(2019 Archived) - HAVOC: THE BEGINNING OF A NEW VENUSIAN ERA (Possibly Outdated - Mostly Accurate)
(Possibly Outdated - Mostly Accurate)
Introduction
As
I have mentioned earlier, every grand plan has its humble beginnings. In
retrospect, the goldilocks zone of the Venusian atmosphere lies at about ~50-55
kilometres from the surface. It is of manageable temperature and pressure and a
haven from cosmic radiation. But how exactly are the Venusians to float within
that altitude range? (It is understood that, this has already been talked about
in the first chapter, but this chapter provides a deeper understanding into
this matter).
The
Concept of Floating Venusian Habitats
It
is universally known that Helium is a lifting gas in regular air. But why? Why
does a Helium balloon rise in the air? It is because the Helium in the balloon
and the balloon’s fabric combined, are lighter
that the air they displace. The Helium balloon will rise to an altitude, where
the weight of the balloon is equal to the weight of the air it displaces.
Furthermore, the pressure and density of the air at that altitude, is equal to
both the pressure and density of the Helium in the balloon; the system would be
at equilibrium.
Similarly,
regular air is a lifting gas in Carbon Dioxide, which is the dominant gas in
the Venusian atmosphere; Air is naturally buoyant in the Venusian atmosphere.
Here is the turn-over: If we were to fill a balloon or a cloud-city with a
geodesic structure, the weight of the balloon or the cloud-city will be lighter
than, the Venusian air it displaces, and float. Quite neat, isn’t it?
If
we were to pressurize a cloud-city with 1 bar (sea-level) pressure, it will
float at an altitude with 1 bar atmospheric pressure, or slightly below. And if
we were to refer the respective altitude, for the aforementioned pressure
range, from a graph: we find out that it coincides with the altitude range of
between 50-55 kilometres; the goldilocks zone of the Venusian atmosphere. It is
a wonderful coincidence, which makes the parameters of establishing the alleged
cloud-city, simpler to a greater extent.
Please
note that the concept, which I believe to truly be used for the floatation of
the cloud cities, is slightly more modified, and once known, almost seem
magical. It isn’t compatible with HAVOC, so we have to begin using this
concept. Until then, stay tuned...
Figure 19: Atmospheric pressure as a function of its altitude (on Venus) [25]
Roots of the Concept
Beforehand,
it should be noted that this concept, although not very much heard-of, is
relatively not new; it has its roots in the 1970s with the Soviets. A similar source of origin dating back to the
1980sis about airships on Venus also is from Soviet Russia. I will discuss this
second source, in the subsequent section.
Flying Laboratory on Venus
(1981)
G.
Moskalenko once reflected on the possibility of a long term flying laboratory
on Venus, in the 1980s. I found his article to be originally in Russian, and
auto-translated it as a reference for this section. He says that we will
naturally arrive to the analogues of aerostat or airship, for this purpose,
mainly because they can stay in flight for a long time, without requiring
energy or fuel [26].
But,
the concept he used is more complex; including a balloon filled with a
two-component working fluid, which could be used to change flight altitude,
using temperature differences of different altitudes. Furthermore,
“Calculations show that in real conditions of the atmosphere of Venus, the
maximum height of ascent, that is, the flight ceiling for a balloon filled with
water vapour, is approximately 39 kilometres; for a balloon filled with methyl
vapours-45 kilometres and ammonia vapours- more than hundred kilometres” [26].
Moreover,
“depending on the mode of supplying the auxiliary working fluid into the
balloon envelope, and the ability to perform translational motion, a wide
variety of ‘ascent-descent’ cycles are possible” [26]. This
could prove useful, especially for the study of Venus, as access to different
altitudes Venus-wide is crucial to it. But in the context of a colony, which
needs to stay at a fixed altitude, amidst the goldilocks zone, it might not be
as helpful. Our previous strategy, with the usage of air as a lifting gas, is
quite adequate.
The Challenges of Venusian Airflight
1. Sulphuric
acid in the atmosphere, might corrode unprotected metal
2. Significant
UV flux in higher altitudes could accelerate degradation through photochemistry
[25].
3. Violent
weather conditions, including super-rotation of the Venusian atmosphere, with
winds exceeding 200mph, with probable high vertical wind shear [25].
4. Less
solar energy below the clouds.
Addressing those Challenges
Teflon
and polypropylene could be used to coat aircraft or airship, in order to
prevent Sulphuric Acid corrosion. The other challenges are a bit more difficult
to address. On the brighter side, the atmospheric density and pressure at
~50-55 kilometres altitude, is similar to that of Earth at sea-level, which
makes flying at that altitude aerodynamically similar to flying slightly above
the Earth’s surface [27]. (It is easy; Crop-dusters do it
without a problem!). Furthermore, the Venusian gravity is slightly lower at
0.904G (8.87ms-1) [12], and slightly aid air
flight.
