Details | |
|---|---|
| Publication Number | US 7967255 |
| Assignees |
|
| Filing Status | Issued Patent |
| US PAIR Status | Patented Case |
| US PAIR Status Date | Jun. 8, 2011 |
| Application Number | 11/782407 |
| Filing Date | Jul. 24, 2007 |
| Publication Date | Jun. 28, 2011 |
Abstract
An autonomous unmanned space flight system and planetary lander executes a discrete landing sequence including performing an initial velocity braking maneuver to remove velocity at altitude, coasting during which the planet surface is imaged and correlated to reference maps to estimate cross-track and along-track navigation errors and one or more lateral braking maneuvers are performed to reduce cross-track navigation error, and performing a terminal velocity braking maneuver(s) to reduce the along-track braking maneuver and remove the remainder of the velocity just prior to landing. A bi-propellant propulsion system provides a very high T/M ratio, at least 15:1 per nozzle. Short, high T/M divert maneuvers provide the capability to remove cross-track navigation error efficiently up to the maximum resolution of the reference maps. Short, high T/M terminal velocity braking maneuver(s) provide the capability to remove along-track navigation error to a similar resolution and remove the remaining velocity in a very short time window, approximately 3-15 seconds prior to touchdown. The propulsive efficiency frees up mass which can be allocated to a fuel to remove the unknown navigation errors, perform hazard avoidance and/or relocate the lander by flying it to another site or be allocated to additional payload.
Claims
- 1. An autonomous planetary lander, comprising: a soft landing impact attenuation system, a payload module; a bi-propellant propulsion module including fuel tanks for storing propellant and a set of nozzles that expel the propellant to perform velocity braking and lateral divert maneuvers, said propulsion module providing a thrust-to-mass (T/M) ratio of between 15:1 and 100:1 per nozzle, said lander having a fuel mass fraction (FMF) of less than 40% of the landed dry mass of the lander; and an avionics module including, a navigation subsystem including at least one sensor that gathers terrain data and a terrain image correlator that correlates the gathered terrain data to reference maps to provide a navigation update; and a guidance subsystem that processes the navigation update to estimate cross-track and along-track navigation errors with respect to a specified landing site designated in the reference map and issues discrete pulse-width modulation command signals to the propulsion module to perform at least one lateral divert maneuver while the lander is coasting to reduce the cross-track navigation error and to perform at least one velocity braking maneuver with approximately 3-15 seconds to touchdown to remove the lander velocity and reduce the along-track navigation error so that the lander lands softly on the landing attenuation system within 1 km of the specified landing site, wherein the FMF to perform the velocity braking maneuver is at most 24%.
- 2. The planetary lander of claim 1, wherein the PMF is between 15% to 40%.
- 3. The planetary lander of claim 1, wherein the T/M ratio is between 25:1 and 60:1 per nozzle.
- 4. The planetary lander of claim 1, wherein the guidance system performs said at least one lateral divert maneuver to reduce the cross-track navigation error to less than 10 m of the specified landing site.
- 5. The planetary lander of claim 1, wherein the guidance system performs said at least one lateral divert maneuver to reduce the cross-track navigation error to the maximum resolution of the reference maps.
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| Oct. 9, 2007 | US AS | ASSIGNMENT | Owner Name: RAYTHEON COMPANY, MASSACHUSETTS Details: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HEAD, JAMES N.;HOPPA, GREGORY V.;GARDNER, THOMAS G.;AND OTHERS;REEL/FRAME:019935/0050;SIGNING DATES FROM 20070918 TO 20071004 |
| Dec. 2, 2010 | US FEPP | FEE PAYMENT PROCEDURE | Details: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
| Jun. 8, 2011 | US STCF | INFORMATION ON STATUS: PATENT GRANT | Details: PATENTED CASE |
| Dec. 3, 2014 | US FPAY | FEE PAYMENT | Fee Payment Year: 4 |
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