When the British Interplanetary Society's Daedalus designs were being created in the 1970s, the scientists and engineers involved quickly realized that interstellar dust would become a problem for a vehicle traveling at 12 percent of light speed. That led to shielding concepts involving materials like beryllium, boron and graphite. But what of concepts like Robert Forward's vast lightsails? If dust posed a problem to Daedalus on its way to Barnard's Star, surely a huge lightsail was even more threatened, there being no effective way to shield it. Forward himself suggested an answer in a 1986 letter to the Society's journal. His optimum sail materials (still far beyond our capabilities) would be much thinner than the diameter of the interstellar grains the starship would likely encounter. The result: such materials would pass right through the sail, creating a hole about as big as themselves. For work within the range of nearby stars, Forward believed, interstellar dust would not pose...

The Interstellar Boundary Explorer is clearly a mission whose time has come. Scheduled for launch in 2008 and recently confirmed for mission implementation, IBEX will provide global maps of the distant interactions where the heliosphere (the 'bubble' of space carved out by the solar wind) meets the interstellar medium. All of this at a time when Voyager 1 is thought in some quarters to have already crossed the 'termination shock,' that region where the solar wind is slowed as it encounters interstellar gases; some evidence suggests that the spacecraft then moved back into the supersonic solar wind. Image: The Sun's movement through the local interstellar medium. IBEX should tell us much about the boundary separating the heliosphere from this region. Credit: Southwest Research Institute. The Voyager findings remain controversial thanks to magnetic field and cosmic ray measurements that suggest different interpretations, but it's clear that Voyager is at the very edge of the...

Here's why we'll have to know a great deal about the interstellar medium -- the stuff between the stars -- before we ever send out probes at a substantial fraction of lightspeed. The gas and dust forming into dark, concentrated knots in the image below creates so-called 'Bok globules,' named after astronomer Bart Bok, who hypothesized their existence back in the 1940s. They're hundreds of light years in size and, when perturbed, can form concentrated pockets of gas and dust that have the potential of turning into stars. But not all of them do become stars. In the image, we're looking at NGC 281, a nearby nebula and star-forming region some 9,500 light years away from Earth in the direction of Cassiopeia. In this region, many of the dust knots seem to be dissipating before stellar formation actually occurs. You can also see the bright blue stars of a cluster called IC 1590, whose young and massive stars put out enough solar wind to energize the surrounding hydrogen gas of the nebula...

The first true interstellar mission may be on the drawing board right now. Yes, Voyager 1 has already crossed the termination shock 94 AU out and is still returning data, but we've never had a mission targeted from day one at interstellar space. Yet that region just beyond the influence of the Sun -- the Very Local Interstellar Medium -- is crucial; it will tell us much about the interface between the solar wind and deep space. Probing it will create new data on everything from gravitational waves to anomalous forces like those that may be acting on the Pioneer spacecraft, not to mention setting the stage for future missions. Now dubbed the Innovative Interstellar Explorer, the concept is for a robotic mission beyond the heliopause, and as refined through studies led by Ralph McNutt (Johns Hopkins University Applied Physics Lab) for NASA's Institute for Advanced Concepts, and now through continuing development as a NASA mission study, the IIE would take a 1000-kg payload on the first...