Reentry - A Space Flight Simulator News

Reentry has been in development for many years now, adding one spacecraft yearly. It all started with the Mercury capsule for the Technical Preview I release in 2016, followed up by the Gemini capsule in Technical Preview II in 2017. The Command Module was then added for the initial Early Access release in November 2018.

In 2019 we saw the addition of the Lunar Module, as well as many improvements to the simulator such as the new physics update introduced in 0.45, and the Lunar Landing with the Lunar Roving Vehicle introduced in version 0.4.

Version 0.5 is now in development, and will be the update where the last parts of a full Apollo mission will be introduced. This includes the Lunar Ascent, the LM/CSM rendezvous, returning to Earth and performing an Atmospheric Entry. These technologies will then be applied to the other space capsules in later patches, starting with Project Mercury in v.0.6.

2020 will be all about improving the simulator, enriching its contents with new missions, failures and systems. New play styles has also been in development and will start to see its light next year.

All in all, I think 2019 was a great year for the simulator, and I really look forward to seeing what we can do in 2020.

I wish to personally thank each and every one of you who has bought Reentry and supported the development, to those being part of the evolving Reentry Community, as well as for all the great feedback I have received from you. A special thanks goes out to all of the Test Pilots who has spent countless of hours in fragile builds, working through checklists and having control of partial spacecrafts in development, It's a lot of work, and the simulator would not have been the same without your flight hours.

The long awaited 0.45 (Early Access) update is finally out!

This update is the largest one written yet, as it impacts everything related to the physics in the simulator, so please keep this in mind as you play. The Test Pilots have worked a lot on testing the various parts of the simulator, and we have managed to fix most of the major and high priority issues we have found related to this update. However, that being said, there are still issues to be fixed, and I'm sure you will find things to report.

Please do so over at the official Reentry Discord channel at http://discord.gg/reentrygame

The physics parts of this update will most likely be invisible for most of the players, but is the basis for the work that will happen in version 0.5 and towards 1.0. It was required by the lunar ascent, as well as planning orbital maneuvers. As we move forward with the next updates and major updates, you will see the introduction of new tools and gameplay mechanics, balancing, as well a rendering improvements - all made possible thanks to the changes in 0.45.

Patch notes:
- Major physics update
- Apollo CM Tools (SPS burns, TLI)
- New Apollo Academy lessons for SPS burn planning and TLI
- Addition of a new Lunar Module Academy exam
- Console (open it in game using Back Quote)
- DevJournal (access it from the main menu or the console)
- First iteration of flight data profiling

Update 0.451.EA:
- timescale logging to identify who timescale is reset back to 1x in some missions
- LM exam panel state should now load C&D

Some major parts of this update still needs work, and going forward we will release minor patches correcting these things.
- Engines (F1, SPS, DPS ..) still needs re-balancing. Please expect longer ascent times, S-IVB and SPS burn times.
- TLI burn precision

The test pilots have been working hard on the latest version of Reentry, and a lot of fixes and changes has been made - big shout out to the Test Pilots!

I haven't really spoken much of what version 0.45 contains, other than that it's a rebase of the game, so in this post, I will try to explain some of the new things!

Physics
First of all, as you probably know, the physics of Reentry has had an upgrade. You will most likely not notice too much of this, but the general feel of the simulator should be smoother. The world size has increased a bit from the physics perspective, allowing me to start looking at the possibility to increase the world size further in future updates.

In addition, this allows for much more stable orbits; previously you would notice that your orbits apogee and perigee would flux and jump with an offset of multiple kilometers within even one orbit. Now, the orbit remains fully stable (with offsets limited to just a few fractions of a km). However, if you fire a thruster or an engine, the orbit will change, as expected!

This stability was really bad around the Moon. In fact, this was one of the major issues that needed to be fixed for me to write a proper Lunar Ascent Guidance algorithm. Lunar Orbits were almost impossible to work with and you had to request Ap and Pe from mission control to get accurate values. In this update, that button is gone, and the orbit is perfectly calculated in real time!

