We're engineers working on the launch vehicle and spacecraft technologies that will help NASA on its Journey to Mars. Ask us anything about how we will get there.

Do any of you play Kerbal Space Program?

Not yet! But, sounds like something I need to check out. - Andy Schorr

In both the Martian and Interstallar the space ship has a similar design wherein there is a large rotating portion, I suppose that's to create a gravity type of effect. Is that feasible or mostly sci-fi?

The theory of a rotating habitat to create artificial gravity is sound, the challenge is always actually building it. To create sufficient artificial gravity the rotating structure would need to be over 700 ft across which makes for an extremely large spaceship. This necessitates multiple launches and assembly in orbit. But if the transit habitat design uses this concept, NASA will be able to leverage past work on the ISS construction as enabling engineering. - Nujoud Merancy

Hey NASA, I have a couple questions about the launch sequence and staging of SLS and Orion.

With both the 70T and 130T launch Systems, will the Core stage go orbital, or will the 2nd stage complete the LEO burn? Will any of the stages be reusable for future launches? What would be a mission that would realistically max out the 70T’s and the 130T’s performance?

Can’t wait to see these things launch in person come 2017!

MT - The core stage does make orbit for both configurations but it is not sustainable and falls back to earth, partially burning up and landing in the ocean. The 70 mT configuration does not have a true second stage, but the 105 mT and 130 mT configs will. This second stage will be what takes us beyond low earth orbit on to places like the Moon or Mars. None of the stages are planning on being reusable at this time. The SLS is designed to handle the heavy Mars missions which is roughly what sized the 130mT configuration.

Would there be value in maintaining the 70mt version once the 105mt version comes online?

MT - The different between the two configurations is the Exploration Upper Stage (second stage) which delivers the 105 mT capability. It's unlikely we would return to the 70 mT config unless it was needed as backup for ISS resupply.

The core stage will re-enter earth atmosphere and burn up like the External Tank for the Space Shuttle. The Upper Stage will provide the insertion burn specific to the mission, for EM-1 it's the translunar injection. For asteroid return, the Upper Stage provides that mission specific burn. Orion is the only reusable part of the system. -- andy schorr

SLS will fly similar to current launch vehicles so generally the 2nd stage completes the mission. Look to see you at the Cape. - Rick and Darby

What is one thing you don't understand and completely blows your mind?

Women. And I've been married for 29 years. - Andy Schorr

Bill Pratt - The multiverse. I can't imagine that somewhere in a parallel universe there is another me who is sitting on a beach instead of doing a Reddit!

JC- I wish there was only one thing I didn't understand. I'd like to know why Mars lost its atmosphere, its magnetic field, and its liquid surface water.... could this happen to us on Earth? That's why I think we need to explore Mars.

Any chance you can do better than first manned landing by 2039? (Phobos while cool doesn't count)

Current funding plans enable the 2039 landing. There are no technology barriers to landing in 2033 or 2035. -Rick and Darby

What do you enjoy most about your job? Did you enjoy watching the Martian?

JC- Working with a team of NASA and industry partners to translate Mars plans into reality. Yes, I loved watching the Martian, everytime I've seen it...

What I enjoy most about my job is putting it together and seeing our work actually fly in space when we are done. That is a satisfaction in engineering to actually have tangible products at the end and we get to do it in the most challenging environment possible to the benefit of humanity. - Nujoud

The opportunity to be a part of something truly historic. To know I am a part of extending human presence beyond our planet. -- andy

Totally enjoyed watching the film and I thought it captured the spirit of NASA in an entertaining yet informative way. Clearly communicated the ability of the team to collectively come together and solve problems that needed to be solved, no matter the challenges. Matt Damon for an Oscar. -- andy

MT - Coming to work with such a capable, passionate and dedicated group of team members every day. Plus, the "yes, I am a rocket scientist" line is fun to use.

Bill Pratt - I love physics and math! Being able to come to work and apply that to real problems gives be great satisfaction. Knowing that what I work will make a lasting difference is also not bad : ) Haven't seen the movie yet so no spoilers (I did read the book though, loved it)!