Figure 20: The
above illustration is of a cloud-city on Venus, illustrated in October 1971.
This illustration is Flying City of Venus by S.
Zhitomorsky, and
extracted from the Soviet magazine Technika Molodezhi (Youth Mechanics). It is
evidence that floating cloud-cities on Venus has its roots conceptualized, as
early as the 1970s.
The Analogues of Airflight
Moskalenko
is still right about us “naturally come[ing] to the analogues of aerostat or
airship[s]” [26], because they can be in long-term flight and
require less energy. Moreover, “airships
generate lift through buoyancy force, whereas aircraft generate lift through
the aerodynamics of fluid flow over the wings. If feasible, each type of
vehicle would provide adequate means of controlled flight within the Venus
atmosphere” [25].
Furthermore,
the most feasible options of powering them are solar power and radioisotope
power: “Solar energy-based power system using a photovoltaic array as the main
power source and a radioisotope heat source power system utilizing a Stirling
engine as the heat conversion device… proved to be the most versatile and
provided the greatest range of coverage both for station-keeping and
non-station-keeping missions” [27].
Solar-Powered Airflight
Venus
receives more solar energy than the Earth or Mars, as it is closer to the Sun:
“The solar flux at the orbit of Venus is 2600W/m2, which is much
greater than the 1360W/m2 available at Earth orbit” [27].
As a matter of fact, it is a ~91.176470588% increase in solar flux, which could
significantly increase the performance of solar-powered vehicles. Additionally,
there is sufficient solar energy, to power a vehicle, within or even below the
cloud-layer: “At the bottom of the cloud layer (45km altitude), the solar
intensity is between 520 and 1300 W/m2 depending on wavelength of
radiation collected” [27]. Simply, air flight is still
technically possible within, and even below the cloud decks.
Radioisotope-Powered Airflight
Long-term
flight in the Venusian atmosphere could be done with a radioisotope heat source
as a means of powering the vehicle. Out of the near-term conversion systems, a
Stirling heat engine is the most recommended, due to its specific power of
8W/kg and conversion efficiency of 32% [25].
Airship Flight on Venus
Airship
flight is possible on Venus, as the thick Venusian atmosphere provides
significant buoyancy for generation of lift. However, thick cloud cover and
high winds might make it a slightly difficult. A solar-powered airship will
have the configuration of a standard cylindrical shape, with three tail fins
and two propulsion pods. Furthermore, its solar arrays will be on the upper
surface of the airship envelope and tail-fins [27].
Figure 21:
A Diagram of a Standard Solar-Powered Venusian Airship [27].
It
should be noted that, mass scaling isn’t a critical factor, as “the high
density environment of the Venus atmosphere, the lift produced by the envelope
volume was more than sufficient to lift the airship and its associated systems”
[27]; we can make the airships as enormous as we want them to
be.
Aircraft Flight on Venus
Similar
to Airships, Aircrafts can run on both solar power and radioisotope powers. The
photovoltaic arrays of a solar-powered aircraft will “convert sunlight to
electricity, which is either stored in a silver-zinc battery or utilize[d]
directly for the aircraft operation” [27].
Furthermore,
“the flight altitude and aircraft size will depend on the power balance between
the available power from the solar array and the drag of the aircraft due to
the velocity of the wind” [27]. But, unlike a Solar-Powered airship,
“the total mass of the solar-powered aircraft is a critical factor in its
feasibility” [27].
Moreover, radioisotope-powered aircrafts are limited, not only by its
mass scaling, but its ability to generate sufficient lift, as well[27].
Living on a Venusian Airship
Airships
and aircrafts are quite good as flying laboratories or means of Venusian
exploration. But, airships are a more preferable mean of habitation, due to mass
scaling not being critical in its feasibility. But, what if we were to live on
a Venusian airship? Couldn’t it prove to
be the foundation and experience, for building cloud-cities in the
future? Dale C. Arney and Christopher A. Jones, from the Space Mission Analysis
and Concepts Directorate at the Langley Research Centre in Virginia, have been
exploring the idea [28]. This lead to the formulation of the
High Altitude Venus Operational Concept (HAVOC), which I believe will
definitely prove to be a milestone in future colonization of Venus, if
successful. But what is HAVOC, and how
does it work?
Figure 22: A conceptual sketch of a solar-powered aircraft, flying above the Venusian cloud-tops. Most of solar arrays can be found on the wings [25].
High
Altitude Venus Operational Concept (HAVOC)
The
HAVOC (though not much of an optimistic name for a mission) is formulated into
five phases, which begins with an exploratory mission with a robotic precursor
followed by four manned missions, which include a 30-day orbital stay, a 30-day
atmospheric stay, a 1-year atmospheric stay, and permanent residence
respectively [28,29}.
