Mass driver - Revision history

Michel Lamontagne at 17:21, 12 October 2022

2022-10-12T17:21:50Z

RichardWSmith: smaller mass drivers.

2022-10-08T11:59:18Z

smaller mass drivers.

Michel Lamontagne at 16:47, 12 March 2021

2021-03-12T16:47:50Z

RichardWSmith: Did some work on heating of mass driver launch. sources are a bunch of google searches.

2021-03-12T03:20:59Z

Did some work on heating of mass driver launch. sources are a bunch of google searches.

RichardWSmith: Did math to find the lengths of mass drivers. Olympus Mons is indeed large enough to place a mass driver on it. Several other edits.

2021-03-12T02:59:32Z

Did math to find the lengths of mass drivers. Olympus Mons is indeed large enough to place a mass driver on it. Several other edits.

RichardWSmith: Suggested 6 gees of acceleration or less for 10 minutes.

2021-03-12T02:26:40Z

Suggested 6 gees of acceleration or less for 10 minutes.

RichardWSmith at 02:22, 12 March 2021

2021-03-12T02:22:36Z

RichardWSmith at 02:21, 12 March 2021

2021-03-12T02:21:28Z

RichardWSmith: Added Pavonus Mons to possible locations. Added link to Sky ramps.

2021-03-12T02:20:42Z

Added Pavonus Mons to possible locations. Added link to Sky ramps.

Jburk at 08:49, 18 December 2018

2018-12-18T08:49:01Z

@@ Line 32: / Line 32: @@
 Since the viability of a mass driver increases with a lowered atmospheric pressure, the location of the mass driver's muzzle should be as high as possible. The top (or rim) of [[Olympus Mons]] (the highest mountain in the [[solar system]]) might be a good choice. It is about 625 km wide and 25 km tall.  It has an air pressure of about 40 Pa at top.<ref name="stanford">[http://www-star.stanford.edu/projects/mgs/tps-public.html Public Access to Standard Temperature-Pressure Profiles] Standard Pressure Profiles measured by MGS Radio Science team at 27 km range from approx 30 to 50 pascals</ref><ref name="stanlate">[http://www-star.stanford.edu/projects/mgs/late.html Late Martian Weather!] ''stanford.edu'' temperature/pressure profiles 1998 to 2005</ref><!-- verifier: assuming 27km elevation, select various datapoints, subtract surface elevation from 27km and read off pressure from graph; errors around ±5% --> (Note that 40 Pa = 0.0004 bar, so this is a high grade vacuum.)
-Olympus Mon also offers a natural ramp.  The mass driver must be almost perfectly straight (there is a slight curve for Coriolis forces caused by the rotation of the planet while launching) so tunnels, cuts and bridges will have to be made.
+Olympus Mons also offers a natural ramp.  The mass driver must be almost perfectly straight (there is a slight curve for Coriolis forces caused by the rotation of the planet while launching) so tunnels, cuts and bridges will have to be made.
 Pavonus Mons is a tall volcano directly on the Equator which could be suitable if equatorial launches are preferred.  It is 375 km wide and 14 km high, so an acceleration of 9 gees for 57 seconds would require a mass driver 143 km long.

← Older revision		Revision as of 11:59, 8 October 2022
Line 14:		Line 14:

	The payload would need to have small rockets to circularize the orbit, or be captured by an orbital catcher.		The payload would need to have small rockets to circularize the orbit, or be captured by an orbital catcher.
		+
		+	Note, that reaching orbital velocity requires a very large and powerful mass driver. But if you wanted to reach (say) ONE HALF orbital velocity, the engineering of the mass driver is much easier and less expensive. A mass driver which thus helps a rocket, would allow single stage to orbit rockets with marvellous mass ratios. So smaller and cheaper mass drivers could be useful for a developing colony.

