processor further being configured to construct the spectroscopic three-dimensional radiant field based on a pair of stereo spectroscopic images of the emission, and to select the simulated emission having a simulated three-dimensional radiant field that most closely matches the spectroscopic three-dimensional radiant field.

20. The system of claim 18, wherein the spectroscopic image is two-dimensional, the processor being configured to generate a plurality of two-dimensional simulated images at different view angles, and to select the simulated plume having a two-dimensional simulated image that most closely matches the spectroscopic image.

21. The system of claim 13, the processor further being configured to select the simulated emission based on an a priori known value of at least one of the N parameters of the actual spacecraft.

22. The system of claim 13, wherein the emission includes a wavelength of approximately 336 nm.

23. The system of claim 22, wherein the atomic or molecular product is nitrogen monohydride.

24. The system of claim 13, wherein the emission is selected from the group consisting of:

OH(A→

X) electronic emission resulting from interaction between atmospheric gas and an atomic or molecular species in the plume, plume CO vibrational infrared emission excited by collisions with atmospheric atomic oxygen, CO(a→

X) Cameron band ultraviolet emission resulting from a two-step interaction of plume methane with atmospheric atomic oxygen, plume H₂O vibrational bend mode infrared emission excited by collisions with the atmospheric gas, and plume H₂O asymmetric stretch mode infrared emission excited by collisions with the atmospheric gas.

25. A method of generating a lookup table, the method including:

(a) obtaining ranges of values and step sizes for each of N parameters characterizing a simulated spacecraft;

(b) selecting a set of values for the N parameters within the respective ranges;

(c) simulating a plume from a simulated spacecraft characterized by the selected set of values;

(d) simulating an interaction between an atmospheric gas and the plume;

(e) simulating an emission from an atomic or molecular product of the interaction;

(f) storing information about the simulated emission and the selected set of parameters in an N-dimensional lookup table stored in a non-transitory computer-readable medium;

(g) selecting additional sets of values for the N parameters by iteratively incrementing values of the parameters by the respective step sizes through the respective ranges; and

(h) repeating steps (c)-(f) for each additional set of values selected in step (g).

26. A N-dimensional lookup table stored in a non-transitory computer readable medium, the N-dimensional lookup table storing information about a plurality of simulated emissions, each simulated emission being from the atomic or molecular product of a simulated interaction between an atmospheric gas and an atomic or molecular species in a plume from a simulated spacecraft characterized by a corresponding set of values of N parameters.