Does it take more energy to get to Venus or to Mars? The 2019 Stack Overflow Developer Survey Results Are InEnergy consumption for travelling to the Moon vs. to MarsCan we get energy from the motion of orbiting bodies?Minimum Delta V to a staging area in cislunar space for a vertical space gunHow large a body could a probe with ion engines land on and launch from?Why has the Earth's motion carried it out of view of Pioneer 11's antenna?How much delta v does it take to get to the Sun-Earth Lagrange 3 point?What precisely is downrange distance - how is it defined mathematically?Parallel orbits around the Earth - effectively?The Martian: Does it really take a supercomputer to calculate spaceflight maneuvers?How can I calculate the delta-v correctly, this way does not seem to be correct?
Is an up-to-date browser secure on an out-of-date OS?
How to deal with fear of taking dependencies
Output the Arecibo Message
Walkie-talkie and its origin
How long do I have to send my income tax payment to the IRS?
Geography at the pixel level
Spanish for "widget"
Can a zener diode with a higher power dissipation be used in place of the original one in an audio amplifier?
How to install public key in host server
Pristine Bit Checking
How is radar separation assured between primary and secondary targets?
Is there a general name for the setup in which payoffs are not known exactly but players try to influence each other's perception of the payoffs?
How can I fix this gap between bookcases I made?
Time travel alters history but people keep saying nothing's changed
Adding labels to a table: columns and rows
Return to UK after being refused entry years previously
How can I make payments on the Internet without leaving a money trail?
How was Skylab's orbit inclination chosen?
Not able to paste multiple components
Patience, young "Padovan"
Should I use my personal e-mail address, or my workplace one, when registering to external websites for work purposes?
Why is the maximum length of OpenWrt’s root password 8 characters?
Does duplicating a spell with Wish count as casting that spell?
What would happen to a Neanderthal today?
Does it take more energy to get to Venus or to Mars?
The 2019 Stack Overflow Developer Survey Results Are InEnergy consumption for travelling to the Moon vs. to MarsCan we get energy from the motion of orbiting bodies?Minimum Delta V to a staging area in cislunar space for a vertical space gunHow large a body could a probe with ion engines land on and launch from?Why has the Earth's motion carried it out of view of Pioneer 11's antenna?How much delta v does it take to get to the Sun-Earth Lagrange 3 point?What precisely is downrange distance - how is it defined mathematically?Parallel orbits around the Earth - effectively?The Martian: Does it really take a supercomputer to calculate spaceflight maneuvers?How can I calculate the delta-v correctly, this way does not seem to be correct?
$begingroup$
Let's assume we use the ideal positions of those planets relative to Earth for launch. And let's assume the spacecraft is launched from the same place on Earth. Also let's assume the goal is to get the same mass of payload to those planets, meaning the launch vehicle could be different, depending on the energy requirements.
"Getting to" could possibly be a bit imprecise, so let's define it as meaning directly impacting the surface with the spacecraft.
Alternatively, does anything change if "getting to" means getting into orbit around those planets?
orbital-mechanics delta-v energy
asked Mar 28 at 9:41
stackzebrastackzebra
28816
$endgroup$
add a comment |
$begingroup$
Let's assume we use the ideal positions of those planets relative to Earth for launch. And let's assume the spacecraft is launched from the same place on Earth. Also let's assume the goal is to get the same mass of payload to those planets, meaning the launch vehicle could be different, depending on the energy requirements.
"Getting to" could possibly be a bit imprecise, so let's define it as meaning directly impacting the surface with the spacecraft.
Alternatively, does anything change if "getting to" means getting into orbit around those planets?
orbital-mechanics delta-v energy
asked Mar 28 at 9:41
stackzebrastackzebra
28816
$endgroup$
$begingroup$
Getting there... slowing down not included... god speed ye brave souls
$endgroup$
– Mikey Mouse
Mar 29 at 10:20
add a comment |
$begingroup$
Let's assume we use the ideal positions of those planets relative to Earth for launch. And let's assume the spacecraft is launched from the same place on Earth. Also let's assume the goal is to get the same mass of payload to those planets, meaning the launch vehicle could be different, depending on the energy requirements.
"Getting to" could possibly be a bit imprecise, so let's define it as meaning directly impacting the surface with the spacecraft.
Alternatively, does anything change if "getting to" means getting into orbit around those planets?
orbital-mechanics delta-v energy
asked Mar 28 at 9:41
stackzebrastackzebra
28816
$endgroup$
Let's assume we use the ideal positions of those planets relative to Earth for launch. And let's assume the spacecraft is launched from the same place on Earth. Also let's assume the goal is to get the same mass of payload to those planets, meaning the launch vehicle could be different, depending on the energy requirements.
