Ride sharing into orbit is one the best ways to come along to "spread the wealth" of the lower costs to orbit that are available to colleges, small businesses, and those who used to have a hard time getting an idea into space to test. SpaceX already had two ride sharing mission profiles, Transporter and Bandwagon, that vary in the specifics of the orbits they're intended for. To date, the company has launched 15 ride sharing flights in its Transporter series and four via Bandwagon.
Today marked the first launch of a third profile, called "Twilight," because it delivers the satellites to a dusk-dawn sun-synchronous orbit, a path that straddles the line between night and day on our planet. The mission launched from Vandenberg Space Force Base in California at 5:44 AM local time. The primary payload of the mission is a NASA satellite called Pandora, intended for a yearlong mission to study planets outside of our solar system, referred to as exoplanets.
During its yearlong orbital mission, the 716-pound (325 kilograms) Pandora will study at least 20 known exoplanets using a 17-inch-wide (45 centimeters) telescope, which it will train on the worlds as they "transit," or cross the face of, their host stars from the satellite's perspective.
(Unless there's something really unusual about this telescope, astronomers refer to a "17-inch-wide" telescope as 17-inch aperture.) Like virtually all observational studies of exoplanets, the Pandora telescope will image these stars to look for planets passing in front of their star from our viewpoint. Not only do these occultations provide an observable small dimming of the star's light proportional to the diameter of the planet compared to the star's, they also allow astronomers to analyze the exoplanets' atmospheres. Different elements and molecules absorb light at specific wavelengths, so studying the spectrum of the star's light before and during the time when the planet passes in front of the star can reveal a great deal about that atmosphere's composition.
Part of the complexity of the mission is that the star itself contributes data, so they need to analyze that to correct for the star's contribution. A common source of more information is sunspots.
"Pandora aims to disentangle the star and planet spectra by monitoring the brightness of the exoplanet's host star in visible light while simultaneously collecting infrared data," NASA officials wrote in a mission description. "Together, these multiwavelength observations will provide constraints on the star's spot coverage to separate the star's spectrum from the planet's."
Pandora will focus on planets with atmospheres that are dominated by water or hydrogen, agency officials added.
There were 40 satellites onboard the ride sharing mission, a mixture of 10 of Kepler Communications' Aether spacecraft and two of Capella Space's advanced new Acadia Earth-imaging radar satellites. That still leaves 28 satellites we have no information on.
This booster flew on its fifth mission, and landed back at Vandenberg successfully a bit over eight minutes after launch.
Artist's concept of the Pandora satellite. Image credit: NASA's Pandora Mission website



















