NASA Mars Helicopter Ingenuity illustration. Credit: NASA/JPL
Ingenuity continued its journey towards the river delta at the start of this month with Flight 24. The flight was the fourth of 5 sorties Ingenuity will make to cross the “Séítah” area of Jezero Crater and arrive in the vicinity of its delta.
The Ingenuity and Mars 2020 groups have huge prepare for the helicopter at the delta. However they have to arrive initially, and prior to Flight 24 an essential decision had to be made on which of 3 various flight strategies used the very best possibility of an effective delta arrival.
Mars Helicopter Route Options out ofS éítah: This annotated overhead image from the HiRISE video camera aboard NASAs Mars Reconnaissance Orbiter (MRO) illustrates 3 alternatives for the agencys Mars Ingenuity Helicopter to take on flights out of the “Séítah” region, in addition to the location of the entry, landing, and descent (EDL) hardware. Credit: NASA/JPL-Caltech/University of Arizona/USGS
The three choices on the table were:
Option A: a single, long flight.
Alternative B: 2 shorter flights.
Option C: a really short Flight 24 to make the long flight out of Séítah a little easier than alternative A.
In deciding which of these options to greenlight, the Mars Helicopter team had to think about multiple aspects: thermal, climatic conditions, flight time, drift, landing websites, and keeping up with the rover. Well check out each of these factors and what function they played in the general threat assessment and choice of our decision.
Thermal Limitations
Every part of Ingenuity has what is called Allowable Flight Temperatures (AFT), which offer a variety of temperatures at which each part is safe to operate. A particular obstacle for Ingenuity is handling the temperature of its actuators, the servos and motors that allow it to fly (see some of these here). These parts generate a lot of heat during flight, to the degree that the optimum flight time is often limited by the maximum AFT of these actuators.
Climatic Seasonal Conditions
Flight 14, for example, was a checkout flight to verify Ingenuity might fly in these conditions. For all flights given that then, Ingenuity has actually been effectively operating with 2,700 rpm. However, utilizing a higher rpm triggers the actuators to warm more quickly and reach their AFTs quicker, limiting maximum flight time.
It is warmer now coming out of the summer season than with our earlier flights in the spring. Even though we have been flying at 10:00 a.m. local mean solar time (LMST)- on Mars throughout the summer, Ingenuity has been hotter than flights at 12:00 LMST in the spring.
Mars Atmosphere Density Model: Models for the seasonal variation in atmospheric density on Mars between summer season (low density) and winter season (higher density) anticipate that air density will be high enough in late March for NASAs Mars Ingenuity Helicopter to go back to its initial RPM. Credit: NASA/JPL-Caltech
Flight Time and Distance
With the existing climatic conditions at Jezero Crater, the AFTs of the actuators are the limiting factor for the total flight time. Lets take a more in-depth take a look at the various options for Flight 24 and beyond:
Alternative A: The long flight out of the delta needs 170 seconds of flight, the optimum of our previous flights. This is not possible until the atmosphere cools down even more.
Option B: The two much shorter flights are running the like our previous “summertime” flights: 130 seconds of flight time. This flight time is possible with no changes.
Alternative C: The first flight, a brief hop, is created to decrease the flight time needed for the second flight to 160 seconds. This is possible if we: i) minimize the rpm to 2,537, and ii) fly earlier in the sol to have lower atmospheric temperatures.
The team determined that by flying 30 minutes previously, at 09:30 LMST, the flight time might be increased by 10 seconds. If we choose to fly at 9:30, we would initially have to evaluate it out– waking Ingenuity at this time without flying, to inspect that it would have adequate charge for a flight.
In summary, the various maximum flight time choices available are:
130 seconds (baseline).
150 seconds (reduced rpm).
160 seconds (reduced rpm and earlier flight time).
Alternative A: one landing ellipse outside of the Séítah that is safe and large.
Choice B: The landing ellipse for Flight 24 is within the Séítah, restricting its size, and requires a medium-distance flight, provided less margin and making it slightly riskier than landing outside the Séítah.
Option C: The very first landing site (for Flight 24) needs only a brief flight, decreasing the quantity of prospective drift, and it stays within the fairly large landing ellipse of the previous flight, 23.
Flight time is generally equivalent to distance traveled, but it likewise depends upon the maneuvers being carried out. For instance, rotating in location (called “yawing”), is done (a minimum of at Mars) slowly, taking a handful of seconds with no range traveled. Because of that, Mars Helicopter flights with more yaw maneuvers do not travel as far in the exact same flight time.
All these factors enter have fun with choice C– the brief hop. This flight would make it possible for the longer 160 2nd flight, for several factors: 1) it is a check-out test for flying back at 2,537 rpm, 2) it is a test for flying at 09:30 LMST, and 3) it lowers the flight time for the subsequent flight by doing the time-consuming yaw maneuvers and moving slightly closer to the target for the 2nd flight. All three of these actions are required to allow a 160-second flight out of the Séítah.