	== Catching a payload ==		== Catching a payload ==

@@ Line 1: / Line 1: @@
 [[Image:MassDriverConcept.png|thumb|right|300px|The basic concept of a mass driver]]
-The transport from the surface of [[Mars]] to Mars' [[orbit]] and vice versa can be achieved by a '''mass driver''' or '''electromagnetic catapult'''. The idea is to install an electrical linear motor on the surface, pointing towards the desired orbit in an appropriate angle.
+The transport from the surface of [[Mars]] to Mars' [[orbit]] and vice versa can be achieved by a '''mass driver''' or '''electromagnetic catapult'''. The idea is to install an electrical linear motor on the surface, pointing towards the desired orbit in an appropriate angle.  Either a orbital catcher system or a smart payload are required to put the payload into orbit.  Otherwise the payload follows either an elliptical orbit back to the surface and is lost, or must exit Mars' influence at faster than the escape velocity.
-A mass driver is powered [[electricity|electrical]] and requires no chemical fuels. While on [[Earth]] this would not work for lifting people to orbit, the conditions of Mars might allow it. The acceleration of persons is limited to a few g, so the linear motor must be very long for that case.
+A mass driver is powered [[electricity|electrical]] and requires no chemical fuels if a catcher is available, or chemical motors on the payload. While on [[Earth]] this would not work for lifting people to orbit, the conditions of Mars might allow it. The acceleration of persons is limited to a few g, so the linear motor must be very long for that case.
-[[Sky ramps]] are very similar, but they use rockets rather than a mass driver, and only acts as a reusable first stage rather than launching a ship directly into orbit.
+[[Sky ramps]] are very similar, but they use rockets rather than a mass driver, and only act as a reusable first stage rather than launching a ship directly into orbit.
 ==Launching a payload==
-The payload is accelerated along the linear motor. Until it reaches the end of the linear motor it gains enough velocity to get to the desired orbit just by inertia. The velocity must be higher than the [[escape velocity]] because of the [[aerobraking|braking effect]] of the Martian [[atmosphere]].
+The payload is accelerated along the linear motor until it reaches the end of the linear motor and gains enough velocity to get to the desired orbit just by inertia. The velocity must be higher than the [[escape velocity]] because of the [[aerobraking|braking effect]] of the Martian [[atmosphere]].  ''(needs equation and air resistance calculation)''
 Mars' escape velocity is 5,020 m/s.  If you accelerated at 6 gravities, then this would take ~86 seconds to reach orbital velocity.  This would require a mass driver which would be 218 km long.  (This distance is about 1/3 of the of the width of Olympus Mons.  If you wished to use a smaller volcano, then a higher acceleration would be needed.)
-The payload would need to have small rockets to circularize the orbit once on the other side of the planet.
+The payload would need to have small rockets to circularize the orbit, or be captured by an orbital catcher.
 ==Landing a payload==
-Just like launching, the landing of a payload can be done. The trajectory of the payload from outer space or from an orbit to the muzzle of the mass driver must be adjusted with nearly perfect accuracy. When entering the muzzle, the payload has a very high velocity, nearly as high as the escape velocity. The payload is decelerated by the linear motor until it comes to a halt.
+Just like launching, the landing of a payload can be done. The trajectory of the payload from outer space or from an orbit to the muzzle of the mass driver must be adjusted with nearly perfect accuracy. When entering the muzzle, the payload has a very high velocity, nearly as high as the escape velocity. The payload is decelerated by the linear motor until it comes to a halt.  However, again du to orbital mechanics, the launcher outlet cannot be the landing inlet and two mass drivers are required, increasing capital costs significantly.
 ==Possible locations==
@@ Line 25: / Line 30: @@
 Since the viability of a mass driver increases with a lowered atmospheric pressure, the location of the mass driver's muzzle should be as high as possible. The top (or rim) of [[Olympus Mons]] (the highest mountain in the [[solar system]]) might be a good choice. It is about 625 km wide and 25 km tall.  It has an air pressure of about 40 Pa at top.<ref name="stanford">[http://www-star.stanford.edu/projects/mgs/tps-public.html Public Access to Standard Temperature-Pressure Profiles] Standard Pressure Profiles measured by MGS Radio Science team at 27 km range from approx 30 to 50 pascals</ref><ref name="stanlate">[http://www-star.stanford.edu/projects/mgs/late.html Late Martian Weather!] ''stanford.edu'' temperature/pressure profiles 1998 to 2005</ref><!-- verifier: assuming 27km elevation, select various datapoints, subtract surface elevation from 27km and read off pressure from graph; errors around ±5% --> (Note that 40 Pa = 0.0004 bar, so this is a high grade vacuum.)
-Olympus Mon also offers a natural ramp.  The mass driver must be almost perfectly straight (there is a slight curve for coriollis forces caused by the rotation of the planet while launching) so tunnels, cuts and bridges will have to be made.
+Olympus Mon also offers a natural ramp.  The mass driver must be almost perfectly straight (there is a slight curve for Coriolis forces caused by the rotation of the planet while launching) so tunnels, cuts and bridges will have to be made.
 Pavonus Mons is a tall volcano directly on the Equator which could be suitable if equatorial launches are preferred.  It is 375 km wide and 14 km high, so an acceleration of 9 gees for 57 seconds would require a mass driver 143 km long.

