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Previously, NASA planned to lower the closest approach to Ceres of the Dawn spacecraft to around 120 miles (200 km) from 239 miles (385 km). Now, the XMO7 orbit will reach an altitude of just 22 miles (35 km) above Ceres. The images returned should be over 9000 times better than what Hubble can capture. This is the final orbit planned:
NASA's Dawn spacecraft is maneuvering to its lowest-ever orbit for a close-up examination of the inner solar system's only dwarf planet.
In early June, Dawn will reach its new, final orbit above Ceres. Soon after, it will begin collecting images and other science data from an unprecedented vantage point. This orbit will be less than 30 miles (50 kilometers) above the surface of Ceres -- 10 times closer than the spacecraft has ever been.
Dawn will collect gamma ray and neutron spectra, which help scientists understand variations in the chemical makeup of Ceres' uppermost layer. That very low orbit also will garner some of Dawn's closest images yet.
The transfer from Dawn's previous orbit to its final one is not as simple as making a lane change. Dawn's operations team worked for months to plot the course for this second extended mission of the veteran spacecraft, which is propelled by an ion engine. Engineers mapped out more than 45,000 possible trajectories before devising a plan that will allow the best science observations.
Previously: Dawn Mission Extended at Ceres
Related: Ceres May Have Had a Global Surface Ocean in the Past
Evidence of a Seasonal Water Cycle and Surface Changes Found on Ceres
(Score: 2) by JoeMerchant on Friday June 01 2018, @12:36PM (8 children)
Meaning: trajectory simulation software calculated more than 45,000 possible paths based on a search-space defined by the engineers.
Unless we still have a room full of black women in Alabama who do this with pencil and paper?
🌻🌻 [google.com]
(Score: 3, Informative) by takyon on Friday June 01 2018, @12:59PM (4 children)
Apparently it's still difficult to make these kinds of calculations (or define the search space):
https://en.wikipedia.org/wiki/Psyche_(spacecraft)#History [wikipedia.org]
Dawn is the first NASA exploratory mission to use ion engines.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by JoeMerchant on Friday June 01 2018, @02:52PM (1 child)
Not belittling the accomplishment (even though it sounds that way...)
The fact that the search space included 45,000 (presumably detailed) course simulations indicates that there is a fair degree of uncertainty (i.e. difficulty) in selecting a course.
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Friday June 01 2018, @07:41PM
You vicious bastard!
(Score: 0) by Anonymous Coward on Friday June 01 2018, @02:52PM (1 child)
What abut Deep Space 1 which was also the first NASA mission to use artificial intelligence?
(Score: 2) by takyon on Saturday June 02 2018, @04:59AM
https://en.wikipedia.org/wiki/Dawn_(spacecraft)#Propulsion_system [wikipedia.org]
Might be due to a definition of "purely exploratory". Since Deep Space 1 was used to test/demo technologies.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Friday June 01 2018, @03:25PM (2 children)
I suspect the 45,000 number is mostly fiction.
But I can believe that the people working on this mission spent a lot of time experimenting by hand to find a trajectory they were happy with.
I am sure computer simulation was used extensively.
(Score: 2) by bob_super on Friday June 01 2018, @07:46PM
44980 trajectories likely ended up in a crash or a loss of orbit...
(Score: 0) by Anonymous Coward on Friday June 01 2018, @10:18PM
No, I suspect that the 45,000 trajectories were calculated via a Monte Carlo analysis (i.e., a statistical analysis) to find the most likely trajectory or trajectories.
And, yes, indeed, computer simulation was used extensively. They do not calculate orbits by hand any more (I think they gave that up 60 years or so ago).