Wander.
As gone over previously, Ingenuity was a tech demo expecting to fly over flat ground. When flying over “non-flat” terrain such as hills, cliffs, large dunes and big stones, Ingenuitys price quote of its position and heading can wander. This drift leads to a larger location where it might land, called the landing ellipse. The further it flies, the larger the potential drift, and the larger the landing ellipse. The Séítah region has a lot of these non-flat features (see the dunes and rocks in the image at the top, or on the interactive map), making it riskier for Ingenuity to fly over this region. An additional difficulty with the upcoming flights is the existence of hardware from Perseverances landing, descent, and entry (EDL), consisting of the sky crane, parachutes and backshell. The green dots (in figure 1) show the predicted locations of this hardware from orbital images. Some of these parts are under the flight course of alternative B, which presents a potential for unforeseen performance from Ingenuitys laser altimeter (a laser that determines the helicopters height above the surface area) and visual odometry system, which could trigger more drift.
Landing Sites.
Each flight of Ingenuity has an organized landing ellipse (or often simply a landing region) that has actually been analyzed to be safe to touch down on, and to be large enough for the expected drift. The obstacle is discovering a big enough landing location that is complimentary of dangers, such as rocks, large slopes, or perhaps EDL hardware. Finding large landing websites is challenging in Séítah, so much shorter flights are preferred, to lower the prospective drift, and thus decrease the required size of the landing ellipse. Outside of Séítah, the terrain is fairly flat and helicopter-friendly, enabling for big landing ellipses and long flights with greater drift. Lets take a look at the various options and their landing websites:.
Staying up to date with the Rover.
Determination is making terrific progress on its drive to the river delta, and it is necessary that Ingenuity keeps up to come to the delta before the rover does. This is for 2 factors: telecoms and security. Ingenuity only communicates with the helicopter base station on Perseverance, so it needs to stay close enough to have a great connection. For security, it is perfect if Ingenuity flies ahead of Perseverance to prevent ever having to fly past or near the rover, to decrease the danger of any close contact in a worst-case scenario.
Balancing Risks.
Lets evaluate each of the aspects above to see which option provides the very best set of trade-offs to stabilize risk:
A.
2,537 (change).
N/A. Too hot.
No landing in Séítah.
Need to wait.
.
Factors.
B.
2,700.
10:00 (no change).
Medium flight in Séítah;.
EDL hardware danger.
On pace.
Option.
RPM.
Time of Sol.
Wander/ Landing Site.
Keeping With Rover.
C.
2,537 (modification).
09:30 (brand-new!).
A brief flight in Séítah.
On pace.
Which alternative would you choose?
As is frequently the case in Ingenuity operations, there is no apparent solution that is the finest for all elements: Trade-offs have actually to be made based upon the readily available information and the judgment of employee. In this case, the helicopter team decided to choose option C.
This image of the main pilots logbook for the Ingenuity Mars Helicopter flights– the “Nominal Pilots Logbook for Planets and Moons”– was taken at NASAs Jet Propulsion Laboratory in Southern California on April 19, 2021, the day of Ingenuitys very first historic flight. Pilot logbooks are utilized by aviators to offer a record of their flights, consisting of present and collected flight time, number and locations of takeoffs and landings, in addition to special operating conditions and accreditations. Credit: NASA/JPL-Caltech.
Flight 24 Summary.
With alternative C, flight 24 was a brief hop and yaw at 09:30 LMST with 2,537 rpm, and set us up to exit Séítah on flight 25.
Flight #: 24Goals: Test flight at 2,537 rpm, 09:30 LMST flightAltitude: 10 metersTime up: 69.5 secondsDistance: 47 meters.
With Flight 24 in our log book, it is now time to anticipate our upcoming effort that charts a course out of Séítah. Flight 25– which was uplinked yesterday– will send Ingenuity 704 meters to the northwest (almost 80 meters longer than the current record– Flight 9). The helicopters ground speed will have to do with 5.5 meters per second (another record) and we expect to be in the rarefied Martian air for about 161.5 seconds.
See you at the delta!
Written by Ben Morrell, Ingenuity Operations Engineer at NASAs Jet Propulsion Laboratory.
These elements produce a lot of heat during flight, to the extent that the optimum flight time is often limited by the optimum AFT of these actuators.
Flight 14, for example, was a checkout flight to verify Ingenuity could fly in these conditions. For that reason, Mars Helicopter flights with more yaw maneuvers dont travel as far in the very same flight time.
This flight would make it possible for the longer 160 2nd flight, for a number of reasons: 1) it is a check-out test for flying back at 2,537 rpm, 2) it is a test for flying at 09:30 LMST, and 3) it decreases the flight time for the subsequent flight by doing the lengthy yaw maneuvers and moving somewhat closer to the target for the 2nd flight. Flight 25– which was uplinked the other day– will send out Ingenuity 704 meters to the northwest (nearly 80 meters longer than the present record– Flight 9).