"Getting to" could possibly be a bit imprecise, so let's define it as meaning directly impacting the surface with the spacecraft.
Alternatively, does anything change if "getting to" means getting into orbit around those planets?
orbital-mechanics delta-v energy
orbital-mechanics delta-v energy
asked Mar 28 at 9:41
stackzebrastackzebra
28816
asked Mar 28 at 9:41
stackzebrastackzebra
28816
asked Mar 28 at 9:41
stackzebrastackzebra
28816
asked Mar 28 at 9:41
stackzebrastackzebra
28816
asked Mar 28 at 9:41
stackzebrastackzebra
28816
28816
$begingroup$
Getting there... slowing down not included... god speed ye brave souls
$endgroup$
– Mikey Mouse
Mar 29 at 10:20
add a comment |
$begingroup$
Getting there... slowing down not included... god speed ye brave souls
$endgroup$
– Mikey Mouse
Mar 29 at 10:20
$begingroup$
Getting there... slowing down not included... god speed ye brave souls
$endgroup$
– Mikey Mouse
Mar 29 at 10:20
$begingroup$
Getting there... slowing down not included... god speed ye brave souls
$endgroup$
– Mikey Mouse
Mar 29 at 10:20
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
To flyby or impact Venus varies from 3.45 to 3.6 km/s from LEO for the optimal time every 19 months. Mars varies from 3.55 to 3.9 km/s for the optimal time every 26 months. So on average, getting to Venus is a little less energy than getting Mars. But not by much. It could even be a tiny bit more in some years.
If you also want to get barely into orbit propulsively, the ranges are 4 to 4.7 km/s for Venus and 4.25 to 7 km/s for Mars.
Mars is more variable than Venus due to its much larger solar orbit eccentricity (0.09 vs. 0.007).
At either planet, you can aerobrake down to the desired orbit. Aerobraking has been demonstrated at both. Or you can aerocapture directly, with just the flyby costs above. Aerocapture has never been demonstrated, but there are no hurdles that would prevent its use in a mission, other than developing an adequate heatshield for Venus (much higher entry velocity). However you incur the substantial mass penalty of the aeroshell, a cruise stage that is discarded before entry, and the structure and mechanisms to discard the aeroshell and deploy the enclosed spacecraft. Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months. (Aerocapture is mission enabling at Uranus, Neptune, and Titan.)
answered Mar 28 at 13:28
Mark AdlerMark Adler
50.8k3130215
$endgroup$
1
$begingroup$
"Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months." Did you mean either? This sentence seems contradictory to me as written.
$endgroup$
– TemporalWolf
Mar 28 at 18:32
5
$begingroup$
The sentence is perfectly grammatical. Neither body is worth aerocapture if you can afford the time to aerobrake instead. @TemporalWolf
$endgroup$
– Nij
Mar 28 at 18:40
1
$begingroup$
@Nij It seems to preclude doing both, which seems strange as I would expect a mission that aerocaptures to aerobrake as well.
$endgroup$
– TemporalWolf
Mar 28 at 19:15
1
$begingroup$
It's inconsistent with NASA publications concerning the feasibility of single pass aerocapture around Venus, which (on page 8 table 4) shows almost double the delivered mass for an aerocapture system to Venus versus a propulsive capture + aerobraking. Venus capture dV is around 1/10th the dV necessary for a LVO aerocapture, which would require even less of a aeroshield. While it's likely to be worth just going straight for the orbit you want, you could save substantial additional mass by combining the two.
$endgroup$
– TemporalWolf
Mar 28 at 21:39
2
$begingroup$
@TemporalWolf (& Mark Adler, too) Unless you're supremely confident of your aerocapture system's ability to have the exit velocity right where you want it, you probably wouldn't try to aerocapture directly into LVO, since there'd be little margin between the required ∆V and the ∆V that would result in complete entry. 24-hr, 12-hr, even 6-hr orbits would be fine. But for LVO I think you'd aerocapture into a looser orbit, then aerobrake down to LVO.
$endgroup$
– Tom Spilker
Mar 29 at 2:51
|
show 8 more comments
$begingroup$
The second table here essentially answers your question. Venus transfer from Low Earth Orbit is 3.5 km/s, Mars transfer is 3.6.
This will allow you to impact either body (on Venus you will need to make sure your vehicle is tough enough to actually impact, rather than dissolving in the atmosphere, but that's not really the point).
