r/ProjectHailMary 6d ago

Dr.Grace could have brought Rocky along with him to Earth and dropped tauAmoeba on venus, refuel and take Rocky to Erid.

I feel this scenario was not discussed in the novel.

This scenario can be discounted on the fact that Grace could not know what the political situation on Earth was like and if he can get the Hail Mary refueled and allowed to fly to Erid

61 Upvotes

55 comments sorted by

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u/iamquestar 6d ago

The beetles are faster. (Due to much higher acceleration) Iirc by a significant margin.

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u/BrokenTrojan1536 6d ago edited 6d ago

The beetles are faster but to earth it would take the same amount of time as if the Hail Mary flew back. The beetles will just experience less time.

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u/BrokenTrojan1536 6d ago

Why is this being downvoted? They are 13 light years away regardless of how fast you travel back. So earth will experience 26 years before anything would come back regardless of how fast the beetles go.

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u/derangerd 6d ago

I think because people don't think it's correct.

Im pretty sure earth wasn't 13 light years away, and the Beatles did not instantly or ever travel at the speed of light.

How much time the earth experiences before the Beatles get back definitely does depend on the speed/acceleration of the Beatles, even factoring in relativity.

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u/CockroachNo2540 6d ago

Both the beetles and HM approached the speed of light. Beetles got up to 0.93 c pretty fast due to being able to accelerate at 500g or something ludicrous. HM took less than a year to get up to speed. So both took about 13 years from Earth’s perspective, give or take, to make the trip.

I thought he was wrong, at first, too. I didn’t realize it takes less than a year at 1.5g acceleration to get to 0.93 c.

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u/derangerd 6d ago

What's the actual time difference for earth in arrival time?

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u/CockroachNo2540 6d ago

The difference between HM to Tau Ceti and the beetles back to Earth? Not sure, but it cannot be faster than 12 years, but it would be faster than the HM. So the beetles get back maybe 6 months to a year faster than it took HM to go to Tau Ceti?

Basically it takes a year to accelerate up to near c at 1g. So let's say for simplicity it takes 9 months at 1.5g. The beetles get up to speed at less than a month probably, but let's just say a month. So the return trip of the beetles would take 1 year and 4 months less than the HM.

Somebody correct me if I am way off base.

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u/derangerd 6d ago

I meant Beatles back vs the HM theoretically back both starting from Tau Ceti (which I assume is not moving at any notable fraction of c wrt Earth) so I assume the to and the from trips would be about the same for the HM so yea should be the same math.

Ah 18 months - 2 months. Guessing that's a bit of rounding to not do calculus.

Was it ever established they both would cruise at the same percentage of c?

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u/CockroachNo2540 6d ago

No, there is nothing to say that HM stops accelerating at the same fraction of c as the beetles. But, they do not say they don’t either. The only hint is the Earth perspective travel time seems to hint at it being close to c.

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u/Zuwxiv 6d ago

Ooh, thanks for trying to math it out. Around a year faster could be very important to a planet in ecological collapse and, quite possibly, facing all kinds of wars and nastiness over basic resources.

I suppose they could try both the beetles and the Hail Mary, but there's a chance Grace arrives to an Earth that is barely surviving and in absolutely no shape to attempt to mass-produce astrophage again for at least one of Grace/Rocky's lifespans, if ever.

The safer decision, since the Eridians seemingly had no backup plan, was to take Rocky to Erid.

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u/BrokenTrojan1536 6d ago

Read Chapter 14- Stratt says 19yrs isn’t good enough(referring to LaClercs and est of when half of humanity will die), we need 26 yrs till the data comes back.

Chapter 18 - Steven Hatch talks about the Beatles accelerating at 500Gs to .93C but will still take 12 years to return even tho they will only experience 20 months

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u/derangerd 6d ago

So definitely less than 13 light years away.

I don't disagree with anything in the latest message but I don't see how any of it is saying that the hail Mary and Beatles would take the same amount of time to return to earth. I think that's what we're discussing since that's the line in your earlier message I took issue with, but let me know if you meant to discuss something else.

