73

Hobbes' answer focuses on why we might want to build SLS. There are also significant barriers to rebuilding Saturn/Apollo. In addition to the (vast) amount of existing technical documentation on those designs, there's a (probably vaster) pool of knowledge that the individuals who actually built the things collected during the process. Nearly all of those ...


38

It's just the aerodynamics. There is high pressure where the air spills out the side that tends to push them apart more than the forces that you mention that pulls them together. Good thing too. A giant parachute with the same drag would take too long to open. Clustering is very commonly used for cargo.


38

There are several reasons: We can do better these days. Saturn and Apollo were designed in the early 1960s, so the design tools used were mainly pen and paper, with some primitive computer tools thrown in here and there. These days CAD can be used to create a design that performs far better (because you can design parts closer to the strength they need, ...


28

NOTE All dollar values are in present day values accounting for inflation. Another reason we're not reusing the Saturn V is the same reason it was cancelled in the first place: cost. The SLS is supposed to be half the cost per launch. Whether that works out remains to be seen. The Saturn V was expensive. The Saturn V program cost \$47 billion over 10 ...


24

The test they were doing didn’t require parachutes. Data-taking ended right after the capsule separated from the tower. Since the capsule’s behavior after that was not part of the test, it could be an inert item. To extend the test through parachute deployment, the capsule would have to be much more complex with the parachutes, deployment system, and a ...


16

Those are covers on the windows. There are 2 large forward-facing windows, and 2 smaller flush-mounted windows: "Do not touch" and "Remove before flight" are not synonyms. The use of "Remove before flight" on a spacecraft that hasn't been fully assembled yet is a bit silly. "Remove before flight" is the standard phrase for covers on an aircraft that must ...


15

From the article: Tuesday’s launch was more focused on testing the launch abort system itself. The parachutes on Orion have been tested 47 times.


13

Back in the early days of space flight, the Soviets did not have large expanses of warm water available to them, where there is no fear of 'enemies'. Unlike the US with large coastlines on the Atlantic and Pacific Oceans. Thus necessity was the mother of invention, and the Soviets needed to land on land. They use parachutes, and solid rockets that fire in ...


13

SpaceX gives the LEO payload of Falcon Heavy as 63.8 tons (presumably in fully expendable mode). Orion, fully loaded with propellant, is about 26 tons. So LEO flight is doable, possibly even with booster recovery, but probably not with 3-core recovery. I can't find specs for the ICPS stage that's going to be used with SLS, but it's a modification of the ...


12

A Venus flyby does little to nothing towards the stated goal: a manned landing on Mars. because you get a lot closer to the Sun than on a Mars mission, you need to modify the spacecraft to reject all that extra heat. There goes the commonality in the spacecraft. A flight time of 5 months vs. 6 months (one way) for a Mars mission is not a significant ...


12

This is not a complete answer as I do not know the status of the parachute development, but here are some reasons a parachute is not needed: Ejected Data Recorders: These ~20 data recorders, literally Raspberry Pis with parachutes and waterproofing, all get the complete telemetry data from the test. This is made up of accelerometer, gyroscope, magnetometer ...


11

A different approach might be to rebuild the Saturn V, with modern techniques, not as a one for one rebuild, but rather take the good parts, and make them better. For example, the F-1 engine of the first stage, (5 used, 1.5 million lbs thrust) is being reconsidered as a more modern version with higher thrust. The nozzle was meticulously assembled in ...


11

The answer is more political than technical. (Will be some opinion here, alas) SLS exists as a booster without much of a mission. Well it has Orion, since SLS is the only booster (except maybe Falcon Heavy once man-rated) that can launch Orion. In Constellation there were several projects. Ares-1 - SRB based manned booster for original Orion design. ...


11

The problem is that Orion + Service Module is very heavy. On the order of 21,000 Kilos. This is too heavy for anything but a Delta 4-Heavy or Falcon Heavy. (SLS probably won't ever really exist). It looks like the Falcon Heavy with cross feed offers 53,000 kilos to LEO. (Cannot find the non-cross feed numbers, since that is a better representation of ...


11

As usual in this sort of thing, there's no single optimal answer because the capsule has to do a few different things, so the shape has to balance different requirements. A narrow cone angle gives less drag on ascent. A large broad base is required for deceleration on re-entry. A squat cylinder gives more convenient usable interior space. I believe the ...


11

Here's an official response: NASA has already fully qualified the parachute system for flights with crew through an extensive series of 17 developmental tests and 8 qualification tests completed at the end of 2018. Test data from 890 sensors was sent in real-time to ground sites as well as recorded on board by 12 data recorders. The 12 data recorders ...