In either case, you can enter orbit for negligible extra energy, but some risk, by aerocapture. Basically you graze the upper atmosphere, losing just enough velocity relative to the planet to enter a long elliptical orbit. At the highest point of that orbit you make a very small boost to raise the lowest point of the orbit to graze the atmosphere even more gently, and then repeated encounters will lower the high point of the orbit. When it's where you want it, you make a further small correction to miss the atmosphere entirely and you are there.
answered Mar 28 at 12:14
Steve LintonSteve Linton
9,40112551
$endgroup$
2
$begingroup$
Do you perhaps know if any actual spacecraft sent to Venus used aerocapture to get into orbit? Edit: I see Wikipedia saying that no.
$endgroup$
– stackzebra
Mar 28 at 12:47
1
$begingroup$
@stackzebra you have a point. On the other hand not that many probes have been sent to orbit Venus at all. Magellan used aerobraking to adjust its orbit.
$endgroup$
– Steve Linton
Mar 28 at 12:53
1
$begingroup$
@stackzebra: Not to get into orbit. Dual-stage atmospheric braking (dive-emerge-dive-land) has been used by "Venus" program landers. And, contrary to the above statement by Steve Linton, there were quite a few orbiters that orbited Venus as part of that program. These orbiters did not use aerocapture though.
$endgroup$
– AnT
Mar 28 at 16:17
$begingroup$
@AnT: Depends on what you understand by "not that many". I count 8: en.wikipedia.org/wiki/List_of_missions_to_Venus vs 14 for Mars: en.wikipedia.org/wiki/List_of_Mars_orbiters
$endgroup$
– jamesqf
Mar 28 at 16:40
add a comment |
Your Answer
StackExchange.ifUsing("editor", function ()
return StackExchange.using("mathjaxEditing", function ()
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix)
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
);
);
, "mathjax-editing");
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "508"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fspace.stackexchange.com%2fquestions%2f35124%2fdoes-it-take-more-energy-to-get-to-venus-or-to-mars%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
To flyby or impact Venus varies from 3.45 to 3.6 km/s from LEO for the optimal time every 19 months. Mars varies from 3.55 to 3.9 km/s for the optimal time every 26 months. So on average, getting to Venus is a little less energy than getting Mars. But not by much. It could even be a tiny bit more in some years.
If you also want to get barely into orbit propulsively, the ranges are 4 to 4.7 km/s for Venus and 4.25 to 7 km/s for Mars.
Mars is more variable than Venus due to its much larger solar orbit eccentricity (0.09 vs. 0.007).
At either planet, you can aerobrake down to the desired orbit. Aerobraking has been demonstrated at both. Or you can aerocapture directly, with just the flyby costs above. Aerocapture has never been demonstrated, but there are no hurdles that would prevent its use in a mission, other than developing an adequate heatshield for Venus (much higher entry velocity). However you incur the substantial mass penalty of the aeroshell, a cruise stage that is discarded before entry, and the structure and mechanisms to discard the aeroshell and deploy the enclosed spacecraft. Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months. (Aerocapture is mission enabling at Uranus, Neptune, and Titan.)
answered Mar 28 at 13:28
Mark AdlerMark Adler
50.8k3130215
$endgroup$
1
$begingroup$
"Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months." Did you mean either? This sentence seems contradictory to me as written.
$endgroup$
– TemporalWolf
Mar 28 at 18:32
5
$begingroup$
The sentence is perfectly grammatical. Neither body is worth aerocapture if you can afford the time to aerobrake instead. @TemporalWolf
$endgroup$
– Nij
Mar 28 at 18:40
1
$begingroup$
@Nij It seems to preclude doing both, which seems strange as I would expect a mission that aerocaptures to aerobrake as well.
$endgroup$
– TemporalWolf
Mar 28 at 19:15
1
$begingroup$
It's inconsistent with NASA publications concerning the feasibility of single pass aerocapture around Venus, which (on page 8 table 4) shows almost double the delivered mass for an aerocapture system to Venus versus a propulsive capture + aerobraking. Venus capture dV is around 1/10th the dV necessary for a LVO aerocapture, which would require even less of a aeroshield. While it's likely to be worth just going straight for the orbit you want, you could save substantial additional mass by combining the two.
$endgroup$
– TemporalWolf
Mar 28 at 21:39
2
$begingroup$
@TemporalWolf (& Mark Adler, too) Unless you're supremely confident of your aerocapture system's ability to have the exit velocity right where you want it, you probably wouldn't try to aerocapture directly into LVO, since there'd be little margin between the required ∆V and the ∆V that would result in complete entry. 24-hr, 12-hr, even 6-hr orbits would be fine. But for LVO I think you'd aerocapture into a looser orbit, then aerobrake down to LVO.