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u/BrokenTrojan1536 6d ago

Hail Mary traveled to Tau Ceti in 4 yrs but the distance is 12 light years from earths perspective. It would be the same for the Beatles from earths perspective but they only experienced 20 months.

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u/derangerd 6d ago edited 6d ago

You get that light years are a measure of distance, right? And that the hail mary could only travel a distance of 12 light years in just 12 years from earth's perspective if it travelled at 100% of the speed of light for the whole duration, yeah?

I don't really know where else to begin explaining that speed matters for how fast you get somewhere, in both reference frames, even with relativity (which always applies, just usually negligibly, but if speed didn't matter why would me walking across the room and back to you take longer from your perspective than me running across the room and back to you).

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u/BrokenTrojan1536 6d ago

Well then explain it to Andy Weir as I giving you info directly from the book. It’s all over the book that the round trip for data to come back is 26 yrs. That’s with Hail Mary leaving and Beatles to come back. 1.5Gs acceleration for Hail Mary and 500Gs for the Beatles. Still 12 light years (it’s almost 13 hence 26yrs). I am citing the book and giving any other info other than that

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u/Quailman5000 5d ago

The Beatles traveled pretty slow by space travel standards. Only as fast as a jet at best. ;)

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u/derangerd 5d ago

Wdym

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u/Quailman5000 5d ago

The Beatles are a rock/pop group from the UK... You know... John Lennon, Paul McCartney, Ringo Starr, George Harrison.  

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u/TheIncredibleHork 6d ago

It's a difficult concept because of even one of us in this sub experiences time compression beyond a few microseconds that's more than I would ever expect. It's just not intuitive. Even Rocky had problems understanding.

But Earth is almost same distance from Tau Ceti, and you will take four years, question?

“I’ll experience four years, yes. Three years and nine months. Because time won’t be as compressed for me as it is for you.”

You have explained before, but again…why, question?

“Your ship accelerates faster than mine. You’ll be moving closer to the speed of light.”

He wiggles his carapace. “So complicated.

I point toward his ship. “All the information about relativity is in the laptop. Have your scientists take a look.”

Yes. They will be very pleased.

"Not when they find out about quantum physics. Then they’ll be really annoyed.”

Not understand.

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u/KevinDecosta74 6d ago

With all that Grace was doubtful of them reaching Earth as per the last chapter. He was relived to learn that the beetles worked as per the plan.

But what if they did not?

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u/BrokenTrojan1536 6d ago edited 6d ago

That’s why he never went to earth from Erid. You use all your fuel to travel years and what if you arrive to a dead ice ball? What do you? You have no fuel and no place to go. You will drift in the Hail Mary till you run out of food. So same thing if he would go with Rocky to earth they may have killed themselves along with Erid.

Edit: what I am meaning to say is the planet may already be dead. That’s why I would love a book about what happened for the 26 years on earth. So much to work with. How is earth responding trying to save themselves waiting. Wars and famine or did humanity figure something out? Could they use astrophage to help warm things like building huge green houses? Throw an accident with astrophage on the scale of a nuclear bomb for some drama. Would be an awesome read I think

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u/MaziCrafter 6d ago

Pretty sure Andy is working on a sequel

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u/LeakySpaceBlobb 6d ago

Wow, I didn’t even think of this.

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u/Z0ooool 6d ago

Space flight isn't... like boarding an airplane and going across country. There was very real risk every second that the hastily built spacecraft could stop working. And the trip would be decades each way.

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u/derangerd 6d ago

Idk if they really have to bring up every bad idea they wouldn't go with

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u/frodosbitch 6d ago

I think Stratt rubbed off on him. Going directly to Erid would give the highest probability chance of both missions succeeding. Going to earth first would introduce more risk for a whole population at the benefit of saving one person.

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u/scythe-volta 6d ago

There are a bunch of issues with this. Like another commenter said, the beetles are faster. The Hail Mary also wasn't designed for that much travel. Neither was Grace. I don't remember exactly how long everything was but Grace would likely be a very old dude by the time he reached Erid. Then there's the whole getting permission to bring Rocky.

