The study of Earth-like planets around other stars will require significant advances in several key technologies. Broadly speaking, these challenges lie in the areas of high-angular resolution sensing and high dynamic range imaging.

Technology for High Angular Resolution

For an optical space telescope to distinguish the presence of planets around nearby stars, it would need a primary mirror more than 8- or 10-m in diameter. At infrared wavelengths, the telescope would need to be more than 10 times larger.

Such large observatories are nonetheless possible through interferometry - the combination of light from several widely separated space telescopes. Technology advances in several areas will enable higher angular resolution:

• Large precision deployable mirrors in space
• Laser metrology and systems to sense and control optics and large mechanical structures (30 feet to 300 feet) to nanometer precision
• Wave-front sensing and control to fine-tune the optical surfaces in the telescope at the sub-nanometer level
• Formation flying technology to provide the ultimate in high-angular resolution - the coordination of arrays of free-flying telescopes in space.

Technology for High Dynamic Range Imaging

Extrasolar planets are extremely faint compared to the stars around which they orbit: about a million times fainter at mid-infrared wavelengths and 10 billion times fainter at optical wavelengths. Technology advances in several areas are needed to enable the high dynamic range imaging needed to detect faint planets:

• Mirror polishing technology to suppress scattered light
• Coronagraph and interferometer starlight suppression
• Thermal control and cryogenic technology to provide the thermal shielding and the darkest background in which to detect planets
• Detector and cooler technology to enable the devices capable of sensing the very faintest extrasolar planets