Twilight: SpaceX Launches 40 Satellites Including NASA's Pandora Exoplanet Observatory

A SpaceX Falcon 9 rocket launched the first "Twilight" rideshare mission on Sunday, (Jan. 11), from Vandenberg Space Force Base’s Space Launch Complex 4 East at 13:44 UTC, carrying  40 payloads into a dusk-dawn sun-synchronous orbit, a trajectory that allows satellites to maintain consistent lighting conditions for observations.

The Falcon 9’s first stage booster (B1097), completed its fifth flight and successfully landed back at Landing Zone 4 (LZ-4) at Vandenberg Space Force Base about 8.5 minutes after liftoff. This marked the 32nd landing at LZ-4 and the 557th booster landing in SpaceX’s history. The first stage had previously launched three batches of Starlink V2 Mini Optimized satellites and the Sentinel-6B spacecraft.

The 40 payloads were deployed over a 90-minute window, beginning about 61 minutes after liftoff and concluding more than 2.5 hours into the mission. The mission was named "Twilight" due to its deployment into a dusk-dawn sun-synchronous orbit, which straddles the terminator—the line between day and night on Earth—providing stable lighting conditions ideal for long-duration observations.

The primary payload was NASA’s Pandora exoplanet observatory, a 325-kilogram small satellite developed under NASA’s Astrophysics Pioneers program and led from Goddard Space Flight Center, with mission operations based at the University of Arizona in Tucson.

Pandora is equipped with a 0.45-meter (17-inch) Cassegrain telescope developed jointly by Corning Incorporated and Lawrence Livermore National Laboratory, and its spacecraft bus was supplied by Blue Canyon Technologies.

The mission’s core objective is to disentangle exoplanet atmospheric signals from stellar variability by repeatedly observing starlight passing through planetary atmospheres during transits. It will conduct long-duration observations—approximately 24 hours per visit—on at least 20 known exoplanets, with some program materials suggesting up to 39 planets could be studied over a broader timeline.

Most of the more than 6,000 alien planets we know of have been discovered via the "transit method."

Transits also allow astronomers to characterize known exoplanets, especially their atmospheres. Different elements and molecules absorb light at specific wavelengths, so studying the spectrum of starlight that has passed through an atmosphere can reveal a great deal about that atmosphere's composition.

However, such work is complicated by stellar complexity. Star surfaces are not uniform; they often feature patches of varying brightness, like the sunspots that speckle our own star. Pandora will help astronomers account for such complexity, if all goes to plan.

Daniel Apai of the University of Arizona, a lead scientist on the Pandora team, described the mission as "a bold new chapter in exoplanet exploration," emphasizing its potential to refine techniques for detecting atmospheric signals and guide future searches for habitable worlds.

"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."

Tjhe satellite will focus on planets with atmospheres that are dominated by water or hydrogen, agency officials added. The mission includes a one-month commissioning phase followed by a one-year primary science campaign, with all data to be made publicly available.

The mission’s $20 million budget cap reflects its role as a cost-constrained, high-impact experiment designed to complement larger observatories like the Kepler and James Webb Space Telescope (JWST).

The Twilight mission also carried a diverse array of secondary payloads. Among them were three NASA CubeSats: the Star-Planet Activity Research CubeSat (SPARCS), developed by Arizona State University, and the Black Hole Coded Aperture Telescope (BlackCAT), operated by researchers at Penn State University.

Additionally, the mission included 10 Aether spacecraft from Kepler Communications, which form part of a low Earth orbit optical data relay network. Capella Space contributed two advanced Acadia Earth-imaging radar satellites for high-resolution imaging. Exolaunch managed the deployment of 22 satellites, including Dcubed-1/Araqys-D1, which will demonstrate on-orbit 3D printing of a boom structure.

Other payloads included nine Lemur satellites from Spire Global for weather and maritime monitoring.

Sunday's mission is part of SpaceX’s broader rideshare program, distinct from its Transporter and Bandwagon series, and marks the first dedicated flight under the Twilight banner. To date, the company has launched 15 such flights in its Transporter series and four via Bandwagon.