Here
is a summary of the five phases of the HAVOC [29];
Phase I: Exploratory mission with Robotic Precursor.
Phase II: 30-day manned mission to Venus Orbit.
Phase III: 30-day manned mission to Venus Atmosphere.
Phase IV: 1-year manned mission to Venus Atmosphere.
Phase
V: Permanent residence in Venus Atmosphere.
The
vehicle that will be used for the HAVOC missions are the Solar-powered
airships, with envelopes filled with Helium [28]. Helium is a better lifting gas, and used to
provide buoyancy to the airship, as HAVOC seems to want to be on the safer
side. It is a reasonable measure for the HAVOC missions, and perhaps even early
colonial missions, with considerable room for error.
Another
defining feature of the HAVOC missions is that it doesn’t go along with the
conventional EDL (Entry, Descend and Landing) protocol, as “landing would
indicate significant failure of the mission” [28], as Dale
Arney says in his own words. The airships are supposed to linger above the
cloud-tops, and will only land if some failure were to happen. The
mission would then truly be havoc! Instead, the HAVOC works in accordance to a
new EDI procedure, with the ‘I’ indicating the inflation of the airship.
The Robotic HAVOC Airship and Mission
(Phase I)
The Robotic HAVOC mission is accomplished, with the assistance of a Helium-filled Solar-powered airship, which is 31 metres long and 8 metres tall. It will have a total mass of 1382kg, with a total volume of 1118m3 [29]. The airship has a gondola slung underneath it, for carrying its instruments.
Figure 23: The
inflated airship of the Robotic HAVOC mission [29].
The
robotic airship will carry a payload of its instruments, weighing at 750kg. It
will have 96kg tanks, designed to carry a total of 118kg of Helium. The
airship’s hull will have a mass of about 201kg, while power and propulsion will
occupy 217kg. Thus, the airship’s total mass will add up to 1382kg. The airship
will have an area of 50.4m2 of solar array on it, along with an
energy storage of 92.9kWh. It will use a power of 11.6 kWe [29].
The airship and its cargo, will be folded up in an aeroshell, and transported to Venus with a spacecraft, which is obviously launched into space with the assistance of a rocket. It will rendezvous (meet/ meet at) with Venus orbit, and de-orbit to enter the atmosphere. It will then jettison its aeroshell and deploy a parachute, allowing the airship to unfurl and inflate. Afterwards, the redundant parachute is jettisoned and the airship will float above the cloud-tops. I suppose the mission will help in scientific study of the atmosphere, along with providing experience for phase-3 of HAVOC. The airship will theoretically have the potential of circumnavigating Venus indefinitely, as long as everything goes as planned. It is, however, surely known that the airship will never return to Earth [Modified from References 29, 30].
Figure 24: A
diagram of a rocket that will be used in the HAVOC mission. The size of the
rocket, along with number of rockets launched will depend on the HAVOC mission
we’re talking about [29].
Sulphuric Acid Issues
The
airships of the HAVOC
missions and future exposed areas of the cloud-cities will have to be resistant
to Sulphuric Acid. As we have seen earlier, the airship would have to be coated
with something acid resistant. Yet, the question remains as to which material
is experimentally proven to be effective in doing so, given the acidic
conditions of Venus.
Out
of the tested materials: Polyvinyl Chloride (PVC) underwent chemical change and
lost its transmittance, with transmittance dropping from 80% to 48% in a day,
and then to 43% in a month. PVC is therefore, not an ideal material for the
purpose. Contrariwise, polypropylene didn’t degrade and had a 90%
transmittance. Nevertheless, it might degrade when exposed to temperatures
above 50oC. Teflon, on the other hand, had the highest melting point
of tested materials, and performed even better with a transmittance of 90-93%. Hence,
Teflon and polypropylene are currently recommended for solving the alleged Sulphuric
acid issues. Future testing, at a temperature range of 75-80oC are
awaited for a more definite result [29].
The Airship of the Manned HAVOC
Mission (Phase III)
Similar to the Robotic HAVOC mission, the manned HAVOC mission is done, with the assistance of a Helium-filled Solar-powered airship. The airship is much larger, with solar arrays on its envelope and tail fins [29].
The airship has a gondola slung underneath it, which carries its ~70 ton payload, which is mostly occupied by an ascent vehicle and an atmospheric habitat. The propellers of the airship, along with the atmospheric habitat are firmly attached, and in fact, a part of the gondola. The ascent vehicle, on the other hand, is a detachable rocket, which could get the crew to Venus orbit [29].