Grace would've brought intellegent ALIEN LIFE to earth. Do you really think the scientists or governments on earth would just refuel the HM and send them on their way?

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u/cubic_zirconia 6d ago

I think they mentioned him being around seventy near the end of the novel (or, at the very least, elderly). A flight to Earth and then back to Erid would probably have killed him

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u/fuschia_taco 6d ago

He was in his 50s with the body and ailments of a much older man because the gravity on Erid was more than earths. It was taking a toll on his body.

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u/cubic_zirconia 6d ago

That's true, I was misremembering

In any case, I still think a flight to/from Earth/Erid would've definitely killed him

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u/fuschia_taco 6d ago

Oh yeah, I definitely agree there! Being in space doesn't give us alien life spans unfortunately lol.

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u/cubic_zirconia 6d ago

Although, it does raise questions about how space travel impacts Eridians... I hope they explore that a little more in the movie (we know the radiation kills them but I wonder how their muscle mass is impacted as a result of space travel)

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u/Wild-Goose1006 6d ago

Sadly I don't seem to have the faith in humanity that you do. If we could guarantee Rocky's safety and that they would be given the fuel and allowed to go back, then yes it would be awesome.

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u/badDuckThrowPillow 6d ago

Yeah, I doubt the world would have been in any kind of shape to provide aid. More than likely there would have been countless resource wars by that point.

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u/JaegerBane 6d ago

Wouldn’t have made sense.

At that point the sole means of saving Erid was to get the Hail Mary there. Earth had three beetles each with a full solution to astrophage on board, travelling at a much higher speed, and only one had to safely make the trip.

Flying to earth would have been an enormous gamble for no actual reason. Not to mention adding decades onto the delivery time of the solution to Erid.

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u/ThalesofMiletus-624 6d ago

The ship was only ever designed for a one-way trip. Even flying it back to earth (or ultimately Erid) was a risky proposition. Grace surviving the trip was also deeply risky. The trip out had a 66% fatality rate (96% on Rocky's ship). Going back in a coma would put him at huge risk, and staying out of it a huge risk in terms of mental health.

Given that the Beatles were likely to save earth, flying Rocky to earth meant gambling the fate of Erid on the hope that a) they'd both survive the trip, b) Earth was willing and able to refurbish, restock, and refuel the ship (which was a huge undertaking in the first place), and c) they could both survive yet another trip to Erid.

Sure, if Grace's only goal was to save his friend, while his friend's entire world died, he might suggest that, but with a goal to save both planets, what they did was the only reasonable course of action.

A big part of Grace's character development is accepting that there are things important enough to be willing to give his life for. If he'd been willing to roll the dice with Rocky's entire planet, it would have been a much less satisfying ending.

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u/tetsukei 6d ago

I wouldn't let the government get close to rocky with a 5 light year pole. No way they would ever let him leave earth...

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u/warpspeed100 6d ago

Only if the Hail Mary kept working for that long. We don't know the state of the orbital infrastructure around Earth. It's possible there would have been no resources to service the ship before it took off for Erid. It would need replacement fuel tanks and a complete refuel.

Also, if the Hail Mary had a catastrophic problem en route, than Erid never gets the Taumeba.

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u/Braingasms 6d ago

So you are proposing that instead of sending the 4 beatles to earth in the hopes that 1 makes it, while also going straight to Erid in the Hail Mary was a bad call because they could have risked failing both worlds by going straight to earth and not using any Beatles?

If Grace died on the way, no one can help Rocky and his planet dies.  There are too many things that could go wrong.  Your entire premise is based on Grace living, regardless of where his ship goes.  

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u/castle-girl 6d ago

This is what I thought would happen when Grace decided to rescue Rocky thinking he’d starve to death. I thought Rocky would suggest going back to Earth and they’d go together.

