Spectrum (rocket)

Spectrum is a two-stage launch vehicle designed to carry both small- and medium-sized satellites.^[1] It has a maximum payload capacity of 1,000 kg (2,200 lb) to low Earth orbit (LEO) or alternatively up to 700 kg (1,500 lb) to a Sun-synchronous orbit (SSO). Isar Aerospace has promoted the launcher as possessing considerable flexibility, better allowing it to fulfill the varying demands of its prospective customers.^[1] According to the company, the vast majority of Spectrum's development and manufacturing is in-house, including that of 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.^[1] It has been designed to achieve a price point of €10,000 ($11,700) per kg.^[2]

The first stage of Spectrum is powered by an arrangement of nine Aquila engines, while the second stage uses a single Aquila engine.^[1] 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.^[3] The propellant is supplied to the engines at high pressure via a turbopump.^[1] 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;^[4] these tests demonstrated greater than anticipated performance with one of these engines being fired on six separate occasions without any intervening refurbishment.^[5]

The rocket's structure is made of a single-part carbon composite and is manufactured with an automated process. This lightweight material offers the highest payload performance.^[6]

In 2021, multiple launch arrangements using Spectrum were announced by companies such as Airbus Defence and Space,^[14][15] EnduroSat,^[16] and Astrocast.^[17] In December 2021, Isar Aerospace and the German Aerospace Center (DLR) announced that a total of seven small satellites would comprise the institutional payload to be carried on Spectrum's first flight.^[18] In early 2023, Spectrum's first American customer, Spaceflight, Inc., agreed to terms for a dedicated launch from Andøya during 2026 along with an option for a 2025 launch.^[19][20]

In December 2021, the first launch of Spectrum was anticipated to take place sometime in 2022.^[18] By March 2023, Isar Aerospace was reportedly aiming for the first flight to occur sometime during the second half of 2023.^[21][22] However, by November 2023, this milestone was postponed again to 2024.^[23] Plans to launch the first rocket in 2024 were delayed until an exhaustive slate of tests could be performed.^[24]

On 21 February 2025, a static fire test of Spectrum was performed that reportedly confirmed that the rocket was ready.^[24] One month later, a launch license was issued by the Norwegian Civil Aviation Authority (NCAA).^[25] Shortly thereafter Isar Aerospace announced that they were in the process of assembling the second and third Spectrum.^[24][26] The first launch attempt on 24 March 2025 was scrubbed due to high winds.^[27]

On 30 March 2025 at 12:30 pm local time, the rocket was launched from Norway for the first time; however, it lost control several seconds later, causing it to fall into the sea and explode.^[28] An investigation found that the rocket's vent valve had opened unexpectedly, leading to a loss of attitude control at the start of the roll maneuver.^[29] The rocket did not carry a payload.^[30]

A second launch on 5 September 2026 was successful, deploying several small satellites into a Sun-synchronous orbit.^[13] The flight carried 5 academic cubesats and 1 undeployable payload to qualify Spectrum for future commercial satellite launches.^[13]