The
airship, which is 129 metres long and 34 metres tall, will have a total mass of
95,776kg, with a total volume of 77,521m3. The robotic airship will
carry a payload of the ascent vehicle and atmospheric habitat, weighing at
~70,000kg. It will have 6,623kg tanks, designed to carry a total of 8,183kg of
Helium. The airship’s hull will have a mass of about 6,455kg, while power and
propulsion will occupy 4,511kg [29].Thus; the airship’s total
mass will add up to 95,776kg. The airship will have an area of 1,044m2
of solar array on it [29],
which is surprisingly large. The ascent vehicle and its structure will be discussed
slightly later in this chapter [in page 102].
An
Abstract on the Manned HAVOC Mission (Phase III)
Similar
to any space mission, the crew and material are first launched into space, with
the assistance of a rocket. It should be known that, the crew and the airship
will undergo the interplanetary voyage separately; the airship folded in the
spacecraft, and the crew will follow in a transit vehicle. After the perilous journey, both the airship
and crew will rendezvous in Venus orbit, where the transit vehicle will link-up
with the airship, with the crew proceeding in entering the airship [28].
Afterwards,
the airship will enter the Venusian atmosphere in an aeroshell, and descend in
a ‘Venus Atmosphere Rendezvous (VAR)’ [29]. It would then
deploy a parachute, and the aeroshell will drop away. The exposed airship will
then proceed with unfurling and inflating. The parachute, which becomes
redundant, will be jettisoned [28]. The inflated airship will
gently float at an altitude of 52km, at the Venusian equator, where the
atmosphere is most stable; and proceed with atmospheric operations [28,
29].
The
crew will spend their 30-day atmospheric stay, in the atmospheric habitat, and
move into the ascent vehicle when it ends. The ascent vehicle is a two-stage
rocket with a tiny capsule known as the ‘ascent habitat’, which would house the
crew during ascent: The ascent vehicle will be dropped and ascend to Venus
orbit, where the crew will again meet with their transit vehicle. The transit
vehicle would again take them on the perilous journey back home, followed by a
rendezvous with Earth orbit [28]. Then they will descend
through the Earth’s atmosphere, and probably impact the Pacific Ocean, as with
the case of Apollo 11. If the mission were to be successful to this extent, the
crew will be well received and likely world-famous. But, more importantly,
humanity will be a step closer to Venusian colonization.
The
above explanation might seem to be quite abbreviated and shallow. I intended it
to be so; in the following segments, we will go deeper into each stage of this
mission. And don’t worry; I will make this experience well illustrated. Now, we
may proceed with A
Detailed Analysis of the Manned HAVOC Mission (Phase 3):
Launch
and Outbound Journey
I
believe that the HAVOC airship and crew will be blasted-off into space in
separate vehicles with the assistance of two rockets. Afterwards, the airship
and crew would begin their outbound journey in space, separately: The airship, which
itself is tightly folded in a spacecraft, will journey towards Venus and the crew
will follow in a transit vehicle [28].
The transit vehicle consists of a habitat, namely the ‘transit habitat’, which is designed to house a crew of two astronauts for ~400 days. It will have a volume of 44m3 and pressurized at 1 bar. Furthermore, it will use a power of 12kWe, and approved for contingency EVA only. The outbound journey to Venus will take ~110 days and end at VOR (Venus Orbit Rendezvous) [29].
Figure 25: This is a representation of the transit habitat, which would house the crew during the outbound journey to Venus and the Return journey back to the Earth. The transit habitat is located in the transit vehicle accessible to the outside by a ‘doorway’ which could interlock with the ‘un-inflated airship’ during Venus Orbit Rendezvous (VOR), so that the crew can enter the airship. It could also interlock with the ascent habitat, after atmospheric stay and ascent, allowing the crew to re-enter.
VOR
and Aerocapture
After ~110days of a hazardous outbound journey, the vehicles will rendezvous with Venus orbit [28]. An aerocapture manoeuvre is required to do this as “the aerocapture manoeuvre is designed to take each vehicle from arrival speeds of approximately 10 to 12 km/s [,] to roughly 7 km/s velocity necessary to hit the desired orbital apogee” [30]. It should be noted that, the airship will arrive to the desired circular orbit after aerocapture, and loiter in Venus orbit until the crew arrives. The transit vehicle will arrive to the same orbit after a little while, again via aerocapture, and link with the airship. The above illustration depicts this scene. The crew will enter the airship, once the vehicles are linked and air-tight [29].
Furthermore,
“during aerocapture, the vehicle takes advantage drag created by flying through
the atmosphere to reduce the speed of the vehicle, without the use of large
propulsive manoeuvre” [30]. Once the vehicle is in desired
orbital apogee, atmospheric entry and descent will proceed.
De-orbit
and Entry
The
airship, once in desired orbital apogee, will de-orbit and descend into the
Venusian atmosphere. The airship isn’t inflated yet, and folded in an
aeroshell, when atmospheric entry commences. The airship in the aeroshell will
enter the atmosphere at a velocity of ~7.2kms-1 (7,200ms-1),
specifically in the entry interface of 200km altitude [28, 29, and 30].