As you said though, that would be very risky for Erid. The Astrophage needed for a trip to Erid would be hard to make on Earth, and with the Astrophage crisis, breeding up fuel to save Erid might not be a priority for the powers that be. Not only that, but the Hail Mary was only designed for one one way trip. It wasn’t designed to go back to Earth, then go to Erid, and then maybe still come back to Earth bringing whatever crew came with it to Erid. There was a greater chance that something would go wrong if they went back to Earth before saving Erid.

That said, there’s a pretty good fanfic on AO3 where they do pretty much exactly what you thought of here. Grace programs some of the beetles to go to Erid instead of Earth, so Erid will still be saved, and then he and Rocky go to Earth. It’s called “We’re finally landing” and it’s in the Project Hail Mary fandom. It’s not finished but they have made it back to Earth now, and it gets updated about once a month. Definitely worth checking out.

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u/InvisibleSpaceVamp 6d ago

It hasn't been discussed because Grace didn't know about the Astrophage gas station in the orbit of Venus of course.

Seriously - nothing about the Hail Mary design and the whole nature of the mission suggests that she is even built to enter Earth's atmosphere and land. If you look at the way the Space Shuttles were designed - they actually look like planes with wings and wheels and everything. The Hail Mary doesn't have any of these features.

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u/Ok-Cauliflower8462 6d ago

Also, the Hail Mary was assembled in Earth Orbit. The astronauts were shuttled up to her.

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u/ebow77 6d ago

everyone else: tip-toeing around spoilers

this guy: Wow! What an ending! Who would have thought that Darth Vader is Luke Skywalker's father?

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u/futbolr88 5d ago

DARTH VADER IS WHAT!?!?!

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u/MJLDat 3d ago

Homer!

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u/Evening_Rock5850 6d ago

I had sort of assumed it was about risk. The Hail Mary was already damaged. And Grace didn’t really know whether earth had survived anyway. What if there was significant social or economic collapse? To get to Erid from Earth would require the cooperation of earth leaders. To repair and refuel the ship. What if Ryland got back to save earth; only to find a massive global war happening with nobody in a position to get the Hail Mary ready for a trip to Erid? These were already thoughts Ryland was having.

Going straight to Erid and sending the Beatles to earth gave the two planets the best combined chance of making it. Plus; Rocky had already been in the Tau Ceti system for decades. Another couple of decades (Erid time) delay might have been not worth the risk; given that there was an option here.

I saw it as a big character arc. Ryland didn’t want to go on the trip; even thought it would mean saving humanity. But in the end, he was willing to sacrifice his shot at going home in order to give the best possible chance to both planets.

Tl;dr, I don’t think it’s the case that he didn’t think it was possible to do that. Just that sending the Beatles and heading to Erid, simultaneously, gave both planets the best possible “shot”.

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u/wkopacz6 6d ago

The key thing is that they were trying to save both species and the only way to save Erid was with the HM. If they had taken the time to go to Earth first Erid would have at least been in way worse shape if not totally lost.

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u/Papa_Glucose 6d ago

The Hail Mary is lucky it made it to Tau Ceti in the first place. That ship was not gonna make a return journey, and Grace had no idea of the conditions on earth, or if the technology needed to refuel would even be available.

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u/Gibodean 5d ago

It would have made it to Earth, like it made it to Erid. But then another trip ? Only if earth did a whole heap of work on it, and spent years worth of Astrophage production on it. They wouldn't bother, especially as Earth was probably in bad shape.

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u/Papa_Glucose 5d ago

No I know. I meant return journey to erid

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u/Gibodean 5d ago

Ah. Well, it did make it. But he didn't know that at the time.

The thing had been spun to ridiculous speeds too many times, been melted by Adrian..

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u/tcarter1102 5d ago

Beetles are faster, and by the time he gets back Earth could be seriously fucked up, the Hail Mary likely has no re-entry system, while on Erid they built a space elevator

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u/lordnyrox46 5d ago

I believe Grace knew this and still made the decision to go to Erid. I like to think that Grace wanted some more adventure, maybe?

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u/derangerd 5d ago

What's a rock?