$endgroup$
– Tom Spilker
Mar 29 at 2:51
|
show 8 more comments
$begingroup$
To flyby or impact Venus varies from 3.45 to 3.6 km/s from LEO for the optimal time every 19 months. Mars varies from 3.55 to 3.9 km/s for the optimal time every 26 months. So on average, getting to Venus is a little less energy than getting Mars. But not by much. It could even be a tiny bit more in some years.
If you also want to get barely into orbit propulsively, the ranges are 4 to 4.7 km/s for Venus and 4.25 to 7 km/s for Mars.
Mars is more variable than Venus due to its much larger solar orbit eccentricity (0.09 vs. 0.007).
At either planet, you can aerobrake down to the desired orbit. Aerobraking has been demonstrated at both. Or you can aerocapture directly, with just the flyby costs above. Aerocapture has never been demonstrated, but there are no hurdles that would prevent its use in a mission, other than developing an adequate heatshield for Venus (much higher entry velocity). However you incur the substantial mass penalty of the aeroshell, a cruise stage that is discarded before entry, and the structure and mechanisms to discard the aeroshell and deploy the enclosed spacecraft. Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months. (Aerocapture is mission enabling at Uranus, Neptune, and Titan.)
answered Mar 28 at 13:28
Mark AdlerMark Adler
50.8k3130215
$endgroup$
1
$begingroup$
"Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months." Did you mean either? This sentence seems contradictory to me as written.
$endgroup$
– TemporalWolf
Mar 28 at 18:32
5
$begingroup$
The sentence is perfectly grammatical. Neither body is worth aerocapture if you can afford the time to aerobrake instead. @TemporalWolf
$endgroup$
– Nij
Mar 28 at 18:40
1
$begingroup$
@Nij It seems to preclude doing both, which seems strange as I would expect a mission that aerocaptures to aerobrake as well.
$endgroup$
– TemporalWolf
Mar 28 at 19:15
1
$begingroup$
It's inconsistent with NASA publications concerning the feasibility of single pass aerocapture around Venus, which (on page 8 table 4) shows almost double the delivered mass for an aerocapture system to Venus versus a propulsive capture + aerobraking. Venus capture dV is around 1/10th the dV necessary for a LVO aerocapture, which would require even less of a aeroshield. While it's likely to be worth just going straight for the orbit you want, you could save substantial additional mass by combining the two.
$endgroup$
– TemporalWolf
Mar 28 at 21:39
2
$begingroup$
@TemporalWolf (& Mark Adler, too) Unless you're supremely confident of your aerocapture system's ability to have the exit velocity right where you want it, you probably wouldn't try to aerocapture directly into LVO, since there'd be little margin between the required ∆V and the ∆V that would result in complete entry. 24-hr, 12-hr, even 6-hr orbits would be fine. But for LVO I think you'd aerocapture into a looser orbit, then aerobrake down to LVO.
$endgroup$
– Tom Spilker
Mar 29 at 2:51
|
show 8 more comments
$begingroup$
To flyby or impact Venus varies from 3.45 to 3.6 km/s from LEO for the optimal time every 19 months. Mars varies from 3.55 to 3.9 km/s for the optimal time every 26 months. So on average, getting to Venus is a little less energy than getting Mars. But not by much. It could even be a tiny bit more in some years.
If you also want to get barely into orbit propulsively, the ranges are 4 to 4.7 km/s for Venus and 4.25 to 7 km/s for Mars.
Mars is more variable than Venus due to its much larger solar orbit eccentricity (0.09 vs. 0.007).
At either planet, you can aerobrake down to the desired orbit. Aerobraking has been demonstrated at both. Or you can aerocapture directly, with just the flyby costs above. Aerocapture has never been demonstrated, but there are no hurdles that would prevent its use in a mission, other than developing an adequate heatshield for Venus (much higher entry velocity). However you incur the substantial mass penalty of the aeroshell, a cruise stage that is discarded before entry, and the structure and mechanisms to discard the aeroshell and deploy the enclosed spacecraft. Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months. (Aerocapture is mission enabling at Uranus, Neptune, and Titan.)
answered Mar 28 at 13:28
Mark AdlerMark Adler
50.8k3130215
$endgroup$
To flyby or impact Venus varies from 3.45 to 3.6 km/s from LEO for the optimal time every 19 months. Mars varies from 3.55 to 3.9 km/s for the optimal time every 26 months. So on average, getting to Venus is a little less energy than getting Mars. But not by much. It could even be a tiny bit more in some years.
