Rotatable stacked spacecraft

1. A system comprising:

at least two spacecraft, including at least a first spacecraft and a second spacecraft, and

an inter-spacecraft coupling arrangement, the at least two spacecraft being mechanically coupled together, in a launch configuration, for launch by a single launch vehicle, by way of the inter-spacecraft coupling arrangement; wherein:

in the launch configuration, the first spacecraft is mechanically coupled with a primary payload adapter of the launch vehicle;

the system is configured to be deployed following injection into a first orbit by the launch vehicle, by separating the first spacecraft from the primary payload adapter while the second spacecraft is mechanically coupled, by way of the inter-spacecraft coupling arrangement, with the first spacecraft;

the first spacecraft includes a thruster configured to execute an orbit transfer maneuver from the first orbit to a second orbit, the thruster delivering thrust along a thrust vector;

each spacecraft includes a respective solar array, each respective solar array having a respective axis of rotation that is substantially orthogonal to the thrust vector;

the inter-spacecraft coupling arrangement, after separating the first spacecraft from the primary payload adapter, is configured, in an on-orbit configuration, to be switchable between a first mode and a second mode, the first mode permitting rotation of the first spacecraft with respect to the second spacecraft about a first axis of rotation that is approximately parallel with the thrust vector, the second mode preventing rotation of the first spacecraft with respect to the second spacecraft about the first axis of rotation; and the first spacecraft is selectively rotatable with respect the second spacecraft such that the respective axis of rotation of the first solar array is at a substantial angle with respect to the respective axis of rotation of the second solar array.

2. The system of claim 1 , wherein the first axis of rotation is approximately co-aligned with the thrust vector.

3. The system of claim 1 , wherein the inter-spacecraft coupling arrangement includes one or both of flexible cabling and flexible propellant lines interconnecting the first spacecraft and the second spacecraft.

4. The system of claim 1 , wherein the inter-spacecraft coupling arrangement is configured to commandably release and separate the second spacecraft from the first spacecraft.

5. The system of claim 1 , wherein, in the launch configuration, the inter-spacecraft coupling arrangement fixedly couples the first spacecraft with respect to the second spacecraft.

6. The system of claim 1 , wherein the inter-spacecraft coupling arrangement includes a V-band clamp.

7. The system of claim 1 , wherein the inter-spacecraft coupling arrangement includes a motorized mechanism for rotating the first spacecraft with respect to the second spacecraft.

8. The system of claim 1 , wherein the inter-spacecraft coupling arrangement excludes any mechanism for rotating the first spacecraft with respect to the second spacecraft.

9. The system of claim 1 , wherein the system includes one or more thrusters or other attitude control actuators configured to rotate the first spacecraft with respect to the second spacecraft.

10. A method comprising:

deploying a payload stack from a launch vehicle, the payload stack including at least a first spacecraft and a second spacecraft, and an inter-spacecraft coupling arrangement, the first spacecraft and the second spacecraft configured to be mechanically coupled together by way of the inter-spacecraft coupling arrangement, in a launch configuration, for launch by the launch vehicle, wherein deploying the payload stack includes separating the first spacecraft from the launch vehicle while the second spacecraft is mechanically coupled, by way of the inter-spacecraft coupling arrangement, with the first spacecraft;

executing an orbit transfer maneuver by performing one or more firings of a thruster delivering thrust along a thrust vector, wherein each spacecraft includes a respective solar array, each respective solar array having a respective axis of rotation that is substantially orthogonal to the thrust vector; and

switching the inter-spacecraft coupling arrangement between a first mode and a second mode, the first mode permitting rotation of the first spacecraft with respect to the second spacecraft about a first axis of rotation that is approximately parallel with the thrust vector, the second mode preventing rotation of the first spacecraft with respect to the second spacecraft about the first axis of rotation, wherein the first spacecraft is selectively rotatable with respect the second spacecraft such that the respective axis of rotation of the first solar array is at a substantial angle with respect to the respective axis of rotation of the second solar array.

11. The method of claim 10 , further comprising rotating the first spacecraft with respect to the second spacecraft about the first axis of rotation.

12. The method of claim 10 , wherein the inter-spacecraft coupling arrangement includes one or both of flexible cabling and flexible propellant lines interconnecting the first spacecraft and the second spacecraft.

13. The method of claim 10 , wherein the inter-spacecraft coupling arrangement is configured to commandably release and separate the second spacecraft from the first spacecraft.

14. The method of claim 10 , wherein the inter-spacecraft coupling arrangement includes a motorized mechanism for rotating the first spacecraft with respect to the second spacecraft.

15. A first spacecraft comprising:

a thruster; and

an inter-spacecraft coupling arrangement, wherein:

the first spacecraft is configured to be launched, by a single launch vehicle, with a second spacecraft;

in a launch configuration, the first spacecraft is mechanically coupled with a primary payload adapter of a launch vehicle; and the second spacecraft is mechanically coupled with the first spacecraft by way of the inter-spacecraft coupling arrangement;

following injection into a first orbit by the single launch vehicle, the first spacecraft is separated from the primary payload adapter while the second spacecraft is mechanically coupled, by way of the inter-spacecraft coupling arrangement, with the first spacecraft;

the thruster is configured to execute an orbit transfer maneuver from the first orbit to a second orbit, the thruster delivering thrust along a thrust vector;

each spacecraft includes a respective solar array, each respective solar array having a respective axis of rotation that is substantially orthogonal to the thrust vector;

the inter-spacecraft coupling arrangement, after separating the first spacecraft from the primary payload adapter, is configured, in an on-orbit configuration, to be switchable between a first mode and a second mode, the first mode permitting rotation of the first spacecraft with respect to the second spacecraft about a first axis of rotation that is approximately parallel with the thrust vector, the second mode preventing rotation of the first spacecraft with respect to the second spacecraft about the first axis of rotation; and

the first spacecraft is selectively rotatable with respect the second spacecraft such that the respective axis of rotation of the first solar array is at a substantial angle with respect to the respective axis of rotation of the second solar array.

16. The first spacecraft of claim 15 , wherein the inter-spacecraft coupling arrangement includes one or both of flexible cabling and flexible propellant lines interconnecting the first spacecraft and the second spacecraft.

17. The first spacecraft of claim 15 , wherein the inter-spacecraft coupling arrangement is configured to commandably release and separate the second spacecraft from the first spacecraft.