Sunday, February 15, 2015

Low cost Europa lander missions.

Copyright 2015 Robert Clark
 NASA has proposed funding for a future orbital mission to Europa. This is expected to have a billion dollar cost. A NASA-funded lander mission to Europa was expected to be too expensive. University of Arizona researcher Christopher Impey suggests doing privately funded missions to Europa:

Let’s Send a Private Mission to Europa, Expert Says.

 Indeed, by following the commercial space approach an actual lander mission, not just orbital, can be mounted for costs in the range of one of NASA's lowest cost Discovery-class missions.

 Some observations by the Hubble telescope were that Europa may have plumes like Enceladus though those observations have not been confirmed. If it does, then it may be the subice ocean on Europa could be reached simply by traveling though the fissures, like on Enceladus, not requiring melting through the ice.

 For getting funding for a privately-financed mission, imagine how much interest there would be among the public if we could actually access this subsurface ocean. As a point of comparison the Mars Pathfinder missions web site caused such overloads, with 40+ million hits per day, that some mirror sites crashed or had to have access limited:

Traffic on Mars
by Chuck Toporek
Asst. Managing Editor
Web Review
However, the most interesting and little known fact about the amount of traffic to the mirror sites comes from France, where the government actually pleaded with computer users to stop accessing the two Mars Pathfinder mirrors. You see, the phone systems in France carry all of the Internet traffic in the country, so when people started visiting the mirror sites at VisuaNet and Le Centre National D'Etudes Spatiales (CNES), they tied up the phone lines and basically disabled the country.

 Private companies that provided funding could be allowed to advertise on the mission web site.

Mission Delta-V requirements.
 The spacecraft first has to be sent on a trajectory towards Jupiter. This requires a delta-v of 6.3 km/s. Following a Hohmann trajectory it takes about 2.7 years to arrive at Jupiter. Aside from this Jupiter transfer delta-v, it will need to be placed into Jupiter/Europa orbit on arrival, and then sent towards a landing on Europa. According to this report this will require a delta-v in the range of 3.9 km/s:
European Cryo-Ocean Exploration Submersible (ECOES).
Preliminary Design Report. 
 We'll use a cryogenic, hydrogen-fueled stage for the injection into a trajectory towards Jupiter. And because of the long travel time, we'll use storable (hypergolic) propellants for the propulsive maneuvers at Jupiter.
Falcon 9 v.1.1 sized launcher.
 The expendable version of the Falcon 9 v1.1 has a payload to LEO of ca. 16.6 metric tons (mT). We'll use the Ariane H10-3 hydrogen-fueled upper stage for the Jupiter trajectory insertion. It has a 11.86 mT propellant mass, 1.24 mT dry mass, and 445 s Isp. Then it can carry 2.4 mT to the 6.3 km/s delta-v needed for the flight towards Jupiter:
445*9.81ln(1 + 11.86/(1.24 + 2.4)) = 6,324 m/s
 For the stage, at Jupiter we'll use the Integrated Apogee Boost Subsystem (IABS) stage.
 An artist's concept of a DSCS satellite being boosted by the IABS. Photo: U.S. Air Force
 This is a small kick-stage used to put geosynchronous satellites in their final orbits. It has a 1,578 kg gross mass and 275 kg dry mass, for a 1,303 kg propellant mass, and a 312 s Isp. Then this could provide a 220 kg spacecraft with the 3.92 km/s delta-v needed to land on Europa:
321*9.81ln(1 + 1303/(275 + 220)) = 3,947 m/s. 
 The Falcon 9 v.1.1 costs in the range of $56 million, the Ariane H10-3 cryogenic stage costs in the range of $12 million and the IABS stage costs in the range of $15 million, for a ca. $83 million launch cost.
 For a model of a low cost lander we might use the Mars Pathfinder mission. This weighed only 264 kg for the lander plus 10.5 kg for the rover. The development cost for the lander was less than $150 million. The development cost of  $150 million is quite low for a planetary mission. However,  privately financed it would be even less than that, perhaps as much as a factor of 10 cheaper.
  SpaceX was able to develop the Falcon 9 at a 90% (!) saving off  the development cost of a fully government-financed launcher of similar size. Planetary Resources Inc. plans to produce imaging satellites at a fraction of the usual cost.
Arkyd 100 space telescope.
 With mission costs this low we might want to produce a separate orbiter mission at Europa. As models for this we might use the small Mars orbiters Mars Odyssey and Mars Climate Orbiter.

