New Mars Forums

  I second that. It's getting ridiculous:

http://www.newmars.com/forums/viewtopic.php?id=6806

 
  Bob Clark

What kind of launch vehicle are you using to lift them to LEO?

  Bob Clark

I was trying to get a lower roundtrip delta-V for lunar missions by flying directly to the lunar surface rather than going first into lunar orbit then descending. Here's a list of delta-V's of the Earth/Moon system:

Delta-V budget.
Earth–Moon space.

http://en.wikipedia.org/wiki/Delta-v_bu … Moon_space

If you add up the delta-V's from LEO to LLO, 4,040 m/s, then to the lunar surface, 1,870 m/s, then back to LEO, 2,740 m/s,  you get 8,650 m/s, with aerobraking on the return.
I wanted to reduce the 4,040 m/s + 1,870 m/s = 5,910 m/s for the trip to the Moon. The idea was to do a trans lunar injection at 3,150 m/s towards the Moon then cancel out the speed the vehicle picks up by the Moons gravity. This would be the escape velocity for the Moon at 2,400 m/s. Then the total would be 5,550 m/s. This is a saving of 360 m/s. This brings the roundtrip delta-V down to 8,290 m/s.
I had a question though if the relative velocity of the Moon around the Earth might add to this amount. But the book The Rocket Company, a fictional account of the private development of a reusable launch vehicle written by rocket engineers, gives the same amount for the "direct descent" delta-V to the Moon 18,200 feet/sec, 5,550 m/s:

The Rocket Company.
http://books.google.com/books?id=ku3sBb … -V&f=false

  Bob Clark

I was discussing two different topics with those last two posts of mine. The first was about the question of producing a lightweight structure when it only had to withstand a 300 psf, 2psi, dynamic pressure as the shuttle does on re-entry.
The second had to do with the likelihood of Elon Musk succeeding at cutting the cost to orbit with reusability when it would require reusable rocket engines at low maintenance costs.

  Bob Clark

Watching the retrospectives on Neil Armstrong on NASA TV, I saw he was a X-15 pilot. This reminded me we actually had reusable rocket engines from the very earliest days of manned rocket-powered flight. The XLR-99 engine used on the X-15 was reusable for 20 to 40 times before overhaul, after which it could be reused again:

XLR-99.
http://www.astronautix.com/engines/xlr99.htm

The 3 copies of the X-15 aircraft flew for a total of 199 flights. Can you imagine how expensive that program would have been if an entire new X-15 aircraft had to be used for each flight?

  Bob Clark

It's late southern Winter transitioning into early southern Spring on Mars.

  Bob Clark

In Friday's teleconference lead Curiosity scientist John Grotzinger
initially gave the max temperature at the landing site as 1 degree
above freezing:

http://www.ustream.tv/recorded/24773693

However, later in response to a question for clarification on that
temperature at about 22 minutes into the teleconference, he gave the
temperature as 276 degrees Kelvin. This is about 3 degrees C, or 37
degrees F. The temperatures are expected to go higher as we get into
Spring at the landing site.
A low lying water ice haze was visible in Gale crater at the time of
the landing. The Mars Pathfinder mission showed the air temperature
can drop as much as 20C just a few feet above the ground compared 
to the ground temperature. So the air temperature where such hazes or
fogs lie, could be at below freezing temperature even when the surface 
is a few degrees above freezing.
However, it is important to note that clouds and fogs can have some
proportion of liquid water even at tens of degrees below freezing:

A liquid water component to clouds and fogs on Mars.
http://exoscientist.blogspot.com/2012/0 … s-and.html

Bob Clark

It's all theoretical until we know if the Falcon Heavy side boosters really wind up having a 30 to 1 mass ratio. The new version of the Falcon 9, version 1.1, is due to be introduced by the end of the year. We'll have a better idea then.

  Bob Clark

Just saw this on NasaSpaceflight:

Saturday Night Banquet (full) - 15th Annual International Mars Society Convention - YouTube
http://www.youtube.com/watch?v=9blyqTwX … r_embedded

It features Robert Zubrin and Elon Musk. Zubrin introduces Musk at about the 58 minute mark.

