Previous Similar Studies

In order to overcome difficulties of reduced gravity condition testing, reel.SMRT brings together concepts from previous studies and applications. In this way, not only is the project aided by the resources compiled by others but it also highlights the possible applications and the desire of researchers for a system such as reel.SMRT.

Capsule Drops from High Altitude Balloons

Much research has been conducted into the possibilities of short reduced gravity periods enabled by dropping from high altitude balloons. A simple dropping capsule has been designed and tested by High Altitude Reduced Gravity Vehicle Experiments (HARVE) (1). This team was able to achieve seven seconds of reduced gravity time from a height of ~24,382 metres. This was without any mitigation of aerodynamic perturbations, similarly to reel.SMRT. A schematic of the HARVE dropped capsule is shown in Figure 1.1.

Schematic of the HARVE craft (1) and Sawai Lab's Vehicle and Microgravity Experiment Unit (2)

There are methods to damp these influences upon experiments within modules that are travelling through the upper atmosphere. Similar to the HARVE experiments, Sawai Lab have been conducting tests of a capsule (2) that is able to re-enter the lower atmosphere much like a space-plane. This module is also designed for reduced gravity testing but also has the added feature of perturbation mitigation via the use of a number of gas jets that supports an experiment away from the structure of the dropping body.

Reel System

Another experiment that embodies many similarities to the reel.SMRT system was developed by a group of Japanese researchers. This experiment fulfils the same objective to increase the sampling height range of experiments on board high altitude balloons. This system was developed specifically for observing stratospheric vertical microstructures and was a slow reel up and down system (4 reel-down and reel-up cycles of 600m on a high altitude balloon flight) (3). YES2 (4) was an ambitious experiment for students that released a dropped payload to 30 km below an orbiting reel system. Although reel.SMRT is not unreeling to the same distances, a review of this project has been conducted and useful caveats have been discovered regarding line tension and braking systems. Two members of SMRT have previously conducted the xgravler experiment (5) onboard the HALE balloon (6) in 2008 . This project had the restriction to use LEGO components and thus was a limited test for a short drop and reel system. xgravler appeared to have ran the experiment during the flight but when data retrieval was conducted, the acceleration data was not found (7).

REEL-E Attached to Gondola and REEL Interior Mechanics

Future Applications

Although some microgravity experiments are require longer periods of reduced gravity environment than a drop tower or high altitude balloon drop can produce, nonetheless, there are a number of fields that take advantage of current techniques and could feasibly fly onboard a reel.SMRT system. Short duration fluid effects such as microdroplet production (8), foam attributes (9) and biphasic fluid investigation (10) are applicable. Loosely also within fluid experimentation are the many biomedical studies that undertake microgravity investigation. Combustion experiments which are not allowed on board parabolic flights can use the safety net of the reel.SMRT tether system to still conduct their important research. Biological experiments such as the behaviour of fish in reduced gravity environments (11) can also be conducted on an upscaled version of reel.SMRT. Crystallisation and metallic microstructure formation (12) are also hot topics in the microgravity field and are ideal for short drop testing. reel.SMRT is particularly useful in the above fields because of the possibility for high amounts of repetition of the drops and is an alternative to most drop tower experiments that may not necessarily require the accuracy of drop tower systems.

Benefits of the reel.SMRT System

The reel.SMRT system has a number of benefits that make it a viable alternative for microgravity testing in the future. The quality of microgravity expected is not to the level of drop towers or specialist rockets, nevertheless, the dropping of a payload from a balloon gives researchers new opportunities. The versatility of the system to act as a low gravity platform, sampling platform or safety tether is also an advantage.

Location Flexibility

A major benefit of conducting microgravity experiments from balloons is that there are many such locations from which they can be done. High quality drop towers are limited to Fallturm (13) in Bremen, Germany, Micro-Gravity Laboratory of Japan (14) and the three towers (15) (16) (17) run by NASA in the USA. This is particularly of interest to those countries that are not close or do not have access to these facilities such as Australia and the South American nations.


Not only are these drop towers limited to location but availability is a significant issue for many researchers wishing to investigate microgravity effects. High altitude balloons are readily available in many countries (18) and in order to use such a system all that is required is the construction of the reeling system. Following feasibility studies, it is envisaged that such systems could be constructed very quickly and are reusable (unless they are lost or damaged during flight)

Frequency of drops

Another issue for many researchers is the number of experiments they can realistically conduct at drop tower locations. For ZARM in Bremen only 15 drops of 4.74 seconds are feasible in a normal weeks operation (13). In order to achieve high levels of microgravity, these facilities must evacuate the chamber of air to reduce air density and as a result, the perturbations on the dropped capsule due to drag. Using a drop and reel system as is being developed by the reel.SMRT team, it would be possible on one flight to conduct more than 100 drops (depending on drop parameters and battery capacity).

Quality of microgravity

The simulations currently investigated by reel.SMRT (refer to Section 3.10 ‘System Simulation’) show that it should be possible to see an achievable quality of 10-3 G’s with the reel.SMRT system. Techniques such as using gas jets (2) or other damping techniques to reduce perturbations being transmitted to an experiment from the dropped capsule could be implemented, if required, in further design iterations. In the future, it is hoped that considerable improvement and refinement will be made upon the quality. This compares favourably to the 10-2 g’s and up that are created during parabolic flights (19).


