Author Topic: HSF Missions to Mercury  (Read 1852 times)

Offline CNYMike

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HSF Missions to Mercury
« on: 09/12/2014 05:56 am »
I'm beginning to wonder if Mercury should be added to the list of potential destinations for HSF.

I found a web site which shows the launch windows for Hohmann transfer orbit between pairs of planets for Jupiter and the inner planets.  I wondered of a Venus orbiter would be a good precursor to Mars because the mission might be shorter.  Wrong: The Spacecraft would be in orbit of Venus for a year before the trip home.  So much for that idea.

Then on a whim I looked at Mercury.  I was shocked to see that three launch windows open every year -- not one every three years but three every year!  With only a two month stay required before the trip back.

So, for instance, if, hypotheitcally, a mission leaves Earth on March 8, 2015, it arrives at Mercury on June 22.  And if the crew takes the first opportunity to come home, they woould leave on August 28 and arrive on December 12.  To Mercury and back in nine months!

Of course, there are disadvantages: Mercury is closest to the Sun and there would be radiation hazards.  I wouldn't be surprised if there were an issue of delta V.

But if you can protect against the radiation at Mercury, you can do it at Mars.  If you can handle the delta V for Mercury, you can do Mars.  And Mercury doesn't have an atmosphere, so a lander could just use rockets.  Whereas at Mars NASA is grappling with slowing something big through the atmosphere.

If we want a manned mission to a known, challenging destination that is short compared to Mars, Mercury should at least deserve a little consideration.
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Offline Lampyridae

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Re: HSF Missions to Mercury
« Reply #1 on: 09/12/2014 06:18 am »
Circular orbit to circular orbit, for Mercury it's 13 km/s as opposed to 5 km/s for Mars...

Offline Helodriver

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Re: HSF Missions to Mercury
« Reply #2 on: 09/12/2014 06:27 am »
I'd think the thermal radiation would be the by far greatest concern (650% of the intensity on Earth) , followed by the delta V to leave.  While there may be ice at the poles, the chance of volatiles anywhere else for ISRU is very low. Very long days and nights with temperature extremes from -275 to +840 F make this exceptionally challenging terrain to design surface hardware for. The Messenger orbiter has to do constant attitudinal gymnastics to keep its sunshade pointed correctly to prevent the vehicle from being cooked on orbit, so even a non landing HSF mission would be no piece of cake.
« Last Edit: 09/12/2014 06:29 am by Helodriver »

Offline Vultur

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Re: HSF Missions to Mercury
« Reply #3 on: 09/15/2014 12:52 am »
I'm beginning to wonder if Mercury should be added to the list of potential destinations for HSF.

Mercury and Venus - definitely the underappreciated planets.
Quote
Of course, there are disadvantages: Mercury is closest to the Sun and there would be radiation hazards.  I wouldn't be surprised if there were an issue of delta V.

Delta V is much more IIRC. And I think we (=humanity) will end up just accepting the GCR and zero gravity risks, which are entirely reasonable compared to e.g early 20th century Antarctic exploration, so mission duration won't be showstopper.

Quote
And Mercury doesn't have an atmosphere, so a lander could just use rockets.  Whereas at Mars NASA is grappling with slowing something big through the atmosphere.

Using the atmosphere to descend saves quite a bit of delta-V in braking.

HSF to Mercury would be great someday, but it's definitely a longer-term destination than Mars (or Moon or NEOs).

Offline KelvinZero

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Re: HSF Missions to Mercury
« Reply #4 on: 09/15/2014 01:02 am »
Definitely a longer term thing.

Like the moon, it has ice which could be very useful and proves there are locations that are not regularly baked.
http://nssdc.gsfc.nasa.gov/planetary/ice/ice_mercury.html

Offline Ben the Space Brit

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Re: HSF Missions to Mercury
« Reply #5 on: 09/15/2014 01:32 pm »
There is a very interesting theory that Mercury may have once been a co-orbital or even a satellite of Venus (Mercury's greater size and much higher density relative to Venus than Luna to Earth would have made the hypothetical Venus/Mercury system virtually a double planet orbiting a barycentre in open space). A sample-return from both worlds might confirm or deny this theory by enabling the analysis the isotopes in the two planets' crusts to see if they might have come from the same part of the proto-solar nebula.

This wouldn't require an HSF visit but this, Venus's many mysteries and Mercury's polar ice could be turned into justification of them being included in an inner solar system 'grand tour'. Being capable of building a crew lander and EVA suits capable of tolerating the conditions on Venus's and Mercury's surfaces would certainly open up all the terrestrial/ice bodies in the Solar System to crewed exploration to a certain degree.

Just a thought on the subject.


[edit]
Fix'd typos
« Last Edit: 09/15/2014 02:23 pm by Ben the Space Brit »
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Offline Silmfeanor

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Re: HSF Missions to Mercury
« Reply #6 on: 09/15/2014 02:01 pm »
A sample-return from both worlds might confirm or deny this theory by enabling the analysis the isotopes in the two planets' crusts to see if they might have come from the same part of the proto-solar nebula.

That'll be in the very far future. Just thinking about the design of a venusian sample return mission...brrr. I wonder what the first rocket looks like that lifts off from venus - The atmosphere is a beast.

Perhaps this thread belongs in advanced concepts  :P

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