Falcon Heavy sized launcher.

 The Falcon Heavy will allow a larger payload to be transported to the Europan surface. It is expected to be able to carry 53 metric tons to LEO. We'll use two Centaur stages together for the injection into a trajectory towards Jupiter. For the maneuvers at Jupiter, we'll use the storable propellant stage Delta K. This has a 6 mT propellant load, 0.95 mT dry mass, and 319 s Isp. Then it can provide a 1 mT spacecraft with the 3.9 km/s delta-v needed for the Europa landing:
319*9.81ln(1 + 6/(0.95 + 1)) = 4,397 m/s.
 The Centaur has several incarnations. It's propellant load is in the range of 20 mT, dry mass ca. 2 mT, and Isp ca. 451 s. Then two Centaurs together could provide the 6.3 km/s delta-v needed for the Jupiter flight carrying the 7.95 mT total mass of the Delta K stage + Europa lander:
451*9.81ln(1 + 40/(4 + 7.95)) = 6,500 m/s.
  The Falcon Heavy will cost in the range of $125 million. The Centaurs cost in the range of $30 million each and the Delta K stage costs ca. $4.35 million. Then the total launch cost will be in the range of $189.35 million.
 As a model of a 1 metric ton lander we might use the Mars Curiosity rover. This is a $1 billion mission however. The commercial space approach however should be able to produce a similar size spacecraft for a fraction of this cost.
   Bob Clark 

UPDATE, February, 20, 2015:

 The web traffic to the NASA web site for the Mars Exploration Rovers was even more extraordinary, measuring in the billions of hits:

NASA’s Web Site for 2005
By Digital Trends Staff — January 7, 2005
The U.S. National Aeronautics and Space Administration Web portal continues to drive high traffic numbers — more than 17 billion hits in 2004, report both NASA and Speedera Networks, a leading global provider of on-demand distributed application hosting and content delivery services. Speedera delivers content from the space agency’s portal to visitors seeking access to the site from around the world. Popular events on the NASA Web site, including the ongoing Mars Exploration Rover mission entering its remarkable second year, as well as upcoming major projects such as the launch and comet encounter of NASA’s Deep Impact satellite mission in 2005, are expected to drive continued high levels of traffic, according to NASA officials.

 It was estimated there were 142 million visits to the site during this period. So the question is how much advertising could be sold for a site this well visited?

Monday, February 2, 2015

Ariane 5 Core plus 4 Ariane 4 side-boosters as a manned launcher.

Copyright 2015 Robert Clark

  In the blog post "Ariane 4 for European manned spaceflight", I suggested resurrecting the Ariane 4 to produce a European manned launcher. In the blog post "A half-size Ariane for manned spaceflight", I suggested using a half-size Ariane 5, so as to be loftable by a single Vulcain 2, to serve as a manned launcher.

 Here, I'll suggest using a full Ariane 5 core but using 4 Ariane 4 liquid side boosters for a manned launcher. I'll use the smaller Ariane 5 "G" version to be loftable by the boosters and the single Vulcain 2 engine. By the on the Ariane 5G, the core has a 12 metric ton (mT) dry mass and a 158 mT propellant mass. By the Astronautix page on the Vulcain 2 used on the core, it had a 1,350 kN vacuum thrust and 434 s vacuum Isp.

 For the liquid-side boosters from the Ariane 4, they had a 4,493 kg dry mass and 39,279 kg propellant mass. The Viking 5C engine used had a 752 kN vacuum thrust and a 278 s vacuum Isp. Plugging these numbers into Dr. John Schilling's Launch Performance Calculator gives the results:

Mission Performance:
Launch Vehicle:   User-Defined Launch Vehicle
Launch Site:   Guiana Space Center (Kourou)
Destination Orbit:  185 x 185 km, 5 deg
Estimated Payload:   15537 kg
95% Confidence Interval:   11748 - 20004 kg

"Payload" refers to complete payload system weight, including any necessary payload attachment fittings or multiple payload adapters
This is an estimate based on the best publicly-available engineering and performance data, and should not be used for detailed mission planning. Operational constraints may reduce performance or preclude this mission.

