For planets with atmospheres of any substance, however, there is an alternative: an autonomous flying robot, or " aerobot ".

Titan, the largest moon of Saturn, is an attractive target for aerobot exploration, as it has a nitrogen atmosphere five times as dense as that of Earth's that contains a smog of organic photochemicals, hiding the moon's surface from view by visual sensors.

As the atmospheres of these planets are largely composed of hydrogen, and since there is no lighter gas than hydrogen, such an aerobot would have to be a Montgolfiere.

As sunlight is weak at such distances, the aerobot would obtain most of its heating from infrared energy radiated by the planet below.

Most aerobot concepts are based on aerostats, primarily balloons, but occasionally airships.

Once operational, the aerobot will be largely on its own and will have to conduct its mission autonomously, accepting only general commands over its long link to Earth.

The aerobot will have to navigate in three dimensions, acquire and store science data, perform flight control by varying its altitude, and possibly make landings at specific sites to provide close-up investigation.

By this time, the Jet Propulsion Laboratory ( JPL ) of the US National Aeronautics and Space Administration ( NASA ) had become interested in the idea of planetary aerobots, and in fact a team under Jim Cutts of JPL had been working on concepts for planetary aerobots for several years, as well as performing experiments to validate aerobot technology.

By 1996, JPL was working on a full-fledged aerobot experiment named PAT, for " Planetary Aerobot Testbed ", which was intended to demonstrate a complete planetary aerobot through flights into Earth's atmosphere.

MABVAP experiments included drops of balloon systems from hot-air balloons and helicopters to validate the tricky deployment phase of a planetary aerobot mission, and development of envelopes for superpressure balloons with materials and structures suited to a long-duration Mars mission.

While these tests and experiments were going on, JPL performed a number of speculative studies for planetary aerobot missions to Mars, Venus, Saturn's moon Titan, and the outer planets.

One mission concept, the Venus Aerobot Multisonde ( VAMS ), envisions an aerobot operating at altitudes above that would drop surface probes, or " sondes ", onto specific surface targets.

Developing an aerobot that can withstand the high pressures and temperatures ( up to 480 degrees Celsius, or almost 900 degrees Fahrenheit ) on the surface of Venus, as well as passage through sulfuric acid clouds, will require new technologies.

An aerobot would be able to penetrate this haze to study the moon's mysterious surface and search for complex organic molecules.

NASA has outlined a number of different aerobot mission concepts for Titan, under the general name of Titan Biologic Explorer.

An ingenious variation on this scheme, the Titan Aerover, combines aerobot and rover.

The aerobot would also carry a miniaturized chemical lab to search for complicated organic chemicals.

A Jupiter aerobot might operate at altitudes where the air pressure ranges from one to ten atmospheres, occasionally dropping lower for detailed studies.

A Jupiter aerobot might also drop sondes deep into the atmosphere and relay their data back to an orbiter until the sondes are destroyed by temperature and pressure.

The engine technology developed for the Skycar has also been adapted as a UAV platform called the aerobot.

It is made up of tumbling, which might be said to start with a somersault, run through such stunts as headstands, handstands, cartwheels, backbends, and culminate in nearly impossible combinations of aerial flips and twists and apparatus work.

Alaska Airlines is by far the largest air carrier in the region, with Juneau's Juneau International Airport serving as the aerial hub for all of Southeast and Ketchikan's Ketchikan International Airport serving as a secondary hub for southern Southeast Alaska.

Travellers through very remote areas should always inform a reliable person of their route and expected destination arrival time, and remember that a vehicle is much easier to locate in an aerial search, than a person, so in the event of a breakdown, they must not leave their vehicle.

Even that distinction is muddied by the availability of aerial refueling, which greatly increases the potential radius of combat operations.

In aerial photographs, the countershaded gun is essentially invisible.

It is said that the rivalry was fueled in the 1970s due to the stark contrast of the teams: the Cowboys, being more of a " flashy " team with Roger Staubach's aerial attack and the " flex " Doomsday Defense ; while the Steelers were more of a " blue-collar " team with a strong running game and the 1970s-esque Steel Curtain defense, a contrast that still exists today.

One of the oldest means of receiving DTV ( and TV in general ) is using an antenna ( known as an aerial in some countries ).

British forces used airpower to shock the Afghans, and the King's home was directly attacked in what is the first case of aerial bombardment in Afghanistan's history.

It is the first aerial victory by the U. S. military.

Guernica is best known to those residing outside the Basque region as the scene of the April 26, 1937, Bombing of Guernica, one of the first aerial bombings by Nazi Germany's Luftwaffe.

In a series of diagrams illustrating the " environments " that influence various painterly styles, the Suprematist is associated with a series of aerial views rendering the familiar landscape into an abstraction ... ( excerpted from Ms. Bekman Chadaga's paper delivered at Columbia University's 2000 symposium, " Art, Technology, and Modernity in Russia and Eastern Europe ")

In addition, from the ground level, it is difficult to tell what the park is supposed to look like, though from an aerial view it does resemble a punched card.

Boosting of moose populations in Alaska for hunting purposes is one of the reasons given for allowing aerial or airborne methods to remove wolves in designated areas, e. g., Craig Medred: " A kill of 124 wolves would thus translate to survival of 1488 moose or 2976 caribou or some combination thereof ".

The epidermis of all aerial organs, but not roots, is covered with a cuticle made of the polyester cutin with a superficial layer of waxes.

A flypast is an aerial parade of anything from one to dozens of aircraft, both in commercial context at airshows and also to mark, e. g., national days or significant anniversaries.

* Primary Scan: A scanning technique where the main antenna aerial is moved to produce a scanning beam, examples include circular scan, sector scan etc.

Researcher Claudia López considered that the Colombian government is winning the strategic and aerial side of the war but not the infantry front, where both the FARC-EP and ELN continue to maintain an offensive capacity.

There is a 1. 5 km aerial tramway connecting the city of San Marino on top of Monte Titano with Borgo Maggiore, a major town in the republic, with the second largest population of any Sammarinese settlement.

Two aerial tramway cars, known as gondolas, and numbered ' 1 ' and ' 2 ', operate in opposition on a cable, and a service is provided at roughly fifteen minute intervals throughout the day.

The upper station of the aerial tramway serves no other purpose ( although it is situated close to a tourist information office ).

The most recent entry in the series is Mario Kart 7 for the Nintendo 3DS, which was released in December 2011 and introduced aerial and aquatic racing to the series, as well as customizable karts.

* 1943 – The Municipal Theatre of Corfu is destroyed during an aerial bombardment by Luftwaffe.

A ceremonial or celebratory form of aerial salute is the flypast ( known as a " flyover " in the United States ), which often follows major parades such as the annual Trooping the Colour in the United Kingdom or the French défilé du 14 juillet.

Also in the first issue is commentary on Signor Muzio Muzzi's proposed device for aerial navigation.