The Stratospheric environment has been singled out as a significant detractor of attempting microgravity experiments from high altitude balloons. Despite this, there are experiments that can actually take advantage of this. Due to the similarities of the stratosphere to the Martian atmosphere some experiments send equipment up on balloons to investigate the effectiveness in such an environment (20). This can also be taken one step further by reel.SMRT, as the system allows for not only free-fall drops but also descents controlled by reeling down, it is possible to replicate Mars gravity level whilst in the low density atmosphere. It is also possible by controlling this reel down speed to mimic the gravity conditions further from Earth and around other solar bodies.

UAV tether drops

A future application upon the scaling up of the reel.SMRT concept will be to tether to experiments wishing to drop from the balloon. This will allow drops of payloads with little to no change compared to an ordinary drop. However, it would be possible over the duration of the balloons flight to drop and recover multiple times; giving experimenters the ability to perform a wider variety of tests or to refine their data. This would be a possibility from lower altitude balloons as well for experiments such as SpaceFish (21) and Icarus (22).

Scientific support

Kjell Lundin and Alf Wikstrom are both supervising this experiment within LTU. They have both spent many years involved in the Space Industry of Kiruna (Esrange, IRF and IRV). Currently they are employed by IRV part time to supervise student projects for balloon and rocket flights (previously including BEXUS(22), REXUS and EXUS launches).


1. A project overview of High Altitude Reduced Gravity VEhicle Experiments. Leavitt, G R, R, Wallace C and Cook, MJ. Arlington, Virginia, USA : AIAA 5th Aviation, Technology, Integration, and Operations Conference (ATIO), 2005.

2. Sawai Lab. Toward Space Plane as Future Space Transportation. Sawai Lab, Institute of Space and Aeronautical Science, JAXA. [Online] 2009. [Cited: 13 03 2009.]

3. Reel-up and -down system for balloon-borne instruments. Matsuzuka, Y, et al. Tokyo, Japan : IN: International Symposium on Space Technology and Science, 14th, 1984.

4. YES2. First step to a YES2 sequel mission: understanding the mishaps. Young Engineers' Satellite 2. [Online] 2009. [Cited: 14 03 2009.]

5. SMRT. Project: xgravler. SpaceMaster Robotics Team. [Online] EDV-Experts, 2008. [Cited: 13 03 2009.]

6. Baumann, C. Participating in the HALE (High Altitude LEGO Extravagana), Part II. Lego Engineering. [Online] 2009. [Cited: 13 03 2009.]

7. Leitner, J and L, Martinez D. Experimental Gravity Research with LEGObased. SpaceMaster Robotics Team. [Online] 2009. [Cited: 13 03 2009.]

8. MNRL. Surface Acoustic Wave Micro to Nanofluidics. Micro/Nanophysics Research Laboratory. [Online] 2009. [Cited: 13 03 2009.]

9. SSC. Campaign Information MAXUS 4 (2001). Swedish Space Corporation. [Online] 2001. [Cited: 14 03 2009.]

10. REXUS BEXUS. REXUS 5/6 Teams. REXUS BEXUS. [Online] 2008. [Cited: 13 03 2009.]

11. ESA Human Spaceflight and Exploration. 7th Student Parabolic Flight Campaign. ESA Human Spaceflight and Exploration. [Online] 28 06 2004. [Cited: 14 03 2009.]

12. SSC. Campaign Information MAXUS 7 (2006). Swedish Space Corporation. [Online] 2006. [Cited: 14 03 2009.]

13. Universitat Bremen. Center of Applied Space Technology and Microgravity. ZARM Center of Applied Space Technology and Microgravity. [Online] [Cited: 14 03 2009.]

14. MGLAB. Micro-Gravity Laboratory of Japan Top Page. Micro-Gravity Laboratory of Japan. [Online] 2009. [Cited: 14 03 2009.]

15. NASA. Zero Gravity Research Facility. National Aeronautics and Space Administration. [Online] 9 01 2008. [Cited: 14 03 2009.]

16. —. 2.2 Second Drop Tower. National Aeronautics and Administration. [Online] 1 02 2008. [Cited: 14 03 2009.]

17. Science @ NASA. Marshall Space Flight Center Drop Tube Facility. Science @ NASA. [Online] [Cited: 14 03 2009.]

18. StratoStar Systems. StratoStar Systems. StratoStar Systems. [Online] 2008. [Cited: 14 03 2009.]

19. Jules, K. Section 2. Working in a Reduced Gravity Environment: "A Primer". s.l. : NASA Glenn Research Center, 2002.

20. IRF. MEAP/P-BACE Balloon Mission. IRF. [Online] 2008. [Cited: 14 03 2009.]

21. Spacefish Project. Spacefish Project. Spacefish Project. [Online] 12 03 2009. [Cited: 14 03 2009.]

22. REXUS BEXUS. BEXUS 6/7 Teams 2008. REXUS BEXUS. [Online] 2008. [Cited: 14 03 2009.]

SpaceMaster Robotics Team

We want to specially thank our sponsors
for their financial support!

SpaceMaster Robotics Team Members

SpaceMaster Robotics Team

A student team consisting of members formerly studying in the Joint European Master in Space Science & Technology (SpaceMaster) programme. It is currently spread all over Europe.

The team consists for this project of the following 9 team members: Katherine Bennell, Mark 'Fitts' Fittock, Mikulas Jandak, Juxi Leitner, David Leal Martínez, Waen Nawarat, Campbell Pegg, Mikael Persson, and Jan Speidel


Interested? Got anything to ask? eMail us