Comments on: Why It Takes A Big Rocket To Reach Mars

By: Steve Jones

Steve Jones — Sun, 11 Nov 2018 17:03:46 +0000

The Saturn V had 35 mega-Newtons of thrust at sea level from its 5 engines, not 3.5,

By: Rahul Saini

Rahul Saini — Sun, 06 Nov 2016 15:12:55 +0000

I have a doubt regarding the way Entry to Mars is shown. The spacecraft by SpaceX could face difficulty in stability while entering Mars ‘atmosphere’ like that and Landing like that. They may face huge turbulence due to dust storms on Mars. Whats wrong with entering head-on like other space craft do on re-entry to Earth?

By: Kayser, Peter

Kayser, Peter — Fri, 28 Oct 2016 17:25:49 +0000

Still being proud on my solid STEM-education 30 years ago:

According to college physics, a force (like gravity) changes an object’s state of rest or motion.
Force = mass x acceleration. A force of 1 Newton imparts an acceleration of 1 m/s2 to a mass of 1 kg. 1 N = 1 kg m/s2.

Hence it takes at least 9.80665 N per kg of mass to (only) counteract the force of gravity.

For a reasonable upward acceleration to escape gravity you need considerably more force per kg of launch time rocket mass.

A rocket like the Saturn V with at a weight of approximately 3’000 metric tons (3’000’000 kg) needs therefore at least a force of 9.80665 N x 3’000’000 (per kg) = 29’419’950 N just for hovering over the launch pad – and not 3.5 million N as stated in the article. A force of 35 million N seems more appropriate.

Similar considerations can be applied for ITS:
13.5 million Newton would only be able to counteract the force of gravity on a vehicle of about 1’350 million kg – or 1’350 metric tons – less than half the weight of a Saturn V. But because ITS is able to launch a payload of 550 tons into LEO, it follows that the forces for ITS given in the article are also off about a factor 10.
I guess 135 million N would work.

Beyond that I consider this article very interesting.

By: Erik suarez

Erik suarez — Fri, 28 Oct 2016 02:55:22 +0000

Just a thought Yu-Gi-Oh fusion power nuclear power nuclear submarines ships that will last a hundred years with not refueling why can’t all nations build a Star track demo I’m a star ship with all the new technology within the last 50 years at one time a computer took up a whole room now it only takes up the palm of your hand the old saying live long and prosper entrepreneur

By: Jean Tate

Jean Tate — Wed, 26 Oct 2016 18:17:04 +0000

Coo!

How could the ITS have so much more thrust than Saturn V, yet be only 10% more massive? They use the same propellants, more or less (right?), so it must be a huge difference in the “empty” mass, right?

By: Aldor

Aldor — Tue, 18 Oct 2016 22:41:14 +0000

As for your question, direct sundiving from Earth orbit requires cancellation of the Earth’s orbital speed (30 km/s), plus some overhead for leaving Earth gravity, total delta-V required is around 32 km/s. Leaving Solar system by parabolic trajectory requires only ~16 km/s. That trajectory leaves you with speed relative to the Sun approaching zero as you reach the limits of Solar system, so you need very little delta-V to sundive from that position.

By: Aldor

Aldor — Tue, 18 Oct 2016 22:28:54 +0000

The lowest (by far) delta-V requirements to travel around Solar system can be achieved with the so-called Interplanetary Transfer Network (google it if you are interested, basically it’s clever maneuvering around Lagrange points). Very slow, very cheap.

By: Christian

Christian — Tue, 18 Oct 2016 17:02:11 +0000

No One know for sure what will happen to humans when we are far away from earth during a longer time.
Logically there shouldn’t be any huge difference.
But there is always a small risk that our bodies need to be nearby earth to survive. Right now we assume it’s only the lack of gravity.
If we had a station on the moon we would probably been able to find out.

By: Jordan

Jordan — Tue, 18 Oct 2016 06:52:16 +0000

Really cool reading. Interesting just thinking we will be there in just a decade or so. I think the first trip is planned for 2029. Is that accurate?

By: jpatrick

jpatrick — Tue, 18 Oct 2016 03:03:50 +0000

There are a lot of medical questions about a trip to Mars. Indeed, it seems that a man who goes to the cold red desert and then returns to Earth may well come back blinded and insane.

By: Alessio Sangalli

Alessio Sangalli — Mon, 17 Oct 2016 19:34:36 +0000

Hello, thanks for the great post. The chart you linked sparked a question that greatly interests me. I would be very happy if I could get your opinion on this. My goal is to calculate how much energy is needed for a Sun dive, basically fall directly into the Sun. We start from a Earth orbit; given arbitrary amounts of time, which option takes the least dV requirement, first going out to some place in the external solar system and then, once at Apogee, perform the maneuver for the Sun-dive, or perform that directly from Earth orbit? I ask because I see that, the further out you go, the orbital speed of the Planets gets lower and lower. I hope my question is clear and appropriate.

By: Christian

Christian — Mon, 17 Oct 2016 17:27:44 +0000

I guess All body needs to be shield from xray not just the head?
How many kW is needed to create a strong enough magnetic field for protection around the parts they live in?