Yes, of course, gimbals are required even for coplanar satellites.
The issue arises when there is a user in a different plane and a different altitude. Depending on the relative positions of the satellite and the user, the slew rate of the gimbals may be very high.
Also, apart from generally pointing the user receiver upwards, where do the user ISR(s) affix to the spacecraft?
If the slew rate is "very high", then you should not attempt to establish an ISL. Pick a satellite that is farther away or is moving in a more appropriate direction.
One popular theoretical approach is to place your major networking satellites at a higher altitude. the usual lower-altitude satellites connect in rings, one per orbit, and several satellites in each ring connect up to the higher "network". The satellites in the "network" do not serve terrestrial users, but they have lots of ISL with each other.
The majority of the launch windows, including the ones with long launch windows, are at night for the next two periods. It's hard for me to imagine NASA will purposefully aim for a day launch if the windows to do so are so limited.
Do we have even rough ideas of a timeline for Polaris 2?
Will Polaris Dawn slipping back 3 months likely push it back as well?
My expectation is that Starship orbital flight would be more responsible for pushing back the second Polaris mission. I don't think Starship *landing* would impede Polaris 2 per se, but landing obviously should be at the top of the priority list after that.
I haven't seen anything official. I happened to see the Madrid DSN pass on DSN Now this morning about 0900 PDT and near the end of the track it was not staying in lock, but that may have been due to low antenna elevation.
SLS was supposed to be ready by the end of 2016. If you assume another $2.64B per year for FY15 and FY16, you get very close to the $11.5B that Nelson was indicating.
Correction, the SLS was supposed to be OPERATIONAL by the end of 2016. From Senate Bill S.3729:
Developmental work and testing of the core elements and the upper stage should proceed in parallel subject to appropriations. Priority should be placed on the core elements with the goal for operational capability for the core elements not later than December 31, 2016.
That means all testing had to be done before that point, so that they could certify the SLS as operational.
In the context of the 2010 NASA Authorization bill, operational capability just meant that you can operate and use it.
Since Congress didn't define what "operational capability" means, in the normal sense that means that testing is done and the transportation system has been certified for normal use. That is what "use it" means, and it does not mean "testing".
Furthermore, clause 303(a)(2) of the 2010 Authorization Act specifically envisions a test flight before operational capability is achieved: "the Administrator may undertake a test of the transportation vehicle at the ISS before that date [Dec. 31, 2016]."
The only out here is that IOC was to be to LEO, not to TLI. But the difference between LEO and TLI is only ICPS, which has always been been the least risky, least troublesome and least expensive component of SLS.