Juno probe to Jupiter

[Satanic Mechanic]

Well I am watching the the launch now.  Originally it was scheduled for today at 11:34am Eastern, but there are a few delays to low fuel pressure.
One interesting note about this probe going to Jupiter, it does not have a RTG!  It has three large photovoltaics to supply power for the craft.  I found it interesting that the engineers went with this approach since Jupiter is 5AU away and the light from the Sun is 1/10th that of Earth at that distance.

SM

p.s. launch pushed to 12:13pm Eastern.

[Satanic Mechanic]

Great launch at 12:25 EDT.

[ijuin]

The fact that photocells can be used on the Juno craft without a prohibitive mass penalty is a testament to how much photocell technology has improved over the past 25+ years since the Galileo craft was built.

Any info on whether a mission extension will be possible after the initial 33 orbits? It seems a bit of a waste to spend five years getting there and then not keep the probe running for as long as reasonably practical--note that every other outer solar system probe (I.E. Jupiter and beyond) ever launched by NASA has had its mission extended past the initial period as well (New Horizons is excepted since its initial mission is still in progress).

[Satanic Mechanic]

I saw the rebroadcast of the Juno webcast today and a number of questions about the photovoltaics were brought up.  The craft can be fully powered if 10% of the photovoltaics are damaged.  They are using a hardened processor that is found in Macs as there computer(s).
I believe they will be plunging this probe into the atmosphere after 33 orbits to get some data.

SM

[Satanic Mechanic]

I was wrong on the sunlight at 5AU, it is 1/25th.  Here is some more detail from the NASA website:http://www.nasa.gov/mission_pages/juno/spacecraft/index.html

Excerpt from website:
Solar Power

Jupiter’s orbit is five times farther from the Sun than Earth’s, so the giant planet receives 25 times less sunlight than Earth. Juno will be the first solar-powered spacecraft designed by NASA to operate at such a great distance from the sun, thus the surface area of solar panels required to generate adequate power is quite large. Three solar panels extend outward from Juno’s hexagonal body, giving the overall spacecraft a span of about 66 feet (20 meters). The solar panels will remain in sunlight continuously from launch through end of mission, except for a few minutes during the Earth flyby. Before launch, the solar panels will be folded into four-hinged segments so that the spacecraft can fit into the launch vehicle.