DOUGHNUT (donut?) and whale FOUND ON PLUTO

E-minus 7 days until NASA's space lab gets intimate with strange dwarf

Heliophysicist waits 10 years for flyby

NASA helioboffin, Nikolaos Paschalidis, has offered up his excitement for the flyby which will be utilising his own mission-enabling technology to uncover details about the atmosphere of the dwarf planet.

"We have been waiting for this for a long time," said the Greek native, who now works as a scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "That’s what happens when it takes more than nine years to get to your destination."

Paschalidis designed five application-specific integrated circuits for the mission's Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI), developed by Johns Hopkins Applied Physics Laboratory (APL) Principal Investigator Ralph McNutt.

PEPSSI, one of seven instruments aboard New Horizons, is designed to measure the composition and density of material, such as nitrogen and carbon monoxide, which escapes from Pluto's atmosphere and subsequently is ionized by solar ultraviolet light.

During its flyby, the mission will use its onboard suite of instruments – three optical, two plasma, a dust sensor, and a radio science receiver/radiometer – to learn more about Pluto's atmospheric structure and composition, as well as that of its surface geology.

Microchips enable small size

PEPSSI is the most compact of the instruments in the New Horizons payload, at just 3.3 pounds (1.5 kilograms), as well at the most compact, lowest-power energetic particle spectrometer to ever be flown on a space mission.

"The challenge with this mission, and the PEPSSI instrument in particular, was making it as small as possible, capable of taking highly reliable measurements using low power, under extreme environmental conditions," Paschalidis said.

As with all "time-of-flight" particle instruments, particles will enter PEPSSI’s sensor and knock secondary electrons from a thin foil. They then will zip toward another foil placed about two inches away before hitting solid-state detectors. The instrument uses just 2.5 watts of power to measure the time between the foil collisions, with an accuracy exceeding one nanosecond.

This information will reveal the particle's speed and its total energy when it collides with the solid-state detector. From this, scientists will be able to determine the mass and energy of each particle.

Paschalidis's five microchips helped reduce the instrument's overall size and power requirements, while advancing science performance.

Two in particular advanced the capabilities needed to take time-of-flight, energy, and look-angle measurements of particles, while another not only monitored and digitised PEPSSI's temperatures, voltages and currents, but also those of several spacecraft subsystems.

"This set of chips was an innovation. It combined science with engineering,” resulting in significant spacecraft mass and power savings," Paschalidis said.

"A mission to Pluto was the ultimate use for the technology," he added. "Without these chips, I don’t think we could have put this instrument on the spacecraft."

Technology infusion

While New Horizons was racing across the solar system for its rendezvous with Pluto, Paschalidis was "infusing" the technology into many other instruments and missions, state NASA.

A second-generation version of the technology is aboard NASA's JUNO mission, which is expected to reach Jupiter next summer, as well as the currently operating Van Allen Probes, and the recently launched Magnetospheric Multiscale mission.

NASA's Solar Probe and the European Space Agency's Solar Orbiter missions, which are now in development, will also fly the technology.

"New Horizons drove innovation for ultra-miniaturized, low-power, and highly reliable instruments. I can't wait to see this probe finally reach its destination after all these years. Gathering data at Pluto was something that really motivated me." ®