Hibiscus Jool Orbiter

[Alienwall]

 

Following on successful science missions to Duna and Eve, many eyes at the KSC turned to the planet Jool. As its five moons orbited and green storms swirled, plans were drafted for a complex mission: send a craft, get a lander on Laythe, and return the science to Kerbin. This would become the Hibiscus Jool Orbiter.

Mods:

Spoiler

Visual:

• Distant Object Enhancement
• Kronal Vessel Viewer
• PlanetShine
• ReStock
• Scatterer
• Waterfall

Physics:

• Ferram Aerospace
• Principia

Objectives

Primary Objectives:

• Gather data from Jool orbit
• Fly by Laythe, Vall and Tylo
• Land on Laythe
• Return to Kerbin

Secondary Objectives:

• Gather data from Bop and Pol
• Get fly-bys through the upper atmospheres of Laythe and Jool

 

Design

After much testing...

Spoiler

the design was finalized. The craft is made of three parts: the Orbiter, Laythe Lander, and Experiment Return Module:

The simplest component is the Experiment Return Module. It is designed to collect all of the experiment results and land them on Kerbin. It will need to survive a (possibly) 4000+ m/s re-entry, and land on the surface to be picked up.

The Laythe lander is designed to enter Laythe's atmosphere and land using parachutes. It has four scientific instruments, which can collect and transmit data upon landing. As it is not equipped with power generation, it will be in contact until the batteries run dry. The powerful antenna on top allows it to maintain direct contact with the Space Center DSN instead of relying on the orbiter as a relay.

Both the lander and the return module will be piggybacking on the orbiter:

         

The orbiter is the main craft of the mission. It is based on a pentagonal probe body and an RA-100 antenna. It has multiple science instruments, including an array of Mystery Goo containers that will be detached after use. The atmospheric analyzer is located on the orbiter, as its power requirements are too high for the landers. Power is provided by four RTGs, and there are six ion engines for propulsion.

Edited January 4, 2022 by Alienwall
Formatting

[Vanamonde]

I like probe missions.  

[Alienwall]

Mission Plan

The HJO is scheduled to launch from the KSC on Year 11 Day 170. A Kerbin gravity assist will be used to get to Jool, as discussed by Mad_Maelstrom here. This gravity assist will save dV, increase the margin of error, and offer a chance to test the spacecraft’s equipment.

Upon Jool arrival, a Tylo Laythe gravity assist will be used to capture into the Jool system (with a capture burn at periapsis). Once in orbit, HJO's time at Jool will be split into a number of science campaigns. Campaign 1 will be dedicated to the Laythe landing; the rest of the campaigns will focus on completing the science objectives at Jool.

Once a Jool-Kerbin transfer window opens, the orbiter will burn to exit the Jool system and return to Kerbin. At the Kerbin encounter, all of the science will be transferred to the Experiment Return Module. Then, the module will be detached, reenter, and land on Kerbin. Since the orbiter has RTGs, it won’t be sent into the atmosphere with the experiment return. If there isn’t an opportunity to crash the orbiter on the Mun, it will be sent into a parking orbit around Kerbol.

To round off the pre-launch rambling, here's some delta V figures for the mission:

• Launch stage: approx. 3700 m/s (sea level)
• Transfer stage: 2018 m/s (vacuum)
• Orbiter: 2976 m/s (vacuum, all modules attached)

 

I promise there will be more pictures from now on.

Edited January 9, 2022 by Alienwall
Wrong moon :P

[Maria Sirona]

Followed

[Alienwall]

Getting To Jool (Part 1)

Launch, Kerbin Escape (0y, 0d – 0y, 2d)

It’s the morning of Year 11, Day 170. A fully-fueled Splatlas V sits on the launchpad, with the HJO hidden away in the fairing. With the rocket ready, and no weather to speak of, it’s time to launch. So…

Liftoff.

Separation of SRBs.

HJO makes it into space.

Kerbin orbit is achieved 7 minutes after the launch.

Then, at 21 minutes, the Kerbin escape burn is performed:

The escape burn lasts 100 seconds.

Kerbin grows smaller and smaller...

The HJO crosses the orbit of the Mun about 2 hours after launch, and escapes Kerbin's influence after about 2 days and 2 hours.

It's now in a ~30.48 billion meter x ~13.34 billion meter orbit around Kerbol, with an orbital period of 2 years and 35 days.

Deep Space Maneuver 1 (1y, 13d)

DSM 1 is performed near the Kerbol apoapsis.

The transfer stage burns 182m/s retrograde to set up a Kerbin encounter, and RCS is used to fine-tune the encounter.

The HJO will pass about 100km from Kerbin. Afterwards, it will have enough velocity to reach Jool’s orbit.

Kerbin Gravity Assist (2y, 56d – 2y, 58d)

The HJO begins to approach Kerbin. The opportunity is taken to test some of the equipment on the satellite.

Closest approach is at 106.5km and 4.3 km/s.

The HJO leaves as soon as it arrived. It’s on to Jool from here.

[Maria Sirona]

Awesome! And also, Splatlas rocket?

[Alienwall]

Getting To Jool (Part 2)

Deep Space Maneuver 2 (2y, 103d)

A second DSM is needed after the Kerbin gravity assist, in order to set up the Jool capture.

A 218 m/s burn provides an inclination change. RCS is used to set up a gravity assist with one of Jool's moons.

After adjustments, the HJO is on a course to capture into the Jool system through a Laythe gravity assist. No capture burn will be necessary.

Jool Injection (4y, 43d – 4y, 103d)

As Kerbol dims, the green patch in the sky grows...