Bob Clark

Congrats to NASA and JPL.

   Bob Clark

According to this report from 2010, ESA was considering plans to use the Orion on the Ariane 5 to get a European manned spaceflight capability:

French govt study backs Orion Ariane 5 launch.
By Rob Coppinger
on January 8, 2010 4:45 PM
http://www.flightglobal.com/blogs/hyper … rench.html

This would cost several billion dollars to man-rate the Ariane 5. I have to believe the solid rocket boosters, which can not be shut down when started, play a significant role in that high cost.
However, the ESA has now given up on an indigenous manned spaceflight capability because of the estimated billion dollar cost to man-rate the full Ariane 5 system:

WSJ: Europe Ends Independent Pursuit of Manned Space Travel.
"LE BOURGET, France—Europe appears to have abandoned all hope of
independently pursuing human space exploration, even as the region's
politicians and aerospace industry leaders complain about shrinking
U.S. commitment to various space ventures.
"After years of sitting on the fence regarding a separate, pan-
European manned space program, comments by senior government and
industry officials at the Paris Air Show here underscore that budget
pressures and other shifting priorities have effectively killed that
longtime dream."
http://www.orbiter-forum.com/showthread.php?t=23006

In contrast, the Ariane 5 core stage with an added, second Vulcain engine could serve as a SSTO to carry a manned capsule to orbit. JAXA was able to add a second cryogenic engine to their H-IIa rockets first stage, which is about the same size as that of the Ariane 5, for less than a $250 million dollar development cost:

Rocketing to the future.
http://www.gov-online.go.jp/pdf/hlj_ar/ … /05-07.pdf

Mitsubishi Heavy To Invest In Next-Generation Rocket.
by Staff Writers
Tokyo, Japan (AFX) Jun 14, 2006
http://www.spacedaily.com/reports/Mitsu … ocket.html

The $250 million cost number I'm getting from the exchange rate from yen to dollars used in the second article. It is important to note about $50 million of this was used to widen the tanks, which wouldn't be needed in the Ariane 5 case. So we can estimate the development cost without widened tanks as less than $200 million. This is about the amount of the subsidy that the ESA gives to ArianeSpace every year. But this would be for a 4 year development, judging by the JAXA case, so would only be $50 million a year.

In the calculations for this multi-Vulcain Ariane core stage, I used this page for the specifications on the Ariane:

Space Launch Report:  Ariane 5 Data Sheet.
http://www.spacelaunchreport.com/ariane5.html#config

For the Vulcain 2 specifications, I've seen different numbers in different sources, though close to each other. I'll use this source:

Vulcain 2.
http://www.astronautix.com/engines/vulcain2.htm

I'll also use the earlier Ariane 5 "G" version that is lighter than the current "E" version to be lofted by two Vulcains without side boosters. According to the SpaceLaunchReport page it had a 170 mT gross mass for the core at a 158 mT propellant load, giving a 12 mT dry mass.
According to the Astronautix page, Vulcain 2 has a 434 s vacuum Isp and 1350 kN vacuum thrust. So two will have a 2700 kN vacuum thrust. The Vulcain's mass is listed as 1,800 kg. So adding another will bring the stage dry mass to 13,800 kg.
Now input this data into Schilling's calculator. Select again default residuals and select "No" for the "Restartable Upper Stage?" option. Select the Kourou launch site for this Ariane 5 core rocket. For the orbital inclination, I input 5.2 degrees. I gather Schilling uses this for Kourou's latitude since deviating from this decreases the payload. I chose also direct ascent for the trajectory.

Then the result I got was 7,456 kg(!) to orbit:

================================
Mission Performance:
Launch Vehicle:     User-Defined Launch Vehicle
Launch Site:     Guiana Space Center (Kourou)
Destination Orbit:      185 x 185 km, 5 deg
Estimated Payload:      7456 kg
95% Confidence Interval:      4528 - 10898 kg
================================

Interestingly, the payload capability of the Falcon 9 v1.1 first stage and of this two-Vulcain Ariane 5 core stage would be about the same as SSTO's.

   Bob Clark

Maybe we need a captcha to register on the forum.

   Bob Clark