Mars Horizon

There are now 38 Milestone Missions spread across the solar system. (The Philae Comet was added as part of the Daring Expeditions Title Update)

1. Mercury 1
2. Venus 2
3. Earth 15
4. Moon 2
5. Mars 10
6. Philae 1
7. Jupiter 2
8. Saturn 2
9. Uranus 1
10. Neptune 1
11. Pluto 1

The milestone locations will be viewable when each era unlocks.

1: Earth and Moon
2: Mercury, Venus, Mars
3: Jupiter, Saturn, Neptune, Pluto
4: (Philae when researched)

Philae will not be viewable until you have researched both the mission and the payload when it will appear between Earth and Mars. Pluto flyby will not have to be researched directly as it is an era reward for researching all of the Era 3 missions.

You can customise your agency for this but I was able to complete this using China unmodified without much issue. The Soviet Union/Russia agency's ability to launch anytime can be used to ensure a first place launch but it's not necessary if you're willing to save and reload enough times. The standard agency traits are:

ESA
+50% bonus for Joint Missions
+50% Science income bonus from friendly/Allied relationships
x2 Joint missions chance

NASA
x2 Support for Top 3 Milestones
+3 contractors
x2 Astronaut pool

Soviet Union/Russia
Invalid launch windows become suboptimal
-50% astronaut bring cost and upkeep
No support penalty for mission failure

China
-25% research cost for buildings
-25% building construction cost and upkeep
receive 100% first phase science from failed launches

Japan
(up to) 25% Science bonus for top 3 Milestones
+25% funding for Lucrative missions
x2 Science building adjacency bonus

All of these are fine but ESA is probably the hardest because the bonuses all lead to development of other agencies alongside yours.

Make sure to regularly save, especially before launches and mission tasks as you will have to rely on risky levels of launch and payload reliability. You can actually sacrifice both of these for construction speed when designing modules and rockets and just reload if they fail. This also applies to focused training which can be set to support or research.
If you fail a mission phase reloading the autosave should put you back in place to try again but a launch failure will need a manual reload.

From the beginning research Small Launchpad first, then Artificial satellite+payload so that you can be building that while researching the rocket parts.
Research Lab and Spacecraft Assembly can be researched to unlock Mission Control research and placing that will give you an additional mission slot. You can set up a rotation of a primary milestone mission and a support request mission to add science and support while researching.

For the first era I would recommend using prototypes, launching as soon as possible and try to make sure that you are always using all available mission slots. Long term support is vital for ensuring regular income but it is important to avoid bottlenecks.
This can make it harder to achieve bonus objectives but it's not impossible. Choosing to auto-resolve and reload upon failure will be quicker but could mean that you are light on support and science especially in the early game.

With Research I found that by focusing on Missions I could unlock the vehicle parts as needed and use the buildings tree as tertiary concern.
I used required buildings research then just set out to unlock Launchpads, PR Office and Mission Control Expansions. The other buildings can all wait until all of the mission research is complete and any final vehicles are unlocked. (You can unlock the 8 first era buildings early to reduce base clearing costs. The Backup Power Generator -20% Payload Build Cost is also useful if you do this.)
Make sure that you have medium and large launchpads researched before rockets requiring them as they will cost a lot of money when clearing room to place and take time to build.
Check that you take advantage of research boosts after completing milestone challenges by switching to the relevant tree unless your current research is vital.

You should also regularly check the progress of other agencies towards milestones, if they have a white science symbol next to one then they have completed the research for it and it will likely be their next mission. If you get a notification of a launch date then you might still have time to build a payload and rocket before they launch but you may have to revert to an earlier save if not. You can also wait until a rival launch date to see if their launch is successful, if it is you can reload until it fails.
Other agencies activity can be checked in the Diplomacy screen as well.

Astronauts can be expensive early on as the Salary builds up over time. Pick one for your first Human in Space at the latest available point, I would recommend Celebrity for additional support but if you're looking for more help on missions then Problem Solver can be extremely helpful. I kept my astronauts and hired new ones when needed but the cost of hiring a new one is 10x their salary so you could save money by firing them after they've completed your mission and hire new ones later on, but it's not necessary and you can't guarantee you'll have better or equal traits in new recruits.