@@ Line 23: / Line 23: @@
 [[Image:MassDriverOnOlympusMons.png|thumb|right|300px|Using the shape of Olympus Mons]]
-Since the viability of a mass driver increases with a lowered atmospheric pressure, the location of the mass driver's muzzle should be as high as possible. The top (or rim) of [[Olympus Mons]] (the highest mountain in the [[solar system]]) might be a good choice. It is about 625 km wide and 25 km tall.  It has an air pressure of about 40 Pa at top.<ref name="stanford">[http://www-star.stanford.edu/projects/mgs/tps-public.html Public Access to Standard Temperature-Pressure Profiles] Standard Pressure Profiles measured by MGS Radio Science team at 27 km range from approx 30 to 50 pascals</ref><ref name="stanlate">[http://www-star.stanford.edu/projects/mgs/late.html Late Martian Weather!] ''stanford.edu'' temperature/pressure profiles 1998 to 2005</ref><!-- verifier: assuming 27km elevation, select various datapoints, subtract surface elevation from 27km and read off pressure from graph; errors around ±5% --> It also offers a natural ramp.
+Since the viability of a mass driver increases with a lowered atmospheric pressure, the location of the mass driver's muzzle should be as high as possible. The top (or rim) of [[Olympus Mons]] (the highest mountain in the [[solar system]]) might be a good choice. It is about 625 km wide and 25 km tall.  It has an air pressure of about 40 Pa at top.<ref name="stanford">[http://www-star.stanford.edu/projects/mgs/tps-public.html Public Access to Standard Temperature-Pressure Profiles] Standard Pressure Profiles measured by MGS Radio Science team at 27 km range from approx 30 to 50 pascals</ref><ref name="stanlate">[http://www-star.stanford.edu/projects/mgs/late.html Late Martian Weather!] ''stanford.edu'' temperature/pressure profiles 1998 to 2005</ref><!-- verifier: assuming 27km elevation, select various datapoints, subtract surface elevation from 27km and read off pressure from graph; errors around ±5% --> (Note that 40 Pa = 0.0004 bar, so this is a high grade vacuum.)
 Pavonus Mons is a tall volcano directly on the Equator which could be suitable if equatorial launches are preferred.  It is 375 km wide and 14 km high, so an acceleration of 9 gees for 57 seconds would require a mass driver 143 km long.
@@ Line 29: / Line 31: @@
 ==Open issues==
-*How strong is the effect of air friction at an altitude of the Olympus Mons top? Does it have a damaging effect on a steel hull?
+*How strong is the effect of air friction at an altitude of the Olympus Mons top? Does it have a damaging effect on a steel hull?  This is mach 14.5 which is about 1/5 of the atmospheric heating caused by reentry on Earth IF the air pressure was equal.  However, maximum heating in Earth reentry is at about 100km attitude, and 40 Pa is 1/4 this. So steel should be able to handle this amount of heating, especially since it would rapidly decrease as the ship went higher.  The friction WOULD be enough that the minimum speed of 5,020 m/s would not reach orbit.  Either the mass driver must give extra speed to make up for friction, or the payload would want a small rocket to over come the velocity lost, and to circularize the orbit once high enough.
-*Normal people can withstand 9 gravities (gees) of acceleration for about 1 minute.  6 gees of acceleration can be withstood for 10+ minutes.
+*Normal people can withstand 9 gravities (gees) of acceleration for about 1 minute.  6 gees of acceleration can be withstood for around 10 minutes.
 ==references==

