Rosetta and New Horizons watch Jupiter in joint campaign

New Horizons made its closest approach to Jupiter on 28 February 2007. Its principal objective was to use the gravity of the giant planet to slingshot it onwards to its rendezvous with Pluto, planned for 2015. However, as Alan Stern, Southwest Research Institute, San Antonio, Texas (USA), and New Horizon’s Principal Investigator says, "We couldn’t pass up this opportunity to study Jupiter’s meteorology, rings, aurorae, satellites, and magnetosphere."

Rosetta, just after having swung by Mars and while on its way to comet 67P-Churyumov Gerasimenko, played an important role in this research, providing global observations of Jupiter’s aurora and the Io plasma torus that can be correlated with New Horizons’ detailed in-situ measurements.

Rosetta’s observation of Jupiter began on the same day as the New Horizons swingby. Because Rosetta is presently close to Mars and Jupiter is still far away, to some of the instruments the giant planet is just a pinprick of light. Nevertheless, Rosetta’s Alice instrument splits this light into a spectrum, in which the separate contributing regions can be distinguished.

"We have now clearly separated the three components that make up the spectrum," says Alice team member Andrew Steffl, Southwest Research Institute. The first component is simply sunlight, reflecting off Jupiter’s cloud tops. The second part of the spectrum is composed of ultraviolet emission given off by particles ejected in volcanic eruptions by Jupiter’s moon Io. The third is light from Jupiter’s aurorae, caused by particles striking the planet’s atmosphere, some from the Sun, some ejected from Io.

Alice is an ultraviolet imaging spectrometer, designed to analyse the composition and density of gas molecules, and an almost identical Alice UVS instrument is on New Horizons. Rosetta’s Alice will measure the rates at which water vapour, carbon monoxide and carbon dioxide are given off by comet Churyumov-Gerasimenko, after the rendezvous in 2014. New Horizons’ Alice instrument will study the tenuous atmosphere at Pluto in mid-2015.

"New Horizons cannot observe Jupiter using its Alice instrument at the moment," says Joel Parker, also at the Southwest Research Institute, and Alice Project Manager. This is because New Horizons’ Alice would have to be pointed back at Jupiter, towards the Sun. If bright sunlight fell into the instrument, it could damage the sensitive optics. Hence the scientists will not take the risk.

Instead, other instruments on New Horizons can detect the actual particles that are trapped in Jupiter’s magnetic field, but to better understand this data, spectra of Jupiter’s aurora and the Io torus are also needed. This is where Rosetta’s Alice makes its important contribution.

Some of the things the team will be looking for are solar wind events. These are gusts in the number of electrically charged particles that the Sun gives out. When they strike the magnetic field of Jupiter, they can cause the aurora to shine more brightly. Rosetta’s Alice will see this, too, and the team can then look for changes in the particles detected by New Horizons. "This is a really nice synergy between the two projects," says Parker.

Rosetta’s observations are set to continue until 8 May, and when complete, will include some 400 hours worth of observations. Using Rosetta’s Alice is proving to be invaluable to the team in their preparations for the 2014 comet rendezvous. "Every time we use the instrument, we learn more about how to get the most out of it when we arrive at the comet," says Parker.

Source: European Space Agency

Rosetta, New Horizons team up
ESA and NASA are mounting a joint campaign to observe Jupiter over the next few weeks with two different spacecraft. Rosetta will watch the big picture from its current position near Mars, whilst New Horizons will take close-up data as it speeds past the largest planet in our Solar System on its journey to Pluto.
New Horizons Spacecraft Gets Boost From Jupiter for Pluto Encounter
NASA's New Horizons spacecraft successfully completed a flyby of Jupiter early this morning, using the massive planet's gravity to pick up speed for its 3-billion mile voyage to Pluto and the unexplored Kuiper Belt region beyond.
New Horizons Pluto Payload Ready For Flight, Exciting Science Campaign
The science payload for NASA's New Horizons mission completed its last major preparations for flight last week. The probe will be the first to visit Pluto and its moon, Charon.
Rosetta monitors Deep Impact
ESA’s comet chaser Rosetta will take part in one of the world’s largest astronomical observation campaigns - the Deep Impact event - while on its cruise to Comet 69P/Churyumov-Gerasimenko. Rosetta will be watching from 29 June to 14 July 2005.
Victims of Britain's tainted blood scandal speak
(AP) -- Robert Mackie trembles with rage when he describes how he and his wife were kept in the dark about his HIV infection - and how doctors published his medical data in journals years before they gave him the devastating news.
Indigenous children don't need number words to 'count', says new study
The study, by researchers from the University of Melbourne and University College London, is set to be published in the journal Proceedings of the National Academy of Sciences.
Viterbi Algorithm goes quantum
The Viterbi Algorithm, the elegant 41-year-old logical tool for rapidly eliminating dead end possibilities in data transmission, has a new application to go alongside its ubiquitous daily use in cell phone communications, bioinformatics, speech recognition and many other areas of information technology.
Redundant System Keeps Embryo in Stitches
(PhysOrg.com) -- A universal system in animal cells that plays a key role in wound-closure and embryonic development can be quickly replicated by other cells if the original system is damaged, Duke University researchers report.

Rosetta and New Horizons watch Jupiter in joint campaign

Related stories:

News discussion: