Environmental Assessment in the Pre-launch Phase of Hayabusa2 for Safety Declaration of Returned Samples From Asteroid (162173) Ryugu: Background Monitoring of Possible Contaminants During Development of the Sampler System

We report the ground-based environmental assessments during development of the sampler system until the launch of the Hayabusa2 spacecraft. We conducted static monitoring of potential contaminants to assess the environmental cleanliness during (1) laboratory work throughout the development and manufacturing of the sampler devices, (2) installation of the sampler system on the spacecraft, and (3) transportation to the launch site at the JAXA’s Tanegashima Space Center. Major elements and ions detected in our inorganic analysis were sodium (Na), potassium (K), and ionized chloride (Cl–); those were positively correlated with the total organic content and with exposure duration in the range from 101 to 103 nanogram per monitor coupon within a ~30 mm-diameter scale. We confirmed that deposits on the coupon were totally less than the microgram-scale order during manufacturing, installation, and transportation in the pre-launch phase. The present assessment yields a nominal safety declaration for sample analysis of the pristine sample (>5 g) returned from asteroid (162173) Ryugu combined with a highly clean environmental background level. We expect that the Hayabusa2-returned sample from Ryugu without severe and/or unknown contamination will allow us to provide native profiles recorded in the carbonaceous asteroid history.

Past experience and future prospects for launching our country's small spacecraft from Plesetsk launch site

The paper provides an integrated analysis of the problem of the fast growing field of development and operation of Small Spacecraft (SS) constellations and participation of domestic launch site Plesetsk in solving this problem. It reviews the history of launches from Plesetsk, and describes the current status of work to build up and replenish SS-based orbital constellations. It describes major methods of SS launches. When describing multiple launches of SS on heavy launch vehicles it cites foreign practices of SpaceX Company, as well as lays down the prospects for development of our country’s heavy launch vehicles. As for the small-lift launch vehicles, it cites the experience of launching from Plesetsk of launch-vehicles Rokot and Soyuz-2 Phase 1v. For the super-small-lift launch vehicles, it cites the experience of USA and PRC, as well as our country’s development project of the launch vehicle Irkut, which is planned to be launched from Plesetsk, among other places. As for changes in the configuration of ground space infrastructure, the paper points out a trend towards processing SS at a single common processing facility (there is no need to construct processing facilities for each specific small spacecraft). The paper presents general trends in the system for operation of space facilities. The trends towards standardizing mechanical handling equipment in particular, and processing facilities in general, make it possible to lower development costs and speed up development schedules for advanced small spacecraft. Reducing small spacecraft processing time has a beneficial effect on the operational efficiency of the launch campaign, while the use of mobile checkout equipment makes it possible to quickly put together mobile and flexible processing facilities, the use of which will undoubtedly contribute to shaping the future of our country’s launch system. An important point made in the paper is the conclusion that in spite of our country’s lagging behind in super-small-lift launch vehicles, it has a significant scientific and engineering potential for developing this type of launch vehicles. Regardless of the value of other conclusions of the paper, the key point is that the current state of the ground space infrastructure facilities and the accumulated experience of specialists at Plesetsk make it possible to address the full spectrum of SS launch operations. Key words: small spacecraft, launch vehicles, ground space infrastructure, system for operation of space facilities.

Geostationary Orbit Transfer with Lunar Gravity Assist from Non-equatorial Launch Site

We show that it is possible to launch a satellite to Geostationary Equatorial orbit (GEO) from the non-equatorial launch site (Naro Space Center in South Korea) even though that is located in the mid-latitudes of the northern hemisphere. When launched from this site, the equatorial inclination after separation will be 80°. We use a lunar gravity assist (LGA) transfer to avoid the excessive ∆V costs of plane change maneuvers. There are eight possible paths for the LGA; there are four paths consisting of Earth departures and free-return types, and there are two nodes of the Moon’s orbit (ascending and descending). We analyze trajectories over five launch periods for each path using a high-fidelity orbit propagation model. We show that the LGA changes the orbital energy of the “cislunar” free-returns more than for the “circumlunar” free-returns, resulting in less geostationary insertion ∆V for the cislunar free-returns. We also show that the geometrical ∆V variation over the different paths is greater than the seasonal ∆V variation. Our results indicate that an ascending departure and cislunar free-return at the descending node have lower ∆V requirements than the other paths, and lower than described in several previous studies.

