First target image from orbit: The image of space debris from Commercial Removal of Debris Demonstration Phase I has been released
April 26, 2024 (JST)
Japan Aerospace Exploration Agency (JAXA)
The Japan Aerospace Exploration Agency (JAXA) is advancing the Commercial Removal of Debris Demonstration (CRD2) (*1) Phase I with the goal of pioneering new space business in space debris removal to ensure sustainable space activities. Astroscale Japan Inc. has released an image captured by the demonstration satellite ADRAS-J (*2) while approaching a non-cooperative target (*3), space debris.
Figure: An image of CRD2 target space debris captured by ADRAS-J onboard camera
(H-IIA upper stage which launched Greenhouse Gases Observing Satellite (GOSAT), also known as Ibuki in 2009, H-2A R/B, International designator: 2009-002J, Catalog Number: 33500)
The image was taken at a close distance of several hundred meters behind the debris. One of the objectives of CRD2 Phase I is to “acquire images that reveal the motion and deterioration of debris that has been in orbit for a long period, for which there is little information at present,” and this image represents one of the initial results.
JAXA has theoretically studied the attitude motion of this target debris and speculated that it could be a pendulum motion centered around the Nadir direction or, in extreme cases, a vertical attitude along the Nadir direction due to the effect of gravity-gradient torque. (*4) Observations from ground-based optical telescopes suggested a high possibility of the vertical attitude. The newly captured image supports these speculations and directly confirms the vertical posture aligned with the Nadir direction. Understanding the attitude motion and its dynamics is crucial for the upcoming capture in CRD2 Phase II.
Furthermore, JAXA has conducted accelerated long-term exposure tests on insulating materials used on rocket surfaces at the Tsukuba Space Center’s ultraviolet irradiation facility. It was speculated that the orange insulating material would turn dark brown after more than ten years in orbit under strong ultraviolet rays, changing its reflective properties accordingly. The recent image confirms this discoloration to dark brown, validating the speculation. The degradation of such surface materials affects the measurable distance of onboard optical sensors for rendezvous and proximity operations, making it an important insight for CRD2 Phase II, similar to attitude motion.
Astroscale Japan Inc. will continue to operate ADRAS-J, and fixed-point and fly-around observations at closer distances are expected in the future. JAXA has provided extensive technical advice, test facility usage, and intellectual property from research results, mainly on orbital rendezvous knowledge, to support the development and operations of ADRAS-J. JAXA will continue to technically support the operation of ADRAS-J and plans to conduct a detailed analysis of the images obtained from CRD2 Phase I.
*1: Commercial Removal of Debris Demonstration (CRD2)
The Commercial Removal of Debris Demonstration (CRD2) is a new initiative by JAXA to acquire active debris removal technology to address the escalating space debris problem and support the commercial activities of the Japanese companies. Astroscale Japan Inc. has been selected as the contract partner for Phase I of the CRD2. In this project, JAXA provides technical advice, test facilities, intellectual properties of research results to support the selected companies.
CRD2 web: https://www.kenkai.jaxa.jp/eng/crd2/project/
*2: ADRAS-J
CRD2 Phase I demonstration satellite developed, owned and operated by Astroscale Japan Inc.
*3: Non-cooperative target
A non-cooperative target refers to a space object that lacks certain features and equipment, such as attitude control functions, communication capabilities, GPS receivers, laser reflectors, image processing markers, and docking mechanisms, which are essential for facilitating its approach or capture by other spacecraft. The absence of these elements significantly increases the technical challenges involved in approaching or capturing such targets, especially when compared to objects that are equipped with these features, like the International Space Station.
*4: Gravity-gradient torque
One of the external torques acting on an object in orbit. It arises due to the slight difference in distance between each constituent particle of the object and the central mass celestial body, resulting in a difference in gravitational forces. This torque acts to orient elongated objects towards the nadir direction.