It should be noted that, the transit vehicle will continue to orbit Venus and wait until the crew returns. The below illustration depicts the airship descending into the Venusian atmosphere. Moreover, “during entry the Entry Vehicle (EV) is guided through the middle and lower atmosphere and may be manoeuvred to prevent excessive heating and aerodynamic load” [30].
However,
this is easier said than done: The sharp density gradient and high entry mass
of the manned mission presents certain challenges, to be addressed;
Atmosphere
Skip-Out: - If the entry vehicle is travelling at
too high a velocity, with too much lift, it might not ‘be captured’ and exit
the atmosphere at a reduced speed, and might even not re-enter. This phenomenon
is known as ‘atmosphere skip-out’ and not much could be done about it, other
than trying to control it; perhaps by using it as a technique for aerocapture
or aerobraking [30].
Excessive
Lofting: - Lofting is “a repeated increase and
decrease in altitude due to excessive lift that may result in atmospheric
skip-out” [30]. During atmospheric entry, lofting will have
to carefully thought-out.
Excessive
G-Loads (Aerodynamic Forces): - Astronauts, in
nearly every mission, would be subject to excessive G-loads, which could prove
to be injurious, over extended periods of time. NASA already addressed this
issue, by establishing G-load limits; which is defined as the “functions of
length of exposure and orientation of crew relative to acceleration vector” [30].
Following the G-load limits, is in need of meticulous planning and accurate
on-the-spot decision-making. G-loads are an interesting concept, and I
recommend looking into it sometime, as I would not feature it as lengthy
explanations are needed, for its comprehension in text.
Excessive
Aerodynamic Heating: - The high heat rates,
which characterize atmospheric entries, would have to be accounted-for. It is
the same heat which burns meteorites in our atmosphere, which is simply VERY
HOT. A Thermal Protection System (TPS) will be needed to dissipate heat and
protect the Entry Vehicle [30].
I
believe that, by the time HAVOC is ready; many of these issues would have been
looked into, and most likely solved.
Deploy
Parachute
~7 minutes (~444-522 seconds) after entry, the aeroshell (i.e. the Entry Vehicle) would have slowed down to ~466ms-1 (in a range of ~451-483 ms-1). At this moment, a parachute is deployed, to further slow it down [29]: “Once the EV has slowed down to supersonic velocities, the descent phase begins when an aerodynamic decelerator, such as a parachute or ballute, is deployed to further reduce descent rate” [30].
The
deployment of the parachute indicates the beginning of the descent
phase, which would further decelerate from supersonic to subsonic velocities.
The parachute of the manned HAVOC mission has a diameter of 24 metres [30],
which would give it an area ~452.5714m2. For further knowledge, the
parachute of the Unmanned Robotic HAVOC mission will have a diameter of 10
metres [30], with an area of ~78.5714 m2.
Furthermore,
“the airship is pressurized during parachute descent” [30].
The parachute will deploy at an altitude of ~75.1 – 82.7 kilometres above the
Venusian surface [29].
The below table the parameters of the
parachutes of both the Unmanned and Manned HAVOC missions [30]:
|
Parameters |
Unmanned Robotic HAVOC mission. (Phase 1) |
Manned HAVOC mission. (Phase 3) |
|
Diameter |
10 m |
24 m |
|
Area |
76.39822369 m2 |
31.41592654 m2 |
|
Supersonic
Drag Coefficient |
0.9 |
0.9 |
|
Transonic
Drag Coefficient |
0.85 |
0.85 |
|
Subsonic
Drag Coefficient |
1.15 |
1.15 |
Jettison
Parachute
~44-64 seconds after the parachute is deployed; the aeroshell will be jettisoned, while the EV is descending at an altitude of ~76.641 - 76.2 km. The exposed and un-inflated airship will now be travelling at a velocity of 96 – 99 ms-1, with the parachute still attached to it. Afterwards, the airship will begin to unfurl and inflate. Before talking of inflation, I would like to talk on the HAVOC Terminal Descent Model (HAVOC-TDM), which was designed during trajectory design. It is a model “developed for analyzing how aerodynamic, buoyancy and inertial forces combine to fix the terminal velocity of the vehicle concept during unpowered descent” [30]. The forthcoming section is based on it.
Figure 26: These rather horribly stitched sets of images are compiled to give an idea on the jettison of the aeroshell.
Airship
Inflation
According
to the HAVOC-TDM, the airship will inflate at a rate of ~400m3s-1,
which would increase its volume sixty-fold, from its original packed volume of
~1,258m3 to its inflated volume of ~77,521m3 [30].