If you also want to get barely into orbit propulsively, the ranges are 4 to 4.7 km/s for Venus and 4.25 to 7 km/s for Mars.
Mars is more variable than Venus due to its much larger solar orbit eccentricity (0.09 vs. 0.007).
At either planet, you can aerobrake down to the desired orbit. Aerobraking has been demonstrated at both. Or you can aerocapture directly, with just the flyby costs above. Aerocapture has never been demonstrated, but there are no hurdles that would prevent its use in a mission, other than developing an adequate heatshield for Venus (much higher entry velocity). However you incur the substantial mass penalty of the aeroshell, a cruise stage that is discarded before entry, and the structure and mechanisms to discard the aeroshell and deploy the enclosed spacecraft. Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months. (Aerocapture is mission enabling at Uranus, Neptune, and Titan.)
answered Mar 28 at 13:28
Mark AdlerMark Adler
50.8k3130215
answered Mar 28 at 13:28
Mark AdlerMark Adler
50.8k3130215
answered Mar 28 at 13:28
Mark AdlerMark Adler
50.8k3130215
answered Mar 28 at 13:28
Mark AdlerMark Adler
50.8k3130215
50.8k3130215
1
$begingroup$
"Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months." Did you mean either? This sentence seems contradictory to me as written.
$endgroup$
– TemporalWolf
Mar 28 at 18:32
5
$begingroup$
The sentence is perfectly grammatical. Neither body is worth aerocapture if you can afford the time to aerobrake instead. @TemporalWolf
$endgroup$
– Nij
Mar 28 at 18:40
1
$begingroup$
@Nij It seems to preclude doing both, which seems strange as I would expect a mission that aerocaptures to aerobrake as well.
$endgroup$
– TemporalWolf
Mar 28 at 19:15
1
$begingroup$
It's inconsistent with NASA publications concerning the feasibility of single pass aerocapture around Venus, which (on page 8 table 4) shows almost double the delivered mass for an aerocapture system to Venus versus a propulsive capture + aerobraking. Venus capture dV is around 1/10th the dV necessary for a LVO aerocapture, which would require even less of a aeroshield. While it's likely to be worth just going straight for the orbit you want, you could save substantial additional mass by combining the two.
$endgroup$
– TemporalWolf
Mar 28 at 21:39
2
$begingroup$
@TemporalWolf (& Mark Adler, too) Unless you're supremely confident of your aerocapture system's ability to have the exit velocity right where you want it, you probably wouldn't try to aerocapture directly into LVO, since there'd be little margin between the required ∆V and the ∆V that would result in complete entry. 24-hr, 12-hr, even 6-hr orbits would be fine. But for LVO I think you'd aerocapture into a looser orbit, then aerobrake down to LVO.
$endgroup$
– Tom Spilker
Mar 29 at 2:51
|
show 8 more comments
1
$begingroup$
"Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months." Did you mean either? This sentence seems contradictory to me as written.
$endgroup$
– TemporalWolf
Mar 28 at 18:32
5
$begingroup$
The sentence is perfectly grammatical. Neither body is worth aerocapture if you can afford the time to aerobrake instead. @TemporalWolf
$endgroup$
– Nij
Mar 28 at 18:40
1
$begingroup$
@Nij It seems to preclude doing both, which seems strange as I would expect a mission that aerocaptures to aerobrake as well.
$endgroup$
– TemporalWolf
Mar 28 at 19:15
1
$begingroup$
It's inconsistent with NASA publications concerning the feasibility of single pass aerocapture around Venus, which (on page 8 table 4) shows almost double the delivered mass for an aerocapture system to Venus versus a propulsive capture + aerobraking. Venus capture dV is around 1/10th the dV necessary for a LVO aerocapture, which would require even less of a aeroshield. While it's likely to be worth just going straight for the orbit you want, you could save substantial additional mass by combining the two.
$endgroup$
– TemporalWolf
Mar 28 at 21:39
2
$begingroup$
@TemporalWolf (& Mark Adler, too) Unless you're supremely confident of your aerocapture system's ability to have the exit velocity right where you want it, you probably wouldn't try to aerocapture directly into LVO, since there'd be little margin between the required ∆V and the ∆V that would result in complete entry. 24-hr, 12-hr, even 6-hr orbits would be fine. But for LVO I think you'd aerocapture into a looser orbit, then aerobrake down to LVO.
$endgroup$
– Tom Spilker
Mar 29 at 2:51
1
1
$begingroup$
"Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months." Did you mean either? This sentence seems contradictory to me as written.
