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The QB50 Program, the First Cubesat Constellations Doing Science SSC10-XII-3 The QB50 Program, the first CubeSat Constellations doing Science Robert Twiggs and Benjamin Malphrus Space Science Center, Morehead State University 235 Martindale Dr, Morehead, KY 40531; 408-230-4728; [email protected] J. Muylaert von Karman Institute of Fluid Dynamics Chaussée de Waterloo; 72 B-1640 Rhode-St-Genèse; Belgium; [email protected] ABSTRACT The QB50 program was originated by Jean Muytaert ments of the Ignorsphere (that part of the atmosphere at the von Karman Institute in Brussels, Belgium. that the atmospheric scientist say has been ignored Through the VKI efforts are underway to provide due to a lack of sufficient measurements to effect- launches for 50 university built 2U CubeSats. These ively study it). This paper will outline the proposed CubeSats will be provided by an international group method used to select US universities to participate of universities of which 10 CubeSats will be provided and other aspects of the mission to be launched in by US universities. The instruments will be provided 2013. by the science community. The expected launch attitude is to be between 300km-325km and during the short lifetime will make atmospheric measure- BACKGROUND The QB50 is project proposed as an international mesosphere and lower thermosphere (MLT Region) network of 50 double CubeSats for multi-point, in- that provide only occasional (a few times per year) situ, long-duration measurements in the lower single-line measurements. thermosphere (90-320km) and for re-entry research. The idea is to have a network of 50 double CubeSats sequentially deployed, (1 CubeSat every orbit or every 2 orbits) at an Initial altitude: 320 km (circular orbit, i=79°). The initial separation will be 200 – 400 km between CubeSats. Total network size will be 10,000 – 20,000 km with atmospheric data providing temporal and spatial variations. The lower thermosphere from 320 km down to 90 km will be explored without the need for on-board propulsion (orbital decay due to atmospheric drag) in 3 months. The data will be downlink using the Global Educational Network for Satellite Operations (GENSO). Why Lower Thermosphere? It is one of the least explored layers of the atmosphere. Stratospheric balloons go up to 42 km max. Remote-sensing by Figure 1. Atmospheric Layers ground based lidars and radars are used up to 105 km. Remote-sensing by Earth observation satellites in The advantages of a network of 50 CubeSats in the higher orbits (600–800 km) only observe constituents lower thermosphere compared to networks in higher in the troposphere, stratosphere and mesosphere orbits has the following advantages: (lower thermosphere is too rarefied). In-situ • The lifetime of a CubeSat in the envisaged measurements are made by sounding rockets in the low-Earth orbit will only be three months, Twiggs 1 24th Annual AIAA/USU Conference on Small Satellites i.e. much less than the 25 years stipulated by On all other missions CubeSats are a secondary international requirements related to space payload, on QB50 the CubeSats are the primary debris payload. • A low-Earth orbit allows high data rates because of the short communication distances involved • In their low-Earth orbits, the CubeSats will be below the Earth’s radiation belts, which is very important because CubeSats use low- cost Commercial-Off-The-Shelf (COTS) components EDUCATIONAL VALUE The time is now. The educational community has • The short mission give rapid feedback on had ten years of promoting picosatellites. Initially it experiments was for education, but picosatellites are now widely • Students can innovation with secondary accepted beyond the university programs. payloads without risk to primary Picosatellites are accepted by major government and • The international interaction will stimulate science agencies. The manufacturing and launch students to show how “smart” they are infrastructure more mature and there are new • International conferences will allow student developments in launch opportunities. We have shown that picosatellites can be built and successfully interactions operated by students at a university level. • Websites can be created that are open to public Using CubeSats for engineering is a great motivator • Encourage maximum exchanges between in space in education. Its smaller size shortens the students development time by limiting complex payloads. Its • Create and encourage open ideas exchange reduced size reduces launch costs. Students can take with open websites advantage of new, miniaturized technology. Using • Students can and do take advantage of CubeSats for student projects allow innovation distributed engineering tools without