Balancing Risks in the “Séítah” Region

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NASA Mars Helicopter Ingenuity

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NASA Mars Helicopter Ingenuity illustration. Credit: NASA/JPL

Ingenuity continued its journey towards the river delta at the start of this month with Flight24 This flight happened Sunday, April 3, and the information showed up back later on that night. The flight was the 4th of 5 sorties Ingenuity will make to cross the “Séítah” area of Jezero Crater and show up in the area of its delta. This multiflight faster way throughout Séítah is being done to keep ahead of the Perseverance rover– which is presently making good time on a more circuitous path to the very same location.

The Ingenuity and < period class ="glossaryLink" aria-describedby ="tt" data-cmtooltip ="<div class=glossaryItemTitle>Mars</div><div class=glossaryItemBody>Mars is the second smallest planet in our solar system and the fourth planet from the sun. Iron oxide is prevalent in Mars&#039; surface resulting in its reddish color and its nickname &quot;The Red Planet.&quot; Mars&#039; name comes from the Roman god of war.</div>" data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]" >Mars2020 groups have huge prepare for the helicopter at the delta. But they need to arrive initially, and prior toFlight24 an essential choice needed to be made on which of 3 various flight strategies provided the very best opportunity of an effective delta arrival.

Mars Helicopter Route Options Out of Séítah

MarsHelicopterRouteOptions out of‘Séítah’: This annotated overhead image from the HiRISE cam aboard NASA’sMars Reconnaissance Orbiter( MRO) illustrates 3 alternatives for the firm’sMarsIngenuityHelicopter to handle flights out of the“Séítah” area, in addition to the area of the entry, descent, and landing( EDL) hardware.Credit: NASA/JPL-Caltech/ University ofArizona/ USGS

The 3 alternatives on the table were:

  • Option A: a single, long flight.
  • Option B: 2 much shorter flights.
  • Option C: a really briefFlight24 to make the long flight out of Séítah a little much easier than alternative A.

In choosing which of these alternatives to greenlight, theMars(************************************************************************************************************************************************************************************************************************************** )group needed to think about several elements: thermal, climatic conditions, flight time, drift, landing websites, and staying up to date with the rover.We’ll check out each of these elements and what function they played in the total threat evaluation and choice of our choice.

Thermal Limitations

For spacecraft, “thermal” describes the management of the temperature levels of each element. Every part of Ingenuity has what is called Allowable Flight Temperatures (AFT), which provide a variety of temperature levels at which each part is safe to run. Even your phone or computer system has actually an advised temperature level variety: Too cold or too hot and it will not work as planned. Keeping “within AFTs” is crucial for making sure the health of Ingenuity, which suggests we are really mindful to handle this– for instance, by utilizing heating systems overnight when it is cold, and restricting activities throughout the day, when it is warmer. A specific obstacle for Ingenuity is handling the temperature level of its actuators, the servos and motors that enable it to fly (see a few of these here). These parts produce a great deal of heat throughout flight, to the level that the optimum flight time is frequently restricted by the optimum AFT of these actuators.

Atmospheric Seasonal Conditions

If you have actually been following this blog site, you will understand that we have actually been running with decreased air density considering that September, needing a boost in rotor rpm from 2,537 to 2,700 Flight 14, for instance, was a checkout flight to verify Ingenuity might fly in these conditions. For all flights ever since, Ingenuity has actually been effectively running with 2,700 rpm. Unfortunately, however, utilizing a greater rpm triggers the actuators to warm more quickly and reach their AFTs earlier, restricting optimum flight time. Practically, this has actually restricted us to flights of 130 seconds or less. Thankfully, we are towards completion of the Martian summertime, with its low air density, and beginning to move into the Martian fall, with greater air densities (see listed below), implying we can now go back to the 2,537 rpm of our very first 13 flights. This modification in rpm enables a boost in flight time to roughly 150 seconds. However, climatic density isn’t the only element at play: The primary chauffeur of the modifications in density is the temperature level of the environment, which likewise has a significant effect on– you thought it– the temperature level of Ingenuity.

It is warmer now coming out of the summertime than with our earlier flights in the spring. So despite the fact that we have actually been flying at 10: 00 a.m. regional mean solar time (LMST)- on Mars throughout the summertime, Ingenuity has actually been hotter than flights at 12: 00 LMST in the spring. A warmer environment suggests warmer parts, implying we reach optimal AFTs earlier. This suggests, flying at 10: 00 LMST, we still can’t fly for as long as we did formerly, such as throughout Flights 9, 10, and 12.

Mars Atmosphere Density Model

Mars Atmosphere Density Model: Models for the seasonal variation in climatic density on Mars in between summertime (low density) and winter season (greater density) anticipate that air density will be high enough in late March for NASA’s Mars Ingenuity Helicopter to go back to its initial RPM. Credit: NASA/JPL-Caltech

Flight Time and Distance

With the present climatic conditions at Jezero Crater, the AFTs of the actuators are the restricting element for the overall flight time. Let’s take a more in-depth take a look at the various alternatives for Flight 24 and beyond:

  • Option A: The long flight out of the delta needs 170 seconds of flight, the optimum of our previous flights. This is not possible till the environment cools off even more.
  • Option B: The 2 much shorter flights are running the like our previous “summer” flights: 130 seconds of flight time. This flight time is possible with no modifications.
  • Option C: The very first flight, a brief hop, is created to lower the flight time required for the 2nd flight to 160 seconds. This is possible if we: i) lower the rpm to 2,537, and ii) fly previously in the sol to have lower climatic temperature levels.

