Persephone Pluto Orbiter |
Persephone Pluto Orbiter |
Sep 2 2020, 08:41 PM
Post
#1
|
|
Senior Member Group: Members Posts: 1585 Joined: 14-October 05 From: Vermont Member No.: 530 |
From fall 2020 OPAG https://www.lpi.usra.edu/opag/meetings/opag2020fall/
Persephone: https://www.lpi.usra.edu/opag/meetings/opag...Howett_6005.pdf There is talk of extended missions out to 2079. Building cathedrals for our grandkids here... |
|
|
Sep 8 2020, 10:04 PM
Post
#2
|
|
Member Group: Members Posts: 291 Joined: 29-December 05 From: Ottawa, ON Member No.: 624 |
About that 27 years trajectory . . . That puts a lot of lifetimes to the wayside when it arrives. With a launch ten years from now, new and better rockets may be available, such as StaceX's Starship should it deliver to expectations, or even Blue Origin's New Armstrong (should it be ever come to pass). If launch costs are reduced by the new (reusable) space rockets along with the massive payloads they are advertising, you could conceivably launch it really fast with loaded with tons of fuel and jam on the breaks hard. That would cut trajectory significantly. Based on the cost per flight, SLS may not even be around by then.
|
|
|
Sep 8 2020, 10:28 PM
Post
#3
|
|
Senior Member Group: Members Posts: 2090 Joined: 13-February 10 From: Ontario Member No.: 5221 |
If launch costs are reduced by the new (reusable) space rockets along with the massive payloads they are advertising, you could conceivably launch it really fast with loaded with tons of fuel and jam on the breaks hard. That would cut trajectory significantly. Based on the cost per flight, SLS may not even be around by then. The trouble is, what sort of fuel will last long enough on the journey to still be available for a Pluto orbit insertion? Cryogenic fuels like liquid hydrogen tend to evaporate, don't they? Would solids be better (like for the Mars Ascent Vehicle being planned?) |
|
|
Sep 9 2020, 04:16 PM
Post
#4
|
|
Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
The trouble is, what sort of fuel will last long enough on the journey to still be available for a Pluto orbit insertion? Cryogenic fuels like liquid hydrogen tend to evaporate, don't they? Would solids be better (like for the Mars Ascent Vehicle being planned?) IIRC, ESA has been looking at hydrogen peroxide monopropellant for attitude control thrusters; and New Shepherd used hydrogen peroxide and kerosene for their oxidizer and fuel. So some propellant combinations could do double duty. With RTG supplying electric , more likely an ion drive for long term course correction, and reaction wheels for fine attitude control. Would need a battery to store power for fast slewing at encounter, so you might still need thrusters as a backup if the reaction wheels failed. IIRC some papers found that eddy currents from solar storm could cause arcing across the bearings that chews them up and causes failure; but until somebody perfects and proves ceramic bearings work on reaction wheels, you'll have redundant systems. |
|
|
Sep 9 2020, 04:39 PM
Post
#5
|
|
Senior Member Group: Members Posts: 1585 Joined: 14-October 05 From: Vermont Member No.: 530 |
I wanted to see if you recalled correctly, because I myself could not recollect this:
https://hackaday.com/2018/09/11/do-space-pr...-space-weather/ |
|
|
Sep 9 2020, 04:54 PM
Post
#6
|
|
Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
I wanted to see if you recalled correctly, because I myself could not recollect this: https://hackaday.com/2018/09/11/do-space-pr...-space-weather/ In 2013, they figured launch shaking or radiation. QUOTE (How Kepler’s Pointing System Might Have Failed) Launch damage or radiation are most likely causes, says CEO of reaction wheel company https://spectrum.ieee.org/tech-talk/aerospa...ght-have-failed By September 2017 they had research and published a paper QUOTE CONCLUSIONS The anomalous friction increases and failures of ITHACO RWAs on the FUSE, Kepler and other spacecraft are the result of the space environment, and likely space charging. This is based on strong statistical correlation of events with geomagnetic storms, and simultaneity of events on different RWAs during geomagnetic storms. Duplication of friction events in the laboratory by applying small voltages across the rotating bearings supports this conclusion. Finally all metal ball bearing control wheels for satellites may be similarly impacted as discussed, when operated in these adverse space weather conditions http://esmats.eu/esmatspapers/pastpapers/p...2017/bialke.pdf About a year later that led to a Youtube episode on reaction wheels that has about 700,000 views. QUOTE (Scientists May Have Figured Out Why So Many Spacecraft Were Failing" [url="https://www.youtube.com/watch?v=KibT-PEMHUU&feature=emb_imp_woyt") Time to put up some cubesats for small scale testing of different types of bearings. QUOTE (Journal of Spacecraft and Rockets 55(1):1-6) Hard Disk Drive Based Reaction Wheels for CubeSat Attitude Control
August 2017 DOI: 10.2514/1.A33866 https://www.researchgate.net/publication/31...de_Control#read |
|
|
Lo-Fi Version | Time is now: 5th June 2024 - 06:52 PM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |