Isar Aerospace Spectrum. Spectrum is a two-stage orbital launch vehicle being developed by the German startup company Isar Aerospace. The company intends for the Spectrum rocket to achieve the first commercial launch of a small-lift launch vehicle to orbit by a private European company.

Development of the Spectrum commenced during the 2010s. Much of its design has been produced internally; a key target during development was the price point of €10,000 ($11,700) per kg, as well as to be as flexible as possible as to suit a wide variety of payload requirements. Isar Aerospace has arranged terms to conduct Spectrum launches from both the Andøya Spaceport in Norway and the Guiana Space Centre in French Guiana. Early customers for the launcher include Airbus Defence and Space, the German Aerospace Center (DLR), and Spaceflight, Inc.. In December 2021, the first launch of Spectrum was anticipated to take place some time in 2022; following delays, it is presently set to occur during 2024.

Design 
Spectrum is a two-stage launch vehicle designed to carry both small and medium-sized satellites. It has a maximum payload capacity of 1,000kg to low Earth orbit (LEO) or alternatively up to 700kg
to a semi-synchronous orbit (SSO). Isar Aerospace has promoted the launcher for possessing considerable flexibility, better permitting it to fulfil the varying demands of its prospective customers. According to the company, the vast majority of Spectrum has been both developed and manufactured inhouse, including its Aquila engines. It is a relatively compact rocket, in part facilitated by the high energy density of its propellant, which comprises a combination of liquid oxygen and propane. It has been designed to achieve a price point of €10,000 ($11,700) per kg.

The first stage of Spectrum is powered by an arrangement of nine Aquila engines, while the second stage is provided with a single Aquila engine. This second stage engine is to be equipped with a multi-ignition system, permitting it to be shut down and reignited if the launch profile should require such an arrangement, eliminating the need for an additional 'kick' stage. The propellant is supplied to the engines at relatively high pressure via a turbopump. In March 2023, Isar Aerospace reported having performed 124 hotfires of the Aquila engine during the prior year, these test runs having been performed at Esrange, Sweden; these tests demonstrated greater than anticipated performance with one of these engines being fired on six separate occasions without any intervening refurbishment.

Launch sites 

During April 2021, a 20-year deal was signed by Isar Aerospace for exclusive access to one of the Andøya Space launch pads in Norway. Due to its location, inclinations between 87.4 and 108 degrees can be reached from this launch site, targeting Sun-synchronous and polar orbits.

In July 2022, Isar Aerospace announced that it had been selected by France's National Centre for Space Studies (CNES) to conduct launch operations at the former Kourou Diamant Launch Site at the Guiana Space Centre, which had been last used for an orbital launch in 1975. Due to the low latitude of this launch site, it can be used for equatorial and medium inclination orbits. The first launch to take place from this launch site has been scheduled for 2024.

Launches 
In 2021, multiple launch arrangements for Spectrum were announced between companies, such as Airbus Defence and Space, EnduroSat, and Astrocast. In December 2021, it was announced by Isar Aerospace and the German Aerospace Center (DLR) that a total of seven small satellites would comprise the institutional payload to be carried on Spectrum’s first flight. During early 2023, it was announced that Spectrum's first American customer, Spaceflight, Inc., had agreed terms for a dedicated launch from Andøya during 2026 along with an option for a 2025 launch.

In December 2021, the first launch of Spectrum was anticipated to take place some time in 2022. By March 2023, Isar Aerospace was reportedly aiming for the first flight was set to occur some time during the second half of 2023. However, by November 2023, this milestone had been postponed again into 2024.

References 

Space launch vehicles of Europe
Space launch vehicles of Germany