Darby- What's not to love about working on the rocket to Mars?! Rick- I like searching for innovative solutions to enduring problems. The Martian - We loved it!

Knowing that we are all working on the mission of a lifetime ... building the systems and teams that will one day take the first humans beyond low earth orbit, beyond the moon, eventually to Mars. For most of us involved in the space program, working on these programs and projects are the fulfillment of a lifelong dream. I loved the Martian!!! It captured many aspects of a future Mars mission very accurately.

Will the Orion capsule be reusable (at least partially - think the space shuttle), or will there be a new capsule made for every new flight (like the Soyuz)? Thanks for the AMA!

Many items from the Orion capsule are reusable, in particular most of the interior items such as the flight computers, displays, environmental systems, etc. However, the primary structure, heatshield, thermal tiles, and external components will not be reused. These are more expensive to refurbish especially after being dunked in salt water which is extremely corrosive. So the "capsule" itself that you see will not, but we will be able to strip the interior and reuse a large portion of very valuable equipment. -NM

What is the timeframe for "refurbishing" a new Orion capsule?

Each capsule will take a couple years to build from "scratch" which starts all the way back at machining out aluminum structure. However, components from one flight don't have to be used on the very next flight and can be 'skipped' or phased into later vehicle build up depending on how long any given component needs to be tested to ensure functionality. -Nujoud

Hi Nasa, you guys are doing awesome work! Are designs in progress for the vehicle that astronauts will live in for the Journey to Mars? And if so, what is the basic setup of such a vehicle?

Bill Pratt – A lot of research has already been done on what a Mars Transit Vehicle would need to look like. There are still questions though such as radiation protection, closed loop life support, propulsion, etc. NASA is currently considering testing these critical capabilities in what they call the “proving Ground” http://www.nasa.gov/sites/default/files/atoms/files/journey-to-mars-next-steps-20151008_508.pdf. A precursor to a Mars Transit Vehicle could be what is known as a cis-lunar habitat. It is a habitat that would live in the area around the moon and provide a small laboratory for NASA to work out these challenges.

Since, at least initially, SLS is using 5 Segment SRBs, that are not reuseable, which are very similar to the 4 segment STS boosters which were designed to be reusable, what differences in construction are there? Weight savings? And are there any major improvements?

MT - We dropped many thousands of pounds from the boosters by eliminating the recovering system the 4 segment version used. Lot of improvements were made in terms of how we manufacture the boosters and the materials we use. Most of these changes were made to improve reliability and reduce cost.

How will the astronauts be shielded from radiation while in the Mars Transit Vehicle?

Bill Pratt – Radiation protection is a critical system needed for long duration deep space transit. Many ideas exist on how to mitigate it but so far no one has been able to test them in a deep space environment. There are two types of space radiation. The first is created by solar particle events. Orion is actually built to provide a safe haven in the event of one of those. The other is what’s called galactic cosmic rays. Those are particles from outside the solar system that are constantly streaming in (although the earth’s magnetic field does a good job of shielding astronauts on the ISS from these—not the case in deep space). The ideas for mitigating that radiation type range from using recycled plastic trash, to recycling the astronauts’ solid waste. Could be the first deep space stucco habitat in history! (sorry, couldn’t help it : ) )

Who is your "Rich Purnell"?

Good news, we have several "Rich Purnells"! There are trajectory design experts at several centers. For mission planning, I have the honor to work with the team hear at JSC, but JPL and other centers also have dedicated folks. We can use a few more though if you get a degree in astrodynamics! - Nujoud

In the movie "The Martian" it seemed water and oxygen were produced while on Mars.

It seems to me that any Mars expedition will likely be pretty long term. With the current state of technology, which, if any, resources would be more feasible to extract/produce on Mars rather than bringing them with?

JC- water is definetly something we will try to produce and oxygen is also likely. There is a small experiment called MOXI that will fly on the next Mars Rover 2020 to demo that technology.

Currently we're in the feasability study phase to both identify and mature the technologies that appeared in the film... Our ISS ECLSS system today provides breathing air and water for our astronauts and we anticipate ECLSS technology advancing for surface habitats, the Veggie mission is growing lettuce and much much more -- andy schorr

I've seen the concept art for the Mars Transit Vehicle, and it shows a habitat module with large solar arrays on the side. How would the mechanics of travel to and from the surface work? Are there any WIP schematics available for us engineering buffs?

Bill Pratt – So a crewed descent to the Mars surface is perhaps the toughest part of a Mars mission. Imagine Seven Minutes of Terror times 10! This would likely be done in a smaller transfer vehicle in order to minimize mass. It’s tricky because of the thin atmosphere of Mars. It would likely combine multiple solutions to perform (aerothermal, retro propulsion, etc.). The ascent would be done very similar to the way you see it in “the Martian”, with a dedicated ascent stage. Many papers have been published on this but I’m not sure about schematics!

The Mars transit vehicle remains in Mars orbit. A separate Mars lander would take the crew to the surface. Look for info in Aviation Week or Space News. - Darby

Outside of funding, what do you consider to be the biggest problems facing the EM-1 launch of SLS and Orion?

Doing something we haven't done in 40 years - developing a human rated launch vehicle and leaving low Earth orbit. The success of the major milestone reviews show we have addressed all of the engineering challenges and are moving to production. Keep the support coming and we'll fly in 2018. - Darby/Rick

In your question, you've hit on the biggest issue ... when managing a large, complex multi-year development program, budget and schedule are major challenges. I have complete confidence in the technical abilities of our team to meet those challenges. Appropriate testing and analysis have been completed and/or are underway to confirm we have a safe vehicle to go fly. - Andy Schorr

MT - Assembling and preparing space hardware for flight is tough business, especially the first time you build up a brand new vehicle. We like to say the devil is in the details. So getting all the interfaces and all the parts and all the systems to work flawlessly can take more time than you plan for. This is why we carry some schedule margin to handle surprises. So far, we are on schedule and the major technical challenges have been addressed.

In the movie, The Martian, a large storm forced the crew to evacuate. Would it not be a good idea for the crew to dig and build an ' underground bunker' for them to store important instruments and seek shelter in case a similar event took place?

The Martian was fantastic for scientific and engineering accuracy, but... the wind storm was the largest glaring error (thankfully over quickly and easily forgiven). The atmosphere is so thin on Mars that a windstorm as portrayed is not possible. Even at 100mph, the wind of Mars would be equivalent to around a 10mph Earth breeze in terms of aerodynamic pressure. So a windstorm alone would not need such serious action to be taken. But the dust devils seen in the movie are very real phenomena captured by rover cameras! - Nujoud

I think that's a great potential solution. Certainly one that requires some investigation. It's easy to be constrained to what you've done before and not necessarily consider creative solutions. Great input! - Andy Schorr

Has the decision been made yet on whether the solid or liquid booster candidate will be used for the second generation SLS? They both seem to be very strong contenders.

No, they are both still candidates. -- andy

Metric or Imperial units?

Both :). The US build Orion in Imperial, but a large part of the Service Module is being developed in Europe in metric. And, yes, we are very focused not to miss a unit conversion! - Nujoud

Hello!

In layman terms, how do the Orion and SLS compare to a rocket like the Saturn V? What are the biggest advancements?

Also, since everybody's wondering, around when will the first manned or unmanned flights for these two rockets be taking place?

Thanks for doing this AMA!

SLS enables the same type of exploration and more than the Saturn V. Biggest advancements are ability to go past cis-lunar; SLS is more than 10% bigger, providing capability to launch the Journey to Mars. And you're very welcome. Thanks for your interest! - Rick/Darby

Check out a previous comment for the answer to your first question. The vehicle will be ready to launch in 2018. - Andy Schorr

Good afternoon! Where does technology stand (in a deployable way) for ISRU systems transportable to the moon/mars?

ISRU Technology has matured significantly over the last 20 years. An ISRU experiment will accompany Mars 2020, a planned $1.9 billion roving laboratory similar to the Mars Curiosity rover currently cruising the Red Planet. Check this link out: http://mars.nasa.gov/mars2020/news/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=1683

Are there any fears of contaminating Mars by landing a manned mission, especially if there are plans to produce water and oxygen, or is that the plan, i.e. to colonize Mars by cultivating aerobic bacteria & plants to kick-start an ecosystem?

JC- Great question! With the recent discovery of flowing water this issue is a hotly debated topic. Any human mission will take along our "bugs." If we explore, we will impact the Martian environment in a limited way. If we colonize, we will have to change the Martian environment to survive. Just like Mark Watney.

Planetary protection program sets the requirements that dictate how we keep spacecraft and crew, as well as Mars, free of cross-contamination. It protects the integrity of both planets. - rick and darby

This may sound silly but are there any plans in case life is found underground during the mission that may compromise the safety of the crew? How long would an emergency evacuation take?

NASA has a stringent planetary protection program that will address those scenarios prior to landing. Evacuation to Mars orbit is most practical and could be done quickly. Rick/Darby

JC- NASA takes planetary protection very seriously. Any indication of extant life from robotic precursor missions will severely limit approach by future human crew or robotic rovers. We won't mess around until we are sure it is safe.

I love the work you guys are doing on the SLS. Two questions: -What are you guys using to launch the Orion capsule for NEO missions? An entire SLS for a single Orion launch to NEO seems rather wasteful.

This one's for Mr. Cassaday: Whatever happened to the RL-60?

Bill Pratt - Actually, an SLS with the exploration upper stage (should be ready by EM-2) will have the ability to launch an entirely separate spacecraft WITH Orion every launch. Two for the price of one!

JC- Current plans for upper stages don't involve RL-60; however, NASA may consider again in future years.

Will SLS be used for unmanned missions? I've heard the opinion that there aren't enough (scheduled) missions for SLS to become financially feasible... is this the case?

JC- yes, SLS will be used for unmanned missions. One, we need it to launch cargo and two, science missions like Europa will benefit from SLS capability (it shortens the time by 5 years)

Yes, carrying crews and cargo have been built into design from day one. On the first uncrewed EM-1 we will carry up to 13 cubesats in addition to our primary mission of checking our Orion and integrated flight systems. Going forward large payloads can benefit from the volume available on the SLS vehicle allowing a less complicated design and higher reliability. Here's a story for more info about science options http://www.nasa.gov/exploration/systems/sls/space-launch-system-to-boost-science-with-secondary-payloads.html -- andy schorr

What kind of fuel and how much of it will be needed to get there?

MT- The type of fuel is really dependent on which part of the propulsion system you are looking at. For example, the core stage uses liquid hydrogen and oxygen. The boosters use solid propellant. Solar electric propulsion systems are being strongly considered for in-space propulsion. These systems would use Xenon. How much fuel again depends on the type of propulsion but suffice it to say it's millions of pounds to get out of earth orbit and thousands and thousands to transit to Mars.

JC- Current plans include solar electric propulsion (SEP) for transporting cargo that will use xenon. Also, will need hydrogen and oxygen and storeable propellants, like hydrazine for crew transfer. By using SEP, you can save more than 50% of propellant mass launched.

What kind of new propulsion systems/new fuels do you have in mind for this journey?

MT - Xenon is being considered for the solar electric propulsion systems. Some nuclear and plasma systems are also being considered.

How many astronauts will be able to fit in Orion, and how long will it take for Orion to get to Mars, and are you considering a flyby mission (manned or unmanned) before sending crews to the surface?

Initially, we are designing for 4 astronauts to fit in Orion with all the food, air, water, and life support needed for 21 days. Space wise, there is the potential to add 2 crew for a total of 6 if mission plans call for it in the future. A one-way trip to Mars will take around 9 months, so clearly Orion can't do this all by ourselves. Mission architectures call for additional habitat modules and equipment to support the Mars mission and the primary Orion function will be to take the crew safely to and from Earth to space. Our first mission will be to cis-lunar space unscrewed to test all the systems out in 2018, followed by a crewed flight in 2021. Longer term plans are not finalized so whether the first Mars mission has a crewed lander or not is unknown. -NM

First off I want to say huge admirer of NASA! My question is considering you need more advanced propulsion systems to send people farther than before at what point do you think an artificial gravity system that mimics earth's would be possible if so?

