4) The continuous viewing zone

TESS will be in Earth orbit (more on that later), and it needs to keep its cameras pointed away from the Sun when making observations. Therefore, it will basically stare at the section of sky opposite the Sun as it sweeps out a one-year solar orbit with Earth. This is actually very similar to how scientists will operate JWST out at the L2 LaGrange point; they can't look near the Sun, so potential observation targets can only be imaged when they are more or less opposite the Sun.

But, there's an exception: the continuous viewing zone!

You'll notice in the above diagram that TESS will miss a little bit of sky near the ecliptic, but get a lot of overlap near the poles. That's intentional. Each observation slice only gets 27 days of coverage, but at the poles, there will be near-continuous viewing. This means we'll be more likely to find planets there, and since JWST can also continuously see the poles, it can more easily follow up discoveries in that part of the sky. That's some nicely planned astronomy mission synergy!

5) TESS mission type

Speaking of mission synergy, this is a good time to mention TESS is an astrophysics explorer mission. These are small- and medium-class missions that aren't full-fledged flagships (like JWST). TESS is a medium-class explorer with a cost cap of $200 million, not including launch costs—which turned out to be $87 million in this case. (This is where I deploy my standard reminder that when SpaceX says the base price of a Falcon 9 is $62 million, that doesn't necessarily include things like payload processing, integration, and mission assurance. It's still a good deal, though!) Explorer missions are led by one principal investigator, and the PI for TESS is MIT's George Ricker.

6) Nerdy camera details

Just because I pretend to be a knowledgeable photographer, I'm always interested in nerdy spacecraft camera details. (Cut to scene of me photographing my daughter and telling her to hold still while I fiddle with exposure settings, at which point she loses interest and walks away.) TESS's cameras continually take images with exposure times of 2 seconds each. Instead of sending all those images back to Earth, the spacecraft does some nifty onboard processing to create two types of data products: postage stamps and full frame images.

For the postage stamps, every 2 minutes, the spacecraft stacks 60 of those 2-second exposures to create a single image. Then, it cuts out "postage stamps" around certain stars, based on a predetermined catalog of 200,000 interesting stars. Those postage stamps are compressed and sent back to Earth.

For the full-frame images, every 30 minutes, the spacecraft stacks 900 of those 2-second exposures to create a single full-frame image, which gets sent back to Earth.

If that's confusing, try this diagram: