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"Dragonfly" Titan explorer drone, NASA funds Johns Hopkins University Applied Physics Laboratory (APL)
vjkane
post Jul 2 2019, 04:14 PM
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QUOTE (mcaplinger @ Jul 2 2019, 08:40 AM) *
Back in 2017 you were still speculating that it would be possible to fly from equator to pole. What changed? wink.gif

I think it's a little early yet to know what the baseline mission profile will look like, though conservatism is not an unreasonable assumption.

In the NASA Live discussions following the announcement, someone said that Dragonfly would land 180 km from the crater and take 2.5 years to get there. Also, it was either there or something I've read since that said Dragonfly would advance 10 km per flight. Assuming one flight per Titan day (which other documents suggest), that limits how far it can go in a year. My back of the envelope imagining suggested 15 km per Titan day if the goal was just to get to somewhere, similar to Opportunity's traverse from Victoria to Endeavour crater.

My earlier post was based on the craft doing little more than putting as many km on the odometer as possible. Once I did the research for my blog post on the mission, I realized that a better way to think of the mission is as a regional explorer that will explore 200 to perhaps 400 km.

It is a shame that Selk crater isn't closer to Adiri. There appears to be lots of interesting terrain and surface materials there.


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atomoid
post Jul 2 2019, 10:49 PM
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...Dragonfly would advance 10 km per flight. Assuming one flight per Titan day ...

looks like that average 10km value already has baked into it having to operate largely within limited communication windows when Selk crater isn't occluded from comm link with Earth, which seems like it would consist of on/off 8-earth-day sessions as the 'Titan day' of activity, since despite autonomous abilities I suspect 'daily' uplinks are still going to be the basis of operation (and someone might do Celestia simulations to enlighten us on communications windows) so apparently no red-eye flights to increase that 10km, but in an extended mission scenario who knows, RTG power allowing.. seems the plan is to send Dragonfly purely on its own, no assistive communications relay or independent sister orbiter with its own suite of experiments, no MarCO analog with jumbo solar array.. but such are hopes and wishes and unlimited budgets...
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vjkane
post Jul 3 2019, 03:02 PM
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QUOTE (atomoid @ Jul 2 2019, 02:49 PM) *
...Dragonfly would advance 10 km per flight. Assuming one flight per Titan day ...

looks like that average 10km value already has baked into it having to operate largely within limited communication windows when Selk crater isn't occluded from comm link with Earth, which seems like it would consist of on/off 8-earth-day sessions as the 'Titan day' of activity, since despite autonomous abilities I suspect 'daily' uplinks are still going to be the basis of operation (and someone might do Celestia simulations to enlighten us on communications windows) so apparently no red-eye flights to increase that 10km, but in an extended mission scenario who knows, RTG power allowing.. seems the plan is to send Dragonfly purely on its own, no assistive communications relay or independent sister orbiter with its own suite of experiments, no MarCO analog with jumbo solar array.. but such are hopes and wishes and unlimited budgets...

One of the technical articles on Dragonfly showed an example power budget over a Titan day. Between the one flight, science, and communications to Earth, the battery was drawn down to about 30%. The craft then went into low power mode for the night with just occasional science activities to recharge the battery.

Another reason for no nighttime flights is that the navigation depends on assessing images taken in flight, which requires daylight.

QUOTE (atomoid @ Jul 2 2019, 02:49 PM) *
...Dragonfly would advance 10 km per flight. Assuming one flight per Titan day ...

looks like that average 10km value already has baked into it having to operate largely within limited communication windows when Selk crater isn't occluded from comm link with Earth, which seems like it would consist of on/off 8-earth-day sessions as the 'Titan day' of activity, since despite autonomous abilities I suspect 'daily' uplinks are still going to be the basis of operation (and someone might do Celestia simulations to enlighten us on communications windows) so apparently no red-eye flights to increase that 10km, but in an extended mission scenario who knows, RTG power allowing.. seems the plan is to send Dragonfly purely on its own, no assistive communications relay or independent sister orbiter with its own suite of experiments, no MarCO analog with jumbo solar array.. but such are hopes and wishes and unlimited budgets...

One of the technical articles on Dragonfly showed an example power budget over a Titan day. Between the one flight, science, and communications to Earth, the battery was drawn down to about 30%. The craft then went into low power mode for the night with just occasional science activities to recharge the battery.

Another reason for no nighttime flights is that the navigation depends on assessing images taken in flight, which requires daylight.


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JRehling
post Jul 3 2019, 08:47 PM
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This is probably already in everyone's consciousness but day/night cycles and radio contact with Earth are almost equivalent, except for superior conjunction when the Sun will block radio contact.

A lander/flyer/floater at high latitudes, however, could spend several terrestrial years in continuous daylight and continuous radio contact with Earth. An equatorial landing site would mean almost uniform periods of day/night.

Terrain types on Titan correlate very strongly with latitude. The polar stuff and the equatorial stuff are almost literally two different worlds.
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climber
post Jul 3 2019, 10:27 PM
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Did you notice that launch will be 29 years after Cassini which means exactely 1 Saturn orbit?
Add another 29 years and I’ll be exactely 100 years old rolleyes.gif
Interesting coincidences


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