JC- Thanks for being a fan; we need you guys! NASA is already developing high-power SEP to transport 80%+ of the material and equipment needed at Mars. By doing this, we can send crew faster using SLS & chemical propulsion. Won't use artificial gravity on first missions, but it could be brought on later.

Are there any plans to make the SLS available to launch payloads other than the Orion spacecraft? For example, lifting segments of a possible successor to the International Space Station?

Yes. SLS is the candidate to launch Europa Clipper. SLS will have cargo capability such as habitats. - Rick and Darby

JC- Yes, plans include using SLS to deploy HAB modules to lunar orbit for "proving ground" extended duration human missions in the 2020s. That will prepare us for Mars missions in the 2030s.

What do you think are the remote sensing applications for the new launch vehicle and spacecraft technologies? Will any of these new technologies be fitted with a spectrometer? If so, what wavelength frequency/frequencies will be examined?

Thanks so much for doing this!

While we are not outfitting Orion with science sensors specifically, we are reserving space, power, and data links for future scientific equipment. So our base vehicle will support science platforms as a generic capability and then depending on the mission could be outfitted as needed. No reason why a spectrometer couldn't be one of the future sensors. - Nujoud

I've read the SAC-503 Saturn V flight manual cover to cover - is there any similar publicly available resource detailing the engineering or construction of the SLS or Orion?

Certainly, an internet search would identify publicly available information that does not violate export control or ITAR restrictions. Conference papers (i.e. AIAA) are a good source of the information you're looking for. - Andy Schorr

Comparatively speaking, how much more or less powerful is the first stage of the SLS versus the SV, the Soviet N1, or the Shuttle?

Thanks for the AMA!

Comparatively speaking, the SLS will be approximately 10% more powerful than either Shuttle or Apollo. This is primarily due to taking the proven 4-segment shuttle solid rocket motors and extending them to 5 segments to up the power from approximately 2.8 million pounds of thrust to 3.6 million. Comparisons to the Russians - do not have any information for that. - Andy Schorr

Given this power increase, are the burn times or staging affected, or does an increased payload make up for the gains over the SV launch vehicle? I guess what I'm asking is - where is this extra power used?

MT - The staging and burn times are all specific to the SLS vehicle. All of the extra power is either being used directly for payload gain or to place payloads into higher energy orbits.

MT - The SLS first is comprised of the boosters and the core stage (with the core stage continuing to burn as the second stage after booster separation). The boosters are 25% more powerful than Shuttle and the core stage has one more SSME than the Shuttle orbiter had. Not sure of the exact N1 total thrust level but it was comparable to Saturn V. SLS is more capable than Saturn V.

Again the plan is to put astronauts in a small capsule, seated, with little opportunity for movement and along period in 0 gravity. Is it too hard to assemble a livable station in orbit then propel it to said destination as a spacecraft? Or is it just too expensive?

Bill Pratt - A multi-year mission to Mars will certainly require larger habitable volume than a single capsule. NASA has in mind building something called a Mars Transit Vehicle which would carry the crew to and from the planet. Such a vehicle could be assembled out in lunar orbit instead of launching in one piece.

Hey NASA! In the Martian, the 'Hermes' spacecraft uses a particle accelarator to reach Mars in a little less than half a year. My question for you guys is what is the engine on board the Orion spacecraft? Is a particle accelarator in long-range space travel possible? Thanks for the AMA and all you guys do!

JC- Orion has a storable bi-propellant engine. In his book, Andy Weir, uses a nuclear powered system for Hermes propulsion. Because it costs less, we are currently developing solar powered electric propulsion (SEP) to deliver and pre-position cargo for human Mars missions. The crew will travel in a separate spacecraft using chemical propulsion. In a sense, we have broken the Hermes into two spacecraft to more efficiently accomplish the mission.

What is currently thee largest hurdle NASA faces in its Jounrey to Mars and how can the public help support that mission and future NASA missions?