 The 15.5 mT payload is surprisingly high. Note this is without even using an upper stage.

   Bob Clark

UPDATE, February 10, 2015:

 The liquid-fueled boosters used on the ISRO's GSLV launcher are virtually identical to those used on the Ariane 4, so could be used for the purpose. Indeed the Vikas engines used on the GSLV were copied from the Viking engines used on the Ariane 4 as they were produced under license from the ESA:

GSLV Launch Vehicle Information.
Photo: Indian Space Research Organization

 Also, at a 15,500 kg payload capacity this Ariane 5 core plus Ariane 4 side-booster launcher could loft the Sierra Nevada Dream Chaser, at 11,300 kg.

 European companies are researching with Sierra Nevada the possibility of using the Dream Chaser as a manned spacecraft.

Saturday, January 24, 2015

Ariane 4 for European manned spaceflight.

Copyright 2015 Robert Clark

The Hermes spaceplane because of its size was intended to be carried by the Ariane 5. However, that plan was cancelled because of cost. But if you use a smaller capsule then it could be carried by the Ariane 4.

Two versions would work for a fully liquid fueled launcher, the Ariane 42L and Ariane 44L, the first with two liquid-fueled side boosters and the second one with four. Versions of the Ariane 4 using solid side boosters were also made however for this manned spaceflight application I'm only considering all-liquid fueled launchers.

According to Astronautix, the Ariane 42L could carry 7,900 kg to LEO and the Ariane 44L, 10,200 kg.

Ariane 42L V56 
Ariane 42L V56 - COSPAR 1993-031

Ariane 44L 
Credit: Arianespace

 A crewed version of the Cygnus capsule probably could be produced to mass in the range of 2,000 kg dry mass:

Budget Moon flights: lightweight crew capsule.

     Bob Clark

UPDATE, February 10, 2015:

 In regards to the question of the suitability of the Ariane 4 for manned missions, i.e., whether it could be man-rated, note that it was considered for the purpose in the 1980's:

Multi-Role Recovery Capsule - BAe,1987.
Credit: NASA via Marcus Lindroos
    British manned spacecraft. Study 1987. Britain was the only European Space Agency member opposed to ESA's ambitious man-in-space plan, and the British conservative government refused to approve the November 1987 plan.
    However, the British aerospace industry did propose some interesting alternatives, such as the $2-billion 'Multi-Role Recovery Capsule'.
    British Aerospace Ltd. (BAe) regarded the French Hermes mini-Shuttle as too expensive and complicated. Instead, they felt a simple crew capsule would make more sense as an 8-man 'lifeboat' for Space Station Freedom (NASA issued a competitive request for proposals in late 1987). MRC was to be launched on the existing Ariane-40 rocket and the capsule could be flown manned or unmanned, for sensitive microgravity experiments in orbit.

Thursday, January 15, 2015

NASA Technology Transfer for suborbital and air-launched orbital launchers.

Copyright 2015 Robert Clark

 I have become enamored of NASA's Morpheus lunar lander project. In the post "NASA Technology Transfer for manned BEO spaceflight", I discussed how it can be used to produce a manned lunar lander, or asteroidal lander, for a few 10's of millions of dollars, far less than the $10 billion estimated to be needed by NASA. And in "NASA Technology Transfer for Orbital Launchers", I discussed how its engines could be used for the small orbital launch system Firefly, resulting in a significant reduction in the launcher's development costs.

 I don't think NASA fully appreciates the usefulness of the Morpheus development. Here I'll show how the Morpheus itself can be used to produce suborbital launchers, and also the stages for orbital launchers. For instance the Morpheus can be used to provide the solution to DARPA's ALASA air launched, small orbital system.

 The Wikipedia page on the Morpheus gives its propellant load as 2.9 metric tons (mT) and dry mass as 1.1 mT. Its methane/LOX engine has an Isp of 321 s with a thrust of 24 kN, 2,450 kilogram-force (kgf).

