Access to microgravity on Earth is a key component of scientific experiments and for testing and demonstrating future aerospace technologies, both for space research and industry.
Here is a brief summary of the main methods being used right now to reproduce microgravity conditions around the world:
Drop Towers are used around the world (USA, Europe and Japan) to achieve up to 9s of free fall. The highest in Europe is the ZARM tower located in Bremen, Germany. While the tower can in theory be used every day, they require the creation of a vacuum inside the whole tower to remove the air drag impact.
Parabolic Flights are often used to conduct experiments and train astronauts in microgravity. ESA and CNES, for instance, conduct one or two campaigns per year with up to 30 experiments, on board the Novespace’s A310.
For Sounding Rockets, REXUS in Europe is the leading initiative, conducting around one campaign per year, only for students.
The International Space Station (ISS) is of course a good platform for conducting long-term microgravity research but is costly and requires long lead times and high Technology Readiness Level (TRL) which can only be achieved through expensive testing beforehand. Moreover, its end-of-life is currently planned for 2024 or 2028.
Clinostats and Random Position Machine (RPM) are accessible but only relevant to niche research, mainly to study cellular biology and plant growth.
Suborbital Reusable Vehicles (SRVs) or Shuttle-like orbital vehicles. Concepts like the military X-37B or the Dream Chaser in the USA are also considered in Europe (SpaceRider and DC4EU) and could provide a platform for long-term experiments that could come back to Earth to be analysed.
All these platforms differ by their characteristics, in terms of duration, quality, mass/volume and costs so one can therefore choose the platform that fits its needs the best. However, it is interesting to note that while some of these platforms offer very high quality of microgravity for extensive duration of up to a few minutes, the cost per second of 0-g is rarely below 300€.
Besides the high costs, the providers of microgravity platforms are centralised in only a few places which can be geographically very far from their customers – forcing them to deal with the complex logistical and regulatory challenges involved in the international shipping of scientific payloads. Thus, availability, affordability and long lead times are the main issues with existing microgravity platforms. However, few people have been looking at designing and bringing to market a new and innovative alternative microgravity platform.
Additionally, in Europe, all these platforms are being currently used by laboratories and students through ESA-financed programs (Fly your thesis, Drop your thesis, Spin your thesis), with long lead times and few flight opportunities. While these initiatives are very beneficial, they artificially raise the number of institutions being able to conduct such research and developments. The question remains whether this sector can be made economically sustainable with less or no institutional support.
Any insights? Want to discuss with us or get more details? Contact me at mehdi@lide.space
Image: Project Mercury astronauts on board a C-131 Samaritan flying as the “vomit comet”, November 1958. Credits: NASA, public domain