Rocket Lab Photon; Features and Missions.

Rocket Lab Photon is a satellite bus based on Rocket Lab’s Electron kick stage. A Launch service provider platform that allows customers to integrate a variety of payloads, from Earth observation cameras to communications equipment, and get them into orbit in less time than if the companies built their own satellites. The Photon spacecraft bus is a high-performance evolution of the Kick Stage developed for missions that require extended payload support on orbit, or for missions exceeding 2,000 km to MEO, lunar, or interplanetary destinations.

Design and Features

Rocket Lab Photon is manufactured at Rocket Labs factory in Huntington Beach, California. It uses the Curie engine and communicates on S-band. Depending on the orbital inclination (37° to Sun synchronous orbit), it is expected to have a maximum payload capacity of 170 kg (370 lb). The low Earth orbit version of Photon can take 130 kg (290 lb) to Sun-synchronous orbit.

Photon as a configurable, modular spacecraft is designed to accommodate a variety of payloads and instruments without significant redesign. Photon is equipped with radiation-tolerant avionics, deep space-capable communications and navigation technology, and high-performance space-storable propulsion capable of multiple restarts on orbit. It has the capacity to both host an external payload and perform secondary mission objectives as a separate operational spacecraft.

A modified version of Rocket Lab Photon would have bigger propellant tanks and the HyperCurie engine for interplanetary missions. The interplanetary version will have a 40 kg (88 lb) payload capacity. HyperCurie is an evolution of the Curie engine, which comes in a monopropellant version and a bipropellant version, while the HyperCurie is a hypergolic version. HyperCurie is electrically pumped.

Rocket Lab has designed Photon for dedicated mission or as a rideshare option without the programmatic complexity, expanded cost, and schedule risk typically experienced when launching with a medium or heavy lift launch vehicle.

Missions and Launch history

The first satellite to test the architecture was Electron Kick Stage Rocket Body/Photon Pathfinder (COSPAR ID 2020-037F). It was launched aboard an Electron rocket on 13 June 2020 on its 12th Electron mission, “Don’t stop me now” as its kickstage. It aimed to extend the function of the kick stage to enable it to function as a satellite in its own right.

Formally the inaugural Photon satellite was the Photon Pathfinder/First Light satellite (COSPAR ID 2020-060A) described by Rocket Lab as its “first in-house designed and built Photon demonstration satellite”. It was launched aboard Electron rocket on 31 August 2020 on the 14^th Electron mission “I Can’t Believe It’s Not Optical”. First Light had a dual role in the mission: first as the final rocket stage delivering the customer satellite (Capella 2) and then as a standalone satellite undertaking its own orbital mission. The purpose of First Light standalone mission is to demonstrate the new (as compared to “plain” kick stage) systems for operating in orbit as a long-duration standalone satellite. To demonstrate Photon bus’ payload hosting, the First Light had a low-resolution video camera.

The second formal test, Photon Pathstone, was launched on 22 March 2021 on the 19^th Electron mission “They Go Up So Fast”. Like First Light, Pathstone will first deliver customer satellites to orbit for transitioning into its own satellite operations. Pathstone operations are aimed at building flight heritage and focused on testing systems in preparation for launching NASA’s CAPSTONE smallsat mission, later in 2021. These tests will include power and thermal management, attitude control via reaction wheels and communications systems.

The first operational launch for Rocket Lab Photon will be NASA’s CAPSTONE smallsat mission. Rocket Lab Photon will deliver CAPSTONE on a trans-lunar injection burn to a near-rectilinear halo orbit. After completing all the mission requirements for NASA, Rocket Lab hopes to utilize its Photon spacecraft for a low-altitude lunar flyby. Qualification of the Photon kick stage for this mission was underway by December 2020.

In August 2021, Varda Space announced that it had signed a contract with Rocket Lab to acquire three Photon satellite bus to carry out missions to build the space station.

According to Burghardt Thomas, Rocket Labs ultimate aim for Photon is that it will enable an interplanetary mission to Venus in 2023, delivering a laser-tunable mass spectrometer into the Venusian atmosphere.