 Note this means when fully fueled the single engine could not lift the vehicle in Earth's gravity. The single engine of course would be fine for its intended purpose as a lunar lander at 1/6th gravity. However, for a Earth launch system we'll use a half-size vehicle to be launchable with a single engine. Rounding off this gives it a propellant mass of 1.5 mT and dry mass of .5 mT. Compared to the full Morpheus this will have only two spherical propellant tanks instead of four, one each for the liquid methane and LOX.

 Since this will be reaching high velocity through Earth's atmosphere it will have to be streamlined. Then we'll place the two propellant tanks inline vertically. We'll also need an aeroshell. To save weight we could make the aeroshell composite. Another possibility would be to make the aeroshell inflatable. Since the aeroshell would not need to be load-bearing and with the possibility to make it inflatable we'll assume it adds only a small proportion to the weight. We could save additionally weight by making the tanks out of aluminum-lithium alloy, titanium, or composites. Alternatively, we could use a cylindrical tank to hold the propellants to eliminate the need for an aeroshell.

 Suborbital Case.

 This page gives the required delta-v for a suborbital flight as in the range of ca. 2,400 m/s:

Flight Mechanics of Manned Sub-Orbital Reusable Launch Vehicles with Recommendations for Launch and Recovery.
Mechanical and Aeronautical Engineering Department, University of California, Davis, CA 95616-5294
Marti Sarigul-Klijn Ph.D. and Nesrin Sarigul-Klijn*, Ph.D.
An approximate delta V to reach 100 km is 7,000 to 8,000 fps (2,100 to 2,400 m/s) for vertical takeoff, with slightly less delta V needed for air launch, and significantly more required for horizontal takeoff.

  Now, at a 1.5 mT propellant load, .5 mT dry mass, .25 mT payload, and 321 s Isp, the vehicle can do a delta-v of 321*9.81ln(1 + 1.5/(.5 + .25)) = 3,460 m/s, sufficient for a suborbital flight.

 There are commercial opportunities for suborbital flight with NASA. Also using two to four copies or scaled up that many times this could also be used for a suborbital tourism vehicle.

DARPA Air-Launched Orbital Vehicle.

 DARPA is funding research into a small air-launched system called ALASA, As described in the blog post "Dave Masten's DARPA Spaceplane, page 2: an Air Launched System", high altitude supersonic air-launch at Mach 2 can cut 1,600 m/s from the delta-v needed for low Earth orbit. This would reduce the delta-v that needed to be supplied by the rocket from 9,100 m/s to 7,500 m/s.

 We'll use two copies of the half-size Morpheus firing in parallel and cross-feed fueling. Cross-feed fueling allows the upper stage to have its full level of fuel after staging, unlike the usual case with parallel staging. As in the earlier blog post, we'll again use the Star 17 solid stage as the final, orbital stage:

Encyclopedia Astronautica.
Star 17
Solid propellant rocket stage. Loaded/empty mass 124/14 kg. Thrust 19.60 kN. Vacuum specific impulse 280 seconds.
Cost $ : 0.580 million.
Status: Out of production.
Gross mass: 124 kg (273 lb).
Unfuelled mass: 14 kg (30 lb).
Height: 0.98 m (3.21 ft).
Diameter: 0.44 m (1.44 ft).
Span: 0.44 m (1.44 ft).
Thrust: 19.60 kN (4,406 lbf).
Specific impulse: 280 s.
Specific impulse sea level: 220 s.
Burn time: 18 s.
Number: 25 .

 Then we can get a payload of 55 kg to orbit by supersonic air-launch:

321*9.81ln(1 + 1.5/(.5 + 2.0 + .124 + .055)) + 321*9,81ln(1 + 1.5/(.5 + .124 + .055)) + 280*9.81ln(1 + .110/(.014 + .055)) = 7,690 m/s.

  Bob Clark

Tuesday, January 6, 2015

NASA Technology Transfer for manned BEO spaceflight.

Copyright 2015 Robert Clark

  The Morpheus lunar lander developed by NASA demonstrates how successful NASA can be when it takes a low cost approach to developing new systems. Not only can the Morpheus be used for unmanned robotic landers, but scaled up it can produce a manned lunar lander at orders (plural) of magnitude lower cost than the $10 billion NASA previously estimated for a lunar lander. Then Project Morpheus becomes a prime example of how NASA's Technology Transfer program can be utilized.