This has made it much easier for me to start writing tools that will execute much faster (remember the TLI and LOI calculations that could take a minute just to get a rather random value?). In 0.45, TLI and SPS maneuvers are planned using a new in-game tool!

Anyways, a lot of other changes has been made within the physical space, but let's keep it brief and move on to the tools!

Tools
Two new tools are added to the Apollo program (currently in experimental phase). Once complete, you can expect similar tools for Gemini and Mercury as well.

The first tools I wish to mention is the SPS Burn Maneuver tool. It's meant to be used by the Apollo CSM/SPS engine. A future update will allow you to select the Lunar Module DPS engine as the propulsion for the CSM (Just like in Apollo 13) as well.

The goal of the tool is to help you plan and execute burns to reach desired orbits. Currently this has not been possible except for eye-balling and manually burning.
Using the new tool, you can select at what point in the orbit you wish that the burn should be executed (in degrees, where 0 is at Pe and 180 is at Ap). Then you select how much delta V you wish to burn, and in what direction. An orange trajectory will then show you the estimated new orbit. In addition, the tool calculates when the burn should start (TIG), and for how long the burn will last. Keep in mind that all of these values are estimates, the actual orbit you will reach will differ based on how well you perform the burn.


Above you can see that I plan to execute a burn around Perigee, with a dV of 50 fps retrograde. The new orbit and burn parameters can be seen to the left, and a TIG icon will be rendered in the orbit view. The number of decimals will be reduced :D.


In the screenshot above, I plan a larger burn in prograde direction, at the orbital phase/true anomaly of 45 degrees from Pe. The orange trajectory shows the new orbit I will reach (again, estimate).


Lastly, I wish to highlight another feature of the tool. In this screenshot, you can see that the tool shows an Atmospheric Entry burn. This is all automatic. If the tool senses that you are planning a burn that will take you into the atmosphere, it automatically classifies this as an atmospheric entry burn/de-orbit. If this happens, it will show you where the entry interface starts and render an EI icon, as well as the entry angle at this point.

When you press REQUEST, mission control will get back to you with the burn data, as well as uploading this to the AGC so you simply can run P30 and P40 to execute the burn.

Let's move on to the next tool; the S-IVB Burn Planner. This tool will take you to the Moon. Previously TLI was calculated by requesting this from Mission Control. They would return to you with burn parameters what might take you to the Moon if you manually corrected the trajectory by eye balling.

This tool changes all that. TLI is now planned by you using some simple parameters. The tool will show you the estimated trajectory that will be recalculated as you change these parameters. This trajectory shows the path from Earth and at what Pe you will reach the Moon. In addition, it will also show you your Free Return trajectory, and at what Pe you will reach when returning to Earth.


Above you can see the tool. It shows you when the burn will happen, and and estimate of your new orbit. You will leave Earth following the blue line, and return following the orange line. A white line shows your trajectory around the Moon as seen below.


Once you reach the Moon, the SPS burn tool is used to calculate your LOI burn.


The tool will also let you know if you plan a path that will collide with the Moon.


Console
Another new feature is the in-game console. It aims at the advanced users and is meant to be used as a tool. It can be use to many tasks such as checking the game log, spaceship data (future), re-orientate the sun, monitor ascent data, check your orbital parameters, save the session state (and provide a file name!) and so on. I have just started working on this, so some programs will have more than others but this will evolve as we progress towards release.


The console is rather simple, and shows a large area for text, and one input field. You write your commands here and press ENTER to submit. By default, back quote is bound as the console button, but this can be re-mapped.

Above, I entered the command setsunphase 180. This moved the sun to a new position, a great tool while debugging or providing feedback.

A lot of commands are available, but much more will come.