The ability to plan over multiple years, which is enabled by solid public support and funding. Let your elected representatives know of your support. - darby/rick VonBraun: "There's one thing I can promise you about the outer space program: your tax dollar will go further."

MT - Stay the course - political will.

What were the deciding points to making the Orion capsule for water landings only, instead of ground landing like Soyuz? I would expect that would make partial capsule re-use easier.

Primarily this was driven by the need to reduce mass and complicated systems. To safely touchdown on land, additional airbags, heatshield release systems, and others were needed while a high level of risk still remained to verify a safe landing (e.g. what happens if there is a rock right where the vehicle lands?). In the end, the safe landing in water in exchange for a lighter vehicle (which means less mass we have to send to the Moon or Mars) was the deciding consideration. - Nujoud

Thanks for the answer, that makes a lot of sense.

One issue I have when landing in KSP from a Mars return in RSS is that you don't have a ton of control over where you land, since you are bound by safe re-entry constraints for the crew and capsule at such high speeds.

In reality, does that translate to having less control over where and when the crew lands in a Mars return flight land? In particular, might this force the crew to land at a time and place where conditions are sub-optimal for capsule recovery?

Orion performs a guided entry to a very specific point to deploy parachutes at 24,000ft. With that precision, even the parachute drift with the wind will land within a 10km circle (not bad considering where you started, Mars!). We also have the ability to retarget entry 'uprange' several hundred miles to divert if there is bad weather at the primary landing site. - Nujoud

How do you track space craft in space ? Low orbit from earth is doable, imho since you have earth "right" there, but how can you be sure that the space craft is where it should be ?

Great question and one I love from my Guidance, Navigation, and Control roots! In LEO, the NORAD radar does an excellent tracking job, in cis-lunar space and beyond though we will be beyond radar capability. The most common tracking method for navigation is to use radiometrics (the Doppler effect) with the communication system back to the Deep Space Network. In effect, the comm system serves two needs in that regard. Other methods we will demonstrate as a backup for safety starting on Orion's EM-1 mission will be with optical navigation which uses cameras and image processing algorithms to measure the Earth or moon radius to determine position. Longer term, this can be applied to Mars missions as well. - Nujoud

whats the main purpose of going to mars? is it for human expansion or military advancement? also is mars the best destination for our first mission? was it picked due to distance or actual factual data supporting the ability to be able to harbor life?

MT - The reasons for human space travel can be very personal and well as practical. History teaches us that nations who have stopped exploring fade from the world stage. Meeting the challenge of exploring and overcoming the risks associated with it make us better and world leaders. In this journey, we develop a whole cadre of technology that benefits everyone, even here on earth. As far as the first mission goes, NASA is looking at an incremental approach where we travel further and further from earth (Moon, L2, etc.) and then on to Mars.

How long are you planning on using Orion and this SLS?

It is an evolvable system encompassing 70 metric tons to 130 metric ton configurations, carrying both crew and/or cargo as we proceed from Earth-dependent missions to proving ground missions to fully Earth-independent missions. It is the launch system for the next generation of space exploration. - Andy Schorr

What are the main remaining challenges for engineering the SLS? Or is it essentially finished in design and it's just a matter of production/testing now?

SLS has successfully completed all major design milestone reviews and the engineering is well understood. EM-1 flight hardware is in production now across the country. Building the largest rocket in the world has its own challenges, but so far, so good. rick/darby

What will a successful landing on Mars bring to the table for the scientific community? How quickly would it (theoretically) make us able to solve many of our current "interstellar space" problems? Thanks for this AMA!

Humans on Mars enables multiple increases in science yield by eliminating communication delays and allowing rapid selection of scientifically interesting experiments. Crew on the surface means you can make quick decisions - improving science yield. Rovers have to 'phone home.' rick/darby

Is it also possible to place a refueling station/launch on the Moon, for safety, in case of disaster for the manned missions; as well as prudence, to refill Mars supplies quicker and more efficiently?

Bill Pratt - Actually, once you've gotten to the moon, you're almost there, in terms of the energy required to get to Mars. What might really be helpful is if we could put a refueling station on one of the moons of Mars (I personally like Deimos) for the ride back.

