As detailed in our final weblog publish, for the primary time in our yearlong prolonged mission we had a lack of communications with Ingenuity from the downlink of Could 3 (Sol 427) and Could 4 (Sol 428). After every week of anomaly investigation, two sols devoted to information assortment, and the heroic efforts of the Perseverance and Ingenuity operations groups, I’m very comfortable to report that we now have reestablished dependable communications with Ingenuity. Based mostly on all accessible telemetry, the helicopter seems wholesome, and we now have resumed a modified type of operations. Assuming winter recommissioning actions full nominally, Ingenuity’s twenty ninth flight might happen within the subsequent few sols.
Telemetry from Ingenuity confirmed that the lack of communications was attributable to inadequate battery state-of-charge (SOC) going into the night time, which resulted in a reset of our mission clock. This day by day SOC deficit is more likely to persist at some stage in Martian winter (till September/October).
Challenges like these are to be anticipated: After a whole bunch of sols and dozens of flights past the 5 flights initially deliberate, the solar-powered helicopter is in uncharted terrain. We are actually working far outdoors our authentic design limits. Traditionally, Mars could be very difficult for spacecraft (notably solar-powered spacecraft). Every sol could possibly be Ingenuity’s final.
Under is a abstract of our anomaly investigation over the past two weeks, our elevated winter threat posture, and the attainable paths forward for Ingenuity throughout winter and past.
Sol 427 and 428 Lack of Communications
We’ve reached the purpose in Martian late fall/early winter at which Ingenuity can not assist the vitality calls for of nominal operations. Beginning on the night of Sol 426, we imagine Ingenuity began experiencing in a single day battery brownouts (drops within the battery’s voltage), which reset the electronics. As a result of seasonal lower in accessible photo voltaic vitality, will increase in airborne mud density, and the drop in temperatures, the vitality demand to maintain the electronics powered and heat all through the night time has surpassed Ingenuity’s accessible vitality finances.
Under is a plot of the environmental situations at Jezero Crater. The black line is a climatological mannequin of airborne mud density (known as “tau”) over a Martian 12 months, and the anticipated day by day insolation (quantity of Solar’s rays reaching the photo voltaic panel) illustrated within the inexperienced dotted line. We are actually within the a part of the Martian 12 months with peak tau, mixed with falling insolation. Not proven on this plot is the extra development of decrease common day by day temperatures, which additionally provides to Ingenuity’s vitality demand. We anticipate to be on this difficult winter vitality paradigm till round Sol 600, at which level we anticipate to return to being power-positive from sol to sol.
Whereas in winter, every night time we anticipate our battery SOC will fall low sufficient to the place:
- Chilly Biking Elements: Our heater thermostat can not hold the battery (and surrounding electronics) at their programmed setpoint (e.g. minus 13° F / minus 25 ° C). Consequently, we anticipate that Ingenuity’s electronics are reaching in a single day ambient temperatures of roughly minus 80 °C (minus 112 °F).
Affect 1: This chilly biking every night time presents a lifetime threat to our digital elements.
- Cleared Mission Clock: The battery can not assist our voltage regulators and mission clock. This nightly brownout resets (or clears) our mission clock.
Affect 2: Every morning when Ingenuity warms up, costs its drained battery, and makes an attempt to activate its laptop, it’s booting in response to a misaligned alarm schedule, which is out of synchronization with Perseverance.
When Perseverance tried communications with Ingenuity on the morning of sols 427 and 428, Ingenuity didn’t reply as a result of it was waking up on the unsuitable time. The staff reacted by uplinking a full-sol search exercise with the Helicopter Base Station (HBS) onboard Perseverance to try to speak with Ingenuity throughout one in every of its misaligned alarm widows, which succeeded.
Since Sol 429 and each sol since (apart from Sols 444 and 445, which didn’t comprise helicopter actions), we now have been in day by day contact with Ingenuity through the use of related morning search actions throughout what we imagine to be the most definitely instances when Ingenuity can be sufficiently charged to try booting its electronics. These morning search actions reprogram the helicopter’s mission clock every sol, which, at some stage in that sol, permits further scheduled actions to utilize the vitality that we do have accessible. At present, we attain sundown with ~68% SOC, with an estimated want of at the least 70% to maintain every little thing powered in a single day. Our 2% SOC deficit is predicted to develop to a 7% deficit as soon as we attain winter solstice (Sol 500 in July), at which level situations will begin to enhance.
All telemetry downlinked to date means that Ingenuity is wholesome, with no indicators of harm from the in a single day chilly cycles. This morning-search adopted by night actions is our new regular for the speedy future.
Winter Danger Posture
Our newest fashions counsel that no matter modifications to our in a single day thermostat technique, it will likely be extraordinarily difficult and even not possible to maintain our electronics core module (ECM) elements heat and inside their nominal temperatures in a single day. Though element failure has at all times been a threat that we now have carried since rover deployment, that threat is now magnified. ECM elements have been usually saved heat in a single day by our battery heater (usually set to five°, minus 4°, or minus 13°F, or minus 15°, minus 20°, or minus 25°C). We anticipate that ECM elements are actually thermal-cycling all the way down to the ambient in a single day temperatures of minus 112 °F (minus 80 °C). We do have restricted ECM element testing to counsel that choose elements might survive via the winter, however we can’t predict how your entire ECM will fare all through winter. Chilly-soaking electronics is believed to have brought about the top of the Alternative and Spirit Mars rover missions.
Winter Operations and Past
Given our elevated threat posture, our focus within the final a number of sols has been to prioritize information downlink from Ingenuity to the HBS. We’ve a handful of Heli-to-HBS switch actions left earlier than all distinctive information are copied from Ingenuity to the HBS. Particularly, we’re copying flight efficiency logs, electronics logs, and high-resolution shade photographs from the final eight flights which can be nonetheless onboard Ingenuity.
In any case important logs are transferred, the staff will proceed with a recommissioning section throughout which we’ll reestablish Ingenuity’s flight-readiness given our ongoing in a single day cold-cycling. Like throughout the expertise demonstration section, we’ll carry out a high-speed spin earlier than continuing to flight. Ought to Ingenuity obtain a clear invoice of well being, we’d be able to execute a brief sortie to the southwest in Flight 29. This flight will enhance our radio hyperlink for roughly the subsequent 4 to 6 months whereas Perseverance samples on the river delta.
Within the meantime, the Ingenuity flight software program staff will probably be getting ready a collection of upgrades to allow superior navigation options. These new capabilities will assist Ingenuity ascend the river delta and proceed its missions as a ahead scout for Perseverance previous winter.
The Perseverance and Ingenuity operations groups have executed a rare job in reestablishing dependable communications with Ingenuity. As of Sol 446, the staff has transferred ~3,500 megabits (Mb) of information from Ingenuity to the HBS on Perseverance. There are roughly ~400 Mb of information remaining on Ingenuity of noncritical logs and pictures that will probably be transferred opportunistically, whereas the staff forges forward with recommissioning efforts this week. If the telecom hyperlink between Perseverance and Ingenuity stays secure, and Ingenuity receives a clear invoice of well being, we hope to execute Flight 29 within the subsequent a number of sols.