At first there were the small satellites. The reason was very prosaic: early rockets simply weren't powerful enough to launch more than a few then kilos to Earth orbit. The Sputnik-1 with its 84 kg and 61 cm diameter sphere was a real monster compared to the first American attempts, the 1.5 kg, grapefruit-sized (and mocked) Vanguard-1 or the 14 kg Explorer-1. Capacities expanded rapidly of course and in a short few years launching a human in a spacecraft wasn't a problem any more. Satellites and space probes grew more and more large and complex and entire space stations were orbiting the Earth. But small ones remained throughout to carry out one or two selected experiments or tasks.

But size was the only real difference: be tiny or enormous, they were built slowly and costly, often topped with overcomplicated management. And to assure success and return of investments, specialized and expensive space-rated hardware was used that lagged behind commercial products as much as 10-15 years in capacities. So the question remains: is there another, cheaper and faster way to reach space?

OSCAR-1, the first radio-amateur satellite, was launched in 1961. It achieved other firsts as well: it was built commercially and flew together with the Discoverer 36 reconnaissance satellite as secondary payload.

The first signs of change were made by amateur satellite-builders. Radio-amateur satellites for example were already built in the first years of spaceflight, starting with the $63 OSCAR-1 that wasn't really more than a transmitter and some batteries but it was the first commercially-built satellite. The subsequent players on the field dominated by governmental and commercial companies were the satellite-building universities of whom two initiatives are highlighted. At the Surrey University in the UK, the UoSat-OSCAR 9 was built in 1981 and UoSat-2 a few years later. In 1985, after the success of those missions, Surrey Satellite Technology Ltd (SSTL) was created. The company that specializes to small satellites also played a crucial role in finishing the first demonstrator of Europe's troubled Galileo navigation satellite system. And although SSTL changed the smallsat market, especially through the pioneering use of COTS (commercial off-the self) technology, the true revolution happened at another university.

Precursors of the CubeSat project were the Stanford-built OPAL and Sapphire microsats. OPAL carried six picosats (less than 1 kg devices) in her to release them once in orbit. (Credit: Stanford SSDL)

Two space projects were under way at the end of the nineties at Stanford University, California. While the Sapphire tested newly developed, small infrared sensors, OPAL (Orbiting Picosatellite Automated Launcher) prepared to release even smaller satellites. Despite the technical difficulties and the failures of some of the picosats, the experiences collected with OPAL were invaluable. In 1999, Bob Twiggs, creator of OPAL from Stanford and Jordi Puag-Suari from the California Polytechnic State University (Cal Poly) developed the CubeSat standard. It consists of a uniform nanosat design of a 10x10x10 cm (~4“) cube that can be fitted with any experiment as long as the mass doesn't exceed 1.33 kg (2.9 lbs) and it doesn't violate the safety and other regulations. The more ambitious can combine two or three cubes together as well. And, although it's not trivial at first, the system has a probably even more important element, the P-POD carrier-ejector box that can be fitted to almost any launch vehicle and takes the burden of integration off the developers' shoulder.

CubeSats usually last no longer than a few weeks or months but the success of the satellite is often not the main accomplishment because the actual “experiment” usually is to allow hands-on experiences to students and even to school-children in satellite-making and spaceflight. The program became massively successful, thanks to the unprecedentedly low costs: an entire project can be accomplished with a budget of $50-100 000. Numerous universities and even high schools work with CubeSats and even the “big guys” use them: the NASA-developed NanoSail-D solar sail was based on the CubeSat design, the US Army returned to the space business (traditionally an Air Force field) with such a microsat last year and even the National Reconnaissance Office ordered a few dozen of them for R&D missions. And last but not least, the first Hungarian satellite, the MaSat-1, being built at the Technical University of Budapest, is part of the same series.

CubeSats among themselves: the AeroCube-2 shot this picture of Cal Poly's CP4 with its miniature camera right after ejection to orbit. (Credit: Aerospace Corp.)

How did CubeSats cut development costs that much? Both the standard architecture and the shift from space-rated, expensive hardvare to cheaper, commercial products were necessary. Those devices may have higher risks (although the percentage of hardvare-related failures is surprisingly low) but also represent more advanced technology and more functions can be carried out through software. A whole project can be executed by a small staff consisting of only a couple a people in a few years, as expected from a university program. But is there any possibility to make it even more cheaper?

Yes, apparently, according to Interorbital Systems, so they've created the even smaller TubeSat. The 0.75 kg (1.6 lbs) device is slightly larger than a beer can and it's offered for $8000, launch included. Beside the do-it-yourself satellites, IOS is also developing their own launch system, the Neptune modular rocket family. Cousin of the OTRAG project from the eighties, it's constructed by joining several smaller and similar, relatively simple rockets (Common Propulsion Modules) together to create the launcher. For example in the case of the smallest one, called Neptune 30, four CPMs surround a fifth which will act as the second stage and the 30-kg payload (hence the number in the name) will be inserted into the final, 310-km orbit by a small third stage booster. But there is a catch: the first test flight of a CPM will happen in the following months and the first Neptune will fly later in this year so the operability and reliability of the system is still to be determined. But thanks to the one magnitude lower costs compared to CubeSats, many TubeSats have been ordered already, including teams competing in the Google Lunar X-Prize. Mind you, IOS itself is a member of the Synergy Moon team.

Artist's impression of Neptune 30 leaving its launch pad in Tonga. (Credit: IOS)

Numerous orders were received for the first orbital test flight already, including GLXP participants as well. Teams Synergy Moon, Part-Time Scientists and STELLAR are preparing TubeSats while EuroLuna plans to launch a double CubeSat called Romit-1. Such cheap and relatively quickly assembled micro- or even nanosats provide invaluable experience in building and managing spacecrafts but aren't time- and resource-consuming and allow the main plan – reaching the Moon – to proceed. For precisely these reasons, Team Puli Space is also joining them and  it's considering its own TubeSat project working on a feasibility study right now. But more about that later!

And what will the future bring? Well, on one hand, hopefully many successful missions for the GLXP teams towards the Moon. On the other hand, what's the limit in satellite miniaturizing? It is technically quite realistic to make pocket satellites by fitting a cpu, a solar panel, a transmitter and some kind of detector onto a printed circuit board that gets tossed out from a rocket or spacecraft into space. But wether the time will come to do it form someone's pocket money, as it happened back in the time of OSCAR-1, or not, still remains to be seen.

László Molnár