HISEA-1: The First C-Band SAR Miniaturized Satellite for Ocean and Coastal Observation

On 22 December 2020, HISEA-1, the first C-band SAR small satellite for ocean remote sensing, was launched from the coastal Wenchang launch site. Though small in weight, the images it produced have a high spatial resolution of 1 m and a large observation width of 100 km. The first batch of images obtained within the first week after the launch confirmed the rich information in the data, including sea ice, wind, wave, rip currents, vortexes, ships, and oil film on the sea, as well as landmark buildings. Furthermore, geometric characteristics of sea ice, wind vector, ocean wave parameter, 3D features of buildings, and some air-sea interface phenomena in dark spots could also be detected after relevant processing. All these indicate that HISEA-1 could be a reliable, remarkable, and powerful instrument for observing oceans and lands.

Optimization of rotate mode at constant change of departure in the level-luffing crane with geared sector

The results of optimization of the rotation mode of the level-luffing boom system of the crane at the launch site, with the steady-state mode of departure change. The object of the study is a boom system with a sector drive of the mechanism of change of departure. The mechanism of rotation consists of an electric motor, a planetary mechanism and an open gear. Variation calculus methods were used to optimize the mode of rotation of the boom system. In this case, a variational problem is formed, which includes the equation of motion of the boom system when turning and changing the departure, the optimization criterion and boundary conditions of motion. The optimization criterion has the form of an integral functional that reflects the root mean square value of the driving torque of the drive mechanism of rotation during start-up. The study was carried out at the starting point of the electric motor of the turning mechanism from the state of rest to reach the nominal speed and at a steady speed of rotation of the electric motor of the mechanism of change of departure. The solution of the problem is presented in the form of a polynomial with two terms, the first of which provides boundary conditions of motion, and the second minimizes the criterion of optimization through unknown coefficients. To do this, use a software package. Graphs of change of kinematic characteristics of cargo and boom system at work of mechanisms of turn and change of departure, and also the driving moment in the course of start of the mechanism of turn which correspond to an optimum mode of movement are constructed. The resulting mode of movement allowed to eliminate the oscillations of the load on the suspension. Based on research, recommendations for the use of the obtained optimal start-up mode have been developed.

Properties of the Transfers from LEO to the Retrograde-GEO using Lunar Swing-by in a Three-Body Model

A monitor-satellite on a retrograde geostationary earth orbit (retro-GEO) gives the GEO-assets debris-warnings per 12 hour. The properties of the transfers from a low earth orbit to the retro-GEO using lunar swing-by without middle-way maneuver are exhibited in a three-body model. Based on the Poincaré-section methodology, the proof of the existence of this transfer is proven in the planar circular restricted three-body problem (CR3BP) model. Then, the maximum altitude of the perilune of this transfer is solved using the sequence quadratic programming optimization algorithm. Besides, the orbital inclination changeable capacity of this transfer is calculated in the spatial CR3BP model by the continuation of the orbital design values in the planar CR3BP model. The numerical results show that the maximum altitude of the perilune is 892 km and the maximum orbital inclination changeable capacity is 138 degree relative to the plane of the Moon’s path. Further analysis show that the minimum sum of the two-impulse velocity increments (i.e., departure from LEO and insert into the retro-GEO) is 4.224 km/s, the change of the orbital inclination is 107 degree relative to the plane of the Moon’s path in this case. Due to the maximum angle of the plane of the Moon’s path on the equator is 28.6 degree per Metonic cycle (i.e., 18.6 years), everyday has a month window to match the longitude of the launch-site for trans-lunar injection.

Design and implementation of remote image processing system for space launch site

Telemetry image has the characteristics of intuitive image in the process of rocket flight. Through real-time acquisition of rocket flight video image, it can provide the working status of key nodes in the process of rocket flight, and provide intuitive decision-marking auxiliary information for commanders. This paper analyzes the design content of the image processing system of the space launch site from the aspects of image transmission mechanism, information flow, image data processing and image decoding, so as to provide technical basis for the image receiving, transmission and decoding process in the engineering practice of the image processing system.

Analytical first derivatives of the direct Hermite-Simpson collocation formulation of optimal control problems

In order to assess the capabilities of South Africa as a launch site for commercial satellites, an optimal control solver was developed. The developed solver makes use of direct Hermite-Simpson collocation methods, and can be applied to a general optimal control problem. Analytical first derivative information was obtained for direct Hermite-Simpson collocation methods. Typically, a numerical estimate of the derivative information is used. This paper will present the solver algorithm, and the formulation and derivation of the analytical first derivative information for this approach. A sample problem is provided as validation of the solver.