The inflation of the airship would take ~3 minute; approximately 190.6575
seconds, to be precise. The values may differ somewhat from reality, but it
shouldn’t seem to be a problem. The table below depicts the entry and descent
phases of the manned airship, in accordance to the HAVOC-TDM [30]:
|
EVENT |
ALTITUDE [h] |
TIME INTERVAL [∆t] |
TIME [t] |
|
Begin Entry |
69.5
km |
58.55
s |
58.55
s |
|
Deploy Parachute |
69.0
km |
2.05
s |
60.60
s |
|
Open Parachute |
68.0
km |
5.48
s |
66.08
s |
|
Jettison Aeroshell |
64.0
km |
30.46
s |
96.54
s |
|
Inflation Starts |
64
km |
35.94
s |
96.54
s |
|
Cut Parachute |
54.5
km |
151.86
s |
248.4
s |
|
Inflation Ends |
52.0
km |
38.8
s |
287.25
s |
|
Zero Velocity |
52.0
km |
66.3
s |
353.50
s |
This
is an illustration of the HAVOC airship, corresponding to its inflation stage.
The parachute would then be jettisoned soon after.
Jettison
Parachute
The
airship, which gets larger due to inflation, will experience an increase in
lift and drag, to the point where the parachute is redundant [28].
This happens ~3 minutes (~210 – 221 seconds) after the jettison of the
aeroshell [29]. If everything happened as planned, the fully
inflated airship would gently float 52 kilometres above Venusian terra [30].
It will gently float near the Venusian equator, where the atmosphere is most
stable, with ~100ms-1 winds encircling the planet in ~110 hours [28].
Atmospheric
Operations
During entry, descent and the 30-day
atmospheric stay, the crew will be housed in the atmospheric habitat. The
habitat has a volume of 21m3, pressurized at 1 bar, and use a total
power of 3kWe [29].
Figure
27: This is an illustration of the atmospheric
habitat [29], which could also be seen in the above image. The front
widow will provide a beautiful panoramic view of the Venusian cloud-tops..
Behold,
the spectacular view I was talking of! I
believe that the door seen on the right of this image is the door which was
linked it the transit vehicle during VOR. The crew will be in the atmospheric
habitat, for the entire atmospheric stay. The airship will use the
super-rotation of the Venusian atmosphere, to circumnavigate Venus every 110
hours [28], which roughly translates to every 4.6 days. Thus, the
airship and its crew will manage to circumnavigate Venus 6 times, during the
atmospheric stay. The crew will be lucky enough to be the first people to
witness 6 sunrises and 6 sunsets, from the perspective of the Venusian
cloud-tops. The winds will veer north, and the airship would have to push south
during the day to stay on course. The might also veer north during the night,
to conserve energy. There isn’t much of a reason to perform EVA, which will make
this mission simpler and safer [28].
The Ascent Vehicle
The ascent vehicle is a two-stage detachable
rocket, which is attached to the gondola of the airship, and occupies majority
of mass of the payload. It is comprised of a fist stage, second stage and a
little capsule known as the ‘ascent habitat’.
Figure 28: A
diagram of the ascent vehicle, which is divided into the rocket stages and
ascent habitat [29].
The
stages are used to propel the ascent habitat into Venus orbit, with the ascent
habitat used to house the crew in that journey [29]. I suppose that
the atmospheric habitat has some ‘back-door’, by which the crew can enter the
ascent habitat, when the atmospheric stay is over. The ascent habitat is
designed to house the crew for up-to a day. It will occupy a volume of 4.6m3,
and pressurized at 1 bar, and will use a total power of 1kWe, with no EVAs
performed in relation to this habitat [29].
The
Ascent to Venus Orbit
Once
the 30-day atmospheric stay is over, the crew will enter into the ascent
habitat and prepare for another breathtaking stunt: The ascent vehicle will be
detached from the gondola and dropped into the Venusian atmosphere [29].
By the way, there is the back-door I was talking of! (Now, the abandoned
airship will continue to circumnavigate Venus, as long as nothing happens to
it). But, the ascent vehicle will not keep falling to the abyss below:
Afterwards,
the rockets of the ascent vehicle will fire, and the ascent vehicle will ascend
to Venus Orbit. Stage-by-stage will detach from the ascent vehicle, until only
the ascent habitat reaches Venus orbit. Remember the transit vehicle? It had
been orbiting Venus, waiting until the crew returns. In Venus orbit, the ascent
habitat and the transit habitat will link [28], with their doors
interlocking.
The above illustration depicts the linkage of the ascent habitat and transit vehicle, in action. The transit vehicle, in turn, will de-orbit and head to the Earth’s direction. The transit vehicle will now bring the crew back home, in a return trip of ~300days [29]. In the following page; the top image is an illustration of the ascent vehicle, during its ascent to Venus Orbit, while the bottom image is an illustration of the ascent habitat, linking-up with the transit vehicle, with the crew docking into it.
