Proponents of small satellites say that tiny spacecraft have potentially big roles to play in planetary exploration.

Today’s small satellites—generally spacecraft weighing around several hundred kilograms—are confined largely to low Earth orbit where they perform remote sensing missions, conduct science operations and serve as technology testbeds and communication relays.

But some forward thinkers are already looking ahead to interplanetary missions and see small satellites as a good fit with the space exploration agendas outlined by the world’s spacefaring nations.

The European Space Agency, for example, is taking a look at a low-cost, multiple spacecraft Venus mission that would utilize small satellite technologies, including a small, deployable weather balloon of sorts, to study the planet. The Indian Space Research Organization last year short listed a gravity-mapping nanosatellite for inclusion on its Chandrayaan-1 lunar orbiter mission.

Andy Phipps, a senior engineer at the British small satellite company Surrey Satellite Technology Ltd., said his team recently completed a so-called technology reference study funded by the European Space Agency to identify the technologies and design philosophy needed for the proposed Venus mission.

Phipps said his team spent 18 months and several hundred-thousand Euros developing a mission concept featuring two orbiters packed with miniaturized instruments and a tiny aerobot that would be dropped into Venus’ corrosive atmosphere.

The aerobot, consisting of an instrument-laden gondola suspended from a balloon, would add about 90 kilograms of mass to one of the orbiters, a data relay satellite that would be placed in a highly elliptical orbit around Venus. The aerobot would be dropped into Venus’ atmosphere where it would float at an altitude of 55 kilometers, circumnavigating the planet several times during its projected 15- to 22-day mission.

The other orbiter would be packed with miniaturized instruments and would circle the planet at a lower altitude, imaging the planet and making scientific measurements.

The proposed orbiters themselves would be relatively small for interplanetary spacecraft, weighing several hundred kilograms apiece. NASA’s Mars Reconnaissance Orbiter, in contrast, will weigh nearly 2,200 kilograms at launch and require an Atlas 5 rocket to reach orbit.

The two satellites and the inflatable robotic stowaway would launch on a single Russian-built Soyuz rocket equipped with an upper stage. The total projectedmission cost, Phipps said, is several hundred-million dollars, or about one-tenth of what the U.S. and Europe spent on the Cassini-Huygens mission to Saturn.

The proposed Venus Entry Probe mission is only one of a half-dozen mission ideas the European Space Agency is considering as it looks ahead to the 2015-2025 timeframe to try to understand what technologies it should be investing in now.

Phipps said the technology needs of the Venus Entry Probe mission are considerable and include: highly protective cover glass to shield imaging instruments from acid rain; steerable planar array antennas to increase data return from the aerobot; higher efficiency solar cells; low-mass structural components that can withstand the planet’s corrosive environment; and lightweight thermal protection system for the aerobot’s entry vehicle.