$endgroup$
– TemporalWolf
Mar 28 at 18:32
$begingroup$
"Aerocapture at neither body appears to be a win if you can afford the time to aerobrake, measured in months." Did you mean either? This sentence seems contradictory to me as written.
$endgroup$
– TemporalWolf
Mar 28 at 18:32
5
5
$begingroup$
The sentence is perfectly grammatical. Neither body is worth aerocapture if you can afford the time to aerobrake instead. @TemporalWolf
$endgroup$
– Nij
Mar 28 at 18:40
$begingroup$
The sentence is perfectly grammatical. Neither body is worth aerocapture if you can afford the time to aerobrake instead. @TemporalWolf
$endgroup$
– Nij
Mar 28 at 18:40
1
1
$begingroup$
@Nij It seems to preclude doing both, which seems strange as I would expect a mission that aerocaptures to aerobrake as well.
$endgroup$
– TemporalWolf
Mar 28 at 19:15
$begingroup$
@Nij It seems to preclude doing both, which seems strange as I would expect a mission that aerocaptures to aerobrake as well.
$endgroup$
– TemporalWolf
Mar 28 at 19:15
1
1
$begingroup$
It's inconsistent with NASA publications concerning the feasibility of single pass aerocapture around Venus, which (on page 8 table 4) shows almost double the delivered mass for an aerocapture system to Venus versus a propulsive capture + aerobraking. Venus capture dV is around 1/10th the dV necessary for a LVO aerocapture, which would require even less of a aeroshield. While it's likely to be worth just going straight for the orbit you want, you could save substantial additional mass by combining the two.
$endgroup$
– TemporalWolf
Mar 28 at 21:39
$begingroup$
It's inconsistent with NASA publications concerning the feasibility of single pass aerocapture around Venus, which (on page 8 table 4) shows almost double the delivered mass for an aerocapture system to Venus versus a propulsive capture + aerobraking. Venus capture dV is around 1/10th the dV necessary for a LVO aerocapture, which would require even less of a aeroshield. While it's likely to be worth just going straight for the orbit you want, you could save substantial additional mass by combining the two.
$endgroup$
– TemporalWolf
Mar 28 at 21:39
2
2
$begingroup$
@TemporalWolf (& Mark Adler, too) Unless you're supremely confident of your aerocapture system's ability to have the exit velocity right where you want it, you probably wouldn't try to aerocapture directly into LVO, since there'd be little margin between the required ∆V and the ∆V that would result in complete entry. 24-hr, 12-hr, even 6-hr orbits would be fine. But for LVO I think you'd aerocapture into a looser orbit, then aerobrake down to LVO.
$endgroup$
– Tom Spilker
Mar 29 at 2:51
$begingroup$
@TemporalWolf (& Mark Adler, too) Unless you're supremely confident of your aerocapture system's ability to have the exit velocity right where you want it, you probably wouldn't try to aerocapture directly into LVO, since there'd be little margin between the required ∆V and the ∆V that would result in complete entry. 24-hr, 12-hr, even 6-hr orbits would be fine. But for LVO I think you'd aerocapture into a looser orbit, then aerobrake down to LVO.
$endgroup$
– Tom Spilker
Mar 29 at 2:51
|
show 8 more comments
$begingroup$
The second table here essentially answers your question. Venus transfer from Low Earth Orbit is 3.5 km/s, Mars transfer is 3.6.
This will allow you to impact either body (on Venus you will need to make sure your vehicle is tough enough to actually impact, rather than dissolving in the atmosphere, but that's not really the point).
In either case, you can enter orbit for negligible extra energy, but some risk, by aerocapture. Basically you graze the upper atmosphere, losing just enough velocity relative to the planet to enter a long elliptical orbit. At the highest point of that orbit you make a very small boost to raise the lowest point of the orbit to graze the atmosphere even more gently, and then repeated encounters will lower the high point of the orbit. When it's where you want it, you make a further small correction to miss the atmosphere entirely and you are there.
answered Mar 28 at 12:14
Steve LintonSteve Linton
9,40112551
$endgroup$
2
$begingroup$
Do you perhaps know if any actual spacecraft sent to Venus used aerocapture to get into orbit? Edit: I see Wikipedia saying that no.
$endgroup$
– stackzebra
Mar 28 at 12:47
1
$begingroup$
@stackzebra you have a point. On the other hand not that many probes have been sent to orbit Venus at all. Magellan used aerobraking to adjust its orbit.
$endgroup$
– Steve Linton
Mar 28 at 12:53
1
$begingroup$
@stackzebra: Not to get into orbit. Dual-stage atmospheric braking (dive-emerge-dive-land) has been used by "Venus" program landers. And, contrary to the above statement by Steve Linton, there were quite a few orbiters that orbited Venus as part of that program. These orbiters did not use aerocapture though.
