ADRAS-J

Astroscale.

Overview

ADRAS-J is a debris inspection spacecraft built by Astroscale Japan and selected by JAXA for Phase I of the Commercial Removal of Debris Demonstration project [1], [6]. Its task was to rendezvous with a large, uncontrolled, unprepared object, hold position relative to it, and characterize its condition and motion by imaging. The target carries no navigation aid, no grapple fixture and no GPS output, so relative navigation had to be derived entirely from onboard sensing of the object itself [6].

The spacecraft has a wet mass of about 150 kg [2], [6]. It launched on a Rocket Lab Electron from Launch Complex 1 in New Zealand on 18 February 2024 at 09:52 Eastern time [2], into an orbit of about 600 km.

Specifications

Parameter	Value	Source
Wet mass	about 150 kg	[2], [6]
Solar arrays	two articulating wings, two panels each	[6]
Thrusters	12, 1 N each	[5]
Propellant	ammonium dinitramide monopropellant	[5]
Rendezvous payload	visible cameras, infrared imaging, LiDAR, laser rangefinders, LED lighting, custom processing unit	[6]
Relative navigation modes	angles-only navigation, model matching navigation	[7]
Collision avoidance	onboard, with autonomous abort authority	[3]

The spacecraft carries no manipulator. Capture hardware is the subject of the follow-on Phase II vehicle, ADRAS-J2, for which the Payload Attach Fitting on the target was surveyed as the intended grapple point [3], [6].

Mission profile

Event	Date	Source
Launch on Electron from Launch Complex 1, New Zealand	2024-02-18	[2]
Rendezvous operations commenced	2024-02-22	[7]
Angles-only navigation phase started	2024-04-09	[7]
Approach to about 50 m; first observation completed	2024-05-23	[7]
First fly-around attempt, aborted at about 120 degrees of arc	2024-06-19	[4]
Fly-around observations completed	2024-07-15 and 2024-07-16	[1], [4], [7]
Approach to about 15 m, terminated by autonomous abort	2024-11-30	[3], [7]
De-orbit operations initiated; CRD2 Phase I complete	2026-03-25	[7]

The target is the H-IIA second stage that launched the GOSAT Earth observation satellite in 2009 [2]. It is approximately 11 m long, 4 m in diameter, and about 3 t [4], [5]. The orbit at launch was 533 to 597 km at 98.20 degrees inclination [5]. Expected duration of the primary objectives at launch was three to six months [2], [6]; operations in fact ran into 2026 [7].

CRD2 Phase II assigns docking with the same upper stage and removing it from orbit to a subsequent mission [6].

Approach and inspection sequence

Operations were staged by navigation method rather than by distance alone. Absolute navigation brought the spacecraft to the vicinity of the target; relative navigation using onboard instruments detected and closed on it; fly-around observation then characterized it [6]. Angles-only navigation, in which bearing measurements alone are used before the target resolves, ran from April 2024 [7]. Model matching navigation, which fits sensor returns against a model of the object, was the technique used closer in.

The fly-around observations of 15 and 16 July 2024 were flown at a controlled fixed-point relative position of approximately 50 m [4], and produced a near-complete circular trajectory around the upper stage [1]. Imaging used a telephoto camera and a wide-angle camera across varying angles and illumination [4]. A first fly-around attempt on 19 June 2024 was aborted after about 120 degrees of arc.

The 15 m approach

On 30 November 2024 the spacecraft closed from a 50 m hold point behind the upper stage along a straight-line approach, then maneuvered to approximately 15 m below the Payload Attach Fitting, matching relative speed, distance and attitude [3]. It held that position until the onboard collision avoidance system triggered an autonomous abort in response to an unexpected relative attitude of the upper stage. The spacecraft departed as designed without reaching the Capture Initiation Point.

The abort was a designed response by the collision avoidance function to a relative attitude outside the expected range [3]. The approach corridor for an unprepared target is defined relative to a body whose rotation state is estimated from the inspection data gathered earlier in the mission rather than known [4], [6].

Sensing

The rendezvous payload is a custom sensor suite of visible cameras, infrared imaging, LiDAR, laser rangefinders, LED lighting, and a dedicated processing unit that performs onboard data handling [6]. Detailed performance figures for the individual sensors are not published in any source obtained.

Released inspection video from the fly-around was captured at 24 frames per second, ran about 34.92 seconds, and yielded 838 frames at 720 by 960 pixels in portrait orientation [1]. Structure-from-motion processing of 419 of those frames registered every frame, with a sparse cloud of 16,505 points, a mean reprojection error of 0.410 pixels, and a recovered focal length of 2396.08 pixels. No official CAD model of the H-IIA upper stage is public, so reconstructions of it can be assessed only qualitatively.

Autonomy

Operations combined autonomous onboard functions with ground control [6]. Relative navigation, station keeping and the collision avoidance function ran onboard; the abort on 30 November 2024 was commanded by the spacecraft, not from the ground [3]. The June 2024 fly-around abort was likewise taken during the maneuver [4].

Propulsion and power

Twelve 1 N thrusters running on ammonium dinitramide monopropellant provide translation and attitude control [5]; the propellant is described by Astroscale as a green monopropellant [6]. Electrical power comes from two articulating solar wings of two panels each, with batteries for eclipse. No power or energy storage figures are published.

Communications

No band assignment or data rate for the ADRAS-J link is given in any source obtained. The mission released inspection imagery to the public in video form rather than as raw frames [1].

Technologies developed

The mission established that a small spacecraft can perform bearing-only acquisition of an uncontrolled rocket body, transition to model-based relative navigation, hold a fixed-point station at 50 m, fly a full circumnavigation at that radius, and close to 15 m of a specific structural feature [3], [4], [7]. It also produced the first public inspection imagery of a large unprepared debris object at close range, which has since been used as a benchmark dataset for non-cooperative surface reconstruction [1]. The 15 m approach ended in an autonomous abort against an unexpected target attitude, which is the specific risk Phase II capture hardware has to close out [3].