When you think of scientific telescopes there’s usually only 2 different types that come to mind. The ones down here on terra firma, with their giant white domes covering their precious mirrors, and the ones up in space like the venerable Hubble Space Telescope. Each of these has is set of benefits and drawbacks, like the ground based ones having massive mirrors and the space based ones not having to deal with our atmosphere. However there’s potential for a telescope that straddles the boundaries of these two types of telescopes, one that’s far above the Earth’s surface but also doesn’t require the heavy energy investment of an orbital craft. Indeed NASA has flown craft like these in the past and they’re now looking to airships to fly the next generation of such telescopes.
Ground based telescopes suffer from 2 major drawbacks related to the atmosphere. The first is the aberrations caused by the shifting atmosphere, the same thing that causes the stars to twinkle at night, which makes precise measurements incredibly difficult. The second is that the atmosphere is great at absorbing a lot of the frequencies of light, specifically infrared, something which we can’t really overcome with special optics or filters. Putting a telescope in space negates these problems but brings with it a whole other set of challenges which is precisely why NASA is looking to develop a sub-orbital telescope concept using an airship as the platform.
NASA has constructed platforms like this in the past, the most notable one of which is SOFIA, an infrared observatory that’s built into the back of a Boeing 747. At its cruising altitude it’s able to see 85% of the total infrared light coming to Earth a considerable amount more than any ground based telescope will be able to see. The primary limit to SOFIA is its endurance time which is around eight hours or so although its capability to be pretty much anywhere in the world does make it incredibly flexible in the operations it can perform. The airship design that NASA is looking to pursue would address this limitation whilst providing some other benefits.
Airships, whilst not being as mobile as their winged cousins, have the advantage of being able to stay aloft in a location for extended periods of time that aircraft simply aren’t capable of doing. For an observatory this provides several advantages such as being able to do longer exposures on targets as well as being able to take advantage of higher bandwidth downlinks to their base sites. There are several engineering challenges that will need to be solved before a viable aircraft will materialize, but it’s certainly within the realms of possibility.
Pending funding of the idea NASA will be funding it X-prize style, looking for designs (and I assume workable craft) that can carry a small or large payload up into the atmosphere. Such programs have proved to be highly successful in the past and I’m sure we’ll see some pretty interesting craft come out of it. Considering that SOFIA is slated to be shut down due to budgetary concerns sometime next year a viable alternative needs to be sought so they don’t introduce more holes in their capabilities. Of course getting an airship with a telescope up in the air before that happens isn’t going to be likely but the sooner the process is started the better.
It’s almost scary how similar Earth and Venus are in some respects. We’re roughly the same size, with Earth edging Venus out by 300KMs in diameter, and consequently roughly the same mass as well. The similarities end when you start looking further however with Venus being the hottest planet in our solar system due to its runaway greenhouse effect, it’s atmosphere a choking combination of carbon dioxide, nitrogen and sulphur. If there was ever a warning about the devastating potential about greenhouse gases it is our celestial sister Venus, but in that chaos lies an abundance of scientific data that could help us better understand ourselves and, hopefully, avoid the same fate.
Studying Venus’ atmosphere isn’t an easy task however as those extreme conditions have meant that the longest our probes have managed to survive down there is a couple hours. We can still do a lot of good work with satellites and spectral analysis but there’s really no substitute for actually being in the atmosphere for an extended period of time. Strangely enough whilst Venus’ atmosphere might be one of the most unforgiving in our solar system its composition, made up primarily of heavy than air elements, provides an unique opportunity that an atmospheric study craft could take advantage of. A concept craft that does just this is called the Venus Atmospheric Maneuverable Platform (VAMP) by Northrop Grumman.
The VAMP is part airship, part traditional aircraft which would spend the majority of its life high in Venus’ atmosphere. To do this the VAMP craft is extremely light, on the order of 500kgs, but it has a wingspan that exceeds that of a Boeing 737. The craft itself would be inflatable, allowing VAMP to cruise at altitudes between 55KM and 70KM above Venus’ surface. It can do this because of the incredible density of Venus’ atmosphere which makes even regular breathable air from Earth a powerful lifting gas. The only limit to its lifespan in the Venusian atmosphere would be its power source and since it could take advantage of the freely available sun a platform like VAMP could run for an incredibly long time.
The concept is actually a rework of another one that was designed to fly through the atmosphere of Saturn’s moon Titan, a mission many have wanted to undertake since the Huygens probe landed there a decade ago. The challenges of flying an aircraft there are far greater than that of Venus, primarily due to the much thinner atmosphere and huge drop in solar radiation to take advantage of. It would still be doable of course, however the mission profile you’d have to go with would have to be much less ambitious and the time frames much shorter. Still it surprises me that the concept didn’t go the other way around as putting balloons in Venus’ atmosphere has always been a concept that many wanted to explore.
Northrop Grumman appears to be quite serious about the VAMP project as they outlined many objectives they wanted to achieve for it back in 2013. I can’t seem to find much more on it unfortunately which means it’s likely still in the concept phase, hoping for a mission profile to come along that suits it. Considering how many incredible envelope pushing missions we’ve had of late I don’t think something like VAMP is too far out of left field, especially considering that it’s based on already proven technologies. Still it doesn’t seem like it will be too long before we have a plane soaring through another world’s atmosphere, another science fiction dream becoming a reality.