115
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Why is it easier to escape the solar system than get to Mercury or the Sun?
Because the earth goes very fast around the sun.
If you want to get to the sun, you need to slow down almost completely so that your speed relative to the sun becomes almost zero.
If you don't slow ...
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40
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Why don't we send a rover to a pole of Mercury?
This question: Calculating the delta V budget from Earth to Mercury
Gives the reason. Mercury is actually very difficult to reach directly due to its location deep inside the Sun's gravitational well. ...
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37
votes
Why is it easier to escape the solar system than get to Mercury or the Sun?
Changing orbits requires delta-v. To reach the Sun, you need to subtract delta-v such that your velocity relative to the Sun is near zero, which allows you to "fall straight down" into the ...
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25
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Why is it easier to escape the solar system than get to Mercury or the Sun?
Escaping the solar system requires adding orbital velocity to the spacecraft. Similarly, getting closer in the solar system requires removing orbital velocity. It turns out Earth is more out of the ...
- 1,033
24
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Mars versus the poles of Mercury WRT colonization
Your delta-v analysis doesn't account for the landing delta-v. On Mars, only a fraction of a km/s has to be done propulsively, on Mercury the entire landing will be propulsive.
You also don't account ...
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24
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If one Starship can transport 100 people to Mars, how many could it safely land near Mercury's north pole after one Hohmann-like transfer?
I take "after one Hohmann-like transfer" to mean a direct Earth to Mercury interplanetary transfer (i.e., no Venus shenanigans), please let me know if that is not the case.
Unless serious ...
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19
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Is GR required to send a probe to Mercury?
In any interplanetary mission, it's impossible to perfectly accurately measure the position and velocity of a spacecraft or a planet, so mission planners generally schedule a number of opportunities ...
- 172k
17
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If one Starship can transport 100 people to Mars, how many could it safely land near Mercury's north pole after one Hohmann-like transfer?
The delta-v to Mercury is 2.5x greater than to Mars; given the dry mass of Starship I doubt that it could land any payload at all without some heliocentric fuel depot, which would be quite tricky and ...
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16
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Which of the 2 delta-v calculations for a Mercury orbit insertion from LEO is right and which is wrong?
Your $v_{inject}$ and $v_{insert}$ equations assume that both the departure and destination worlds are in coplanar, circular orbits.
This is manifestly not the case with Mercury.
Mercury is in an ...
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15
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Why the thermal imaging of Mercury's surface requires a telescope on a jet flying through an eclipse?
Why not a satellite-based telescope to observe Mercury in the thermal infrared?
Space-borne satellites that are designed to look at the Sun (e.g., SOHO) aren't instrumented to look in the thermal ...
- 77.4k
14
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Why is it easier to escape the solar system than get to Mercury or the Sun?
Based on the calculations presented by @uhoh I generated a plot showing the necessary delta-V for
a fly-by mission, i.e. entering into a Hohmann transfer with a far point intersecting the orbit of a ...
- 15.2k
13
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If one Starship can transport 100 people to Mars, how many could it safely land near Mercury's north pole after one Hohmann-like transfer?
Landing on Mercury is supremely difficult due to how deep Mercury lies in the Suns gravitational well. In addition it has no significant atmosphere so retro propulsive landings would be required ...
- 10.4k
12
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Is a graviational slingshot around Mercury a feasible solution for space probes?
Using Mercury for a slingshot has 3 major problems:
Low energy transfer: Mercury is moving relatively quickly but it's low mass means you don't get much benefit
You have to slow down to get to it. ...
- 20.4k
11
votes
Accepted
Which of the 2 delta-v calculations for a Mercury orbit insertion from LEO is right and which is wrong?
I think I have it sorted: this answer giving the lower values is "correct". The key part you have missed is emphasized (by me) here:
That means a delta-v cost of 4.37km/s to get captured ...
- 10.1k
10
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Why is it easier to escape the solar system than get to Mercury or the Sun?
Many quantitative questions about orbits can be answered using the vis-viva equation
$$v^2 = GM\left(\frac{2}{r} - \frac{1}{a} \right)$$
where $a$ is the semi-major axis, $r$ is the current distance ...