NASA is studying a variety of missions near the Moon. These include using lunar resources for fuel and crew supplies like oxygen. It takes less rocket fuel to leave for Mars from the Moon so this would be more efficient. - rick/darby

Why skip the moon, shouldn't we build a base? Is this just because policy from higher up, not necessarily what makes the most sense?

No final decisions have been made. Depending on the mission, the most appropriate stepping stones to achieve an ultimate destination will be considered and selected as appropriate. - Andy Schorr

I know NASA has been utilizing and modifying 3D printing technology at it would be beneficial for long term/long distance space explorations. I was wondering what kind of role it's playing in this specific effort, if any at all? I'm currently doing a project on this, so this AMA came at the perfect time. Thanks guys :)

Additive manufacturing is a focused technology being developed and matured because it has amazing potential and capability to allow spare-part manufacture, tool manufacturing or other capabilities that would not be possible to manifest for the long duration missions envisioned. We are also using 3D-printing technology to evolve and improve rocket engine performance, reliability and production. - Andy Schorr

Bill Pratt - Great question! I believe that 3D printing will be a must for a mission to Mars. Imagine having to take 2 or 3 of everything in case something breaks! Being able to print spare parts could be a huge mass/volume savings. We are just realizing the benefits in mass, time, and cost in designing components on the ground to be 3D printed instead of manufactured in traditional ways (allowing us to bring more critical supplies). For example, Orion flew 3D printed pressure vents on EFT-1.

Will Orion be used to bring astronauts to mars orbit or it will be used for launch and re-entry?

The primary goal for Orion is to bring the crew safely to and from Earth orbit to destinations beyond LEO. FOr long duration missions, such as a Mars mission, additional modules for habitation, landing on Mars and returning will be needed. Because the atmosphere of Mars and the Earth are so different, the landing technology is not easily made to suit both purposes. Earth = high heat & thick atmosphere, Mars = low heating and insufficient braking for a parachute only type of design. - Nujoud

I'm interested in doing stuff like this when I grow up- what classes should I take in high school and what major should I pursue to get a career in this field? Space travel has always been amazing to me, and I'd love to help humanity in the way that you guys are.

My journey to the space program was enabled by my mechanical engineering degree, as I was interested in structures and propulsion systems. However, what you are most interested in is what you will most enjoy and be able to contribute as a result. While technical degrees will always have a place, it takes a family of disciplines, such as budgeting, industrial safety, human factors, etc., for mission success. - Andy Schorr

Much of what we do at NASA involves engineering and science. You should consider taking as many science and math courses as possible such as physics, chemistry, biology, earth science, algebra, trigonometry, statistics and my favorite, calculus. These classes will help you prepare for a degree in science and/or engineering. Internships in science and engineering are also a great way to learn more about a potential career. Shawn, Charlie and Amber

How much influence did the spacecraft used during the Apollo missions have on this new system you guys are building? What kind of things did you learn from it? What will you do differently and what will you do the same?

Bill Pratt - Probably the biggest similarity is in the shape. Those Apollo guys did a great job there! However, there are probably more differences than similarities. From the controls and displays to guidance and navigation, Orion is quite a bit more advanced

Clearly, we are building and standing on the shoulders of those that developed those groundbreaking systems. The data gathered and lessons learned through both Apollo and Shuttle have been leveraged in developing the system we are fielding today. - Andy Schorr

Are there any concepts for MAV and MDV? Will those ships be based on Orion spacecraft?

Early concepts are in development. The functions of the MAV and MDV will require unique engineering solutions that may borrow from Orion approaches, or the Mars transfer vehicle, or International Space Station, or even NASA's current Mars landers. - Darby/Rick

A followup on the "Why skip the Moon" question. Is the Altair Lander still a viable lander for Lunar missions or was that scrapped completely ?

JC- Unfortunately, Altair was a casualty of the Constellation Program cancellation. No current work on lunar landers.

Will the core stage of the SLS have enough fuel/thrust to place the ICPS or EUS into orbit, or will either the ICPS or EUS have to use its engines to finalize insertion?