consequences of risk that is found in • They make use of tools like webinars with government and aerospace laboratories. These are recorded sessions programs that are a stimulus to the total education program and provide industry experience with QB50 program has exceptional public relations minimum side distractions. value for space exploration. The subject of study, the near earth effects on everyday life, is Some other factors in a program like the QB50 are: of interest to everyone. The short mission will keep public attention with a great outreach topic • Direct interaction with customers that is easy to understand. It is also an • Learning the “ropes” of how government outstanding example of international works cooperation. One major factor is that it has no • Team and management building skills long term debris issues. • Using tools for distributed engineering – learning from each other • International collaboration • Allowed to experiment without punishment • Stimulated environment for innovation • Students are the right age to innovate • It is way to get families re-interested in space Twiggs 2 24th Annual AIAA/USU Conference on Small Satellites SCIENTIFIC CHALLENGE Physics and Chemistry of the UPPER emission by ozone and water vapor in the Atmosphere middle atmosphere The areas of scientific interest of the physics and Dynamics of the Upper Atmosphere chemistry of the upper atmosphere are the: Vertical Structure There is solar EUV-driven (magnetically-quiet) Energetics circulation and 0-N2 composition in the 100- Dynamics 500km altitudes. Upwelling occurs in the Chemistry summer hemisphere, which upsets the diffusive Ionization equilibrium. Molecular-rich gasses are transported by horizontal winds towards the Vertical Structure winter hemisphere, where diffusive balance is progressively restored, from top (where In the vertical structure there are measurements diffusion is faster) to bottom. of the temperature and density distributions. In the lower part of the atmosphere, molecular and Gravity waves are small scale waves mainly eddy diffusion coefficients are important. generated in the troposphere by mechanisms Primary constituents in the lower atmosphere of such as topography, wind shear, and the range of science for the QB50 (below 300km) convection. The gravity wave amplitudes program are where oxygen and nitrogen increase as they propagate upwards dominate. From the lower to the Upper (conservation of momentum). atmosphere, above the turbopause (~105km), molecular diffusion causes constituents to drop Chemical Composition of the Upper off according to their mass. Below, the Atmosphere atmosphere is fully mixed: 78%N2, 21%O2, <1% Ar, <0.1% CO2. The density decreases with a There is solar forcing of the neutral atmosphere mean scale height: H = kT/mg ~7km. The UV/EUV. There is precipitating particles in lower thermosphere is also the transition from a auroral regions. Other events such as solar molecular to atomic atmosphere. proton events (SPEs) produce highly-relativistic electrons (HREs) >1MeVand the bombardment Energetics of the Upper Atmosphere of the galactic cosmic rays have important impacts of the composition. Sources of diabatic heating/cooling are absorption of solar radiation and energetic Coupling processes of the downward transport particles (e.g. ozone), the chemical heating of thermospheric produces nitric oxide by through exothermic reactions (A + B -> AB + E), ~1keV electrons. There is NOy production in the collisions between ions and neutrals (Joule lower mesosphere and upper stratosphere via heating), the IR cooling (e.g. CO2 and NO) and energetic electron precipitation (4-1000 keV). airglow Both processes lead to stratospheric ozone destruction. Radiative cooling is a function of IR atomic oxygen emission (63 µm) in the upper Ionization of the Upper Atmosphere thermosphere, non-LTE IR emission of NO (5.3 µm) 120 to 200 km, where CO2 15 µm (LTE and Given the solar spectrum shown in Figure xx, non-LTE) important below 120km and IR this energy causes ionization of the upper atmosphere as shown in Figure xx. Twiggs 3 24th Annual AIAA/USU Conference on Small Satellites Conclusions In addition to scientific value of this project, the The QB50 program offers the resources of to educational training and experience that will be make measurements of the atmosphere below received by an international group of students 300km with a constellation of satellites to sets a standard a significant value return on a produce important data that far exceeds the space scientific mission. individual efforts to gain a better understanding of the fundamental physics and chemistry in this region. Twiggs 4 24th Annual AIAA/USU Conference on Small Satellites .
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