95
votes
Accepted
Would it be easier to put humans on Venus rather than Mars?
Technically, yes, it would be easier to put people on Venus. You need less of a kick for the interplanetary trip and slowing down is trivial with that dense atmosphere...one of the Pioneer Multiprobe ...
- 10.7k
75
votes
Accepted
Is Nibiru real or totally science fiction?
Nibiru is fiction.
Nibiru, a purported large object headed toward Earth, simply put - does not exist. There is no credible evidence - telescopic or otherwise - for this object's existence. There ...
- 126k
59
votes
Why was Venus rather than Mars targeted for the first interplanetary landings?
The reason is delta-v, which is a crucial concept in Spaceflight. It means change in velocity, and is the primary 'currency' that space mission have to expend in order to reach places in the solar ...
- 8,414
59
votes
Accepted
Assuming a spacecraft is traveling in a constant rate and our Astronaut will exit it to a space walk, will she be "left behind" by the spacecraft?
As long as neither spacecraft nor the astronaut are accelerating or decelerating, the relative speed of the spacecraft and the astronaut remains the same. So the astronaut will hover near the ...
- 12.5k
52
votes
Are there any greater risks of traveling significantly faster to another planet?
The biggest risk on a flight to Mars is cumulative exposure to radiation, so a 1-2 month flight would actually be much healthier for a crew than a 7-8 month flight. I don't know of any risks that ...
- 167k
50
votes
Do you need to burn fuel between gravity assists?
Yes, Trajectory Correction Maneuvers (TCMs) are always performed during cruise phases, whether before or after gravity assist flybys. This NASA tutorial serves as a good general reference.
One source ...
- 18.2k
50
votes
Would it be easier to put humans on Venus rather than Mars?
As others have already pointed out, getting humans to Venus would be marginally easier than getting them to Mars.
Let's consider survival on Venus in a little more detail though. Although there haven'...
- 641
48
votes
Accepted
Why is it so hard to build crewed rockets/spacecraft able to reach escape velocity?
Delta-V to LEO is about 10 km/s. From there to C3 (Earth escape) is another 3.2 km/s. It's just another 30% delta-V.
The problem is the Tyranny of the Rocket Equation. More delta-V means more fuel. ...
- 7,996
41
votes
Is Nibiru real or totally science fiction?
The name Nibiru does appear in science fiction.
However, the stuff to which you refer is not science fiction. It's just baloney, malarkey, or "fake news."
According to Wikipedia's article Nibiru ...
- 149k
38
votes
Accepted
Exactly why does Starship need to be this big for interplanetary travel?
A lot of launch costs are independent of rocket size. It's no cheaper to clear the flight path for a smaller rocket, for example. It also takes a lot longer to do 10 launches instead of one large ...
- 10.7k
37
votes
Why was Venus rather than Mars targeted for the first interplanetary landings?
We didn't know how hostile Venus's surface was, until we had landed there. The atmosphere of Venus makes it easier to land there than Mars. From Wikipedia, we learn:
Before radio observations in ...
- 121k
35
votes
Assuming a spacecraft is traveling in a constant rate and our Astronaut will exit it to a space walk, will she be "left behind" by the spacecraft?
It turns out that outer space is not a perfect vacuum: there are a few hydrogen atoms per cubic centimeter. (reference)
For large X, non-relativistic physics, the astronaut and spacecraft will stay ...
- 421
34
votes
Accepted
Why are we interested in visiting the giant planets' icy moons?
The icy moons are of interest for exploration as part of the overall "follow the water" strategy of exploration that NASA (and others) have been exploring for some time. The "where else can water be ...
- 2,506
34
votes
Why is it so hard to build crewed rockets/spacecraft able to reach escape velocity?
It's not hard, it's just expensive. We know exactly how to do it. Compare this to building computer processors with 1nm transistors, or making reliable self-driving cars. Those are both things that we ...
- 441
30
votes
Why haven't telescopes been sent to other planets?
We have sent telescopes to other planets, almost all the optical sensors on probes are in fact telescopes so they can focus on a specific area in detail. These sensors are to explore the planets they ...