Apollo ascent trajectory data
I have decided it's time to open up the simulator a bit more, and give you a glimpse into the details. The main reason is that I wish to create a better simulator, and creating algorithms that works equal on all hardware is a huge problem.
Given that, I have added another useful feature of the console: the possibility to export flight data. Currently, only Apollo Saturn V ascent and Lunar Module Powered Descent data is available but this will expand. The ascent trajectories in the sim are still rather coarse, but this data will be really valuable for me once I get to focus more on them. The data can be exported as either text or json.


This data can then be used in other tools and programs. A future update will also bring live and realtime graphs into the game so you can see this data nicely directly from the sim.


In addition, you can monitor this data live during your ascent.
To do this, you can use the monitor command:
mon -ascent



DevJournal
Another missing feature is the ability to talk to you directly inside the game. A news/DevJournal section is added to the main menu, but is also accessible from the in-game console in case you with to read the news while coasting towards the Moon, or Agena. This feature will keep you posted about news, major issues, fun stuff and so on.





Graphics improvements
Not a huge focus on graphics in this update but a lot have still be done. Shadows has received an overhaul, as well as some reflections and materials. Not too much to mention, but here are a few pictures to describe.


This sums up the new major features of 0.45.

Thanks again for your patience!
- Petri

The long awaited 0.45 update has rolled out to the Test Pilots!

This is a major update with a lot of fundamental changes to Reentry. I will post another post very soon with details of what this update contains and how it will affect Reentry, but for now please refer to my previous post.

The update has changed how the physics is Reentry works, and will improve many aspects of the game play. This update required me to rewrite a lot of the logic, and the Test Pilots will spend some time testing each of the spacecrafts in Reentry.

The 0.45 update will be tested in 4 waves:
1. The first will focus on Project Mercury (the testers has started testing this today).
2. The next will be Gemini and everything Gemini has to offer
3. Then the Apollo Command Module and Saturn V, ascent guidance, Earth orbit, TLI etc. needs to be tested and verified.
4. Then the Lunar Module and powered descent/lunar landing will be tested

The reason for this in-depth testing is due to the fundamental changes of the simulator.

I suspect there will be some major issues that has to be fixed, but once this is done, the update will roll out to you who are part of the Early Access of Reentry - An Orbital Simulator.

Thank you for your patience - I will keep you posted as we make progress with the testing!

- Petri

A lot is happening on the internal side of Reentry. As we are progressing towards version 0.5 where the Lunar Ascent and CSM/LM rendezvous will be introduced, a decision was made to rebase the physics in Reentry (this covers all programs; Mercury, Gemini, Apollo CSM and the LM).

This has required me to uncouple most of the internal maneuvering functions such as ascent guidance, mechanics, rendezvous (Gemini), orbital maneuvering, TLI, LOI etc, create the rebase, and rewire everything back together using the new methods. It has been taking a lot of time, but it's well worth the wait - it brings Reentry to a whole new level!

So, what does this really mean?
This means we can finally get much more stable physics. The orbital parameters will be more reliable, and new tools for burn planning and TLI is introduced, allowing the player to plan better and more precise burns. Also, the orbits around the Moon are now stable (no more fluxing ap, pe etc), and maneuvering around it is much easier.

Most of the work is complete, with the exception of the TLI burn planning tool. This is almost done but requires some tweaking to get right. Once this is ready, the first build of 0.45 will roll out to the test pilots!

This physics update is also required by version 0.5 to get a stable ascent from the lunar surface.

Stay tuned as we progress towards 0.45! :)


So, what's ahead?
Version 0.45 will be the physics update needed for version 0.5
Version 0.5 will cover lunar ascent, rendezvous and returning to Earth, as well as atmospheric entry for the Apollo command module.
Version 0.6 will cover major rework in Project Mercury, introducing failures, missions and better systems, as well as some awesome surprises I have in-line for you.
Version 0.7 will cover major rework in Project Gemini.
Version 0.8 will cover major rework in Project Apollo.
Post 0.8 will be mostly around content and polish.

Post version 1.0 will be all about looking ahead, and figuring out what's missing in Reentry ;)