• We hope all of you have a great holiday season and an incredible New Year. Thanks so much for being part of the Space community!

Limits of ballistic tourism?

Status
Not open for further replies.
J

JonClarke

Guest
Motivations for space tourism include: the experience of being on the edge, participating in a high tech venture doing something few other people have done, experiencing zero G, viewing the earth from extreme altitude, and vicariously experiencing what professional astronauts experience. The longer the flight the more reward for the passenger, whatever their motivation. By contrast the shortest orbital missions would give a 90-minute space flight experience of which only 3 minutes is in space at zero G as opposed to Spaceship One which gives three minutes in space at zero G in a 80 minute flight.<br /><br />Hence the common assumption for the next phase of space tourism is to move from ballistic to orbital flights. Major and costly hurdles need to be surmounted by any private company wishing to do this. These include the need to boost to 8 km/s, high velocity reentry requiring thermal shielding, high G loadings on spacecraft and occupants, global tracking and communications.<br /><br />An alternative to orbital flights are higher suborbital ones. The higher they go the longer the experience for the customer. Commensurate with that is the fact that the higher the flight the higher the velocity and more stringent the entry requirements. Eventually the velocity is equivalent to what is required for an orbital mission and there is no difference to the thermal and acceleration loads. But before this point has been reached some quite spectacular altitudes can be achieved. A quick survey of the literature indicates that ballistic missions as high as 1500 km have been flown using the Russian Vertikal sounding rocket. This is higher than any astronaut has flown (even Gemini 11) except those going to the moon. The view for paying passengers would be spectacular from this altitude.<br /><br />So the questions I have for those for familiar with the calculations are these:<br /><br />1) What is the highest ballistic flight that can be flown before reaching the propulsive requ <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
H

hardsf

Guest
If you fly straight up, eventually you'll reach an altitude where the orbital speed will be equal to the earth's rotational speed at the place you took off from. Depending on where you started, this is at about 100.000 km. It would take less energy to get to orbit, I think the cut-off is about 7000 km altitude, but IANARS (I am not a rocket scientist).
 
C

CalliArcale

Guest
<blockquote><font class="small">In reply to:</font><hr /><p>Hence the common assumption for the next phase of space tourism is to move from ballistic to orbital flights.<p><hr /></p></p></blockquote><br /><br />Of course, there is one other possible outcome -- faster intercontinental travel. SpaceShipOne lands where it takes off. If you can get the energy and trajectory right, you can get to Europe very fast on a ballistic trajectory. (That is, after all, the idea behind an ICBM.) Then again, that market seems to be fairly soft right now as it is no longer able to support SST using conventional aircraft like the Concorde. But ya never know. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
M

mrmorris

Guest
<font color="yellow">"...IANARS (I am not a rocket scientist). "</font><br /><br />IYUAAOATIEIANUIAWWTPOUTAITFP <br /><br />(If You Use An Acronym Once And Then Immediately Explain It And Never Use It Again -- What Was The Point Of Using The Acronym In The First Place?)
 
N

najab

Guest
><i>IANARS (I am not a rocket scientist).</i><p>Also, TNSTAAFL (there's no such thing as a free lunch) - I didn't do the math yet, but I'm 99% sure that the energy required to get to 100,000km is more than the energy required to achieve LEO - if it wasn't they would do it that way all the time!</p>
 
C

CalliArcale

Guest
BIF?<br /><br />(Because It's Fun?)<br /><br /><img src="/images/icons/tongue.gif" /><br /><br />My favorite acronym is "TLA" -- Three Letter Acronym. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
N

nexium

Guest
Hi jon: Most of what you typed is likely correct. The answers to 1,2,4 and 5 depend at least a little on the acceleration and duration of each rocket stage and the coast time between stages.<br /> Approximently zero g occurs at any altitude (over about 100 KM) during the coast seconds. <br /> The radiation exposure of the passengers is much higher at 1500 km than at 300 km, (Van Alllen belt) so it may not be prudent to go much higher than 300 KM until light weight weight shielding has been developed. Neil
 
P

propforce

Guest
OK (is that an acronym?) I give up...<br /><br />What is TLA ? <div class="Discussion_UserSignature"> </div>
 
B

bobvanx

Guest
<font color="yellow">faster intercontinental travel</font><br /><br />They should ferry WK/SS1 over to White Sands, and do a ballistic back to Mojave. Or maybe from Denver to Mojave. Show that they make the trip faster than a jetliner. Smart folks like us get what a ballistic trajectory is, but if you could report to the GP (general public) that the flight lasted 20 minutes and covered 400-700 miles, they'd have a reaction to that.<br /><br />'course, the shuttlecock config is designed for straight down, so TTT (there's that, than).
 
P

propforce

Guest
<i>"... Two Letter Acronym = TLA..." </i><br /><br />Smacking myself on the forehead .....<br /> <div class="Discussion_UserSignature"> </div>
 
J

JonClarke

Guest
Hi Neil<br /><br />I understand that zero gravity occurs the moment an objects enters free fall. So it essentially happens on a ballistically trajectory the moment engine cut off occurs. Free fall towers and shafts are used for microgravity experiments for example, With significant atmospheric density the effect of air resistance comes to to play quite soon, causing terminal velocity, at which point the object is no longer in free fall. The significance of the rather arbitary 100 km figure is that (a) air resistance is low enough to allow a satellite to orbit for some time and (b) its a nice round number.<br /><br />I thought about the van Allen belts but a few minutes in them on a ballistic trajectory will not cause enough harm to be an issue, any more than it was for the Apollo astronauts going to the moon or those on Gemini 11.<br /><br />Cheers<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
B

bobvanx

Guest
>van Allen belts... on a ballistic trajectory will not cause enough harm to be an issue<br /><br />Yeh, just turn off the cabin lights and tell the passengers to enjoy their personal light show on their retinas.
 
