Tense Times for ESA ExoMars and NASA Juno Teams

The European Space Agency (ESA) was hoping to announce its first successful landing on Mars today, but the fate of its Schiaparelli lander is unknown at this time.  Meanwhile NASA’s Juno spacecraft, which arrived at Jupiter in July, has an engine problem and, separately, went into safe mode last night. Both teams remain optimistic, but it will a tense wait until they have answers to the fate of these two spacecraft.

On the good news front, Schiaparelli is part of ESA’s ExoMars 2016 program and traveled to Mars with the ExoMars Trace Gas Orbiter (TGO).  TGO successfully went into orbit around Mars today.

Schiaparelli is a small demonstration spacecraft to test entry, descent and landing technologies for a Russian lander and ESA rover currently planned for launch in 2020 (delayed from 2018). ESA sometimes refers to Schiaparelli as EDM — entry, descent, and landing demonstrator module.

Artist’s illustration of Schiaparelli landing on Mars.  Image credit:  ESA

Schiaparelli and TGO separated from each other three days ago to finish their journeys on their own with Schiaparelli headed for the surface and TGO to orbit. 

TGO joins five other spacecraft currently operating in Mars orbit today:  ESA’s Mars Express, India’s Mars Orbiter Mission (MOM), and three from NASA — Mars Reconnaissance Orbiter (MRO), Mars Odyssey, and MAVEN.  NASA also has two rovers operating on the surface of Mars — Opportunity and Curiosity.  NASA is the only space agency to land spacecraft on Mars that can be counted as unequivocal successes (Viking 1, Viking 2, Mars Pathfinder + Sojourner, Spirit, Opportunity, Phoenix, and Curiosity).  The Soviet Union sent four landers (Mars 2, Mars 3, Mars 6 and Mars 7), but only Mars 3 sent back a signal after landing and it lasted for less than 20 seconds.  Britain’s Beagle 2 lander was sent to Mars along with Mars Express in 2003, but it was never heard from after separation.  It was recently located on the surface in imagery from MRO showing that it landed in a partially deployed configuration that prevented communication.

During its descent, Schiaparelli was sending data to Mars Express and emitting a beacon that allowed its
progress to be tracked by a telescope on Earth, India’s Giant
Metrewave Radio Telescope.  ESA knows it successfully entered the Martian atmosphere and deployed its parachutes.  Next, the “backshell” heat shield was to release, followed by retrorocket braking, and a final fall from a height of 2 meters (6 feet) protected by a crushable structure.  At some point in that sequence, the signal was lost.

If it reached the surface and is still functioning, its batteries will allow it to transmit signals for 3-7 days.  Mars Express, MRO and MAVEN will be listening.

ESA will hold a pre-scheduled news conference tomorrow, October 20, to discuss Schiaparelli and TGO from 4:00-5:00 am Eastern Daylight Time (EDT), which is 10:00-11:00 am local time at the European Space Operations Centre (ESOC) in Darmstadt, Germany. 

The mixed news from ESA — good for TGO, uncertain for Schiaparelli — was quickly followed by worrisome news about a completely different deep space probe, NASA’s Juno.  NASA launched Juno in 2011 and the solar powered spacecraft entered orbit around Jupiter on July 4, 2016. 

Artist’s illustration of NASA’s Juno spacecraft and its science instruments.  Image credit: NASA/JPL.

The initial orbit is highly elliptical, with a period of 53.5 days. The plan was to circularize it into a 14-day orbit as close as 5,000 kilometers (3,100 miles) above Jupiter’s cloud tops for science observations.

An engine burn to change the orbit was planned for today (October 19), but an anomaly was detected in a pair of helium check valves in the engine.  Juno project manager at the Jet Propulsion Laboratory (JPL), Rick Nybakken, said the valves should have opened in a few seconds, but took several minutes instead for unexplained reasons.  After consulting with spacecraft manufacturer Lockheed Martin, NASA decided to postpone the engine firing until the next opportunity on December 19.

The spacecraft already was on a path to come close to Jupiter’s cloud-tops, although most of the science instruments were to be off during that pass.  Instead, the decision was made to turn all of them on to gather whatever data was possible.

However, Juno Principal Investigator Scott Bolton said a media briefing today that as Juno neared that close approach (perijove) last night, the spacecraft went into safe mode.

Spacecraft are designed to go into safe mode when an anomaly occurs and the goal is to protect the spacecraft systems and instruments while awaiting instructions from Earth.  In safe mode, all non-essential systems, including science instruments, are turned off.  Therefore no science data was acquired.

It is not all that uncommon for spacecraft to go into safe mode.  Often the problem is diagnosed by ground controllers who then upload new instructions and the mission continues.  One cannot be assured of that outcome, however.

As it is, Juno remains in orbit.  Assuming whatever caused safe mode to engage can be resolved, Bolton said today that scientists can obtain the science data they need even if the engine burn cannot be made and the orbital period is not reduced to 14 days.  It simply will take longer.

The twin anomalies underscore the increasingly trite, but nevertheless true, expression that “space is hard.”