Towards the Use of Commercial-off-the-Shelf Small-Satellite Components for Deep-Space CubeSats: a Feasibility and Performance Analysis

The aim of this paper is to assess the feasibility of using currently available commercial-off-the-shelf (COTS) small-satellites components in deep-space scenarios, studying their applicability and performance. To evaluate the performances, an asteroid fly-by mission is briefly introduced, but several of the selection criteria and ideas can be extended to other deep space mission concepts. This particular mission scenario requires to follow three main trends: miniaturization, standardization and automation. For this reason the mission represents a good test bench scenario to analyze the products of the current small-satellites industry. Once the reference mission has been defined, the preliminary ΔV is computed and the micro-propulsion system is selected. Afterwards, for several satellite subsystems the requirements are compared with the expected performance of a set of small-satellite components currently available on the market. Once the most promising hardware solutions are identified, mass and volume budgets are defined. Subsequently, drawbacks and limits of using COTS components for deep-space exploration are highlighted, focusing on the readiness level of each subsystem. Finally, recommendations are given on what methods and hardware are needed in the near future to overcome the limiting factors and to allow deep-space exploration using low-cost CubeSats

Development of the Pico Star Tracker ST-200 – Design Challenges and Road Ahead

The Pico Star Tracker ST-200 under development by Berlin Space Technologies GmbH (BST) is specifically designed keeping the limitations of CubeSats in mind. It comes in a compact 29x29x37mm³ package. It weights 74g and has a power consumption of 220mW average (620mW peak). The ST-200 offers a set of standard interfaces (I²C, SPI, RS485, RS232) and accepts input voltages of 3.3 to 5V. It can detect stars with a limiting magnitude of 6 and has an accuracy of 30 arc seconds (~0.01°). Using its internal star catalogue ST-200 calculates the satellite attitude from lost in space solution and delivers the Euler angles or quaternion with an update rate of 5 Hz in tracking mode. The ST-200 is based on 20 years of star tracker development in Berlin including TUBSAT missions and multiple international customers. It is the successor of the Micro Star Tracker ST-100 developed by BST. For the electronics miniaturization as well as the implementation of new strategies for star tracker with ultra low power and low mass BST cooperates with Syspa B.V. of the Netherland

Combined optical line-of-sight and crosslink radiometric navigation for distributed deep-space systems

Abstract This manuscript aims to present and evaluate the applicability of combining optical line-of-sight (LoS) navigation with crosslink radiometric navigation for deep-space cruising distributed space systems. To do so, a set of four distributed space systems architectures is presented, and for each of those, the applicability of the combination is evaluated, comparing it to the baseline solutions, which are based on only optical navigation. The comparison is done by studying the performance in a circular heliocentric orbit in seven different time intervals (ranging from 2024 to 2032) and exploiting the observation of all the pairs of planets from Mercury to Saturn. The distance between spacecraft is kept around 200 km. Later, a NEA mission test case is generated in order to explore the applicability to a more realistic case. This analysis shows that the technique can also cope with a variable inter-satellite distance, and the best performance is obtained when the spacecraft get closer to each other

Spread-Spectrum Modulated Multi-Channel Biosignal Acquisition Using a Shared Analog CMOS Front-End

The key challenges in designing a multi-channel biosignal acquisition system for an ambulatory or invasive medical application with a high channel count are reducing the power consumption, area consumption and the outgoing wire count. This article proposes a spread-spectrum modulated biosignal acquisition system using a shared amplifier and an analog-to-digital converter (ADC). We propose a design method to optimize a recording system for a given application based on the required SNR performance, number of inputs, and area. The proposed method is tested and validated on real pre-recorded atrial electrograms and achieves an average percentage root-mean-square difference (PRD) performance of 2.65% and 3.02% for sinus rhythm (SR) and atrial fibrillation (AF), respectively by using pseudo-random binary-sequence (PRBS) codes with a code-length of 511, for 16 inputs. We implement a 4-input spread-spectrum analog front-end in a 0.18 μ m CMOS process to demonstrate the proposed approach. The analog front-end consists of a shared amplifier, a 2nd order Σ Δ ADC sampled at 7.8 MHz, used for digitization, and an on-chip 7-bit PRBS generator. It achieves a number-of-inputs to outgoing-wire ratio of 4:1 while consuming 23 μ A/input including biasing from a 1.8 V power supply and 0.067 mm2 in area.</p