J

JonClarke

Guest
I thought it was cosmic rays not VAB particles that caused retinal flashes.<br /><br />By the look of it nobody knows the answer to my question. So i have another one. Does the advant of commerical ballistic travel also open the way for commerical ballistic parcel Certain high cost products, such as short-lived isotopes might well be worth the cost.<br /><br />Cheers<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
S

spayss

Guest
There's a huge barrier. It's called the environment. How many new toys do we need spewing more crap into the atmosphere. Especially to keep the wealthy amused with a greater high? <br /><br /> Tourism, hopefully, will 'not fly'. Perhaps these flights can replace conventional flights for an environmental benefit but that seems a remote possibility.
 
K

kmarinas86

Guest
airplanes used to (and still do) keep the wealthy amused with a great height. there can be other uses besides tourism for these ballistic suborbital space vehicles. they would make great use for low-cost zero-gravity missions that only need a few minutes in space. microsatellites are another possibility. also... cars, lawn mowers, and restaurants are polluting, but their emissions can be improved or even elimanated. although rockets are defined by their propulsive "emissions," spacecrafts of the future are not limited to these charateristics.
 
J

JonClarke

Guest
Compared with air pollution from conventional air travel or vehicles or coal fired power stations, that which would result from space tourism is a drop in the ocean. There are air pollution issues bigger by several orders of magnitude.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
S

spayss

Guest
Jon,<br /><br />We don't need to add more pollution because, as you say, the situation is already bad . That's a reason to NOT add more unnecessary crap to the atmosphere.<br /><br /> The Concord would not have flown if developed 5 years later. It was a drop in the bucket but society is getting leary of all these drop in the buckets adding up to a full pail. <br /><br /> Technology has consequences. Sometimes positive. Hopefully the private space missions will contribute to less use of resources and less pollution. But, just maybe.
 
N

najab

Guest
><i> The Concord would not have flown if developed 5 years later. It was a drop in the bucket...</i><p>The Concord<b><u>e</u></b> would still have flown. Contrary to the propaganada put out by the US DOT, it was not significantly more damaging to the environment than a regular commercial transport. People saw them on takeoff and thought "Oh my God, look at all that smoke!", but that was because the engines were in full reheat. Once it got to cruising altitude and speed and the engines were put in high bypass mode, it was actually <b>more</b> fuel efficient than a Boeing 747 - the majority of the 'thrust' was produced by the airflow around the aircraft.</p>
 
J

JonClarke

Guest
Spayss<br /><br />Let's look at this logically.<br /><br />Yes, the less pollution we put into the atmosphere the better. Is stopping space tourism going to have a significant or even detectable impact? No.<br /><br />How much fuel is going to be burned by a thousand flights a year of space ship one compared to a single trans Pacific flight of a 747? Are you going argue against international air travel?<br /><br />Conversely what is the cost of not developing space tourism? This is the only road that foreseeable at present that offers the slightest chance of cheap, reliable access for large numbers of people to go into space. It has the pntential to lead to more cost effective research and commerce in earth orbit and better transport for high value perishables, such as medical isotopes. Are you arguing against further development of space commerce?<br /><br />Rather than wanting to stop space tourism and its benefits in the interests of better air quality it would be better to push for stripping of C02 from LNG production and reinjecting it into the ground, more fuel efficient cars, less use of cars, more efficient coal-fired power stations, development of alternatives forms of electricity generation (including nuclear where appropriate). How about doing something personally - get a more efficient car, walk and ride a bike more, put on a jacket instead of turning up the heating?<br /><br />take care<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
B

bobvanx

Guest
Jon,<br /><br />be nice. You can't know whether or not Spayss has low-flow shower heads, flushes only when the bowl is full, drives a bio-diesel car, has only compact flourescents, or maybe lives in a PV powered home.<br /><br />Unless you two are neighbors ..?
 
B

bobvanx

Guest
<font color="yellow"> military applications of an SS2 </font><br /><br />The ultimate first/fast strike vehicle would have been Rotary's Roton. It carried less fuel than a big transport, had the ability to get anywhere in the world in about an hour, would have come in at supersonic speeds, had enough cross-range capability to compensate for countermeasures, and didn't require an airfield to land.<br /><br />It had the payload capacity to heft about a dozen troops and their gear.<br /><br />So the mission a squad of those could have flown would be to anywhere that a few dozen troops needed to drop into a zone and secure it ahead of a occupying force.<br /><br />There is some question that the rotors would have provided enough stability during re-entry. And clearly the Roton would stay in place at the landing site until its infrastructure got set up to recover it.<br /><br />But it's a great way to deliver a surgical strike team without having bases everywhere.
 
N

najab

Guest
True, but even that wasn't the final nail in the coffin.<p>Rolls-Royce had started development on the Olympus 610-25 engine which, in the Concorde 'B' model, would have removed the need for reheat on takeoff and also increased fuel efficiency by about 3% during supersonic cruise. This would have allowed trans-Pacific operation (for example Los Angles to Tokyo with one stop in Hawaii) which is where the speed would really have paid off.<p>It was the cancellation of the 'B' model that sealed the bird's fate. It wasn't OPEC that did them in, it was Airbus.</p></p>
 
Status
Not open for further replies.

ASK THE COMMUNITY

TRENDING THREADS