So it’s come down to this: Two space shuttle launches until the entire fleet’s mothballed. Tomorrow’s launch of space shuttle Endeavour counts as second-to-last, before space shuttle Atlantis takes the stage in late June for the fleet’s swan song voyage.
(More on TIME.com: NASA Delays Endeavour Shuttle Launch to April 29)
Endeavour should launch tomorrow from NASA’s Kennedy Space Center at 3:47 p.m. EDT (that’s launch pad 39A for locals and tourists). The crew consists of Commander Mark Kelly (husband of Congresswoman Gabrielle Giffords, gravely wounded last January in a Tucson, Arizona shooting), Pilot Gregory H. Johnson and Mission Specialists Michael Fincke, Greg Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori. Congresswoman Giffords is expected to attend.
Weather’s looking good at the moment, and NASA reports the forecast calls for “a 70 percent chance of favorable conditions at launch time.” There’s a front moving into Central Florida that could cause retraction of the “rotating service structure” to be delayed if storm cells develop. The RSS (not the newsfeed feature) is NASA’s way of providing protected access to the shuttle during servicing–basically that massive multi-gridded thing you’ve probably seen in pictures pressed up against the shuttle prior to liftoff. NASA says external tank fueling should begin at 6:22 a.m.
(More on TIME.com: A Rose of Galaxies? NASA Rings In Hubble’s 21st Birthday)
What’s Endeavour doing this time? During its 14-day mission, the crew will drop something off at the International Space Station called an Alpha Magnetic Spectrometer–basically a $2 billion particle physics experiment module designed to scour cosmic rays for unusual matter. The crew will also deliver two S-band communications antennas (used by NASA to communicate with shuttles and the ISS), a high-pressure gas tank, and miscellaneous spare parts.
We’ll cover the launch tomorrow. If you’ve never seen one (or your kids haven’t) it’s worth tuning in. As liftoff’s go, it’s hard to believe that after three decades we’re down to a remainder of two.