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OSIRIS-REx Asteroid Sample Return


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Dangit! I was hoping to leave off on KSP for a few more months while mods update and bugs get fixed, but I've got to try this. Got to install so many mods, and I don't trust ckan... I'll hopefully be popping back into this thread sometime soon with my mission attempt, failure or not. But first I have to get an RSS install stable with far too many mods ;.;

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7 minutes ago, TheUnamusedFox said:

Dangit! I was hoping to leave off on KSP for a few more months while mods update and bugs get fixed, but I've got to try this. Got to install so many mods, and I don't trust ckan... I'll hopefully be popping back into this thread sometime soon with my mission attempt, failure or not. But first I have to get an RSS install stable with far too many mods ;.;

Note that any version after 1.0 is permitted, so if you have an older stable build that is fine.  It is also not due until October, so you can still stick to your schedule.

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Rather than go with the cube shape of the actual osiris, I made it egg shaped and rearranged instrument locations. It may not look all that like the genuine thing, but it has stand-ins for most of the instruments, and I absolutely hate trying to build replicas of something - I much prefer put my own twist to a design, within some of the originals specifications/limitations. The spectrometer is the TAGSAM, as its the closest thing to it I was able to find in the hour and a half I've spent building this. It uses UDMH/NTO, rather than hydrazine, for the engine, and the same for the RCS thrusters. The total area and wattage of the panels comes within the ballpark of the real thing, but it is twice as heavy as the osiris. Dry mass of mine is about the wet mass of the Osiris. I'm going to try and plan out the mission later because I'm going to sleep for an hour or two, I can't do something as precise as an asteroid rendevous on 3 hours sleep. Also, I'm using KillAshley's real mass RSS Bennu, frustration will abound. I've only done a handful of successful missions out of Earth's SOI, so wish me luck!

...Just realized I left the name as something random, don't judge my lazy naming habits :P

Edited by TheUnamusedFox
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4 hours ago, TheUnamusedFox said:

Rather than go with the cube shape of the actual osiris, I made it egg shaped and rearranged instrument locations.

So this looks a little like an early OSIRIS concept.  Have fun.

osiris-2004.png

https://dslauretta.com/2014/03/06/ten-years-of-spacecraft-design/

For those striving for spacecraft aesthetic authenticity, here are a couple hundred images (all approved for release).  They are roughly in reverse chronological order of the construction, integration, and testing phase of OSIRIS-REx.

 

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2 hours ago, IonStorm said:

So this looks a little like an early OSIRIS concept.  Have fun.

osiris-2004.png

https://dslauretta.com/2014/03/06/ten-years-of-spacecraft-design/

For those striving for spacecraft aesthetic authenticity, here are a couple hundred images (all approved for release).  They are roughly in reverse chronological order of the construction, integration, and testing phase of OSIRIS-REx.

 

Those will definitely come in handy.

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23 hours ago, IonStorm said:

For those striving for spacecraft aesthetic authenticity...

It may not be obvious, but the red things are remove-before-flight covers as the the plate (with sticker) over OVIRS.  For example in this image you can see the RCS thrusters on the corners are covered in red, there are red lifting eyelets, PolyCam and MapCam have red jackets, and OVIRS has a tan plate with a logo sitcker.  All removed before flight.  Obviously, so is the bag over the SRC at OTES.

AurO657.jpg

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5 hours ago, Bev7787 said:

What are the specs for the thrusters?

Details on the propulsion system are ITAR controlled, but here is some public information:

https://dslauretta.com/2014/12/16/integration-of-the-osiris-rex-main-propellant-tank/

Quote

OSIRIS-REx propulsion system uses a total of 28 engines that are divided into four groups: a bank of four main-engine propulsion thrusters, six medium-thrust engines, sixteen attitude control thrusters, and two specialized low-thrust rocket engines.

and https://dslauretta.com/2013/12/03/six-degrees-of-freedom/

Quote

The main engines are 200-Newton (N) thrusters directed at the spacecraft center of gravity. A Newton is a unit of force that is equivalent to the gravitational force exerted on a mass of roughly one-quarter of a pound on the surface of Earth.  These engines are used to perform the deep space maneuvers, the asteroid approach braking burn, and the asteroid departure burn.

In addition, the spacecraft has a set of 22-N Trajectory Control Thrusters that provide attitude control (pitch and yaw) during the large maneuvers described above. These engines also provide thrust to perform smaller trajectory correction maneuvers, which are used to clean up the spacecraft state after the large burns.  Most importantly, two of these thrusters are used to accelerate the spacecraft away from Bennu after sample acquisition.

The ultimate in spacecraft attitude control is provided by a series of 4.5-N Attitude Control System thrusters. These thrusters are mounted on each corner of the spacecraft and provide full 6-DOF control. They are used for small thrusting maneuvers. In addition, since the reaction wheels continuously build up momentum, these thrusters are fired to remove this momentum in a process called “reaction wheel desaturation” or “taking a momentum dump”.