The HJO enters Jool’s gravitational influence at 4 years, 43 days. By 4 years, 70 days, it is within 1 million km of the gas giant. Some of the moons become visible:

  

The orbiter even has the good fortune of observing Laythe’s shadow passing across Jool.

Jool soon dominates the probe’s FOV.

Joolian periapsis occurs at 4 years, 89 days, 04:18. The HJO swings by at 4227km and ~7.7 km/s.

The probe is still traveling at escape velocity, but the Laythe gravity assist is soon to come.

   

The HJO passes into the shadow of Jool, and observes Laythe doing the same.

Just over an hour past Jool periapsis, the HJO enters Laythe’s influence for the first time. Connection to Kerbin is lost.

Laythe periapsis occurs at 431km and 4.5 km/s. The HJO slips, uncontrolled, between the giant and its moon.

As the HJO leaves Jool's shadow, connection is reestablised. It is now in orbit of Jool. On the way up to apoapsis, it passes Vall and Bop:

 

4/5 of Jool's moons have been imaged, and the HJO isn't even fully deployed yet!

The orbiter reaches Jool apoapsis at 4 years, 103 days.

Before it can begin the science mission, the transfer stage needs to be detached and disposed of. So, the RCS is used to send the craft on a crash course to Jool.

The transfer stage is decoupled, and the ion thrusters put the HJO back into orbit.

The Hibiscus Jool Orbiter is fully deployed and operational in Jool orbit. Finally, the science can begin.

Here's the orbital history of the trip to Jool:

[Alienwall]

Science Campaign 1 (SC1)

With the Orbiter ready to go, it’s time to start the first science campaign. The main goal of SC1 is to perform the Laythe landing.

First, though, the Laythe encounter needs to be planned out. Should the landing happen on the first go, or should a few fly-bys be done to study the surface beforehand? Should gravity assists be used to get an optimal Laythe approach (on the day side, lower velocity)? What kind of orbit will the HJO be on after the encounter?

         

 

While the Kerbals at Mission Control argue about these questions, the HJO takes measurements of its environment.

Ultimately, the simplest approach is taken for the Laythe landing: go on the first encounter.

A prograde burn sets the craft on an encounter with Laythe. After some adjustments, the encounter is set:

In fourteen days, the craft will pass over Laythe’s south pole at a periapsis of 39.5km. This approach saves delta v and complexity (no more encounters/burns needed). Although the path over the pole changes the HJO’s inclination, the apoapsis/periapsis remain similar.

There are some risks. The lander will land on Laythe at night, and given the awkward angle to Kerbin, relay through the Orbiter will be necessary. There’s only been one Laythe fly-by before this, so a lot of trust is being put in the lander’s design to survive the unknown environment. Furthermore, the lander is almost certainly going to land in the ocean, where SAS will be needed to keep it pointing upright.

Oh, and the lander will be entering the atmosphere at about 4 km/s. But that’s part of the fun.

In preparation for Laythe approach, the batteries of the lander are disabled. If the orbiter needs to expend any energy, it won’t drain the lander’s batteries. Since the lander only has batteries, and no power generation, it needs a full bank on detachment.

 

Laythe Landing (4y, 117d – 4y, 118d)

The HJO enters Laythe influence at 4y, 117d, 04h. It is 16 minutes to Laythe periapsis, and the craft is already travelling at 3200 m/s relative to Laythe.

At 14 minutes to periapsis, the lander’s batteries are reactivated. Then...

The lander is detached.

With the lander now separate, the Orbiter needs to make a burn to avoid entering the atmosphere as well. After the adjustment, it has a periapsis of 100km, and 3282 m/s of dv.

During the adjustments, measurements are taken high over Laythe. After this, all focus shifts to the lander.

The lander is now autonomous. All systems look good, and there is good connection to the KSC via the HJO Orbiter.

The lander shoots over the south pole.

Atmospheric entry begins at t+ 14min 02s from decoupling, over the day/night terminator. The lander travels at over 4 km/s, and plasma quickly envelops it. Though the Lander was built to shrug the high temperatures off, the antenna on the top needs to be kept out of the way. If it loses the antenna, control will be lost.

The lander feels over 6g of deceleration.

The ablator did its job well, and the lander survives entry.

At 17min 03s, the drogue chute deploys.

Then at 10km, and 18min 47s, the drogue is cut and the main parachutes deploy.

The main parachutes open at 1km ASL, 21min 50s since decoupling. The lander is now falling at less than 5 m/s, and the sight of the approaching water is reminiscent of the landing tests on Kerbin.

At 25min 40s, the lander splashes down… and sinks.

Luckily, it bounces back – just enough to get the antenna clear.

No time is wasted in doing the science. The accelerometer doesn’t function on water, but the other instruments take their readings.

The antenna unfurls, and the science is beamed back to Kerbin. All data are transmitted as of t+ 28min, just a few minutes after landing.

Even though the lander’s mission is complete, it still has quite a bit of charge…

The lander sees sunrise on Laythe.

Kerbol arcs across the sky, and soon it hides behind the giant Jool.

But shortly after the eclipse is finished, the lander runs out of battery. It’s at the mercy of the sea, showing its butt to Jool for the rest of time.

Meanwhile, the orbiter – now lighter – swings away from Jool. The landing may be complete, but the science mission is just getting started.

Edited January 24, 2022 by Alienwall

[Maria Sirona]

Awesome! Those pictures of the Laythe lander descending with Jool behind it are so beautiful. But in the map view Laythe flyby shot the trajectory is purple. Do you have Principia? Shouldn't Vall have been ejected by now?

Edited January 24, 2022 by Maria Sirona

[Alienwall]

14 hours ago, Maria Sirona said:

Do you have Principia? Shouldn't Vall have been ejected by now?

Thanks! I am using Principia. iirc the mod changes the Jool system to make it stable.