The group figured out that by flying 30 minutes previously, at 09: 30 LMST, the flight time might be increased by 10 seconds. However, Ingenuity had actually never ever flown at 09: 30 LMST prior to, so this would be a brand-new “first.” And flying earlier brings with it associated dangers with the charge state of the helicopter’s batteries: Ingenuity utilizes power to heat itself over night and charges its batteries with its photovoltaic panel, implying the batteries have less charge in the early morning. If we pick to fly at 9: 30, we would initially need 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 optimum flight time alternatives readily available are:

  • 130 seconds (standard)
  • 150 seconds (reduced rpm)
  • 160 seconds (reduced rpm and earlier flight time)

Flight time is usually comparable to distance taken a trip, however it likewise depends upon the maneuvers being carried out. For example, turning in location (called “yawing”), is done (a minimum of at Mars) gradually, taking a handful of seconds without any range took a trip. For that factor, Mars Helicopter flights with more yaw maneuvers do not take a trip as far in the very same flight time.

All these elements enter have fun with alternative C– the brief hop. This flight would allow the longer 160 2nd flight, for numerous 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 minimizes the flight time for the subsequent flight by doing the lengthy yaw maneuvers and moving a little closer to the target for the 2nd flight. All 3 of these actions are needed to allow a 160- 2nd flight out of the Séítah.

Drift

As gone over formerly, Ingenuity was a tech demonstration anticipating to fly over flat ground. When flying over “non-flat” surface such as hills, cliffs, big stones and big dunes, Ingenuity’s quote of its position and heading can wander. This drift causes a broader location where it might land, called the landing ellipse. The further it flies, the bigger the prospective drift, and the bigger the landing ellipse. The Séítah area has a lot of these non-flat functions (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 area. An extra obstacle with the approaching flights is the existence of hardware from Perseverance’s entry, descent, and landing (EDL), consisting of the sky crane, parachutes and backshell. The green dots (in figure 1) reveal the anticipated places of this hardware from orbital images. Some of these parts are under the flight course of alternative B, which provides a capacity for unforeseen efficiency from Ingenuity’s laser altimeter (a laser that determines the helicopter’s height above the surface area) and visual odometry system, which might trigger more drift.

Landing Sites

Each flight of Ingenuity has an organized landing ellipse (or often simply a landing area) that has actually been evaluated to be safe to touch down on, and to be big enough for the anticipated drift. The obstacle is discovering a big adequate landing location that is devoid of risks, such as rocks, big slopes, and even EDL hardware. Finding big landing websites is challenging in Séítah, so much shorter flights are chosen, to lower the prospective drift, and for this reason lower the needed size of the landing ellipse. Outside of Séítah, the surface is fairly flat and helicopter-friendly, permitting big landing ellipses and long flights with higher drift. Let’s take a look at the various alternatives and their landing websites:

  • Option A: one landing ellipse beyond the Séítah that is big and safe.
  • Option B: The landing ellipse for Flight 24 is within the Séítah, restricting its size, and needs a medium-distance flight, provided less margin and making it a little riskier than landing outside the Séítah.
  • Option C: The very first landing website (for Flight 24) needs just a brief flight, decreasing the quantity of prospective drift, and it stays within the fairly big landing ellipse of the previous flight, 23.

Keeping up With the Rover

Perseverance is making terrific development on its drive to the river delta, and it is necessary that Ingenuity keeps up to come to the delta prior to the rover does. This is for 2 factors: telecoms and security. Ingenuity just interacts with the helicopter base station on Perseverance, so it requires to remain close enough to have a great connection. For security, it is perfect if Ingenuity flies ahead of Perseverance to prevent ever needing to fly previous or near the rover, to lessen the threat of any close contact in a worst-case situation.

Balancing Risks

Let’s evaluation each of the elements above to see which alternative offers the very best set of compromises to stabilize threat:

Factors
Option RPMTime of SolDrift/ Landing SiteKeeping With Rover
A 2,537 (modification) N/A. Too hotNo landing in SéítahHave to wait
B 2,70010: 00 (no modification)Medium flight in Séítah;.

EDL hardware threat

On speed
C 2,537 (modification)09: 30 (brand-new!) A brief flight in SéítahOn speed

Which alternative would you pick?

As is frequently the case in Ingenuity operations, there is no apparent service that is the very best for all elements: Trade- offs need to be made based upon the readily available information and the judgment of staff member. In this case, the helicopter group chose to choose alternative C

Ingenuity Mars Helicopter Pilot's Logbook

This picture of the main pilot’s logbook for the Ingenuity Mars Helicopter flights– the “Nominal Pilot’s Logbook for Planets and Moons”– was taken at NASA’s Jet Propulsion Laboratory in Southern California on April 19, 2021, the day of Ingenuity’s very first historical flight. Pilot logbooks are utilized by pilots to offer a record of their flights, consisting of present and collected flight time, number and places of departures 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 as much as leave Séítah on flight 25.

Flight #: 24
Goals: Test flight at 2,537 rpm, 09: 30 LMST flight
Altitude: 10 meters
Time up: 69.5 seconds
Distance: 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 the other day– will send out Ingenuity 704 meters to the northwest (nearly 80 meters longer than the present record– Flight 9). The helicopter’s ground speed will have to do with 5.5 meters per 2nd (another record) and we anticipate 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 < period class ="glossaryLink" aria-describedby ="tt" data-cmtooltip ="<div class=glossaryItemTitle>NASA</div><div class=glossaryItemBody>Established in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. It&#039;s vision is &quot;To discover and expand knowledge for the benefit of humanity.&quot;</div>" data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]" > NASA ‘sJetPropulsionLaboratory