Yes. In combination with the powerful 5-segment solid rocket motors, the first stage of the launch phase is capable of placing the ICPS and associated Orion crew capsule or satellite in an orbit for injection specific to the mission. - Andy Schorr

It will depend on the mission. The SLS with EUS allows us to send Orion and additional payloads to the moon on a single launch. No other launch vehicle can do that. - rick/darby

which sudden technological advance might make you go back to the drawing board in the biggest way (e.g. if suspended animation becomes viable, exotic construction materials becomes plentiful, etc...)?

My personal opinion is a technological advance in propulsion would be the biggest game changer. Being able to take transit time from the Earth to Mars on the order of days or weeks vs. months and years would enable an entirely different approach. - Nujoud

What are your views on the Dutch Mars One project? Do you think it is feasible to have a manned mission as early as 2025?

Bill Pratt - Anyone who can make progress in putting humans on Mars is welcomed! My personal opinion is that we ought to also bring them back to Earth safely...except for a few people I can think of that won't be named.

Thanks for taking the time to do this guys!

What do you think is the largest problem that we face in getting people to Mars? What are the coolest ways we've thought up to get past this?

In my opinion, working the launch vehicle, we have to make sure we have the safest vehicle we can provide to the crew. That's Job 1. Mission safety = mission success. En route and on the surface, life support systems will become the primary objective as noted and utilized in the movie "The Martian." - Andy Schorr

How is the interplanetary stage rocket different from the launch stage?

The launch stage is required to be much more powerful, because it needs to overcome Earth's gravity. That same challenge does not exist in space, therefore a less-powerful, more efficient system can be utilized. - Andy Schorr

What are your favourite sci-fi movies or books that involve futuristic space exploration?

MT - Daddy loves him some Star Wars. And I'm jones'n for the new X-files episodes.

Darby- "Aliens." Kudos to the future Marine Corps! Same director as "The Martian." Rick - "Star Trek - Wrath of Khan."

To what extent does international collaboration surrounding Orion exist? Obviously it is an American led project, but are any other countries providing support or resources?

Bill Pratt - Actually, Orion's service module (provides power, propulsion, and commodities) is being furnished by the European Space Agency and is being built by Airbus. In terms of heading towards Mars, many opportunities exist to collaborate with international partners. No one country will likely get there alone.

I followed the Morpheus Lander project, even wrote an article on it, one of the things they were testing was the use of LOX / Methane as a propellant. And I know the whole is there Methane on Mars controversy still rolls on, but is Methane being considered for a fuel to be harvested on Mars for ascent vehicles, manned or unmanned?

JC- That's great that you know about Morpheus. It is a great test-bed for many technologies, including LOX/Methane propulsion. Methane is likely for Mars ascent vehicle as an in-situ produced propellant.

Considering fuel load and use of optimal transfer windows/burns, is Mars the farthest away SLS/Orion can take a crew?

SLS/Orion is designed to take the first big step into space beyond Earth orbit. The crew will need other vehicles to support them on the Journey to Mars and beyond that are designed for in-space transfers. All of those spacecraft will need SLS to begin their journey. Darby/Rick

The value and necessity of the SLS launch vehicle is the tremendous performance capability that it provides, enabling deep-space destinations that were not possible with the space shuttle system. With this capability, Mars is a stepping stone and not a limiting destination. - Andy Schorr

Will the martian version of Orion vary from EM-1/EM-2 Orion (I ask about communications systems, guidance systems etc.) or would EM-1 version of Orion be ready to go to Mars?

We are building Orion with the explicit capabilities to support long duration (including Mars missions) with ability to be upgraded over time for specific systems. Given budget and schedule resources it doesn't make sense to build "everything and the kitchen sink" on the first versions. The EM1 Orion will be the primary "base" vehicle design with the comm, guidance, and propulsion systems, etc. EM2 adds additional human and environmental control systems. Follow on additions will include docking systems, kits for added thermal control, or potentially other equipment such as for additional people, and specifically a comm system upgrade for long distances (as in even farther than the moon which EM1/2 will support). So the plan is to build a base vehicle design that support Mars missions now, but add on systems as future missions need. - Nujoud