- 151k
9
votes
Why did the MESSENGER probe get deorbited?
Why was MESSENGER deorbited?
It wasn't. (The wikipedia page on MESSENGER is wrong in this regard.)
MESSENGER was inserted into an orbit about Mercury with a high inclination, a high eccentricity, ...
- 77.4k
9
votes
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Friendly temperatures at day/night junction in Mercury?
We can at least talk about the temperature of the surface of Mercury. There's no atmosphere so we can't talk about the air temperature, and the temperature that an object (space suit, lander) would ...
- 151k
9
votes
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Is Mercury's orbit still considered potentially unstable (in the very long term)?
Here is the first paragraph of the introduction from Abbot et al. (2023):
Since the landmark study of Laskar (1994), the potential for Mercury’s orbit to destabilize has been widely recognized. The ...
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9
votes
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How much delta-v could be saved with a Hohmann-like transfer orbit to the aphelion of Mercury 's orbit instead of its perihelion?
All the relevant velocities can be obtained from the vis-viva equation. The transfer/capture costs can then be derived from the $v^2 = v_e^2 + v_{\infty}^2$. I'm going to ignore Mercury's 7 degree ...
8
votes
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Why must "Mercury’s core (be) partially molten" to explain its weak magnetism?
tl;dr: because any solid iron would still be above the Curie temperature and so unable to retain any residual magnetization.
The magnetic phenomena associated with liquid metal in (the cores of) ...
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7
votes
Mars versus the poles of Mercury WRT colonization
You can't land on the day side of Mercury nor on a peak of perpetual light because it's far too hot (800 deg F / 430 deg C), even if not as hot as on Venus. A crewed mission must land either on the ...
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7
votes
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Does it even make sense to talk about Mercury's triangular libration points (L4, L5)?
You're right, the Sun-Mercury libration points (all five of them) are merely mathematical curiosities of a hypothetical two-body system. As you've calculated, the actual gravitational effects of ...
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7
votes
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Starting refueled in LEO, how much payload could a heat-protected Starship softly land on Mercury after a gravity assist from Venus?
A single Venus flyby helps, but it does not make the journey possible for Starship.
Below is a plot of 2025-2030 trajectories from Earth to Mercury that flyby Venus once. They are plotted by the Earth ...
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7
votes
Accepted
What does LMO mean?
The Chrome extension NASA Acronyms (and accompanying website) suggest these three options for LMO:
Low Mars Orbit
Low Moon Orbiter
Lunar Magma Ocean
According to the master json list these ...
- 10.1k
6
votes
What was Mariner 10's lowest perihelion radius?
Rodger D. Bourke and Joseph G. Beerer, "Mariner Mission to Venus and Mercury in 1973"
http://www.gravityassist.com/IAF3-1/Ref.%203-110.pdf
page 55:
At Mercury encounter the spacecraft has ...
6
votes
How tectonically active is Mercury?
A study by Stern et al. (2018) introduced a "Tectonic Activity Index" (TAI) to represent the tectonic activity of planetoids. The TAI is determined by looking at three criteria:
Recent ...
5
votes
Starting refueled in LEO, how much payload could a heat-protected Starship softly land on Mercury after a gravity assist from Venus?
One thing to keep in mind is the trade off between use of gravity assists, the alignment of the planets at launch and the mission duration.
It is theoretically possible to use multiple passes of the ...
- 10.4k
4
votes
Mars versus the poles of Mercury WRT colonization
There are several arguments which favour Mars over Mercury as a candidate for human missions.
Getting there and coming home
As the question and other answers have highlighted, the delta-v for ...
- 1,426
4
votes
Accepted
When an how will BepiColombo and MIO separate? (JAXA’s Mercury Magnetospheric Orbiter)
From ESA site:
When approaching Mercury, the transfer module will separate and the
two spacecraft, still together, will be captured into a polar orbit
around the planet. Their altitude will be ...
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Only top scored, non community-wiki answers of a minimum length are eligible