Earth
Orbit Rendezvous and Landing
The final stage of this HAVOC mission is to rendezvous with orbit, descent into the Earth’s atmosphere and land [28]. The final capsule will most likely land in the Pacific Ocean, similar to the Apollo11 mission. If the mission were successful, the crew will get to see their families, become world-famous, and be happily received by everyone on the Earth. But again, more importantly, humanity will be a step closer to Venusian colonization.
The Operational Complexities of the
Mission and Abort Options of the Rendezvouses
The
VOR (Venus Orbit Rendezvous) poses time delay issues [29], as
commands sent as radio waves take time to travel the vast interplanetary
distances between the crew and airship, and the ground control on the Earth.
Those time delays will have to be accounted-for, with commands likely to be
sent accordingly in advance. If anything were to go wrong in VOR, the crew
could abort back to the Earth from Venus, in ~300 days [29].
The
VAR (Venus Atmosphere Rendezvous) will be challenging, especially for early
missions. Unfortunately, VAR is a one-shot trial-or-error manoeuvre, with no
abort options [29].
The
EOR (Earth Orbit Rendezvous) will be similar to other in-space assembly
operations, and we have gained quite a lot of experience in doing so.
Nevertheless, if something were to go wrong in EOR, a quicker rendezvous or
integration operations are potential abort options [29].
Very
Brief Summary of the Manned HAVOC Mission (III)
If
this HAVOC mission was hard to visualize or sparks curiosity as to how it might
actually look like, then I recommend seeing this link on YouTube: (https://www.youtube.com/watch?v=0az7DEwG68A),
which is a lovely animation of this HAVOC mission, published by the Langley
Research Centre. I have extracted all un-cited illustrations in this chapter,
by freezing that video. Enjoy!
Here is a stage-wise summery of the
entire mission:
1.
Launch
airship and transit vehicle to space.
2.
Outbound
journey to Venus.
3.
Venus
Orbit Rendezvous (VOR).
4.
Aerocapture.
5.
Linking;
Crew enters the airship.
6.
De-orbit
and Entry; Venus Atmosphere Rendezvous (VAR).
7.
Deploy
parachute.
8.
Jettison
aeroshell.
9.
Airship
unfurls and inflates.
10. Jettison parachute.
11. Atmospheric stay and
operations.
12. Crew enters ascent
vehicle.
13. Detach ascent vehicle.
14. Ascent to Venus orbit.
15. Linking; Crew return to
transit vehicle.
16. Return Journey to the
Earth.
17. Entry and descent into
the Earth’s atmosphere.
18. Landing (perhaps in the
Pacific Ocean).
The
below illustration is a detailed and diagrammatic depiction of the entry and
descent phase, of the HAVOC airship. (Extracted from reference 29):
Proof
of Concept
A 1:50 scale model of the HAVOC airship,
developed by the HAVOC team, was successfully packed into an aeroshell and
inflated out of it and floated [28, 29]. It proves that the HAVOC
airship could do what it is supposed to do.
Figure 29: The 1:50 scale model of the HAVOC airship, developed by the HAVOC team, which was successfully packed into an aeroshell, and inflated out of it [29].
Conclusion
[In association with reference 28]
The HAVOC team believes that the concept
“offers a realistic target for crewed exploration in the near future, pending
moderate technological advancements and support from NASA” [28]. My
belief is similar: Venus has been largely ignored since the 1980s despite its
potential for scientific discovery and as a second home. Even if Mars were to
be a destination for a manned mission, the HAVOC missions could give a leg-up
in advancing the related technologies and would be similar to a practice run.
Moreover,
it will give us the experience we need regarding long-duration habitats,
aerobraking, aerocapture and Carbon Dioxide processing. The HAVOC mission would
play a major role in humanity’s future in space.
The
Manned Mission to Venus Orbit (Phase II)
There
is an intermediary mission between the Unmanned Robotic HAVOC mission, and the
already discussed manned HAVOC mission (Phase 3). The Unmanned Robotic HAVOC
mission will give us the experience of entry, descent and inflation; but it is
a bit too soon for an immediate manned mission of a similar calibre (referring
to phase III). The Phase II manned mission was formulated for more practice,
before the phase III manned mission, which we discussed.
Not
much is revealed of this mission, but a general idea can be obtained in
comparison with objective of the mission; a 30-day stay in Venus orbit, and the
phase III mission. I believe it to be as follows: The crew will be blasted-off
into space in a single vehicle, with the assistance of a single rocket, and
head outwards to Venus in a journey of ~110 days. Afterwards, the crew will
rendezvous with Venus orbit, and orbit Venus for 30 days. Afterwards, the crew
will return to Earth in a journey of ~300 days, rendezvous with Earth orbit,
enter and descend into the Earth’s atmosphere, and finally land.