- 19.9k
30
votes
Accepted
After the loss of Challenger, why weren’t Galileo and Ulysses launched by Centaurs on expendable boosters?
The performance of Shuttle-Centaur would have greatly exceeded that of either the Atlas-Centaur or Titan-Centaur combination.
Neither the Atlas nor Titan were able to put a fully fueled Centaur into ...
- 167k
27
votes
What is the rarest launch window?
Comet West with its unpredictable but estimated at 558 000 years period is a good contender.
Since launch windows can aim for the alignment of N objects, the answer obviously tend to infinity.
You ...
- 12.6k
26
votes
Is 2001: A Space Odyssey's Discovery One still a plausible design for interplanetary travel?
Considering that the film was made before humankind first set foot on the Moon it is a fictional technological triumph and if you create something like that it should age well. And it has aged far ...
- 8,954
25
votes
Elon Musk's ITS Travel Time to Mars Estimate
What is unique about the ITS that would make the travel time so much shorter? Is the propulsion method described in existence today?
The current manifestation of the ITS is Starship, and the ...
- 9,685
23
votes
Is Nibiru real or totally science fiction?
To resonate with @Hobbes general characterization: Nibiru is contrived nonsense.
Ignoring the fact that previously announced dates for the Earth cataclysm have come and gone with no such mayhem, some ...
- 18.2k
23
votes
Pictures from Mars
Let's compare with 4G, for which I could find some numbers:
Your cell phone is transmitting with speeds of up to 50MBps with a maximum of 1 Watt (can be as low as a few µW!), using a tiny antenna ...
- 12.5k
21
votes
What is the rarest launch window?
Hohmann launch windows occur each synodic period. Or a more general version of a Hohmann transfer would be a transfer orbit tangent to both departure and destination orbits. This also occurs each ...
- 15.6k
21
votes
Assuming a spacecraft is traveling in a constant rate and our Astronaut will exit it to a space walk, will she be "left behind" by the spacecraft?
I feel this sort of question benefits from a series of thought experiments.
Imagine instead that you've got two astronauts, side by side, zipping through space at some constant speed.
They're kind ...
- 1,857
20
votes
Why was Venus rather than Mars targeted for the first interplanetary landings?
One picture is worth all your base to us.
Before we sent probes to Venus we had no pictures of its surface. Whether it lands or not you have to penetrate the atmosphere of Venus to take pictures of ...
- 566
19
votes
Viability of orbital refueling
This is basically the approach being considered for getting all of the hardware to Mars for a crewed mission. However instead of refueling an upper stage that was used to get you to orbit, it is ...
- 58.5k
18
votes
Accepted
Traveling through the asteriod belt?
The asteroid belt isn't nearly as dense as popular media makes it out to be.
An answer from the Dawn Mission's FAQ, specifically "What is the average distance between individual asteroids? (6/13/10)",...
- 1,043
18
votes
Accepted
Which 3D space simulation/visualization software (free or commercial) can I use as a post processor of data calculated with Fortran?
One option is SPICE-Enhanced Cosmographia. You could convert your output text files to SPICE SPK (.bsp extension) kernels or more simply a text file with structured data (see the InterpolatedStates ...
- 1,393
17
votes
Is the concept of the Epstein Drive based on actual theorized scientific research which is considered plausable?
From what I've been able to find, the "fluff" is that the Epstein Drive electromagnetically accelerates the exhaust, improving propellant consumption over a "standard" inertially-confined fusion drive....
- 10.7k
16
votes
Accepted
What is the rarest launch window?
The launch of New Horizons was very critical.
The NASA scientists had 5 years to develop a space probe to Pluto and make sure it got a gravity assist through Jupiter, which is only possible if ...
16
votes
Why are we interested in visiting the giant planets' icy moons?
The motivation is the growing understanding, from the Voyager, Galileo and Cassini probes, that these icy moons (I'd throw in Enceladus) are geologically active with sub-surface oceans of liquid water,...
- 1,073
Only top scored, non community-wiki answers of a minimum length are eligible