JAXA has developed a Balloon-based Operation Vehicle (BOV) to provide a long and cost-effective microgravity environment for scientific experiments. The BOV separates from a high-altitude balloon and maintains a stable microgravity condition inside a shielded inner shell for over 30 seconds using thrusters. GPS experiments were conducted from the BOV at around 40km altitude. Future flights will test controlling the BOV's attitude to achieve supersonic horizontal flight duration.

1. JAXA
MICROGRAVITY RESEARCH USING A
BALLOON BASED OPERATION VEHICLE
Since 1981 on average 100 million dollars are spent every year on microgravity
research by space agencies in the US, Europe and Japan [1]. There are many ways to
achieve microgravity conditions such as, in order of experiment duration: drop tow-
ers, parabolic ights, balloon drops, sounding rockets, space shuttle, recoverable
satellites and the international space station. The order of the previous summation
is also approximately the order of increasing experiment cost (table 1), with the
exception of the balloon-drop. From the table, it is apparent that a balloon-based
system could be the most cost-e cient microgravity environment. Another advan-
tage of such a system is that no large acceleration is required before the experiment
can be performed. In this article we will describe a balloon-based system.
TEXT Tatsuaki Hashimoto, Shujiro Sawai, Shin-ichiro Sakai, Nobutaka Bando, Shigehito Shimizu, JAXA-ISAS, Japan
Peter Buist, Sandra Verhagen, MGP, DEOS, Delft University of Technology, the Netherlands
Table 1. Available Microgravity Research Platforms (adapted from [1]) BALLOON BASED OPERATION
Platform Duration [s] Gravity level [10 -x
g] Cost [$ /kg] VEHICLE
with x Scienti c balloons have been launched
Drop tower 2-9 2-5 3000 in Japan by ISAS/JAXA since 1965, and
Parabolic flight 25 2-3 3000 JAXA currently holds the world record for
Balloon-drop 60 2-5 750 the highest altitude reached by a balloon
Sounding rocket 360 3-4 10000 (53km). Prof. Hashimoto’s group has been
Space Shuttle < 14 days 3-5 30000 developing a system to provide a long
Space station >months 5-6 >30000 duration, high quality microgravity envi-
Recoverable >months 5-6 10000-200000 ronment based on a capsule that can be
satellite released from a high altitude platform [2].
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2. JAXA
JAXA
JAXA
Figure 1. BOV Overview Figure 2. The balloon used to lift o the vehicle
The capsule, coined: Balloon-based Op- tant challenge for balloon launches is the tion experiment onboard the BOV and the
eration Vehicle (BOV) and shown in g. 1, gusty wind during gas in ation that can gondola of the balloon. The BOV and the
has a double shell drag free structure and cause damage to either the balloon or gondola provide a challenging environ-
is controlled so it does not collide with the the payload. At the new facility, the in a- ment, because of the rather rapidly vary-
inner shell. The ight capsule consists of tion of the balloon can be performed in- ing attitude (due to wind and rotation)
a capsule body (the outer shell), an ex- doors in a huge hangar. A so called sliding and high altitude. For a GPS experiment,
periment module (the inner shell) and a launcher is used to launch balloons with the altitude of around 40 km is interest-
propulsion system. The inner shell is kept a volume up to two million cubic meter. ing as not many experiments have been
in free-fall conditions after the release of performed at this height, which is higher
the BOV from the balloon, and no distur- MICROGRAVITY EXPERIMENTS than the altitude reachable by an aircraft
bance forces are working on this shell or Within the eld of uid physics, material but below Low Earth Orbits for spacecraft.
the microgravity experiment it contains. science, combustion, biology, and colli- Furthermore the antennas are placed un-
The outer shell has a rocket shape to re- sion dynamics researchers have identi ed der the balloon, which will a ect the GPS
duce aerodynamic disturbances. The dis- the need for micro gravity experiments. signals. More information about the GPS
tance between the outer and inner shell is Speci cally they required longer and experiments can be found in [3][4].
