StratoBus seeks to occupy the midpoint between airship and satellite

StratoBus seeks to occupy the midpoint between airship and satellite
The StratoBus will hover up out of the way of airliners, but won't need to be launched into space
The StratoBus will hover up out of the way of airliners, but won't need to be launched into space
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The StratoBus will hover up out of the way of airliners, but won't need to be launched into space
The StratoBus will hover up out of the way of airliners, but won't need to be launched into space

Satellites may be very useful for communications, navigation and other applications, but they're awfully expensive to build and launch, and once they're in orbit ... well, there's no reusing them. That's why a consortium led by Thales Alenia Space is developing the StratoBus. It's a planned autonomous airship that can be launched like a regular blimp, but that will be able to hover at an altitude of 20 km (12 miles) – that's up in the stratosphere, hence the name.

According to the company, the StratoBus will be 70 to 100 meters long (230 to 328 ft), and 20 to 30 meters (66 to 98 ft) in width. Its envelope will be made mainly of UV-resistant woven carbon fiber, and its two fuel cell-powered prop motors will allow it to maintain its position, even when subjected to winds blowing at up to 90 km/h (56 mph).

The fuel cell will be located in its nacelle (the bottom part, that sits where the gondola would be on a manned airship), along with an electrolyzer for obtaining hydrogen from an onboard water supply, plus its communications and other electronics. Different nacelles will be swapped on and off of one airship body between missions, as each one will be specially outfitted for its intended purpose. Payloads of up to 200 lb (91 kg) will be possible.

The electrolyzer will be solar-powered. Sunlight will stream into the airship's "balloon" through a transparent section of the envelope, then reflect off an internal concentrating mirror, and onto a row of solar panels. That section will be able to stay aligned with the sun, as the balloon will rotate relative to the rest of the vehicle.

Suggested applications for the StratoBus are much the same as those currently served by satellites, including observation, security, telecommunications, broadcasting and navigation. It is estimated that each airship should have a lifespan of about five years, which is also the amount of time that Thales Alenia Space believes it will take to build the first prototype. The company is collaborating on the project with Airbus Defence & Space, Zodiac Marine and CEA-Liten.

The whole thing sounds not unlike Google's Project Loon, which is aimed at getting high-speed internet to underserved parts of the world via radio-equipped balloons. According to Thales Alenia, though, "The advantage of StratoBus is that it offers long endurance and complete autonomy from a fixed position, while the high-altitude balloons in Loon move around the Earth and will offer only limited autonomy."

It also, however, brings to mind Lockheed Martin’s HALE-D airship, and Titan Aerospace's fixed-wing Solara "atmospheric satellite."

Source: Thales Alenia Space via

How does it deal with expanding gases at higher altitudes?
probably the same way they deal with it today, either a compressor and tank that can be filled from the gasses in the balloon as it rises and released at it descends or you just calculate the rate of expansion and make sure your balloon has enough excess space and elasticity to compensate for it.
A 90 kg payload might be too little for much of a radar, but enough for an InfaRed Search & Track system & a telescope.
Stephen N Russell
Airship can beam comm from shore to ship, Internet or from HI to Mainland US & Alaska alone for Communications. & aid Search & rescue IE MH370.
Nice but I would prefer to see it powered by a ground based laser.
Ikeleaka Kaluva
Another great advantage is there will be no space junk floating around at high speeds. Also no aircraft will ever encounter the blimps because they are operating at altitudes most aircraft engines would cease to function at.
So, why the convoluted power system? Solar → electrolysis → hydrogen fuel cells → electric propulsion motors... why not directly from Solar to motors? You would need an intermediate storage cell array of course, but surely a battery or capacitor system able to last through the night wouldn't weigh much more than all that extra hi-tech conversion (read inefficient) of power via water/hydrogen? Too much to go wrong, I'd think.
Less than 100kg payload for something that size seemed a bit low, but with 15,000-30,000 cubic meters of lift gas and a lift of about 9.5g/m^3 at 20km and outside air 20K above normal temp., they have a gross lift of only 1400 - 2800 kg, which is not really enough for the craft.
Going down to 55kft / 17km gives 63% more lift, and is still well above air traffic - but getting down to 36kft/11km would give 4x the lift at 20km. Airships work much, much better at lower altitudes.
@ MzunguMkubwa They probably think that the hydrogen system will last longer than batteries but they might plan to have the waste heat from the fuel cells warm the lift gas through the night stabilizing the lift.
Bob Ehresman
@ EH The system will not work at lower altitudes due to wind speed. At approximately 70,000 ft (actual altitude varying by latitude and season and not at all at high latitudes) there is a very sweet spot in terms of annual average wind speed (about 12 kph). This is where the energy required for station keeping is absolutely lowest. This band of nullified wind is also relatively thin, only a couple thousand feet thick. If you are above or below this very much then annual average wind speeds are significantly higher.
Any system intended to operate here also has to be able to fairly tightly stabilize altitude against daytime heating and nighttime cooling of the lift gas.
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