@@ Line 5: / Line 5: @@
 A mass driver is powered [[electricity|electrical]] and requires no chemical fuels. While on [[Earth]] this would not work for lifting people to orbit, the conditions of Mars might allow it. The acceleration of persons is limited to a few g, so the linear motor must be very long for that case.
-[[Sky ramps]] are very similar, but they use rockets rather than a mass driver, and only acts as a reusable first stage rather than launching directly into orbit.
+[[Sky ramps]] are very similar, but they use rockets rather than a mass driver, and only acts as a reusable first stage rather than launching a ship directly into orbit.
 ==Launching a payload==
 The payload is accelerated along the linear motor. Until it reaches the end of the linear motor it gains enough velocity to get to the desired orbit just by inertia. The velocity must be higher than the [[escape velocity]] because of the [[aerobraking|braking effect]] of the Martian [[atmosphere]].
 ==Landing a payload==
@@ Line 19: / Line 23: @@
 [[Image:MassDriverOnOlympusMons.png|thumb|right|300px|Using the shape of Olympus Mons]]
-Since the viability of a mass driver increases with a lowered atmospheric pressure, the location of the mass driver's muzzle should be as high as possible. The top (or rim) of [[Olympus Mons]] (the highest mountain in the [[solar system]]) might be a good choice with only about 40 Pa.<ref name="stanford">[http://www-star.stanford.edu/projects/mgs/tps-public.html Public Access to Standard Temperature-Pressure Profiles] Standard Pressure Profiles measured by MGS Radio Science team at 27 km range from approx 30 to 50 pascals</ref><ref name="stanlate">[http://www-star.stanford.edu/projects/mgs/late.html Late Martian Weather!] ''stanford.edu'' temperature/pressure profiles 1998 to 2005</ref><!-- verifier: assuming 27km elevation, select various datapoints, subtract surface elevation from 27km and read off pressure from graph; errors around ±5% --> It also offers a natural ramp.
+Since the viability of a mass driver increases with a lowered atmospheric pressure, the location of the mass driver's muzzle should be as high as possible. The top (or rim) of [[Olympus Mons]] (the highest mountain in the [[solar system]]) might be a good choice. It is about 625 km wide and 25 km tall.  It has an air pressure of about 40 Pa at top.<ref name="stanford">[http://www-star.stanford.edu/projects/mgs/tps-public.html Public Access to Standard Temperature-Pressure Profiles] Standard Pressure Profiles measured by MGS Radio Science team at 27 km range from approx 30 to 50 pascals</ref><ref name="stanlate">[http://www-star.stanford.edu/projects/mgs/late.html Late Martian Weather!] ''stanford.edu'' temperature/pressure profiles 1998 to 2005</ref><!-- verifier: assuming 27km elevation, select various datapoints, subtract surface elevation from 27km and read off pressure from graph; errors around ±5% --> It also offers a natural ramp.
-Pavonus Mons is a tall volcano directly on the Equator which would be suitable.
+Pavonus Mons is a tall volcano directly on the Equator which could be suitable if equatorial launches are preferred.  It is 375 km wide and 14 km high, so an acceleration of 9 gees for 57 seconds would require a mass driver 143 km long.
 ==Open issues==

@@ Line 4: / Line 4: @@
 A mass driver is powered [[electricity|electrical]] and requires no chemical fuels. While on [[Earth]] this would not work for lifting people to orbit, the conditions of Mars might allow it. The acceleration of persons is limited to a few g, so the linear motor must be very long for that case.
 ==Launching a payload==
@@ Line 18: / Line 20: @@
 Since the viability of a mass driver increases with a lowered atmospheric pressure, the location of the mass driver's muzzle should be as high as possible. The top (or rim) of [[Olympus Mons]] (the highest mountain in the [[solar system]]) might be a good choice with only about 40 Pa.<ref name="stanford">[http://www-star.stanford.edu/projects/mgs/tps-public.html Public Access to Standard Temperature-Pressure Profiles] Standard Pressure Profiles measured by MGS Radio Science team at 27 km range from approx 30 to 50 pascals</ref><ref name="stanlate">[http://www-star.stanford.edu/projects/mgs/late.html Late Martian Weather!] ''stanford.edu'' temperature/pressure profiles 1998 to 2005</ref><!-- verifier: assuming 27km elevation, select various datapoints, subtract surface elevation from 27km and read off pressure from graph; errors around ±5% --> It also offers a natural ramp.
 ==Open issues==
@@ Line 25: / Line 29: @@
 ==references==
-<references/>
+<references />
 [[Category: Settlement Transport Systems]]

← Older revision		Revision as of 08:49, 18 December 2018
Line 27:		Line 27:
	<references/>		<references/>

−	[[Category: ~~Hi-tech]]~~	+	[[Category: Settlement Transport Systems]]
−	~~[[Category:~~ Transport]]