measured using four laser range sensors higher quality micro gravity conditions
and besides the attitude of the BOV, the and a shorter time of return for the results IN FLIGHT QUALIFICATION OF THE
propulsion system ensures that the two of their experiments. A Balloon-based Op- BOV’S MAIN BODY, THE ATTITUDE
shells don’t collide. It incorporates sixteen eration Vehicle could potentially be used DETERMINATION PACKAGE AND GPS
dry-air gas-jet thrusters providing 60N of for this kind of experiments, but a heavy SYSTEM
thrust each, providing control not only in lifting balloon would then be required. To Flight experiments with the BOV were car-
vertical direction but also in the horizon- reach a su ciently high altitude (neces- ried out in 2006 (BOV1) and 2007 (BOV2)
tal direction to compensate for distur- sary for long-duration microgravity condi- and a ne micro-gravity environment was
bances caused by, for example, wind. The tions) a balloon must be light enough and established successfully for more than
procedure of a typical ight with the BOV thus made of ultra thin lm. But as the 30 seconds. To achieve a longer period
is shown as follows: rst the BOV lifts o payload is very heavy, this lm should also of micro-gravity conditions and, in the
due to the balloon. Then the vehicle sepa- be incredibly strong. To cope with these long term, safe horizontal landing, usage
rates from the balloon and measurements con icting requirements, a lm based on of an air-breathing engine to surmount
are performed during free fall. Finally, a 2.5 micrometer thick Polyethylene was air resistance has been investigated and
safe landing is assured by the deployment developed. A multilayer lm was applied is now under development for the next
of a parachute. for the top of the balloon where the stress ight experiment. This will be performed
is concentrated; the rest of the balloon on BOV3, a wing type version of the BOV
BALLOON FACILITIES consists only of a single layer in order to ( gure 3), for which the attitude will be ac-
In the north of Japan’s main island Hon- minimize weight. tively controlled to maintain the safety of
shu, the Sanriku Balloon Centre was ight, i.e. the ight direction oversea and
opened in 1971 and since then 413 bal- GPS EXPERIMENT away from inhabited areas. The main goal
loons have been launched from this site. The Mathematical Geodesy and Position- of this next experiment is to achieve su-
In order to facilitate the launch of larger ing Section of the Faculty of Aerospace personic horizontal ight.
balloons and utilize better meteorological Engineering of Delft University of Technol-
conditions, the Balloon base was moved ogy is involved in a precise GPS-based rel- An altitude of about 40km is a harsh en-
to Taiki in Hokkaido in 2008. One impor- ative positioning and attitude determina- vironment for electrical devices because
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3. JAXA
Figure 3. 3D-CAD drawing of BOV3
the pressure is about 1/1000atm and the calculate the full attitude of the gondola, References:
temperature ranges from -60 to 0 de- and the nominal performance of the ADP
grees Celsius. Therefore in September package could be con rmed by the at- [1] V.A. Thomas, N.S. Prasad, A.M. Reddy,
2008, we performed a test for the atti- titude determined by the GPS system. Microgravity Research Platforms – A
tude determination system of BOV3 and Furthermore, we used a ground station study, Special Section: Microgravity
a GPS system containing two GPS receiv- to demonstrate the combination of GPS- Materials Science, Current Science, Vol.
ers. The purpose of this ight was to test based attitude determination and relative 79, No3, 10 August 2000
the equipment on the gondola without positioning between the platform and the
launching the BOV. By this test, nominal ground station (more information on this [2] T. Hashimoto, S. Sawai, S. Sakai, N.
performance of some of the sensors in approach can be found in [5]). Therefore Bando, H. Kobayashi, K. Fujita, Y. Inatomi,
the real environment was con rmed (for a this ight was an example of a fruitful co- T. Ishikawa, T. Yoshimitsu and Y. Saito,
Progress of Balloon-based Micro-gravity
more detailed description see [4]). operation bene cial for both JAXA and
Experiment System, 26th International
Delft University of Technology. Symposium on Spacecraft Technology
FLIGHT OF BOV4 and Science, Hamamatsu, Japan, 2008.
In May 2009, the third ight of the BOV FUTURE PLANS
took place (this ight is called BOV4 and After the ight of BOV3 (planned for next [3] P.J. Buist, S. Verhagen, T. Hashimoto,
is launched before the wing-type BOV: year), the system is quali ed for utiliza- S. Sakai, N. Bando: GPS Field Experiment
BOV3). The balloon reached an altitude of tion and could be used for micro gravity for Balloon-based Operation Vehicle,
more than 41 kilometers from which the experiments in a cost e cient way. In or- Proceedings of the Astrodynamics and
BOV was subsequently dropped. The BOV der to do so we plan to increase the size of Flight Mechanics Symposium, Sagami-
maintained micro gravity condition for the inner shell in which the experiment is hara, Japan, 2008.
about 35 seconds. The BOV and gondola contained and to further reduce the cost
landed in the sea using their own para- of system. [4] S. Shimizu, P.J. Buist, N. Bando, S.
Sakai, S. Sawai, and T. Hashimoto. Design
chutes. The BOV, including the micrograv-
of Multi-sensor Attitude Determination
ity experiment, was successfully recov- ACKNOWLEDGMENTS
System for Balloon-based Operation Ve-
ered from the ocean by a helicopter and Peter Buist: His research on precise rela- hicle. Proceedings of the 27th ISTS (Inter-
the gondola was picked up by a vessel. tive positioning and attitude determina- national Symposium on Space Technol-
tion for formation ying is supported by ogy and Science), Tsukuba, Japan, 5-12
During this balloon ight, a second test the MicroNed-MISAT framework. July 2009, 2009.
of the attitude determination package
(ADP) and a GPS system was performed [5] P. J. Buist, P. J. G. Teunissen, G. Giorgi,
on the gondola to con rm the nominal S. Verhagen, Instantaneous GNSS-based
performance of all the sensors. For the Kinematic Relative Positioning and
purpose of this experiment, we acquired a Attitude Determination using Multi-An-
new GPS receiver, which is able to collect tenna Con gurations, 2009 International
data from three antennas simultaneously. Symposium on GPS/GNSS, Jeju, Korea,
4-6 November 2009
Using this new equipment we are able to
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