$endgroup$
– AnT
Mar 28 at 16:17
$begingroup$
@AnT: Depends on what you understand by "not that many". I count 8: en.wikipedia.org/wiki/List_of_missions_to_Venus vs 14 for Mars: en.wikipedia.org/wiki/List_of_Mars_orbiters
$endgroup$
– jamesqf
Mar 28 at 16:40
add a comment |
$begingroup$
The second table here essentially answers your question. Venus transfer from Low Earth Orbit is 3.5 km/s, Mars transfer is 3.6.
This will allow you to impact either body (on Venus you will need to make sure your vehicle is tough enough to actually impact, rather than dissolving in the atmosphere, but that's not really the point).
In either case, you can enter orbit for negligible extra energy, but some risk, by aerocapture. Basically you graze the upper atmosphere, losing just enough velocity relative to the planet to enter a long elliptical orbit. At the highest point of that orbit you make a very small boost to raise the lowest point of the orbit to graze the atmosphere even more gently, and then repeated encounters will lower the high point of the orbit. When it's where you want it, you make a further small correction to miss the atmosphere entirely and you are there.
answered Mar 28 at 12:14
Steve LintonSteve Linton
9,40112551
$endgroup$
2
$begingroup$
Do you perhaps know if any actual spacecraft sent to Venus used aerocapture to get into orbit? Edit: I see Wikipedia saying that no.
$endgroup$
– stackzebra
Mar 28 at 12:47
1
$begingroup$
@stackzebra you have a point. On the other hand not that many probes have been sent to orbit Venus at all. Magellan used aerobraking to adjust its orbit.
$endgroup$
– Steve Linton
Mar 28 at 12:53
1
$begingroup$
@stackzebra: Not to get into orbit. Dual-stage atmospheric braking (dive-emerge-dive-land) has been used by "Venus" program landers. And, contrary to the above statement by Steve Linton, there were quite a few orbiters that orbited Venus as part of that program. These orbiters did not use aerocapture though.
$endgroup$
– AnT
Mar 28 at 16:17
$begingroup$
@AnT: Depends on what you understand by "not that many". I count 8: en.wikipedia.org/wiki/List_of_missions_to_Venus vs 14 for Mars: en.wikipedia.org/wiki/List_of_Mars_orbiters
$endgroup$
– jamesqf
Mar 28 at 16:40
add a comment |
$begingroup$
The second table here essentially answers your question. Venus transfer from Low Earth Orbit is 3.5 km/s, Mars transfer is 3.6.
This will allow you to impact either body (on Venus you will need to make sure your vehicle is tough enough to actually impact, rather than dissolving in the atmosphere, but that's not really the point).
In either case, you can enter orbit for negligible extra energy, but some risk, by aerocapture. Basically you graze the upper atmosphere, losing just enough velocity relative to the planet to enter a long elliptical orbit. At the highest point of that orbit you make a very small boost to raise the lowest point of the orbit to graze the atmosphere even more gently, and then repeated encounters will lower the high point of the orbit. When it's where you want it, you make a further small correction to miss the atmosphere entirely and you are there.
answered Mar 28 at 12:14
Steve LintonSteve Linton
9,40112551
$endgroup$
The second table here essentially answers your question. Venus transfer from Low Earth Orbit is 3.5 km/s, Mars transfer is 3.6.
This will allow you to impact either body (on Venus you will need to make sure your vehicle is tough enough to actually impact, rather than dissolving in the atmosphere, but that's not really the point).
In either case, you can enter orbit for negligible extra energy, but some risk, by aerocapture. Basically you graze the upper atmosphere, losing just enough velocity relative to the planet to enter a long elliptical orbit. At the highest point of that orbit you make a very small boost to raise the lowest point of the orbit to graze the atmosphere even more gently, and then repeated encounters will lower the high point of the orbit. When it's where you want it, you make a further small correction to miss the atmosphere entirely and you are there.
answered Mar 28 at 12:14
Steve LintonSteve Linton
9,40112551
answered Mar 28 at 12:14
Steve LintonSteve Linton
9,40112551
answered Mar 28 at 12:14
Steve LintonSteve Linton
9,40112551
answered Mar 28 at 12:14
Steve LintonSteve Linton
9,40112551
9,40112551
2
$begingroup$
Do you perhaps know if any actual spacecraft sent to Venus used aerocapture to get into orbit? Edit: I see Wikipedia saying that no.
