SpaceX launched NASA’s Pandora observatory in rideshare mission
SpaceX has launched 40 payloads on the Twilight rideshare mission, which lifted off from Vandenberg Space Force Base (VSFB) on January 11th, at 13:44:50 UTC.
The launch carried these payloads, including 3 important NASA missions, to a so-called dawn/dusk SSO (Sun-Synchronous Orbit), meaning they pass over the same places at the same local solar time. Now, let’s dive in:
What’s an SSO orbit?
An SSO (Sun-Synchronous Orbit) is a special kind of polar orbit with an inclination of roughly 98°. It is important because it allows a satellite to pass over the same places when the Sun is in the same position in the sky: for example, it could pass over Rome at 10:30 AM local time and Tokyo at 10:30 AM local time - different clock times due to time zones, but the Sun's position in the sky will be the same in both locations (for example, always 30° above the horizon). This allows any satellite in SSO to witness the same lighting conditions over a place, allowing imaging and monitoring satellites to do accurate comparisons of water levels, snow coverage, deforestation, and more throughout time. The slight inclination of the orbit compared to a polar one (98° instead of 90°) allows the orbit to precess, or rotate, along with Earth, so that the local solar time will remain the same even when seasons change.
The key to understanding how an SSO works is local solar time: it represents the Sun’s position in the sky regardless of the time zones, so, if 12:00 is considered as local noon, and the satellite is put in a 10:30 AM orbit, that means it will always pass above every place when the Sun is near its highest point in the sky.
Now, satellites in a dawn/dusk SSO (like those in the Twilight mission) ride along the terminator, or the line that separates day from night on Earth. This means the Sun will always be at the same position above the horizon in every place, whether it’s rising or setting, allowing once again for the same light and shadow conditions.
The biggest advantage of this variant is the presence of the Sun for the majority of the time, which allows for almost-continuous solar power and almost no eclipse periods, which is important as we take a look at the main payloads of this mission.
NASA payloads: Pandora, BlackCAT, and SPARCS
Among the 40 payloads riding on this mission, there are 3 NASA payloads, one of which is the main one.
Pandora
Pandora, allegedly named after the planet in Avatar, is a NASA telescope with the goal of characterizing exoplanets’ atmospheres: when a planet passes in front of a star, this star’s brightness lowers in an event called transit. Data from transits can help determine the planet’s size, mass, orbit, and even its atmospheric composition by analyzing the spectrum coming from the star’s light. However, a serious problem arises with the presence of dark spots on the surface of the star, which can change the spectrum, remove features of the planet’s atmosphere to our eyes, and taint the data. And here’s when Pandora comes in:
By taking multiwavelength observations via visible and infrared light, Pandora will collect data on the star’s spot coverage, separating the star’s spectrum from the planet’s, and providing a detailed overview of the planet’s atmosphere. It will concentrate on hydrogen- and water-rich atmospheres, in the search for life; it will also determine which exoplanets deserve a follow-up by more powerful telescopes, such as JWST (James Webb Space Telescope) or future telescopes.
After 1 month of commissioning, Pandora will begin a 1-year-long primary science mission, with the possibility of extension, during which it will observe 20 known exoplanets, with observations lasting even 24 hours, spanning multiple exoplanets’ orbits.
Pandora marks the first of NASA’s Astrophysics Pioneer program missions, which aim at being low-cost, high-reward preparatory missions; a way to achieve this was using a spare near-infrared detector from JWST for Pandora, which will work along a 45-cm telescope onboard.
BlackCAT
The Black Hole Coded Aperture Telescope (BlackCAT) is a NASA wide-field X-ray telescope mounted on a 6U cubesat. Its main goal is to observe high-energy transient astronomical events such as gamma-ray bursts.
SPARCS
The Star-Planet Activity Research CubeSat (SPARCS) is a NASA-developed 6U cubesat with the objective of monitoring flares and sunspot activity of at least 10 low-mass M- and K-type stars. Its data will provide a better overview of the stellar activity around these kinds of stars, which host the majority of exoplanets we know.
Other payloads
Aether
10 Aether satellites (nr. 3-12) from the Canadian company Kepler Communications will launch on this mission, marking the first layer of their satellite constellation for optical relay data. Following the launch of 2 pathfinders in November 2023, the company is excited to begin operations.
Connecta IoT
4 Connecta IoT satellites (nr. 13-16) will launch as part of the planned 200-satellite constellation by Plan S for the Internet of Things.
Lemur-2
9 Lemur-2 satellites will be launched by US-based Spire Global carrying Earth observation and traffic monitoring payloads.
Tomorrow-S
Tomorrow-S 10 and 11 satellites are launching as part of Tomorrow.io’s 18-satellite constellation for low-latency weather monitoring.
Cluster 13
The 3 Hawk satellites from Cluster 13 (Hawk-13A, B, and C) are launching as part of Hawkeye 360’s constellation, delivering RF data for maritime tracking, national security, emergency response, and spectrum analysis applications.
Acadia
2 Acadia satellites (nr. 8 & 9) are launching as part of Capella Space’s constellation of SAR (Synthetic Aperture Radar) satellites for various applications.
ICEYE
Iceye is launching 2 satellites (nr. 1 and 2), adding to their constellation of SAR satellites.
Umbra
Umbra is launching their 12th satellite on this mission, delivering timely SAR images.
Hydra 2
This satellite from all.space is a software-defined, interoperable platform for military purposes. Terminals deployed to the U.S. Navy and Army allow for a multi-satellite connection with just 1 device.
Flamingo 1
Vyoma Space will launch the first of their planned 12 Flamingo satellites for in-situ space situational awareness, with telescopes and software to detect and track space debris as little as 1-2 cm.
CarbSAR IOD
This small satellite delivers high-resolution X-band SAR imagery from Surrey Satellite Technology Ltd (SSTL) and will also carry a Wrapped Rib antenna from OOS (Oxford Space Systems) to showcase both organizations’ capabilities in hardware and integration.
Dcubed-1/ARAQYS-D1
This 3U cubesat by in-space manufacturing company Dcubed will launch as the first satellite of the company, with the goal of demonstrating production of a 60-cm boom directly in space.
Mission profile
These satellites launched on a SpaceX Falcon 9 rocket from SLC-4E at Vandenberg, California.
Falcon 9 is a 2-stage, partially reusable rocket developed by SpaceX. The first stage is powered by 9 Merlin 1D engines at its base and is designed for propulsive landing and reuse; the second stage uses a single Merlin 1D Vacuum (MVac) engine and is capable of multiple ignitions to deliver the payloads to their precise orbit.
On this launch, SpaceX used the first stage B1097-5 on its 5th flight, landing it at Landing Zone 4 (LZ-4) after stage separation. Meanwhile, the second stage reached an initial parking orbit before reigniting its engine multiple times, for a total of 4 (not including the deorbit burn after the end of mission).
After 2 burns, it released 13 payloads starting a little more than 1 hour into the mission. Then, following 2 more burns, it released the rest of the satellites, including all 3 NASA ones.
Given the nature of the mission, the second stage is equipped with a MEK (Mission Extension Kit): this adds hardware to the second stage, enabling it for longer and more complex missions, which includes a dark grey band for thermal control, more COPVs (Composite Overwrapped Pressure Vessels) for pressurization, and additional TEA-TEB fluid for ignition.
References
SmallSat Missions @ Goddard Pandora
NASA’s Pandora Satellite, CubeSats to Explore Exoplanets, Beyond
