Japanese Supply Spacecraft Set for Launch

Artist rendering of the HTV. Credit: Japan Aerospace Exploration Agency (JAXA)

Japan's space agency has been working diligently since the 1990s on an unmanned spacecraft, called the H-II Transfer Vehicle (HTV), to resupply the International Space Station (ISS). On September 11 (September 10 in the United States), the HTV will finally lift off from Tanegashima Space Center in southern Japan.

Japan's new spacecraft is 10 meters long and capable of carrying 4.5 metric tons of internal cargo and 1.5 tons of external cargo. It is comprised of two segments--one pressurized and one unpressurized--and can carry supplies as well as scientific experiments. The HTV, along with the Russian Progress vehicles and the European Space Agency's Automated Transportation Vehicle, is among a handful of spacecraft that delivers supplies to the space station. Now that the station has doubled its crew capacity, the extra vehicle is much needed.

Dan Hartman, manager of integration and operations for the ISS program, said in a media briefing earlier this year that HTV will be "a major new capability to resupply the station, allowing for the launch of rack modules and external payloads."

On its first trip, HTV will carry 2.5 metric tons internally and two scientific payloads externally: a Japanese instrument to study the effects of trace gases on Earth's ozone layer, and a NASA experiment to study the oceans and map the ionosphere and thermosphere.

The new spacecraft is larger and has a simpler docking system than the Progress spacecraft. It will be flown just close enough to the station to allow the station's robotic arm to pull it in, before attaching to the Earth-facing docking port on the station's Harmony module. The crew will then start unloading the supplies and will move the experiments to the Japanese Experimental Module, called Kibo. The HTV will spend about six weeks attached to the station. Two days after release, it will re-enter Earth's atmosphere.

The vehicle is an important step in Japanese efforts to solidify a strong role in the development and operations of the space station, which is scheduled to be completed by 2011 (and operational until at least 2016). The HTV will be another vehicle that the United States will have to rely on for sending supplies to the station once the space shuttles retire in 2010, according to the current schedule.

HTV will launch aboard an H-IIB rocket at 2:00 A.M. Japan time, 1:30 P.M. EST.

Nano Printing Goes Large

A rolling nanoimprint lithography stamp could be used to print components for displays and solar cells।

A printing technique that could stamp out features just tens of nanometers across at industrial scale is finally moving out of the lab. The new roll-to-roll nanoimprint lithography system could be used to cheaply and efficiently churn out nano-patterned optical films to improve the performance of displays and solar cells.

Nano press: This 10-by-30-centimeter plastic sheet (top) has been patterned with a series of nanoscale polymer lines using roll-to-roll nanoimprint lithography (bottom). The film is iridescent because of the way its nanoscale features scatter light. Credit: ACS Nano

Nanoimprint lithography uses mechanical force to press out a nanoscale pattern and can make much smaller features than optical lithography, which is reaching its physical limits. The technique was developed as a tool for miniaturizing integrated circuits, and a handful of companies, including Molecular Imprints of Austin, TX, are still developing it for this application.

So far, however, it's been difficult to scale up nanoimprint lithography reliably. To achieve the resolution needed to print transistors, for example, it's necessary to use a flat stamp that's a few centimeters square and must be repeatedly moved over a surface. This isn't practical when printing large-area films for many other applications. "Displays and solar cells require printing over a much larger area and then cutting it up into sheets," says Jay Guo, associate professor of electrical engineering and computer science at the University of Michigan. "You have to do it in a continuous fashion."

To solve this problem, Guo developed a stamp that can be used for roll-to-roll nanoimprinting over large areas. His setup uses a polymer mold wrapped around a rolling cylinder to press a pattern into a material called a resist that sits on top of either a rigid glass backing or a polymer one. To make the finished component, the pattern is then fixed by a flash of ultraviolet light. The process, described in the journal ACS Nano,can be done continuously at a rate of a meter per minute, and Guo says he's used it to print features as small as 50 nanometers over an area six inches wide. That resolution isn't good enough to make integrated circuits, but it is adequate for printing optical devices such as light concentrators and gratings.