9

Orion is: expensive to operate. It's heavier, bigger, but primarily the development was done in ways that drove the costs up significantly. It is capable of flight to lunar orbit - and it's an overkill to ISS. Too expensive and too overengineered for that purpose. Dragon 2 and Starliner are simply far more cost-efficient solutions. significantly behind ...


8

Without arm and cargo bay and with only one EVA because the Orion has no airlock, the cabin can be refilled with air once, there would be some serious limitations. Orion could maybe be extended with an extra module for such a mission. Orion is not really a complete spaceship like the shuttle was, it is an exploration vehicle component which needs a larger ...


8

This is such an expansive question that it is difficult to answer without writing an entire essay. The answer comes down to the systems engineering process and the mission requirements. As in all spaceflight missions, the payload needs to be protected, especially when a human is the payload. The shape will largely be derived from payload, aside from its ...


7

Geoffc gives all the main information, but it's worth adding that precision in such a landing is low. If you splashdown in an ocean, you have no risk of hitting something you wouldn't want to, like a tree, or a sharp boulder, or a car. Also, a landing Soyuz normally hits the surface and then rolls for a bit, rather than hitting, sinking, and then bobbing ...


7

A big difference is that Lockheed Martin has spent a lot of money on radiation management in the Orion vehicle. That is, they have looked at shielding, placement of bulkheads, food and water storage, etc, so as to quantify the level of radiation you would take in the vehicle. Also, should there be a solar storm, where is the safe spot in the vehicle, and ...


7

Hicks' text on reentry provides a really good look at the derivations of the reentry problem, and touches on the impacts of top-level design choices. For example, although dependent on the actual entry profile, total heat transfer often has the following form: \begin{equation} \bar{Q}_{f} \approx \left(\frac{c_{f}A}{C_{D}S}\right)f(V,\vec{p}) \end{equation} ...


6

Anything that goes into space needs to be robust enough to withstand cosmic rays. That's why computer chips that go into space are usually of the older variety with thicker connections. Mechanical devices such as buttons and switches are more intuitive. You can feel them when they click into place. They don't change what they do because someone updated the ...


6

Much more air flows out the top of a round parachute than out the sides - round canopies without vents oscillate rather violently, notice all the openings in that picture. If you see a canopy with no vents it's probably made of porous fabric, nylon woven for the purpose leaks a LOT of air - you could tape it over your mouth and still breathe comfortably. ...


6

Yes, they can, at least they are designed to do such. Here's some links supporting that: http://www.space.com/21541-nasa-orion-spacecraft-reusable.html http://en.wikipedia.org/wiki/Orion_%28spacecraft%29#Crew_module_.28CM.29 " The CM is designed to be refurbished and reused." http://www.informationweek.com/government/leadership/nasa-orion-space-capsule-has-...


6

The big question is if the Service Module can be refueled in orbit. It is based on the ESA's ATV, which can transfer fuel from itself to the Zvezda module of the ISS. So could it flow fuel in reverse? Seems like a smaller step, than being able to transfer fuel at all. However it seems that the main engine on the ATV uses different fuel (same oxidizer though)...


6

They might be externally alike (as in design/looks), but they are very different spacecrafts. CST-100's design is for commercial use, and for use within LEO, whereas Orion is intended for use beyond LEO. This alone involves a lot of differences between the spacecrafts, such as heat shield design (Orion needs a more resistant heat shield for entrances from ...


6

It appears that the Solar Array Drive Mechanism (SADM) serves two primary purposes: Orient the solar panels toward the sun for maximum power generation. From Spaceflight 101: The wing is connected to the spacecraft structure via a two-degree of freedom Solar Array Drive Assembly that allows the array to be oriented in two independent axes by the Solar ...


5

Orion has already had a pad abort test back when it was part of the Constellation program, in 2010. Pad Abort 1 has its own Wikipedia entry, strangely enough. Pad Abort 1 test was a test of the tractor-style launch abort system (which pulls the capsule with a small rocket mounted on top, a la Apollo). There was a proposed alternate launch abort system, ...


5

Orion, the official current, manned payload for SLS is pretty heavy. Heavy enough that a Delta-4 Heavy is about the only American vehicle currently flying that could otherwise launch it. But Orion is not meant for missions to LEO, everyone is agreed that would be a stupendous waste of money. It is meant for BEO (Beyond Earth Orbit) missions, like ...


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