By using modern, high performance electronic circuits, the size of a normal satellite can be greatly reduced. This development is comparable to the recent advances in smart phones. CubeSats come in three sizes: 1-unit (10x10x10 cm, weighing 1 kg), 2-unit (10x10x20 cm, 2 kg) and 3-unit (10x10x30 cm, 3 kg). It takes a university team of 10-15 students under the guidance of an experienced professor about two years to build a CubeSat. The development of a flight-ready CubeSat costs between 100,000 and 300,000 €, depending on size and complexity. This is only a small fraction of the cost of a normal satellite. Up to now, about 100 CubeSats have been launched, most of them in the last few years. Another 150 are being planned or are in various stages of development.
The introduction of a CubeSat standard in 1999 that applies worldwide was a breakthrough, comparable to the introduction of a standard in the size of shipping containers. On the launch vehicle, CubeSats are accommodated in standard-size boxes making the interfaces very simple. Once in orbit, the doors of these boxes are opened by ground command and the CubeSats are deployed from these boxes by spring pushers. The CubeSat standard allows to accommodate any CubeSat into any deployer, it allows to develop and sell standard subsystems, and it allows to replace one CubeSat by another at any time, even as late as during the launch campaign.
A 1-unit CubeSat is simply too small to also carry sensors for significant scientific research. Hence, for the universities the main objective of developing, launching and operating a CubeSat is educational. However, when combining a large number of CubeSats with identical sensors launched at the same time into a network, in addition to the educational value, fundamental scientific questions can be addressed which are inaccessible otherwise. Networks of CubeSats have been under discussion in the CubeSat community for several years, but so far no university, institution or space agency has taken the initiative to set up and coordinate such a powerful network. CubeSat reliability is not a major concern because the network can still fully achieve its mission goals even if a few CubeSats fail. QB50 will be the first network of CubeSats in orbit.
The QB50 Project was proposed to the European Commission in November 2010 by a Consortium of 15 institutes and space industries, which include Stanford University in the US, the Northwestern Polytechnic University in China and the Institute of Theoretical and Applied Mechanics in Russia. The von Karman Institute for Fluid Dynamics (VKI) in Brussels is the lead institute of this Consortium. VKI now manages this international Project which involves over 1000 people in 50 countries.
QB50 is a network of about 40 2-unit CubeSats in a ‘string-of-pearls’ configuration for atmospheric research and about 10 special 2-unit and 3-unit CubeSats for science and technology demonstration. These 50 CubeSats will be launched together in 2014 by a single Shtil-2.1 from Murmansk, Northern Russia into a circular orbit at 320 km altitude, inclination 79º. The 50 CubeSats will not all be deployed at once; one CubeSat will be deployed per orbit, i.e. every 90 minutes. In this way, the 50 CubeSats will spread out and eventually, after about a month, form a network that goes all the way around the Earth. Due to atmospheric drag, the orbits will decay and progressively lower and lower layers of the thermosphere/ionosphere will be explored without the need for on-board propulsion until, about three months later, the CubeSats burn up in the denser layers of the atmosphere at 90-100 km.
Space agencies are not pursuing a multi-satellite network for in-situ measurements in the lower thermosphere/ionosphere because the cost of a network of 50 satellites built to industrial standards would be extremely high and not justifiable in view of the short orbital lifetime. A network of satellites for in-situ measurements in the lower thermosphere/ionosphere can only be realised by using very low-cost satellites, and CubeSats are the only realistic option.
Normally, CubeSats are launched as secondary passengers. That means they have to accept the orbit and the launch date of the primary payload, usually a larger satellite. These orbits are often not ideal for CubeSats and, also, sometimes CubeSats have to wait for a year before they can be launched because the primary satellite is not ready in time. “With QB50, for the first time, CubeSats are the primary payload, we select the orbit and the launch date. Otherwise we would not be able to bring the CubeSats into the lower thermosphere/ionosphere because no primary satellite wants to go into this region because of the limited orbital lifetime”, explains Jean Muylaert, the Director of VKI and the lead person in the QB50 Consortium.
The 40 atmospheric 2-unit CubeSats and most of the 10 special 2-unit and 3-unit CubeSats will carry a set of standardized sensors for multi-point, in-situ, long-duration measurements of key parameters and constituents in the largely unexplored lower thermosphere and ionosphere. Satellites in highly elliptical orbits (typically perigee: 200 km, apogee: 3000 km) and sounding rockets are expensive and offer only a few minutes of observing time. There are numerous Earth observation satellites in higher orbits (600-800 km), carrying powerful remote-sensing instruments which emit laser light and receive the backscattered signal from atmospheric constituents at various altitudes. While this is an excellent tool for exploring the stratosphere and the mesosphere, it is not ideally suited for exploring the lower thermosphere/ionosphere because there the atmosphere is so rarefied that the return signal is weak. The same holds for remote-sensing observations from the ground with powerful lidars (light detection and ranging) and radars. Finally, even the largest stratospheric balloons can only go up to 50 km.
At the end of January/early February 2012, two major CubeSat conferences with international participation will be held in Brussels, both organised by VKI
- On 30 January-1 February, the 4th European CubeSat Symposium at the Ecole Royale Militaire (over 200 participants expected, press welcome)
- On 2 February, the 3rd QB50 Workshop at VKI (130 participants, participation by invitation only)
Useful websites:
www.qb50.eu for the QB50 Project
www.cubesatsymposium.eu for the 4th European CubeSat Symposium
For more information contact:
Dr. Cem O. Asma
Von Karman Institute for Fluid Dynamics (VKI)
Chaussée de Waterloo 72
1640 Rhode-Saint-Genèse (Brussels)
Press release issued by the von Karman Institute for Fluid Dynamics, Brussels