 The orders of magnitude reduction in cost is important for enabling the low cost commercial space approach to BEO (beyond low Earth orbit) spaceflight. For this to work, first, the companies that engage in the commercial space approach have to be convinced they can make a profit on such ventures. This is much easier to do when the development costs are in the ten's of millions of dollars range rather than the billions of dollars range

 Now note that by taking a smaller, modular approach to BEO spaceflight, as exemplified for example by the Early Lunar Access proposal, it is only a lander that would be needed to be developed for lunar flights.

Early Lunar Access. Credit: NASA

This actually is also the case for asteroidal flights since the delta-v to near Earth asteroids is actually less than that to the Moon. No hugely expensive super heavy lift launchers would be required. Only currently existing launchers, or those fully paid for by the developer such as the Falcon Heavy, would be used. Then that huge proportion of the development cost of such missions for the HLV would be eliminated.

 Then at least the development costs, aside from the launch costs, can become manageable for private financing. Then private BEO proposals such as by Golden Spike Company. Planetary Resources, Inc., Deep Space Industries, etc. become feasible.

  Bob Clark

Saturday, January 3, 2015

NASA Technology Transfer for Orbital Launchers.

Copyright 2015 Robert Clark

 NASA's Technology Transfer Program intends to partner with U.S. companies to commercialize technology developed at NASA. One example is the autonomous landing system for robotic lunar landers (ALHAT) developed by NASA which will be used by the Moon Express team for their Google Lunar X-prize entrant. 

 I suggest another example that has more important commercialization potential are the methane engines developed for NASA's Project Morpheus robotic lunar lander. The Firefly launch company intends to make small methane fueled orbital launchers. The largest single development cost for a launcher are usually the engines. By using the engines already developed for the Morpheus lander for the Firefly, a significant proportion could be cut from the development cost.

  Bob Clark

Tuesday, December 30, 2014

A half-size Ariane for manned spaceflight, Page 2.

Copyright 2014 Robert Clark

  Whether Europe will build a manned launcher is not an engineering question. It's an economics and politics question. The European Union has the greatest economic might in the world as measured by GDP, including that of the U.S. It's greater than that of the space faring nations of Russia, China, and India combined. Moreover, Germany, France, Italy, and the UK, individually have greater economic power than India. Yet Europe has no plans to produce a man-rated vehicle. 

The currently accepted plan for the Ariane 6 is to cut down the size of the Ariane 5 core and spend funds on developing an upgraded version of the solid stages used on the Vega launcher to be used as side boosters. The ESA has agreed to spend $10 billion developing the Ariane 6 and upgrading the Vega to the Vega-C.

The half-size Ariane would have much smaller development cost since you would not need these new side boosters. Nor would you need the larger second stage using the Vinci engine. It would use the current cryogenic upper stage of the Ariane 5.

It would have a smaller payload than the Ariane 6 at about 4,800 kg for the two stage vehicle . But it would have about the same payload capacity of the upgraded Vega, the Vega-C. The Vega-C will have about 2 metric ton greater payload than the Vega, which will put it in the range of 4,500 kg.

The Vega already costs in the range of $50 million per launch. The cost of the Vega is in the range of $20,000 per kilo to orbit. The high cost probably deriving from its high development cost, in the range of $1 billion. The Vega-C needs an approx. 50% upgrade in size of the main solid stage, likely resulting in high additional development costs. Then judging by the approx. 50% upgrade in payload capacity, this would give it an estimated cost of $75 million.

In contrast, due to the low additional development needed for the half-size Ariane its cost would likely be comparable to other liquid fueled rockets in the range of $10,000 per kilo, or $48 million per launch.

Beyond that another very important advantage is that it could be made reusable if SpaceX succeeds in reusability. If SpaceX does succeed in cutting costs by reusability then the Vega and Vega-C immediately become obsolete. The half-size Ariane on the other hand would be able to keep pace with the price cuts by also being made reusable.

I mentioned the considerations on whether this could be undertaken were financial and political. The main financial reasons it should be undertaken are that it would have lower development cost than the Vega-C and would serve as a hedge against SpaceX succeeding in reusability.

Ironically, this might be the same reason why it might not be undertaken for political reasons, because it would undercut the Vega rocket, which is largely being built in Italy.

  Bob Clark