Don't ignore the era bonuses, some are irrelevant to this achievement but others will make things a lot easier. I found these to be the most useful:

Missions Era 3 -20% Payload built time
Buildings Era 1 -50% Obstruction Removal Cost
Buildings Era 3 No cost to moving buildings
Buildings Era 4 -35% buildings upkeep
Vehicles Era 3 Wyvern Booster

Having bonuses for carefully placed buildings can mitigate the cost of clearing room. By the endgame you should have cleared the entire base area anyway just be sure to do it so that you don't delay construction of payloads or rockets. Once you have the no cost to moving buildings reward you can rearrange the base as you like but you cannot store buildings, only remove them and rebuild. Adjacency bonuses are helpful but not essential for success, place when you can but don't worry about having neutral buildings, just avoid negative connections.

You can also unlock upgrades for rockets but most are not relevant if you're focused on speed and therefore cost cutting. Reducing chances of failure or negative effects are not needed if you're going to reload failed missions. I would recommend the Composite Casing (-10% vehicle build cost) for most things but Horizontal Integration (-1 month vehicle build time) can be useful in a pinch. The only other one I used was Advanced Guidance System (Neutral Event becomes Positive Event at Launch) for the final Mars or experimental request missions.

Once you can afford one a reusable shuttle can be a cheaper and quicker alternative to building a new rocket for any earth based missions (with bonuses and upgrades I ended up refitting shuttles in 4 months for 863k as opposed to 5 months for a 1000K+ rocket).


I never did any joint missions and didn't work with agencies on any of the pop-up events like working together on reliability issues, etc. I also didn't build the diplomacy office and remained neutral to competing with all of them throughout most of the game.

The Longest missions are the Philae landing, Pluto Flyby, Neptune Flyby and the Grand Tour which are all over 10 years. If you have enough mission slots you can have multiple ones running at the same time with enough space to complete other missions. By the time you are completing the final 10 or so milestones the other agencies should be significantly behind you so you can afford to skip ahead and auto-resolve missions. Achieving 1st in all of those milestones should have built up enough support to not worry about money and you can choose the more expensive power or crew versions of payloads to make missions easier.
All of the Earth launches (except The Grand Tour) are completed in 1 month. Venus and Mercury are 4-5 months, Mars missions are usually 9-10 months, everything else is 2-12 years. By the end I was able to launch Pluto, Grand Tour and Philae close enough to each other that they all completed within about a year of each other. Other agencies had only launched Grand Tour by the time I finished so you have plenty of time to spread them out if you need the extra mission slots.

My order by launch date was:

1. Test Launch (1 Month)
2. Artificial Satellite (1 Month)
3. Lunar Orbit (1 Month)
4. Animal in Space (1 Month)
5. Satellite Imaging (1 Month)
6. Human in Space (1 Month)
7. Mars Flyby (9 Months)
8. Venus Impacter (4 Months)
9. Multicrew Orbit (1 Month)
10. Orbital EVA (1 Month)
11. Mars Orbit (10 Months)
12. Venus Orbit (5 Months)
13. Mercury Orbit (6 Months)
14. Commercial Satellite (1 Month)
15. Crewed Moon Landing (1 Month)
16. Jupiter Flyby (21 Months)
17. Space Station (1 Month)
18. Saturn Flyby (37 Months)
19. Uranus Flyby (109 Months)
20. Mars Lander (10 Months)
21. Neptune Flyby (145 Months)
22. Modular Space Station I (1 Month)
23. Modular Space Station II (1 Month)
24. Jupiter Orbit (49 Months)
25. X-Ray Telescope (1 Month)
26. Modular Space Station III (1 Month)
27. Saturn Orbit (77 Months)
28. Space Telescope (1 Month)
29. Mars Prep: Ground Hab (10 Months)
30. Pluto Flyby (157 Months)
31. The Grand Tour (153 Months)
32. Mars Prep: Crewed Rover (10 Months)
33. Philae Landing (129 Months)
34. Mars Prep: Mars Exploration (28 Months)
35. Mars Prep: Robotic Rover (10 Months)
36. Mars Req: Engine & Habitat (1 Month)
37. Mars Req: Send Lander (10 Months)
38. Crewed Mars Landing (10 Months)

I was able to complete the final milestone in February 2008 with none of the other agencies having done more than research the Mars prep and requirement missions.

Good luck Director

Ad Aspera Per Astra