One of the most critical maneuvers that OSIRIS-REx will perform is the orbit departure burn leading to sample acquisition. It is essential that we line up the spacecraft orbit and the asteroid rotation with extreme precision, so that we fly over the desired sample site at the right time. For this ultra-fine maneuver, the spacecraft will thrust using a tiny 0.07-N low-thrust rocket engine. Fortunately for us, these engines were just recently developed and qualified for the NASA GOES-R mission.

Further searching finds http://www.aiaa-space.org/OSIRIS-REx/ which states:

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The propulsion system on OSIRIS-REx is a monopropellant hydrazine system “borrowed” from the Mars Reconnaissance Orbiter, the Juno probe that’s scheduled to arrive in orbit around Jupiter on July 4, and Maven, the Mars Atmospheric and Volatile Evolution probe that has been orbiting Mars.

Additional searching gives http://spaceflight101.com/maven/spacecraft-information/ which states that Aerojet is the vendor for MAVEN.

5676892_orig.jpg

A search for GOES-R thrusters comes up with http://www.moog.com/products/thrusters.html as the vendor and a search for Aerojet gives http://www.rocket.com/propulsion-systems/monopropellant-rockets

So other you can study Moog and Aerojet brochures to get all kinds of details.

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6 hours ago, the_Demongod said:

@IonStorm So how is the fuel tank pressurized in vehicles like this to avoid ullage problems? A membrane that separates the pressurized gas and the fuel? That's the only method I've heard of but I'm definitely no expert in reaction control systems.

I really can't go into details about the propulsion system https://books.google.com/books?id=P5dBC_JgSLEC&pg=PA67 discusses how it us often done.  This post https://dslauretta.com/2014/12/16/integration-of-the-osiris-rex-main-propellant-tank/ (mentioned several times in this thread) explains much of what you are asking:

Quote

The helium tank is a high-pressure (4800 psi) composite overwrapped pressure vessel that supplies helium on demand to the propellant tank. The function of the overwrap is to evenly distribute pressure loads across the entire tank...The helium tank is needed because the OSIRIS-REx propellant system operates in a pressure-regulated mode for our large main-engine burns...For each of our major maneuvers the helium is used to maintain constant pressure in the propulsion system. Prior to the start of one of these burns an upstream latch-valve is opened, ensuring a steady flow of hydrazine to the rocket engines. The latch valve is closed at burn completion. With these regulated burns, OSIRIS-REx achieves a higher thrust. In addition, the precise control of system pressure allows us to accurately predict burn performance and timing prior to maneuver execution. For the maneuvers using the smaller thrusters, OSIRIS-REx operates in “blow-down” mode. In these instances, the latch valve to the helium tank remains closed, and the residual pressure in the main propellant tank is used to flow hydrazine to the rocket engines. This strategy works because the burns are very short, compared to the main-engine burns, and the thrusters use a very small amount of hydrazine.

 

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6 hours ago, AnTREXon said:

This is not really an entry, but more of a summary of the mission and an invitation to others to participate

Cool.  Did you notice that Dante Lauretta, PI of OSIRIS-REx (basically my boss) commented on your video:

Quote

 

Great job Anton! I am happy to discuss the acronym choice in more detail - maybe on a future episode?

 

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Changed my entry to stock- built a decent Atlas V 411 as well, was also going to do a launch tower as well but gave up on it. I'm testing my replica now.

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1 minute ago, Bev7787 said:

Changed my entry to stock- built a decent Atlas V 411 as well, was also going to do a launch tower as well but gave up on it. I'm testing my replica now.

Remember nothing is due until actual launch +30 days, so no earlier than October 8.  This allows people to use actual launch audio and to mimic the actual launch timeline, should anyone wish to.  Until then, no entry is considered final.

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So I had more time than I thought... Video making time then! Also, how many parachutes does the return capsule have?

Edited by Bev7787
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22 minutes ago, Bev7787 said:

So I had more time than I thought... Video making time then! Also, how many parachutes does the return capsule have?

1 Drogue and 1 main.  Just like Stardust.  

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On 7/4/2016 at 2:28 AM, IonStorm said:

Cool.  Did you notice that Dante Lauretta, PI of OSIRIS-REx (basically my boss) commented on your video:

 

haha no I didn't. Thanks for the notice.

 

I hope you don't get in trouble for playing so much KSP  :)

Although admittedly, I do it at work all the time too. I'm a full time math teacher and convinced my principal to give me free reign in using KSP to teach concepts.

 

 

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2 hours ago, AnTREXon said:

I hope you don't get in trouble for playing so much KSP  :)

Although admittedly, I do it at work all the time too. I'm a full time math teacher and convinced my principal to give me free reign in using KSP to teach concepts.

No, I play on my own time.  And not that much lately.  

But I compliment your strategy:

orbital_mechanics.png

Spoiler

"To be fair, my job at NASA was working on robots and didn't actually involve any orbital mechanics. The small positive slope over that period is because it turns out that if you hang around at NASA, you get in a lot of conversations about space." https://xkcd.com/1356/

 

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