
SpaceX is testing new powerful engines for its mission to Mars - kungfudoi
http://www.techradar.com/news/world-of-tech/spacex-is-testing-new-powerful-engines-for-its-mission-to-mars-1329373
======
rory096
For those who aren't already aware, tomorrow (Tuesday 9/27) at 1:30pm CDT
(18:30 UTC) SpaceX will be revealing their Mars colonization plans in full at
the International Astronautical Congress.

The live stream will be available here:
[https://youtu.be/A1YxNYiyALg](https://youtu.be/A1YxNYiyALg)

~~~
otabdeveloper
Venus' atmosphere is a better colonization target than Mars from every
conceivable angle. I don't think they have really thought this through.

~~~
obmelvin
My understanding is that Venus' surface conditions aren't great, and that one
needs to be miles above the surface for tolerable conditions.

That being said since you seem to have thought about this I'd be curious to
read any resources you can recommend.

~~~
RobertoG
The grandparent is talking about Venus atmosphere.

It seems the conditions in the upper atmosphere of Venus are acceptable. If
you can manage living in floating cities (that it's cool but makes it a very
difficult endeavour) then, Venus is close to Earth than Mars and the gravity
is similar to the one in Earth.

As always, Wikipedia have this covered:
[https://en.wikipedia.org/wiki/Colonization_of_Venus#Aerostat...](https://en.wikipedia.org/wiki/Colonization_of_Venus#Aerostat_habitats_and_floating_cities)

PS: I'm upvoting the GP, by the way. Why people downvote instead of asking for
clarification.

~~~
kinkrtyavimoodh
The GP was mostly downvoted because of the unnecessarily supercilious tone.
Instead of explaining why they thought Venus was better for this purpose, GP
just chose to end with a haughty-sounding "I don't think they have thought
this through." Considering GP is a random stranger on the internet, and "they"
is SpaceX/Elon, the downvoting is natural.

~~~
RobertoG
Maybe. But I think that it's, precisely, because we are random strangers in
the Internet and we all know how easy is to misunderstand intentions by text,
that we should think two times before downvoting.

It's my personal opinion that downvoting is used too easily in HN.

Sometimes it seems that we are trying to filter opinions that we don't agree
with, instead of policing good manners and filter irrelevant to the subject
comments.

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dluan
This combined with the recent congressional bill $20B budget for NASA's manned
Mars mission (yes, you read that right) is very good news for the next
generation of space.

The bill, introduced by Ted Cruz and Marco Rubio, among others, has good
bipartisan support.
[https://www.commerce.senate.gov/public/_cache/files/f9467082...](https://www.commerce.senate.gov/public/_cache/files/f9467082-5e29-4a91-84f2-ace2bdbf7b48/902B6E41BE19BF614D5DEDD888529A34.nasa-
bill.pdf)

~~~
chriskanan
I don't have time to look through this since my PDF reader isn't allowing me
to search it, but how much of it is allocated to a manned Mars mission that
does not use SLS? I have very low expectations for SLS, and I'd much rather
see them support SpaceX's efforts. It does call explicitly for the continued
use of SLS.

[http://www.usatoday.com/story/news/politics/2016/09/21/senat...](http://www.usatoday.com/story/news/politics/2016/09/21/senate-
panel-authorizes-money-mars-mission-shuttle-replacement/90793160/)

I do agree strongly with the general sentiment that NASA's goals should not be
changed every time we get a new administration, but SLS seems like such a pork
barrel project.

~~~
ngoldbaum
Note as the GP mentioned that this bill comes from the likes of Ted Cruz
(Texas) and Marco Rubio (Florida). What government agency do those two states
have in common?

The space program isn't really about exploring space, it's a jobs program.

------
sandworm101
From wikipedia:

>> As of August 2016, a scaled version of the[12][verification needed] Raptor
engine has been shipped to Texas where it will undergo development testing.

I was looking at the pics and thinking this thing is way too small for what it
is meant to be. But after reading wikipedia I understand. The pics/tests are
of a tabletop version. The real engine hasn't been built yet. So it's good
news, but not the news I was looking for.

Title should perhaps reflect the fact that the "new powerful engine" doesn't
yet exist for testing.

~~~
mikeyouse
The pics / tests are absolutely not a tabletop version.

Here's Musk's pic from the test:

[https://twitter.com/elonmusk/status/780275236922994688](https://twitter.com/elonmusk/status/780275236922994688)

You can see a staircase to the bottom-right, and the railing on the left side
(if built to code) is likely 38" tall. It looks like the nozzle is roughly a
meter across.

 _Edit: This one shows the scale a bit better:_

[https://twitter.com/elonmusk/status/780278836860628992](https://twitter.com/elonmusk/status/780278836860628992)

 _Further edit:_

Everyone is rightly pointing out that it's not a huge engine, but two things
to keep in mind.. Musk's ISP figures correspond to operating in a vacuum and
of course at that point the bell will be significantly larger (14ft like
mentioned). If used for the first stage, the Raptors will likely have similar-
sized bells to the current Merlin engines. The bell is just the expansion
chamber and doesn't really relate to the actual engine size (except of course
to optimize expansion ratio).

The shuttle engines weren't huge, but the bells were quite large, I think the
expectation is that the Raptor will be between 1/2 and 1/4 of the Shuttle
engine size/weight:

[http://extras.mnginteractive.com/live/media/site200/2012/092...](http://extras.mnginteractive.com/live/media/site200/2012/0921/20120921__shuttle_engine_01.JPG)

~~~
sandworm101
Those are still tiny. Unless Musk has invented some new radically new
classical physics, that bell is nowhere near big enough to match the shuttle
engines, not at the published isps. Maybe I'm wrong and he deserves a noble
prize. Or maybe his tweets aren't the full story and this is a scaled
technology demonstrator.

Perhaps someone should rewrite the raptor's wikipedia page to indicate that
raptor is in a different league. Pics from this "test firing" are right beside
numbers claiming thrusts above shuttle, which is comical given the size
differences between the engines.

[https://en.wikipedia.org/wiki/Raptor_(rocket_engine)](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine\))

>>Raptor - 2.7 MN (610,000 lbf) Shuttle main engines - 512,300 lbf (2,279 kN)

~~~
rory096
This is thought to be the Raptor prototype SpaceX is developing under a USAF
contract for a methalox Falcon 9 upper stage concept.[0] Thus it's about the
size of a Merlin 1D-Vac. Nobody is claiming otherwise.

[0] [http://www.defense.gov/News/Contracts/Contract-
View/Article/...](http://www.defense.gov/News/Contracts/Contract-
View/Article/642983)

------
dgudkov
A naive question: with all those benefits of methane/LOX engines why weren't
they widely used previously instead of kerosene/LOX engines?

~~~
shirro
Methane can be generated on Mars using the Sabatier reaction to refuel for the
trip home. Methane should help re-usability as there will be less soot on the
engines. Methane can self-pressurize and SpaceX has lost two rockets in 14
months due to suspected problems related to their helium pressurisation
system.

~~~
iamcreasy
What does it mean by "Methane can self-pressurize"?

~~~
shirro
I wish I knew for sure. It is just something I read. Rockets need to maintain
the pressure in the tanks as fuel is depleted. Most fuels will not vaporize
fast enough as they are used. Helium seems to be the best option but hard to
obtain on Mars. I guess nitrogen is another choice but it is less than 2% of a
very thin Mars atmosphere. I am not sure if methane will do the job by itself
or if you might need to heat some up.