$endgroup$
– stackzebra
Mar 28 at 12:47
1
$begingroup$
@stackzebra you have a point. On the other hand not that many probes have been sent to orbit Venus at all. Magellan used aerobraking to adjust its orbit.
$endgroup$
– Steve Linton
Mar 28 at 12:53
1
$begingroup$
@stackzebra: Not to get into orbit. Dual-stage atmospheric braking (dive-emerge-dive-land) has been used by "Venus" program landers. And, contrary to the above statement by Steve Linton, there were quite a few orbiters that orbited Venus as part of that program. These orbiters did not use aerocapture though.
$endgroup$
– AnT
Mar 28 at 16:17
$begingroup$
@AnT: Depends on what you understand by "not that many". I count 8: en.wikipedia.org/wiki/List_of_missions_to_Venus vs 14 for Mars: en.wikipedia.org/wiki/List_of_Mars_orbiters
$endgroup$
– jamesqf
Mar 28 at 16:40
add a comment |
2
$begingroup$
Do you perhaps know if any actual spacecraft sent to Venus used aerocapture to get into orbit? Edit: I see Wikipedia saying that no.
$endgroup$
– stackzebra
Mar 28 at 12:47
1
$begingroup$
@stackzebra you have a point. On the other hand not that many probes have been sent to orbit Venus at all. Magellan used aerobraking to adjust its orbit.
$endgroup$
– Steve Linton
Mar 28 at 12:53
1
$begingroup$
@stackzebra: Not to get into orbit. Dual-stage atmospheric braking (dive-emerge-dive-land) has been used by "Venus" program landers. And, contrary to the above statement by Steve Linton, there were quite a few orbiters that orbited Venus as part of that program. These orbiters did not use aerocapture though.
$endgroup$
– AnT
Mar 28 at 16:17
$begingroup$
@AnT: Depends on what you understand by "not that many". I count 8: en.wikipedia.org/wiki/List_of_missions_to_Venus vs 14 for Mars: en.wikipedia.org/wiki/List_of_Mars_orbiters
$endgroup$
– jamesqf
Mar 28 at 16:40
2
2
$begingroup$
Do you perhaps know if any actual spacecraft sent to Venus used aerocapture to get into orbit? Edit: I see Wikipedia saying that no.
$endgroup$
– stackzebra
Mar 28 at 12:47
$begingroup$
Do you perhaps know if any actual spacecraft sent to Venus used aerocapture to get into orbit? Edit: I see Wikipedia saying that no.
$endgroup$
– stackzebra
Mar 28 at 12:47
1
1
$begingroup$
@stackzebra you have a point. On the other hand not that many probes have been sent to orbit Venus at all. Magellan used aerobraking to adjust its orbit.
$endgroup$
– Steve Linton
Mar 28 at 12:53
$begingroup$
@stackzebra you have a point. On the other hand not that many probes have been sent to orbit Venus at all. Magellan used aerobraking to adjust its orbit.
$endgroup$
– Steve Linton
Mar 28 at 12:53
1
1
$begingroup$
@stackzebra: Not to get into orbit. Dual-stage atmospheric braking (dive-emerge-dive-land) has been used by "Venus" program landers. And, contrary to the above statement by Steve Linton, there were quite a few orbiters that orbited Venus as part of that program. These orbiters did not use aerocapture though.
$endgroup$
– AnT
Mar 28 at 16:17
$begingroup$
@stackzebra: Not to get into orbit. Dual-stage atmospheric braking (dive-emerge-dive-land) has been used by "Venus" program landers. And, contrary to the above statement by Steve Linton, there were quite a few orbiters that orbited Venus as part of that program. These orbiters did not use aerocapture though.
$endgroup$
– AnT
Mar 28 at 16:17
$begingroup$
@AnT: Depends on what you understand by "not that many". I count 8: en.wikipedia.org/wiki/List_of_missions_to_Venus vs 14 for Mars: en.wikipedia.org/wiki/List_of_Mars_orbiters
$endgroup$
– jamesqf
Mar 28 at 16:40
$begingroup$
@AnT: Depends on what you understand by "not that many". I count 8: en.wikipedia.org/wiki/List_of_missions_to_Venus vs 14 for Mars: en.wikipedia.org/wiki/List_of_Mars_orbiters
$endgroup$
– jamesqf
Mar 28 at 16:40
add a comment |
Thanks for contributing an answer to Space Exploration Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fspace.stackexchange.com%2fquestions%2f35124%2fdoes-it-take-more-energy-to-get-to-venus-or-to-mars%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
$begingroup$
Getting there... slowing down not included... god speed ye brave souls
$endgroup$
– Mikey Mouse
Mar 29 at 10:20