Novel 3U stand-alone cubesat architecture for autonomous near earth asteroid fly-by

The purpose of this work is to present a novel CubeSat architecture, aimed to explore Near Earth Asteroids. The fast growth in small satellite commercial-off-the-shelf technologies, which characterized the last decade of space industry, is exploited to design a 3U CubeSat able to provide a basic scientific return sufficient to improve the target asteroid dataset. An overview of the current available technologies for each subsystem is presented, followed by a component selection driven by the mission constraints. First a typical asteroid fly-by mission is introduced together with the system and performance requirements. Then each characterizing subsystem is critically analyzed, and the proposed configuration is presented, showing the mission feasibility within only 3.9 kg of wet mass and 385 m/s of total ∆V.Space Systems EgineeringSpace Engineerin

Orbit design of a swarm for ultra-long wavelength radio interferometry with preliminary swarm and thruster sizing

Observing the universe in the Ultra-Long Wavelength (ULW) regime has been called the ‘last frontier in astronomy’—real imaging capabilities here are yet to be achieved. Obtaining an image of the sky in this frequency band can be done by employing a swarm of satellites that together act as an interferometer and collect the required imaging information pieces throughout the course of their operational life. Meeting the mission objective is challenging for such a swarm, since this imposes restrictions on the operational environment and the relative position and velocity vectors between the swarm elements. This work proposes an orbit solution in a Heliocentric Earth-Leading Orbit (HELO) for an autonomous CubeSat swarm with chemical thrusters. A distributed formation flying algorithm is used to aid the collection of the required imaging information pieces. Furthermore, the estimated total mission launch mass is reduced by optimising cost functions and finding favourable position and velocity at start of operational life, as well as by finding favourable thrust manoeuvre patterns. The results show that the mission objective—obtaining a 3D map of the Universe in ULW—can be achieved with 68 6U spacecraft (S/C). Moreover, the swarm can remain in a Radio Frequency Interference (RFI) quiet zone of &gt;5 × 106 km, whilst not drifting further than ~ 6.6 × 106 km from Earth for an operational life of one year.Space Systems EgineeringAstrodynamics & Space Mission

Micro-Power Analog-Filter Design

There are fundamental minima for the power consumption of filters. We will see how these minima can be found approximately, and also how filters that approach these minima can be designed for supply voltages down to about 1V

DEVELOPMENT AND TEST RESULTS OF SINPLEX, A COMPACT NAVIGATOR FOR PLANETARY EXPLORATION

SINPLEX is an innovative, very compact, multipurpose and self-standing highly integrated suite of instruments designed for Guidance, Navigation and Control (GNC) applications. The GNC applications for which SINPLEX has been designed for is the support throughout various navigation phases, from space travel to rendez-vous and landing, to spacecrafts and their robotic landers. The system can be tailored to also fit applications such as Active Debris Removal (ADR). SINPLEX in its full redundant configuration exhibits a mass of 4.8 kg, a volume of 170 x 210 x 200 mm3, and a power consumption of 32 W. The instrument is packed with redundant sets of Star Trackers (STR), Navigation Cameras (NAVCam), Inertial Measurement Units (IMU) and Laser Altimeters (LA). The two Navigation Cameras have a partly overlapping field of view to enable stereoscopic observations. The combination of these sensors provides reliable, robust and high frequency information on the relative position and attitude to enable spacecraft timely and well-informed attitude and orbit actuation. SINPLEX is a research and development project funded by the European Commission (7th Framework Programme, project no. 284433) and has been developed by a consortium of European entities, comprising of DLR from Germany, TNO, cosine and SystematIC from The Netherlands and ÅAC Microtec AB from Sweden

TARGET RELATIVE NAVIGATION PERFORMANCE RESULTS FROM SINPLEX: A MINIATURIZED NAVIGATION SYSTEM

The goal of the SINPLEX project is to develop an innovative solution to significantly reduce the mass of the navigation subsystem for exploration missions which include landing and/or rendezvous and capture phases. The system mass is reduced by functionally integrating the navigation sensors, using micro- and nanotechnology to miniaturize electronics and fusing the sensor data within a navigation filter to improve navigation performance. A breadboard system was built and includes a navigation computer, IMU, laser altimeter/range finder, star tracker and navigation camera. This system was tested at short distances with realistic trajectories in DLR’s TRON testbench. This paper covers an overview of the hardware and testbench and presents performance results from the hardware-in-the-loop tests