The
Manned HAVOC Mission with 1-Year Atmospheric Stay (Phase IV)
This
mission will take place after the phase-III HAVOC mission with 30-day
atmospheric stay. This mission isn’t very discussed because; (i) It is meant
for the future, which isn’t as much a priority as the first three HAVOC
missions.(ii) It would require development in self-sufficiency, resource
management systems and methodologies of using the Venusian environment for the
crew’s benefit and for extracting resources. (iii) The dimensions and plan of
the mission have not been comprehensively designed yet, and the potential
problems are not worth solving at present.
However,
based on our current knowledge, there are a few features we can identify of
this mission. (1) I believe that the mission will have a larger crew who would
carry-out activities of more variety. (2) The airship will have to have larger
dimensions – most likely enormous! Or it might even be comprised of many
airships. (3) I believe that more rockets would be used to send the crew and
required material to Venus. (4) The airship would likely circumnavigate Venus
~80 times, before atmospheric stay is over. (5) The ascent and transit vehicle
will have larger dimensions, or many ascent and transit vehicles might be used.
(6) I believe that either the crew will happen to use their resources in a
self-sufficient system, or that supplies will arrive for them via aeroshells,
or both. (7) The mission might include EVA during atmospheric stay, due to long
duration. (8) There will be a lot of experimentation and scientific research
happening on-board this mission. (9) The astronauts might be provided more
facilities and activities. (10) I believe that systems for extracting resources
from the Venusian atmosphere might be used and maintained.
I
believe that this is quite an advanced mission, which is quite a huge leap from
the phase-III manned mission, and that the mission could be re-done based on
success, ‘non-success’, or even failure of this mission. Still, true failure
would tend to be quite unlikely, as (11) more abort options could be
formulated. Nevertheless, based on my views, (12) success in this mission would
be synonymous to success in establishing a Venusian presence, like a
proto-colony. What I meant here is that; if we can sustain a proto-colony in
the Venusian cloud-tops for a year, we could do so for much longer periods of
times; perhaps for decades, centuries, even millennia!
And
that is exactly the next phase, if this mission were a success: permanent
residence in the Venusian cloud-tops.
Permanent
Residence (Phase V)
The
final phase of HAVOC aims at establishing a permanent human presence on the
Venusian cloud-tops. It will include large floating structures, which are
solar-powered and float on the buoyancy of the Helium. The colonists would live
in these structures, extract resources and utilize them in a self-sufficient
system. The below illustration depicts how the Venusian cloud-tops might look
like in the beginning of this stage [29].
I
would sometimes imagine the lives of the first official Venusian colonists, who
would call these structures home. I believe that they will be amazed at the
blueness of the sky above, and the whiteness of the clouds below; for an alien
world, it does a good job at resembling the Earth! It would be interesting to
see the sun rise from the west and set in the east, but twice as slowly. I
believe that the colonists would maintain and harvest communal farms, while
potentially surviving on some supplies from the Earth, which arrive in
aeroshells. While not farming or performing EVA, I believe that that they would
spend their time experimenting or enjoying their leisure, perhaps communicating
with their kith and kin, or perhaps with creative activities or forms of
entertainment.
The night might be of their fancy too, perhaps with stargazing with altered constellations; Orion’s belt not straight, and the Great Dipper warped. But the highlight of the night sky would be a distinctive blue star, reminiscent of the colonists’ origins; The Earth. Furthermore, I appreciate the role those pioneer colonists, in the utopian future humanity will behold.
Restrictions
for HAVOC
In
its current incarnation, the manned HAVOC mission “depends on the massive Block
IIB configuration of the space launch system, which may not be ready to fly
until the late 2020s” [28]. But I believe that it isn’t the main
restriction; That would be belief itself. I feel that we’re almost conditioned
to appreciate and support manned Martian exploration and Martian
colonization; to believe that Mars is more suitable for the purpose,
even when the possibility of another is exposed. After all, I used to be the
same, before stumbling across that life-changing article. A similar story might
have happened to others, in an ever-increasing population of people who see
potential in Venus.
On
the True colonization of Venus: A Foreword to the Subsequent Chapters.
But,
a question arises: Is the HAVOC series of missions truly the colonization of
Venus? I’m afraid not; The HAVOC missions are only the foundation; the
pioneering; the initial stage before true colonization of Venus. Still, I
regard the phase- IV HAVOC mission to be a proto-colony, while the phase V
HAVOC mission to be an initial colony. But, before asking how to colonize
Venus, we have to answer another question, or rather a series of questions:
What
is colonization? What makes a colony, a colony? How does a colony grow to
independence? How can we apply our knowledge of successful and triumphant
colonization, to the context of Venus?
Well, the consequent chapter is dedicated to answering all these concerning questions, along with the aspiration of providing an insight to the milieus of Venusian colonization
Achinthya Nanayakkara (31.03.2025)
Original - 2019
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